experiment chlorophyll is necessary for photosynthesis

Photosynthesis: Step by Step Guide (Experiments Included)

• May 10, 2021
• Science Facts

Have you ever wondered how plants eat or drink? How do they get energy? Well, just like we need food and water to live, plants do too. However, unlike humans, they make their food from sunlight and carbon dioxide! How? They do it by a process known as photosynthesis.

This article will explore photosynthesis and learn the difference between chemical compounds like carbon dioxide, sugar, and energy. We’ll look at how plants store energy as starch.

What is Photosynthesis?

Plants and a few other organisms “put together” organic matter from carbon dioxide and water, using the energy of sunlight to power the process.

It is derived from the Greek word, ‘photo’ meaning light, and ‘synthesis’ meaning putting together.

Plants are the basis for almost all life on Earth: animals (including humans) either eat plants or eat other animals that eat plants. Also, plants provide us with oxygen.

Ingredients for Photosynthesis

When you’re hungry, you may ask your mom for food. However, plants can’t do that. So, they use the nutrients and water present in the soil, light energy from the sun, and Carbon Dioxide from the air to form a compound called glucose.

Glucose is a sugar that plants need to survive on. It’s their form of food, like you eat rice or noodles, they consume glucose for energy!

Why is photosynthesis important for life?

All living organisms on Earth are dependent on photosynthesis. Plants would not survive without photosynthesis, and thus, neither would animals that depend on the plants for food. Autotrophs, like plants and algae, produce glucose through photosynthesis.

Animals cannot do this. Therefore, they eat plants and use this energy in the process of cellular respiration. Otherwise, they get their energy through organisms that feed off autotrophs.

Organisms, who cannot synthesize their own food independently, are known as heterotrophs. These include:

• Herbivores such as cows and deer, who eat plants.
• Carnivores such as lions and wolves, who eat other animals.
• Omnivores such as humans and bears, who eat both plants and animals.

So, the plants are the start of all food chains and sustain all organisms. For example:

How Green Plants Make their Food

Green plants carry out photosynthesis by using a special green pigment called chlorophyll.

The chlorophyll inside the leaves captures the energy from sunlight, combines carbon dioxide with water, and makes sugar (glucose).

The plant transports this simple sugar to every part of its body. All in all, the steps involved in this process are:

●     Absorption of Light Energy

Have you seen the sunflower plant moving towards the sun when kept in the shade? This is because the trapping of light energy is key to the process of photosynthesis.

Without sunlight, there will be no energy to make food. So, the first and most crucial step is that the chlorophyll in green plants absorbs sunlight.

●     Conversion of Light Energy to Chemical Energy

Plants cannot directly utilize sunlight. So, they convert it into ATP (Adenosine TriPhosphate), a form of chemical energy.

When sunlight is absorbed, the chlorophyll atoms become photochemically excited and lose an electron, thus undergoing a process known as oxidation.

This electron is then used to convert non-usable sources of energy such as ADP and NADP+ compounds to primary chemical energy sources such as ATP and NADPH.

Then, to replace the electron lost in by the photochemically excited chlorophyll, the water absorbed by the plants splits into its two components- Hydrogen and water.

Since, hydrogen has only one electron, it breaks into protons and electrons, and then it uses the electron to bring the chlorophyll back to its original state.

This completes the process of conversion to immediate chemical energy, which is used to form glucose.

●     Conversion of Carbon Dioxide to Glucose

When the water splits into hydrogen and oxygen, it undergoes an oxidation reaction as it loses Hydrogen. Similarly, carbon dioxide undergoes a reduction reaction as it gains electrons. So, as a result, water is converted to oxygen gas, and carbon dioxide is converted to glucose.

This is known as a redox reaction. Observe the following diagram to understand it better. A is water converting to oxygen, and B is Carbon Dioxide converting to simple carbohydrates (glucose) in photosynthesis.

Photosynthesis Chemical Reaction in Words

Now that you understand how reactions occur and the resultant products are formed, it’s essential to know how to put them into words. One glance over this summarises everything explained above- that is what a chemical formula does!

The above equation represents the following chain of processes:

• Sunlight coming in contact with the chlorophyll in the thylakoid membrane of the chloroplast.
• Chlorophyll molecules get excited, and water splits into hydrogen and oxygen.
• Electrons from hydrogen (from the water) combine with Carbon Dioxide. This process is known as reduction, and glucose is formed.
• Oxygen is a by-product. Since it is of no use, it is excreted or thrown out from the cell.

Chemical Reaction Formula for Photosynthesis

Physical chemistry can be tricky because there are so many terms and factors to keep track of. So, you must understand these simple equations before you are allowed to work with natural chemicals.

A chemical equation is simply a list of all the chemical reactants and products and their relative quantities at its heart.

Chemicals are complex systems that can exist in very different states. Nonetheless, they can easily be represented as simple lists of these elements and their numbers. So, one can describe photosynthesis as:

However, this isn’t a balanced equation. According to the Law of Conservation of Mass, mass can neither  be created nor destroyed. Count the number of Carbon atoms on the reactant side (the left side.)

Now, count the number of Carbons on the product side (the right side.) One carbon can’t magically turn into six carbons, right? So, to rectify it, form a balanced equation of the reaction.

6CO 2  +  6H 2 O  →  C 6 H 12 O 6  + 6O 2

Note that the number before the Carbon Dioxide, Water, and Oxygen represents the individual compound molecules.

Therefore, the number of Carbons on both sides of the equation is 6, oxygens are 18 (twelve from Carbon Dioxide and six from water), and hydrogens is 12.

Since the total number of atoms from each element are equal on the reactant and product side, this is now a balanced equation!

What does photosynthesis produce?

The release of chemical energy due to the formation of ATP and NADPH compounds, and the synthesis of oxygen, are light-dependent reactions.

However, a series of light-independent reactions- constituting the Calvin Cycle, actually form the food.

How is glucose formed? Does excess glucose undergo some changes? Read to find out.

The Calvin Cycle

This cycle consists of a series of light-independent reactions- which means they do not directly require sunlight to work. So, they can take place at night or day. They include:

• Carbon Fixation

One of the most critical functions of carbon is that it can be converted from Inorganic compounds (carbon dioxide in the atmosphere) to organic compounds such as G3P and glucose. This process is known as Carbon fixation.

Before glucose is formed in plants, first, they synthesize an intermediate compound known as glyceraldehyde-3-phosphate. Here, the carbon from carbon dioxide is used to manufacture G3P- C 3 H 7 O 6 – a three-carbon molecule.

• Formation of glucose and other carbohydrates

G3P is a raw material used in the formation of glucose. The Calvin Cycle involves 18 ATP and 12 NADPH molecules to synthesize one molecule of C 6 H 12 O 6 (glucose).

It’s also used to form starch, sucrose, and cellulose, depending on the plant’s needs.

Starch also plays a significant role in nutrition in animals. When animals eat plants, their digestive processes break down the starch present to form glucose again.

This glucose is then used as a source of energy for metabolic processes. So, the starch in animals sustains the plant, the herbivore, the carnivore, and the decomposer.

What happens to excess carbohydrates which are not utilized immediately?

When carbohydrates are not utilized immediately, they are stored in various parts of the plant’s body in the form of starch. It’s a polysaccharide- a compound formed by binding a chain of

glucose molecules together. It stores a significant amount of energy for cell metabolism.

The stored starch gives the cell energy to perform all the processes necessary for its survival. Any unused energy is stored as a fat deposit.

Factors that affect the Rate of Photosynthesis

Just as human beings need various nutrients to survive, plants need several environmental conditions for photosynthesis to happen appropriately.

Even if one of the optimum requirements is affected, so is the rate of photosynthesis in plants. So, photosynthesis is based upon several factors. They include:

1. Light Intensity

If the light energy provided to plants is too low, the plants cannot photosynthesize properly. At the optimum amount of sunlight, the plant makes the food faster.

However, the speed slows down again if the light energy given increases above the plant’s maximum tolerance level. In winter or colder areas, the rate decreases and falls to zero at night.

Therefore, light intensity plays a vital role in the rate of photosynthesis.

2. Carbon Dioxide Concentration

Up to the maximum tolerance of carbon dioxide in plants, increasing the amount of exposure to gas maximizes the rate of photosynthesis.

After that, increasing carbon dioxide concentration in the air will not affect the plants.

This is because the plants can only intake a certain amount of carbon dioxide to convert into glucose. So, one can represent the rate of photosynthesis as:

3. Temperature

In photosynthesis, a lot of enzymes need to work to fulfill the requirement of energy. However, they can only work at the optimum temperature.

Raising the temperature increases kinetic energy. So the molecules start moving at a higher speed and collide faster, increasing the rate of photosynthesis.

Like in all the other cases, very high temperature is just as bad as very high temperature. In both cases, the enzymes will gradually be destroyed, and the photosynthesis will eventually stop.

Energy Result of Photosynthesis

As we have seen, there are two types of reactions in photosynthesis- the light reactions and the dark reactions.

The light-dependent processes synthesize energy in the form of ATP and NADPH.

The dark reaction uses already made energy to manufacture glucose and other carbohydrates, which are further used in metabolic processes required for the plant’s survival.

So, let’s look at these chemical processes from the perspective of energy used and released.

1. Light-Dependant Reactions

Sunlight gives plants the energy to photochemically excite the chlorophyll, which leads to the splitting of water. This allows the conversion of ADP and NADP+ molecules into ATP and NADPH, which can be used in other processes.

2H 2 O + 2 NADP+ + 3 ADP + 3 P i + Light Energy → 2 NADPH + 2 H + + 3 ATP + O 2

2. Dark Reactions

The energy synthesized in the light-dependant reactions is used to reduce carbon dioxide and form glucose. The carbon fixation process takes place here; that is, the carbon gets converted from an inorganic form to an organic compound.

3 CO 2 + 9 ATP + 6 NADPH + 6 H + → C 3 H 6 O 3 -phosphate + 9 ADP + 8 P i + 6 NADP+ + 3 H 2 O

Further, it takes 18 ATP and 12 NADPH compounds to convert the G3P molecule into glucose.

3. Respiration

When the glucose molecule is formed, the plant performs a process known as respiration. The glucose molecule is combined with oxygen and breaks down into carbon dioxide and water.

In this process, a considerable amount of energy is released.

This energy is used to help the plant perform all its metabolic functions needed to survive. It’s a constant cycle, which the following diagram can explain:

How Do Plants Absorb Energy From the Sun?

As we’ve seen, photosynthesis cannot take place without energy from the Sun. So, the plants have a mechanism set in place to observe light energy.

This is done by the pigment chlorophyll, present in chloroplasts, present in the cells of green leaves of plants. Let’s look at the structure of the chloroplast to help you understand.

Sunlight has a lot of components. All the parts have a certain amount of energy. The main components of sunlight used by the plants are blue, red, and green.

With the thylakoid’s help in the chloroplasts (observe the diagram), which contain chlorophyll, the light energy is absorbed—specifically, the blue and red components.

The green is reflected into the environment. Now, can you answer the question, ‘why do plants look green?’ It’s because of the reflected green light!

Look at the diagram again. Can you see that the thylakoids are present in stacks? These are known as grana, which is the site of converting light energy to chemical energy!

The aqueous fluid surrounding them is known as the stroma. The transformation is completed here.

Where Do Plants Get the Carbon Dioxide Needed?

Just like we breathe through our noses, plants have millions of tiny openings on the surface of their leaves. These are known as stomata.

These stomata pores are protected by a pair of guard cells, which regulate the opening and closing of these pores.

When they do open, the atmosphere’s carbon dioxide flows through the stomata, from where it’s sent to the chloroplast- the site of photosynthesis.

Various environmental stimuli control the guard cells. When all the optimum conditions (water and sunlight) are present, the guard cells swell and curve.

This movement is because it takes in water through a process known as osmosis, which triggers the opening of the guard cells and allows the carbon dioxide to enter.

At night, when there’s no light or the plant wants to conserve water, the stomatal pores lose water through osmosis.

This causes the stomata to become straight, and once again, they are closed. One can also show this process with a diagram:

Why Do Plants Produce Glucose?

Now that we know how plants produce glucose, it’s essential to understand why? Why are these six-carbon molecules so crucial for life? Let’s find out.

1.   Storage

Sun is essential for the release of energy. Therefore, during the winter or the night, when there is not enough sunlight, the plant uses the glucose stored in various parts of the plant.

The process of respiration takes place, and the energy for metabolic processes is released without the presence of the Sun.

Without the stored glucose, the plant would’ve died during the night or the long winters.

2.   Seed Formation and Flowering

Glucose is stored in the seed in the structures known as cotyledons. They allow the seedling to stay alive even deep inside the soil, without leaving to synthesize food.

Furthermore, they provide the energy required for germination and encourage leaf growth. Moreover, glucose stored in some plants also helps in the flowering of some unique plants.

Hyacinths, daffodils, and tulips are some plants that depend upon the glucose to flower. These beautiful flowers attract pollinating agents towards them, which helps the plant to reproduce.

3.   Formation of other nutrients

Several glucose molecules combine to form starch- a complex carbohydrate present in plants.

They also react with nitrates present in the soil to form amino acids, which eventually form proteins. Carbohydrates and proteins are major nutrients for both humans and plants.

Thus, glucose plays an essential role in nutrition.

4.   Circadian Rhythms

Plants need to maintain their body temperature and stay in tune with the day-and-night cycles. So, the formation of glucose in the day and respiration during the night helps the plant to maintain its daily clock and energy reserves.

How Do Plants Eat?

Now, since glucose has been synthesized, the next step is transportation and utilization. So, the sugar is transported through various parts of the plant, where it’s needed.

A vascular tissue known as phloem accomplishes this movement.

Then, similar to humans, cellular respiration takes place in plants as well. Plants convert glucose and other sugars, in the presence of oxygen, into energy.

Carbon Dioxide and water are by-products of this process. Just like you need the energy to breathe, walk, run, study, and survive- plants need it for:

• Growth processes
• Making more food
• Other cellular maintenance functions

So, just like we eat our food, plants synthesize glucose and other carbohydrates and convert them to energy!

Since it doesn’t require light energy, it can take place during the day or the night. So, the plant doesn’t starve.

Role of Leaves in Photosynthesis

Leaves are sites of photosynthesis. So, they have a series of features that help them perform their function efficiently. Leaves have adapted to the environment in various ways, such as:

• Large Surface Area

Broader leaves can absorb more light energy and thus, increase the surface area for photosynthesis.

• Shorter Width

The leaves are thin so that the absorbed carbon dioxide has to travel a short distance to reach the chloroplasts (sites of photosynthesis).

Otherwise, a considerable amount of energy would have to be spent on CO 2 transport, which the plant couldn’t afford.

Observe the given diagram. Have you ever touched a vein? Is it harder or softer than the surface of the leaf?

Veins in the leaf provide support, and transport food, water, and minerals as well. They are extensions of the vascular bundles- Xylem (which transports water and minerals) and Phloem (which transports synthesized food.)

• Chloroplasts

Of course, the main adaptation of leaves is the chloroplasts with the pigment chlorophyll inside of them.

These absorb light energy, then convert it into a usable form- chemical energy. Without these small components, photosynthesis wouldn’t take place, and life wouldn’t exist.

Role of Water in Photosynthesis

• Converts NADP+ to NADPH

When photosynthesis takes place, water splits into its components- hydrogen and oxygen. The H + ions are then used to reduce the NADP molecules to NADPH molecules, which can be used to synthesize glucose. It also eventually leads to the formation of ATP- the energy currency of the cell.

• Provides Oxygen

The oxygen, which is obtained from the splitting of water, is released into the atmosphere and used by animals and humans for respiration. Most living organisms on the face of this planet need this oxygen released by plants to survive.

• Reduces chlorophyll

When the sunlight hits chlorophyll, it becomes photochemically excited, loses an electron, and undergoes oxidation. So, to return to its original state- water donates an electron and acts as a reducing agent.

Do All Plants Photosynthesize?

We sometimes look at photosynthesis as the defining characteristic in plants. However, there are some plants, which do not have chlorophyll and do not perform photosynthesis.

Instead, they choose to get their energy by stealing from their neighboring plants. These are known as holoparasites.

They are entirely dependent on their host and obtain nutrients required from living off of them. So, they do not need to perform photosynthesis, but the host eventually dies due to the continuous stealing of nutrients by the parasites.

Photosynthesis in Oceans

Have you ever wondered how marine plants perform photosynthesis in seas or oceans, where there is a limited amount of light and carbon dioxide?

So, most marine plants stay near the surface of the water to fulfil their requirements. Furthermore, chemical molecules known as phycobiliproteins are present in some tiny organisms known as cyanobacteria, which absorb the light available in the ocean and convert it into light energy that the chlorophyll can use.

Marine organisms release half the Earth’s oxygen, even though their biomass is less in magnitude than bulky terrestrial organisms. They reproduce faster, a new generation every day or two! More significant numbers help in the process of photosynthesis as well.

Science Experiments that Prove Photosynthesis in Plants

Experiments on photosynthesis in plants are fascinating. Children will soon find out that there is no need to fear biology because it’s been fun all along. The four experiments on photosynthesis in this article will create joy and excitement among children who love science.

Experiment #1

Aim: To prove that plants need sunlight to grow

Materials Required:  A potted plant, a boiling tube, 70% alcohol, iodine solution, bunsen burner, forceps, beaker, water, dropper, black paper, and a petri dish.

• Place the potted plant in the dark for about 72 hours. This inhibits the process of photosynthesis, and all the leaves become free of starch.
• After three days, take a strip of black paper and put it on a section of one of the potted plant leaves on both sides.
• Put the plant in the sunlight for a few hours.
• Detach the partially covered leaf from the plant and remove the black covering.
• Boil this leaf in a 70% alcohol solution using a bunsen burner until it loses its green color. This is because we are removing chlorophyll.
• Wash the leaf with water and add iodine solution with a dropper.

Observation: The whole leaf turns blue-black, except for the section covered with black paper. This is because iodine changes color in the presence of starch. However, since the covered portion did not come in contact with the sun, it didn’t photosynthesize, and thus, starch wasn’t present.

Conclusion: We realize that plants need sunlight to photosynthesize and manufacture food.

Experiment #2

Aim: To prove that Carbon Dioxide is necessary for photosynthesis.

Materials Required: A healthy potted plant with long and narrow leaves, Potassium Hydroxide solution, 70% alcohol solution, a jar with a large mouth and cork, grease or vaseline, bunsen burner, petri dish.

• Open the jar and pour in a couple of millimeters of potassium hydroxide. This absorbs the carbon dioxide gas present in the atmosphere.
• After three days, choose a long and narrow leaf and put half of it in the jar.
• Seal the jar and make sure it’s airtight. Put grease on the corners of the cork.
• Detach the leaf from the plant and boil it in a 70% alcohol solution using a bunsen burner until it loses its green color.

Observation: The half of the leaf exposed to the air turns blue-black due to the presence of starch. The other half was deprived of CO 2, and therefore, it didn’t form starch.

Conclusion: Carbon Dioxide gas is necessary for the process of photosynthesis.

Experiment #3

Aim:  To prove that oxygen gas is released during photosynthesis.

Materials Required: A large beaker filled with water, a short transparent funnel, pondweed, or an aquatic plant such as Hydrilla, and a test tube.

• Place a few twigs of the aquatic plant into the transparent funnel.
• Immerse the funnel into the beaker full of water.
• Now, fill the test tube until it’s almost overflowing with water. Cover the mouth of the tube with your thumb.
• Invert the test tube and put it over the funnel, as shown in the diagram.
• Place the setup in the sunlight.
• Observe until the test tube is completely filled with gas.
• Take out the test tube carefully without letting the gas out.
• Bring a burning splinter in contact with the gas. Observe.

Observations: After a few hours in sunlight, there are bubbles in the water, proving the presence of a gas. The burning splint reignites with a pop sound when it’s brought in contact with the test tube- confirming the presence of oxygen.

Conclusion: Photosynthesis releases oxygen.

The Conclusion

Next time you see a tree, stop to hug it. It does a lot of work to make sure that we, humans can live by being one of our resources.

Knowing how photosynthesis works and how it nourishes all the animals in the world should help us realize that plants give us life.

Learning about photosynthesis also explains what makes plants unique. With the information and activities in the article, you now understand what photosynthesis is; and what it means to the environment.

One comment

Dear Angela, Great article on photosynthesis. I could comprehend it easily. It’s explanation method was superb.

Leave a Reply Cancel Reply

Your email address will not be published. Required fields are marked *

Name  *

Email  *

Add Comment  *

Save my name, email, and website in this browser for the next time I comment.

Post Comment

This page has been archived and is no longer updated

Photosynthetic Cells

Cells get nutrients from their environment, but where do those nutrients come from? Virtually all organic material on Earth has been produced by cells that convert energy from the Sun into energy-containing macromolecules. This process, called photosynthesis, is essential to the global carbon cycle and organisms that conduct photosynthesis represent the lowest level in most food chains (Figure 1).

What Is Photosynthesis? Why Is it Important?

Most living things depend on photosynthetic cells to manufacture the complex organic molecules they require as a source of energy. Photosynthetic cells are quite diverse and include cells found in green plants, phytoplankton, and cyanobacteria. During the process of photosynthesis, cells use carbon dioxide and energy from the Sun to make sugar molecules and oxygen. These sugar molecules are the basis for more complex molecules made by the photosynthetic cell, such as glucose. Then, via respiration processes, cells use oxygen and glucose to synthesize energy-rich carrier molecules, such as ATP, and carbon dioxide is produced as a waste product. Therefore, the synthesis of glucose and its breakdown by cells are opposing processes.

However, photosynthesis doesn't just drive the carbon cycle — it also creates the oxygen necessary for respiring organisms. Interestingly, although green plants contribute much of the oxygen in the air we breathe, phytoplankton and cyanobacteria in the world's oceans are thought to produce between one-third and one-half of atmospheric oxygen on Earth.

What Cells and Organelles Are Involved in Photosynthesis?

Chlorophyll A is the major pigment used in photosynthesis, but there are several types of chlorophyll and numerous other pigments that respond to light, including red, brown, and blue pigments. These other pigments may help channel light energy to chlorophyll A or protect the cell from photo-damage. For example, the photosynthetic protists called dinoflagellates, which are responsible for the "red tides" that often prompt warnings against eating shellfish, contain a variety of light-sensitive pigments, including both chlorophyll and the red pigments responsible for their dramatic coloration.

What Are the Steps of Photosynthesis?

Photosynthesis consists of both light-dependent reactions and light-independent reactions . In plants, the so-called "light" reactions occur within the chloroplast thylakoids, where the aforementioned chlorophyll pigments reside. When light energy reaches the pigment molecules, it energizes the electrons within them, and these electrons are shunted to an electron transport chain in the thylakoid membrane. Every step in the electron transport chain then brings each electron to a lower energy state and harnesses its energy by producing ATP and NADPH. Meanwhile, each chlorophyll molecule replaces its lost electron with an electron from water; this process essentially splits water molecules to produce oxygen (Figure 5).

Once the light reactions have occurred, the light-independent or "dark" reactions take place in the chloroplast stroma. During this process, also known as carbon fixation, energy from the ATP and NADPH molecules generated by the light reactions drives a chemical pathway that uses the carbon in carbon dioxide (from the atmosphere) to build a three-carbon sugar called glyceraldehyde-3-phosphate (G3P). Cells then use G3P to build a wide variety of other sugars (such as glucose) and organic molecules. Many of these interconversions occur outside the chloroplast, following the transport of G3P from the stroma. The products of these reactions are then transported to other parts of the cell, including the mitochondria, where they are broken down to make more energy carrier molecules to satisfy the metabolic demands of the cell. In plants, some sugar molecules are stored as sucrose or starch.

This page appears in the following eBook

Topic rooms within Cell Biology

Within this Subject (25)

• Basic (25)

Other Topic Rooms

• Gene Inheritance and Transmission
• Gene Expression and Regulation
• Nucleic Acid Structure and Function
• Chromosomes and Cytogenetics
• Evolutionary Genetics
• Population and Quantitative Genetics
• Genes and Disease
• Genetics and Society
• Cell Origins and Metabolism
• Proteins and Gene Expression
• Subcellular Compartments
• Cell Communication
• Cell Cycle and Cell Division

© 2014 Nature Education

• Press Room |
• Terms of Use |
• Privacy Notice |

Practical Biology

A collection of experiments that demonstrate biological concepts and processes.

Observing earthworm locomotion

Practical Work for Learning

Published experiments

Investigating the light dependent reaction in photosynthesis.

It is fairly easy to show that plants produce oxygen and starch in photosynthesis . At age 14–16 students may have collected the gas given off by pond weed (for example Elodea ) and tested leaves for starch.

It is not quite so easy to demonstrate the other reactions in photosynthesis. For the reduction of carbon dioxide to carbohydrate there must be a source of electrons . In the cell, NADP is the electron acceptor which is reduced in the light-dependent reactions, and which provides electrons and hydrogen for the light-independent reactions.

In this investigation, DCPIP (2,6-dichlorophenol-indophenol), a blue dye, acts as an electron acceptor and becomes colourless when reduced, allowing any reducing agent produced by the chloroplasts to be detected.

Lesson organisation

This investigation depends on working quickly and keeping everything cool. Your students will need to understand all the instructions in advance to be sure that they know what they are doing.

Apparatus and Chemicals

Per student or group of students:.

Centrifuge – with RCF between 1500 and 1800g

Centrifuge tubes

Fresh green spinach, lettuce or cabbage, 3 leaves (discard the midribs)

Cold pestle and mortar (or blender or food mixer) which has been kept in a freezer compartment for 15–30 minutes (if left too long the extract will freeze)

Muslin or fine nylon mesh

Filter funnel

Ice-water-salt bath

Glass rod or Pasteur pipette

Measuring cylinder, 20 cm 3

Beaker, 100 cm 3

Pipettes, 5 cm 3 and 1 cm 3

Bench lamp with 100 W bulb

Test tubes, 5

Boiling tube

Pipette for 5 cm 3

Pipette for 0.5 cm 3

Pipette filler

Waterproof pen to label tubes

Colorimeter and tubes or light sensor and data logger

0.05 M phosphate buffer solution, pH 7.0: Store in a refrigerator at 0–4 °C ( Note 1 ).

Isolation medium (sucrose and KCl in phosphate buffer): Store in a refrigerator at 0–4 °C ( Note 2 ).

Potassium chloride (Low Hazard) ( Note 3 ).

DCPIP solution (Low Hazard): (1 x 10 - 4 M approx.) ( Note 4 )

Health & Safety and Technical notes

Although DCPIP presents minimal hazard apart from staining, it is best to avoid skin contact in case prolonged contact with the dye causes sensitisation. Do not handle electric light bulbs with wet hands. All solutions used are low hazard – refer to relevant CLEAPSS Hazcards and Recipe cards for more information.

Read our standard health & safety guidance

1 0.05 M phosphate buffer solution, pH 7.0. Na 2 HPO 4 .12H 2 O, 4.48 g (0.025 M) KH 2 PO 4 , 1.70 g (0.025 M). Make up to 500 cm 3 with distilled water and store in a refrigerator at 0–4 °C. Low hazard – refer to CLEAPSS Hazcard 72.

2 Isolation medium. Sucrose 34.23 g (0.4 M) KCl 0.19 g (0.01 M). Dissolve in phosphate buffer solution (pH 7.0) at room temperature and make up to 250 cm 3 with the buffer solution. Store in a refrigerator at 0–4 °C. Low hazard – refer to CLEAPSS Hazcard 40C.

3 Potassium chloride 0.05 M. Dissolve 0.93 g in phosphate buffer solution at room temperature and make up to 250 cm 3 . Store in a refrigerator at 0–4 °C. Use at room temperature.(Note that Potassium chloride is a cofactor for the Hill reaction.) Refer to CLEAPSS Hazcard 47B and Recipe card 51.

4 DCPIP solution DCPIP 0.007–0.01 g, made up to 100 cm 3 with phosphate buffer. Refer to CLEAPSS Hazcard 32 and Recipe card 46.

Keep solutions and apparatus cold during the extraction procedure, steps 1–8, to preserve enzyme activity. Carry out the extraction as quickly as possible.

Preparation

a Cut three small green spinach, lettuce or cabbage leaves into small pieces with scissors, but discard the tough midribs and leaf stalks. Place in a cold mortar or blender containing 20 cm 3 of cold isolation medium. (Scale up quantities for blender if necessary.)

b Grind vigorously and rapidly (or blend for about 10 seconds).

c Place four layers of muslin or nylon in a funnel and wet with cold isolation medium.

d Filter the mixture through the funnel into the beaker and pour the filtrate into pre-cooled centrifuge tubes supported in an ice-water-salt bath. Gather the edges of the muslin, wring thoroughly into the beaker, and add filtrate to the centrifuge tubes.

e Check that each centrifuge tube contains about the same volume of filtrate.

f Centrifuge the tubes for sufficient time to get a small pellet of chloroplasts. (10 minutes at high speed should be sufficient.)

g Pour off the liquid (supernatant) into a boiling tube being careful not to lose the pellet. Re-suspend the pellet with about 2 cm 3 of isolation medium, using a glass rod. Squirting in and out of a Pasteur pipette five or six times gives a uniform suspension.

h Store this leaf extract in an ice-water-salt bath and use as soon as possible.

Investigation using the chloroplasts

Read all the instructions before you start. Use the DCPIP solution at room temperature.

i Set up 5 labelled tubes as follows.

j When the DCPIP is added to the extract, shake the tube and note the time. Place tubes 1, 2 and 4 about 12–15 cm from a bright light (100 W). Place tube 3 in darkness.

k Time how long it takes to decolourise the DCPIP in each tube. If the extract is so active that it decolourises within seconds of mixing, dilute it 1:5 with isolation medium and try again.

Teaching notes

Traditionally the production of oxygen and starch are used as evidence for photosynthesis. The light-dependent reactions produce a reducing agent. This normally reduces NADP, but in this experiment the electrons are accepted by the blue dye DCPIP. Reduced DCPIP is colourless. The loss of colour in the DCPIP is due to reducing agent produced by light-dependent reactions in the extracted chloroplasts.

Students must develop a clear understanding of the link between the light-dependent and light-independent reactions to be able to interpret the results. Robert Hill originally completed this investigation in 1938; he concluded that water had been split into hydrogen and oxygen. This is now known as the Hill reaction.

You can examine a drop of the sediment extract with a microscope under high power to see chloroplasts. There will be fewer chloroplasts in the supernatant – which decolourises the DCPIP more slowly, reinforcing the idea that the reduction is the result of chloroplast activity.

Sample results

Using a bench centrifuge

The experimental procedure was followed. A standard lab centrifuge was used to spin down the chloroplasts (Clifton NE 010GT/I) at 2650 RPM, 95 X g for 10 minutes.

The experiment was started within 5 minutes of preparing the chloroplasts. The reaction was followed using an EEL colorimeter with a red filter – readings taken every minute.

Tube 3 (incubated in the dark) gave a reading of 5.4 absorption units after 20 minutes. Tube 2 (DCPIP with no leaf extract) was 6.2 absorption units.

Using a micro-centrifuge

The experiment was repeated using a micro-centrifuge.

Tube 3 (incubated in the dark) gave a reading of 4.9 absorption units after 10 minutes.

Tube 2 (DCPIP with no leaf extract) was 6.4 absorption Units.

The relative activity of the pellet was higher than when the bench centrifuge was used. The micro-centrifuge tubes were only 1.5 cm 3 capacity – not ideal for this practical. A higher speed bench centrifuge would be better.

In order to check for loss of chloroplast activity, the experiment was repeated using the same chloroplast suspension 1 and 2 hours after preparation. Chloroplast suspension was kept in a salt-ice bath. There was no loss of activity when the extract was kept in ice for up to 2 hours.

Student questions

1 Describe and explain the changes observed in the five tubes. Compare the results and make some concluding comments about what they show.

2 The rate of photosynthesis in intact leaves can be limited by several factors including light, temperature and carbon dioxide. Which of these factors will have little effect on the reducing capacity of the leaf extract?

3 Describe how you might extend this practical to investigate the effect of light intensity on the light-dependent reactions of photosynthesis.

1 Colour change and inferences that can made from the results: Tube 1 (leaf extract + DCPIP) colour changes until it is the same colour as tube 4 (leaf extract + distilled water). Tube 2 (isolation medium + DCPIP) no colour change. This shows that the DCPIP does not decolourise when exposed to light. Tube 3 (leaf extract + DCPIP in the dark) no colour change. It can therefore be inferred that the loss of colour in tube 1 is due to the effect of light on the extract. Tube 4 (leaf extract + distilled water) no colour change. This shows that the extract does not change colour in the light. It acts as a colour standard for the extract without DCPIP. Tube 5 (supernatant + DCPIP) no colour change if the supernatant is clear; if it is slightly green there may be some decolouring. The results should indicate that the light-dependent reactions of photosynthesis are restricted to the chloroplasts that have been extracted.

2 Carbon dioxide will have no effect, because it is not involved in the light-dependent reactions.

3 Students should describe a procedure in which light intensity is varied but temperature is controlled.

Health and safety checked, September 2008

Related experiment

Investigating photosynthesis using immobilised algae

Chlorophyll Definition and Role in Photosynthesis

Understand the importance of chlorophyll in photosynthesis

• Biochemistry
• Chemical Laws
• Periodic Table
• Projects & Experiments
• Scientific Method
• Physical Chemistry
• Medical Chemistry
• Chemistry In Everyday Life
• Famous Chemists
• Activities for Kids
• Abbreviations & Acronyms
• Weather & Climate
• Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
• B.A., Physics and Mathematics, Hastings College

Chlorophyll is the name given to a group of green pigment molecules found in plants, algae, and cyanobacteria. The two most common types of chlorophyll are chlorophyll a, which is a blue-black ester with the chemical formula C 55 H 72 MgN 4 O 5 , and chlorophyll b, which is a dark green ester with the formula C 55 H 70 MgN 4 O 6 . Other forms of chlorophyll include chlorophyll c1, c2, d, and f. The forms of chlorophyll have different side chains and chemical bonds, but all are characterized by a chlorin pigment ring containing a magnesium ion at its center.

Key Takeaways: Chlorophyll

• Chlorophyll is a green pigment molecule that collects solar energy for photosynthesis. It's actually a family of related molecules, not just one.
• Chlorophyll is found in plants, algae, cyanobacteria, protists, and a few animals.
• Although chlorophyll is the most common photosynthetic pigment, there are several others, including the anthocyanins.

The word "chlorophyll" comes from the Greek words chloros , which means "green", and phyllon , which means "leaf". Joseph Bienaimé Caventou and Pierre Joseph Pelletier first isolated and named the molecule in 1817.

Chlorophyll is an essential pigment molecule for photosynthesis , the chemical process plants use to absorb and use energy from light. It's also used as a food coloring (E140) and as a deodorizing agent. As a food coloring, chlorophyll is used to add a green color to pasta, the spirit absinthe, and other foods and beverages. As a waxy organic compound, chlorophyll is not soluble in water. It is mixed with a small amount of oil when it's used in food.

Also Known As: The alternate spelling for chlorophyll is chlorophyl.

Role of Chlorophyll in Photosynthesis

The overall balanced equation for photosynthesis is:

6 CO 2 + 6 H 2 O → C 6 H 12 O 6 + 6 O 2

where carbon dioxide and water react to produce glucose and oxygen . However, the overall reaction doesn't indicate the complexity of the chemical reactions or the molecules that are involved.

Plants and other photosynthetic organisms use chlorophyll to absorb light (usually solar energy) and convert it into chemical energy. Chlorophyll strongly absorbs blue light and also some red light. It poorly absorbs green (reflects it), which is why chlorophyll-rich leaves and algae appear green .

In plants, chlorophyll surrounds photosystems in the thylakoid membrane of organelles called chloroplasts , which are concentrated in the leaves of plants. Chlorophyll absorbs light and uses resonance energy transfer to energize reaction centers in photosystem I and photosystem II. This happens when energy from a photon (light) removes an electron from chlorophyll in reaction center P680 of photosystem II. The high energy electron enters an electron transport chain. P700 of photosystem I works with photosystem II, although the source of electrons in this chlorophyll molecule can vary.

Electrons that enter the electron transport chain are used to pump hydrogen ions (H + ) across the thylakoid membrane of the chloroplast. The chemiosmotic potential is used to produce the energy molecule ATP and to reduce NADP + to NADPH. NADPH, in turn, is used to reduce carbon dioxide (CO 2 ) into sugars, such as glucose.

Other Pigments and Photosynthesis

Chlorophyll is the most widely recognized molecule used to collect light for photosynthesis, but it's not the only pigment that serves this function. Chlorophyll belongs to a larger class of molecules called anthocyanins. Some anthocyanins function in conjunction with chlorophyll, while others absorb light independently or at a different point of an organism's life cycle. These molecules may protect plants by changing their coloring to make them less attractive as food and less visible to pests. Other anthocyanins absorb light in the green portion of the spectrum, extending the range of light a plant can use.

Chlorophyll Biosynthesis

Plants make chlorophyll from the molecules glycine and succinyl-CoA. There is an intermediate molecule called protochlorophyllide, which is converted into chlorophyll. In angiosperms, this chemical reaction is light-dependent. These plants are pale if they are grown in darkness because they can't complete the reaction to produce chlorophyll. Algae and non-vascular plants don't require light to synthesize chlorophyll.

Protochlorophyllide forms toxic free radicals in plants, so chlorophyll biosynthesis is tightly regulated. If iron, magnesium, or iron are deficient, plants may be unable to synthesize enough chlorophyll, appearing pale or chlorotic . Chlorosis may also be caused by improper pH (acidity or alkalinity) or pathogens or insect attack.

• 10 Fascinating Photosynthesis Facts
• Photosynthesis Vocabulary Terms and Definitions
• What Are the Products of Photosynthesis?
• Chemosynthesis Definition and Examples
• What Is the Primary Function of the Calvin Cycle?
• Calvin Cycle Steps and Diagram
• The Balanced Chemical Equation for Photosynthesis
• Thymine Definition, Facts, and Functions
• What Is the Most Abundant Protein?
• The Definition of Bioenergy
• Photosynthesis Quiz
• Food and Other Products Formed By Fermentation
• Essential Amino Acids and Their Role in Good Health
• Equilibrium Constant Kc and How to Calculate It
• Transcription Factors
• Animals With Blue or Yellow Blood Instead of Red

on Annual Courses

Use code UNLOCK25

Share this article

Table of Contents

Latest updates.

1 Million Means: 1 Million in Rupees, Lakhs and Crores

Ways To Improve Learning Outcomes: Learn Tips & Tricks

Visual Learning Style for Students: Pros and Cons

NCERT Books for Class 6 Social Science 2024 – Download PDF

CBSE Syllabus for Class 9 Social Science 2023-24: Download PDF

CBSE Syllabus for Class 8 Maths 2024: Download PDF

NCERT Books for Class 6 Maths 2025: Download Latest PDF

CBSE Class 10 Study Timetable 2024 – Best Preparation Strategy

CBSE Class 10 Syllabus 2025 – Download PDF

CBSE Syllabus for Class 11 2025: Download PDF

Tag cloud :.

• entrance exams
• engineering
• ssc cgl 2024
• Written By Umesh_K
• Last Modified 25-01-2023

Experiments Related to Photosynthesis: Definition & Demonstration

Experiments Related to Photosynthesis : Green plants exhibit an autotrophic mode of nutrition. We all know that leaves are the site of photosynthesis. Leaves possess chlorophyll that traps the sunlight to synthesise food (glucose) by utilising inorganic raw materials, i.e., carbon dioxide and water. Oxygen is released as a by-product of photosynthesis. The glucose units combine and form a complex carbohydrate called the starch that remains stored in the plant cells for further utilisation.

Different experiments related to photosynthesis can be performed to demonstrate the utilisation of carbon dioxide, involvement of chlorophyll, presence of starch, and release of oxygen by the plant leaf subjected to perform photosynthesis. Let’s read the article to study the detailed procedure of different experiments related to photosynthesis.

What is Photosynthesis?

Photosynthesis is the process by which the chlorophyll-containing cells synthesise food (glucose) from carbon dioxide and water in the presence of sunlight. Photosynthesis is the process of conversion of solar energy into chemical energy.

Chloroplasts – The Site of Photosynthesis

The leaves are the parts of plants that participate in the process of photosynthesis. In herbaceous plants, green and flexible stems also perform photosynthesis. The mesophyll cells of leaves contain chloroplasts that possess a green coloured pigment called chlorophyll to trap the sunlight for photosynthesis. Thus, inside the mesophyll cells of leaves, chloroplasts are the site of photosynthesis.

Events Occuring During Photosynthesis

The following events occur during the process of photosynthesis:

• Absorption of water from the soil through root hairs.
• Diffusion of Carbon dioxide through stomata.
• Absorption of light energy by chlorophyll.
• Production of glucose.
• Conversion of glucose into starch.
• Release of oxygen

Conditions Necessary For Photosynthesis

The following conditions are necessary for photosynthesis:

• Chlorophyll
• Carbon dioxide

The effect of the presence and absence of these factors on the process of photosynthesis can be proved by performing certain experiments related to photosynthesis.

Experiments to Demonstrate the Requirement of Materials for Photosynthesis

1. theoretical demonstration for the requirement of chlorophyll during photosynthesis:.

I. Aim: Chlorophyll is a green coloured pigment that traps the sunlight to proceed with the synthesis of food by leaves by utilising carbon dioxide and water. To demonstrate the requirement of chlorophyll in photosynthesis, the following experiment is performed.

II. Materials required: Variegated leaf, water, alcohol, iodine solution.

III. Procedure: a). Take a plant with variegated leaves: The leaves of the Coleus, Croton plant can be taken. The leaves of these plants have yellow and green patches, and The green patches contain chlorophyll. b). Destarching the plant: The plant is placed in a dark room to prevent photosynthesis and thereby allows the plant to utilise the food that is stored in the form of starch. c). Removal of chlorophyll: The leaf is boiled in the water, followed by boiling of leaf in the alcohol (place the beaker containing alcohol and leaf in a water bath) till it becomes pale white, i.e., the chlorophyll is removed, and the alcohol turns green. The leaf is then washed with warm water so that it becomes soft. d). A few drops of iodine solution are poured over the leaf.

IV. Observation: The green coloured portion of the leaf that turns colourless in the alcohol now turns into blue-black patches after putting the iodine, while the yellow-coloured portion of the leaf does not show any colour change.

V. Conclusion: The results obtained from the iodine test prove that chlorophyll is necessary for the process of photosynthesis. The blue-black colour is due to the presence of starch. As in the yellow portion, no photosynthesis takes place, so there is no colour change due to the addition of iodine.

Fig: Experiment to demonstrate the necessity of chlorophyll for photosynthesis

2. Theoretical Demonstration for the Requirement of Sunlight During Photosynthesis:

I. Aim: All living beings utilise energy for several life processes. Likewise, plants utilise light energy for the process of photosynthesis. The requirement of sunlight can be demonstrated by following the below-mentioned steps:

II. Materials required: Green plant, black paper or aluminium foil, water, alcohol, iodine solution.

III. Procedure: a). Destarching the plant The plant can be destarched naturally by placing it in the complete dark for about 2-4 days so that all the stored starch is utilised by plants to fulfil its food and energy requirement in the absence of photosynthesis. b). Covering one of the leaves with black paper The destarched plant is then placed in the sunlight for about 2-4 days by covering any of its leaves with black paper or aluminium foil. Since the black colour absorbs the maximum amount of sunlight and therefore obstructs the pathway of light to the leaf surface, therefore black paper is used to cover the leaf. c). Boiling of covered leaf in water The covered and uncovered leaves are immersed in the boiled water before testing for the starch because immersing the leaf in boiled water breaks down the cell membranes of the mesophyll cells and makes the leaf more permeable to the iodine solution. d). Removal of chlorophyll Since chlorophyll interferes in the test for starch due to its green colour, therefore it is necessary to remove the chlorophyll to get the appropriate findings of the experiment. Chlorophyll removal involves the boiling of leaf in water then into alcohol and further washed with hot water to soften it. e). Test for the starch The covered and processed leaf is further tested for the presence of starch by adding 2-3 drops of iodine on the leaf surface.

III. Observation: It will be observed that the leaf does not show any colour change. However, an uncovered leaf gives a positive result for the presence of starch by changing its colour to blue-black.

IV. Conclusion: This shows that the leaves that are exposed to sunlight could only perform photosynthesis, while the covered leaf could not perform photosynthesis due to the absence of sunlight.

Fig: Experiment demonstrating the necessity of sunlight

3. Theoretical Demonstration for the Requirement of Carbon Dioxide During Photosynthesis

I. Aim: Carbon dioxide is the waste product of respiration that is utilised in the process of photosynthesis. To demonstrate the requirement of carbon dioxide the following steps are performed:

II. Material required: Two green potted plants, bell jar, alcohol, water, potassium hydroxide, iodine solution.

III. Procedure: a). Destarching of plant Plants can be destarched by keeping them in the dark for about 2 days. In this experiment, two destarched plants are taken. b). Designing the artificial boundaries for plant The two plants are individually placed on separate glass plates and are covered separately with a bell jar to restrict their boundaries within the surrounding area. c). Role of potassium hydroxide Potassium hydroxide is a carbon dioxide absorbent. It is placed with any of the potted and covered plants that absorb the carbon dioxide in its vicinity. The setup should be airtight to ensure to restrict the further entry of carbon dioxide in the jar. d). Removal of chlorophyll The chlorophyll interferes in the test for starch due to its green colour. Therefore it is necessary to remove the chlorophyll from the leaves of both plants to get the appropriate findings of the experiment. Chlorophyll removal involves the boiling of leaf in water then into alcohol and further washed with hot water to soften it. e). Test for the presence of starch Both the experimental setup are tested for the presence of starch by putting 2-3 drops of iodine solution on the leaf of both plants from which the chlorophyll has been removed.

III. Observation: It has been observed that the leaf of the plant that is placed in the bell jar along with potassium hydroxide will not show any colour change, while the other placed alone in the bell jar shows the presence of starch in its leaves by turning the colour into blue-black.

IV. Conclusion: Since the potassium hydroxide crystals absorb the available carbon dioxide present in one of its jars, therefore photosynthesis does not occur. This proves that carbon dioxide is necessary for photosynthesis.

Fig: Experiment demonstrating the necessity of carbon dioxide

Experiment to Demonstrate the Production of Substances in Photosynthesis

1. theoretical demonstration for the presence of starch.

I. Aim: Plants utilise inorganic raw materials, i.e., water and carbon dioxide, to synthesise organic materials called glucose. These glucose units combine to form a complex carbohydrate called starch that remains stored in the stroma of the chloroplast and in the cytoplasm of the leaves. The iodine test is prominently performed to test the presence of starch that is discussed as follows:

II. Material required: Green plant, iodine solution, dropper.

III. Procedure: a). The healthy plant is placed in the sunlight and left undisturbed for about one day before this experiment. b). Now, the chlorophyll is removed from the leaf by boiling the leaf in water then into alcohol and further washed with hot water to soften it. c). The leaf of the plant is then tested for the presence of starch by adding 2-3 drops of iodine solution with the help of a dropper to the leaf surface.

III. Observation: It will be observed that the colour of the leaf turns blue-black.

IV. Conclusion: The blue-black colour ensures the presence of starch and therefore ensures that photosynthesis takes place in the leaf.

2. Theoretical Demonstration for the release of oxygen during photosynthesis

I. Aim:  Plants release oxygen during photosynthesis that is utilised in the process of respiration. To ensure the release of oxygen, the following steps should be followed:

II. Material required: An aquatic plant, sodium bicarbonate, water, beaker, funnel.

III. Procedure: a). Design the experimental setup A beaker full of water is taken, and any aquatic plant such as Hydrilla is placed at the bottom of the beaker. The plant is further covered with the inverted funnel. An inverted test tube is placed over the funnel. b). Plant subjected to perform photosynthesis The experimental setup is then placed in the sunlight to facilitate the process of photosynthesis to occur in the plant. Sodium bicarbonate is added to the water to provide carbon dioxide that is needed for photosynthesis. c). Observation: A number of air bubbles can be observed at the top closed end of the test tube. Since there is no place for the oxygen to escape from the inverted test tube. IV. Conclusion: The presence of bubbles ensures that oxygen is released during photosynthesis. We can test for the presence of oxygen bubbles by taking a glowing splinter in contact with the air bubbles.

Fig: Experiment demonstrating the release of oxygen

Photosynthesis is the process of synthesising food by utilising carbon dioxide and water in the presence of sunlight. The leaves are the kitchen factories of the plant as they contain chlorophyll in their mesophyll cells to absorb the sunlight. The importance of chlorophyll can be tested by using variegated leaves that show only green patches of the leaves can absorb sunlight since they contain chlorophyll and perform photosynthesis. On the other hand, if a small portion of the entire green leaf is covered with black paper, it does not perform photosynthesis due to the absence of sunlight.

The presence of starch can be confirmed by performing an iodine test. The release of oxygen can be tested by taking an aquatic plant placed in a water-filled beaker along with the inverted funnel and test tube that are placed one after another over the plant and later tested for the release of oxygen. By studying these experiments, we came to know about the importance of carbon dioxide, sunlight, and water in a plant for photosynthesis. These experiments also ensure the type of food synthesised by plants and the release of life-supporting gas.

Frequently Asked Questions (FAQs) On Experiments Related to Photosynthesis

Q.1. Why only Hydrilla is used in photosynthesis experiments? Ans: Hydrilla is a small, aquatic plant that is easy to handle and able to breathe in the water, therefore used in the demonstration of the release of oxygen during photosynthesis.

Q.2. How can we destarch the plant? Ans: We can destarch the plant by keeping the plant in the dark for about one to two days.

Q.3. How do you decolourise the leaf? Ans: We can decolourise then placing it into a beaker containing alcohol and boiling the leaf in a water bath.

Q.4. How do you test the presence of starch in a leaf? Ans: The presence of starch can be tested by putting 2-3 drops of iodine on the leaf. If the colour turns blue-black, it ensures the presence of starch in the leaf.

Q.5. Which experiment proves that carbon dioxide is essential for photosynthesis? Ans: Moll’s half-leaf experiment proves that carbon dioxide is essential for photosynthesis.

We hope this detailed article on experiments related to photosynthesis helped you in your studies. If you have any doubts, queries or suggestions regarding this article, feel to ask us in the comment section and we will be more than happy to assist you. Happy learning!

Related Articles

1 Million Means: 1 million in numerical is represented as 10,00,000. The Indian equivalent of a million is ten lakh rupees. It is not a...

Ways To Improve Learning Outcomes: With the development of technology, students may now rely on strategies to enhance learning outcomes. No matter how knowledgeable a...

Visual Learning Style: We as humans possess the power to remember those which we have caught visually in our memory and that too for a...

NCERT Books for Class 6 Social Science 2024: Many state education boards, including the CBSE, prescribe the NCRET curriculum for classes 1 to 12. Thus,...

CBSE Syllabus for Class 9 Social Science: The Central Board of Secondary Education releases the revised CBSE Class 9 Social Science syllabus. The syllabus is...

CBSE Syllabus for Class 8 Maths 2023-24: Students in CBSE Class 8 need to be thorough with their syllabus so that they can prepare for the...

NCERT Books for Class 6 Maths 2025: The National Council of Educational Research and Training (NCERT) textbooks are the prescribed set of books for schools...

CBSE Class 10 Study Timetable: The CBSE Class 10 is the board-level exam, and the Class 10th students will appear for the board examinations for...

CBSE Class 10 Syllabus 2025: The Central Board of Secondary Education (CBSE) conducts the Class 10 exams every year. Students in the CBSE 10th Class...

CBSE Syllabus for Class 11 2025: The Central Board of Secondary Education (CBSE) has published the Class 11 syllabus for all streams on its official...

NCERT Solutions for Class 7 Science Chapter 16 Water – A Precious Resource

NCERT Solutions for Class 7 Science Chapter 16 Water – A Precious Resource: In this chapter, students will study about the importance of water. There are three...

NCERT Solutions for Class 7 Science Chapter 10 2024: Respiration in Organisms

NCERT Solutions for Class 7 Science Chapter 10 Respiration in Organisms: NCERT solutions are great study resources that help students solve all the questions associated...

Factors Affecting Respiration: Definition, Diagrams with Examples

In plants, respiration can be regarded as the reversal of the photosynthetic process. Like photosynthesis, respiration involves gas exchange with the environment. Unlike photosynthesis, respiration...

NCERT Solutions for Class 7 Science Chapter 12

NCERT Solutions for Class 7 Science Chapter 12 Reproduction in Plants: The chapter 'Reproduction' in Class 7 Science discusses the different modes of reproduction in...

NCERT Solutions for Class 7 Science Chapter 11

NCERT Solutions for Class 7 Science Chapter 11: Chapter 11 of Class 7 Science deals with Transportation in Animals and Plants. Students need to ensure...

NCERT Solutions for Class 7 Science Chapter 15: Light

NCERT Solutions for Class 7 Science Chapter 15: The NCERT Class 7 Science Chapter 15 is Light. It is one of the most basic concepts. Students...

NCERT Solutions for Class 7 Science Chapter 13

NCERT Solutions for Class 7 Science Chapter 13: Chapter 13 in class 7 Science is Motion and Time. The chapter concepts have a profound impact...

NCERT Solutions for Class 7 Science Chapter 14: Electric Current and its Effects

NCERT Solutions for Class 7 Science Chapter 14: One of the most important chapters in CBSE Class 7 is Electric Current and its Effects. Using...

General Terms Related to Spherical Mirrors

General terms related to spherical mirrors: A mirror with the shape of a portion cut out of a spherical surface or substance is known as a...

Animal Cell: Definition, Diagram, Types of Animal Cells

Animal Cell: An animal cell is a eukaryotic cell with membrane-bound cell organelles without a cell wall. We all know that the cell is the fundamental...

NCERT Solutions for Class 10 Science 2024 – Download PDF

NCERT Solutions for Class 10 Science: The National Council of Educational Research and Training (NCERT) publishes NCERT Solutions for Class 10 Science as a comprehensive...

NCERT Books for Class 12 Chemistry 2024: Download PDF

NCERT Books for class 12 Chemistry: NCERT publishes chemistry class 12 books every year. The NCERT chemistry class 12 books are essential study material for...

CBSE Class 9 Mock Tests 2025: Attempt Online Mock Test Series (Subject-wise)

We all have heard at least once that the secret to success is practice. Some of you could say it's a cliché, but those who...

NCERT Books for Class 10 Maths 2025: Download Latest PDF

NCERT Books for Class 10 Maths: The NCERT Class 10 Maths Book is a comprehensive study resource for students preparing for their Class 10 board exams....

Arc of a Circle: Definition, Properties, and Examples

Arc of a circle: A circle is the set of all points in the plane that are a fixed distance called the radius from a fixed point...

CBSE Class 10 Mock Test 2025: Practice Latest Test Series

CBSE Class 10 Mock Test 2025: Students' stress is real due to the mounting pressure of scoring good marks and getting into a renowned college....

NCERT Solutions for Class 10 2024: Science and Maths

NCERT Solutions for Class 10 2024: Students appearing for the CBSE Class 10 board exam must go through NCERT Solutions to prepare for the exams...

39 Insightful Publications

Embibe Is A Global Innovator

Innovator Of The Year Education Forever

Interpretable And Explainable AI

Revolutionizing Education Forever

Best AI Platform For Education

Enabling Teachers Everywhere

Decoding Performance

Leading AI Powered Learning Solution Provider

Auto Generation Of Tests

Disrupting Education In India

Problem Sequencing Using DKT

Help Students Ace India's Toughest Exams

Best Education AI Platform

Unlocking AI Through Saas

Fixing Student’s Behaviour With Data Analytics

Leveraging Intelligence To Deliver Results

Brave New World Of Applied AI

You Can Score Higher

Harnessing AI In Education

Personalized Ed-tech With AI

Exciting AI Platform, Personalizing Education

Disruptor Award For Maximum Business Impact

Top 20 AI Influencers In India

Proud Owner Of 9 Patents

Innovation in AR/VR/MR

Best Animated Frames Award 2024

Trending Searches

Previous year question papers, sample papers.

Unleash Your True Potential With Personalised Learning on EMBIBE

Ace Your Exam With Personalised Learning on EMBIBE

Enter mobile number.

By signing up, you agree to our Privacy Policy and Terms & Conditions

Investigating the Need for Chlorophyll, Light & Carbon Dioxide ( Cambridge O Level Biology )

Revision note.

Investigating the Need for Chlorophyll

• The occurrence of photosynthesis can be demonstrated by observing the presence of its products
• Although plants make glucose in photosynthesis, leaves cannot be tested for its presence as the glucose is quickly used or converted into other substances
• Starch is stored in chloroplasts, where photosynthesis occurs, so testing a leaf for starch is a reliable indicatorthat photosynthesis is taking place
• A leaf is dropped in boiling water to kill the cells and break down cell membranes
• Care must be taken at this stage as ethanol is extremely flammable ; the Bunsen burner should be turned off before any ethanol is poured into the boiling tube
• A water bath could be used to avoid the need for naked flames
• The leaf is dipped in boiling water to soften it
• The leaf is spread out on a white tile and covered with iodine solution
• In a green leaf, the entire leaf will turn blue-black as photosynthesis is occurring in all areas of the leaf
• The areas that have no chlorophyll remain orange-brown as no photosynthesis is occurring here and so no starch is stored

Testing a leaf for starch diagram

Iodine can be used to test for the presence of starch in different parts of a leaf

Investigating the Need for Light

• This ensures that any starch already present in the leaves will be used up and will not affect the results of the experiment
• Partially cover a leaf of the plant with aluminium foil and place the plant in sunlight for a further 24 hours
• Remove the leaf and test for starch as shown above
• The area of the leaf covered with aluminium foil will remain orange-brown , as it did not receive any sunlight and could not photosynthesise, while the area exposed to sunlight will turn blue-black
• This demonstrates that light is necessary for photosynthesis and the production of starch

Investigating the Need for Carbon Dioxide

• Remove starch from two plants by placing them in the dark for 24 hours
• Sodium hydroxide will absorb carbon dioxide from the surrounding air
• Water here acts as an experimental control , demonstrating that it is the presence of the sodium hydroxide, and not any other factor, that is affecting the plant
• Place both plants in bright light for 24 hours
• Test both plants for starch using iodine, as shown above
• The leaf from the plant placed near sodium hydroxide will remain orange-brown , as a lack of carbon dioxide will prevent it from photosynthesising
• The leaf from the plant placed near water should turn blue-black as it had all necessary materials for photosynthesis

Experiment that demonstrates the need for carbon dioxide in photosynthesis diagram

You've read 0 of your 10 free revision notes

Get unlimited access.

to absolutely everything:

• Downloadable PDFs
• Unlimited Revision Notes
• Topic Questions
• Past Papers
• Model Answers
• Videos (Maths and Science)

Join the 100,000 + Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Author: Naomi H

Naomi graduated from the University of Oxford with a degree in Biological Sciences. She has 8 years of classroom experience teaching Key Stage 3 up to A-Level biology, and is currently a tutor and A-Level examiner. Naomi especially enjoys creating resources that enable students to build a solid understanding of subject content, while also connecting their knowledge with biology’s exciting, real-world applications.

• Open access
• Published: 24 August 2024

Selenium improved arsenic toxicity tolerance in two bell pepper ( Capsicum annuum L.) varieties by modulating growth, ion uptake, photosynthesis, and antioxidant profile

• Muhammad Nawaz 1 ,
• Eram Shahzadi 1 ,
• Aqsa Yaseen 1 ,
• Muhammad Rehan Khalid 1 ,
• Muhammad Hamzah Saleem 2 ,
• Adel I. Alalawy 3 ,
• Awatif M. E. Omran 3 ,
• Fatma Mohamed Ameen Khalil 4 ,
• Meshari A. Alsuwat 5 ,
• Sezai Ercisli 6 ,
• Tabarak Malik 7 , 9 &
• Baber Ali 8 , 10  

BMC Plant Biology volume  24 , Article number:  799 ( 2024 ) Cite this article

Metrics details

Bell pepper ( Capsicum annuum L.); an important spice crop of the region is a rich source of vitamins and antioxidants having many health benefits. Many biotic and abiotic factors contribute towards growth and yield losses of this crop. Arsenic (As) toxicity is a global issue, but it is particularly critical in developing countries. The current study was designed to evaluate the efficacy of selenium (Se) in mitigating the toxic effects of As in two varieties (HSP-181 A and PS09979325) of Capsicum annuum L. Different concentrations of As (0, 50, and 100 µM) and Se (0, 5, and 10 µM) were tested using 14 days old seedlings of C. annuum L. The As stress caused a significant ( P  ≤ 0.001) reduction in growth, uptake of nutrients, and eco-physiological attributes in both varieties however, the response was specific. While the overproduction of osmo-protectants and antioxidants intensified the symptoms of oxidative stress. The maximum reduction in shoot length (45%), fresh weight (29%), and dry weight (36%) was observed in under 100 µM As stress. The organic acids exudation from the roots of both cultivars were significantly increased with the increase in As toxicity. The Se treatment significantly ( p  ≤ 0.001) improved growth, nutrient uptake, gas exchange attributes, antioxidant production, while decreased oxidative stress indicators, and As uptake in the roots and shoots of all the subjects under investigation. It is concluded from the results of this study that Se application increased photosynthetic efficiency and antioxidant activity while decreasing As levels, organic acid exudation, and oxidative stress indicators in plants. Overall, the var. PS09979325 performed better and may be a good candidate for future pepper breeding program.

Peer Review reports

Introduction

The As is a well-documented carcinogenic metalloid, its contamination across the board is hazardous for agriculture, and all kinds of living organisms worldwide [ 1 ]. It alters the morphological, biochemical, and physiological processes in plants even at low concentrations (range 20–100 µM), particularly those that are consumed by humans [ 2 , 3 , 4 ]. Various human endeavours, such as mining or naturally occurring chemical processes are increasing As concentration in soil (1–40 mg kg-1). In soil, drinking water (6–12 ng ml-1), and air (3–30 ng m-3), it can be found in four different oxidation states i.e. -III, 0, +III, and + V [ 5 ]. As (III) and As (V), as well as their interconversion, cause oxidative stress by producing reactive oxygen species (ROS). This affects the regulatory control of a variety of metabolic activities [ 6 ].

According to a recent investigation, As contamination has also been found in Hungary, Mexico, Argentina, Australia, and the United States, among other areas. It is well known that South-East Asia suffers from groundwater pollution [ 7 ]. The As may cause severe devastation to plants and animals in various parts of Pakistan [ 8 ]. A high As concentration in both surface and groundwater has been recorded in different regions of Punjab and Sindh province of Pakistan [ 9 ]. However, a number of variables, including soil type, plant species, and uptake processes, significantly impact the pace of As absorption and accumulation [ 10 ].

Vegetables are regarded as the best diet for promoting health and preventing disease because they contain essential nutrients for body repair and growth. Vegetables, with their high vitamin and mineral content, help the body maintain its alkaline reserves [ 11 ]. C. annuum L., sometimes known as the bell pepper, hot pepper, sweet pepper, and chilli, is a well-known vegetable crop. It belongs to the Solanaceae family and is consumed as a pickle, sauce, spice, and vegetable. All over the world, chilies are utilized as a spice and have also found their way into foods like beverages and medicines [ 12 ]. The As contents in vegetables grown in soils with high As extractability are more likely to be higher than soils with low As extractability [ 13 ].

Developing effective strategies to address pollution is critical because it poses a serious risk to agricultural production globally [ 14 ]. Various remediation techniques reduce As accumulation in vegetables, including soil replacement, leaching, electrokinetic remediation, phytoremediation, flood culture, organic additions, intercropping, and breeding for low As accumulating genotypes [ 15 ]. Another environmentally friendly strategy for reducing negative impacts of As is the exogenous use of ions and essential micronutrients like Se. The Se was once believed to be harmful, but it is now understood to be an essential nutrient for plants. Exogenous application of Se reduces plant damage caused by various environmental adversities either used as topically or as a root zone treatment [ 16 ]. Heavy metal absorption and translocation such as Cd, Cr, Pb, As, Cu, Hg and others is also significantly declined [ 17 ]. By preserving cell membrane stability, mineral absorption, and cellular processes, as well as minimising oxidative stress damage, the Se treatment decrease toxicity of heavy metal [ 18 ]. The objective of the current study was to examine the protective role of Se under As stress and to ascertain the potential of the Capsicum annuum L. cultivars employed in the study to withstand As stress. Because of their diverse parentage, both cultivars have genetic differences that could explain this differential behaviour towards As tolerance. The As tolerance and translocation in bell pepper under Se treatment described here will contribute to the existing body of knowledge for bell pepper and will be useful in selecting cultivars for future variety development programmes.

Materials and methods

Acid washed sand (pH 5.5-6) filled pots (40 cm in height and a diameter of 34 cm) with established volumetric field capacity 0.072 m 3 /m 3 were used for C. annuum L. (HSP-181 A and PS09979325) seed sowing. Karam Ceramics Limited in Karachi supplied the acid-washed sand. The day/night temperature was 25 ± 1/15 ± 1 °C. Ali’s method [ 19 ] was used to prepare the nutrition solution. The plants were irrigated with Hoagland solution. Young seedlings from nursery were shifted to each sand filled pot and every pot received 500 mL of nutritional solution throughout the early stages of development, and this amount was subsequently increased to 1000 mL at alternate days. Five plants were maintained in each pot and 14 days old seedlings were subjected to different treatments. The As (50 and 100 µM) stress was maintained for two weeks then Se (5 and 10 µM) was applied using nutrient solution for two weeks and plants were harvested at four leaf stage for further analyses.

The plants were classified into the following categories

Control (nutrient solution alone), control with 5 µM Se, control with 10 µM Se, As (50 µM), As (100 µM), As (50 µM) with Se (5 µM), As (100 µM) with Se (5 µM), As (50 µM) with Se (10 µM), and As (100 µM) with Se (10 µM). Preliminary tests employing a variety of As concentrations, (0, 10, 20, 30, 40, 60, 70, 80, 90, 100 µM), were used to determine effective levels of As (unpublished data). Similarly, the Se levels (5, 10 µM) were determined in a preliminary investigation in which three-week-old bell pepper seedlings were watered using a nutrient solution containing different levels (0, 1, 3, 5, 7, 10, 12 µM) of Se. Sodium selenate (Na 2 SeO 4 ) and meta-arsenate (Na 2 HAsO 4 .7H 2 O) were purchased from Sigma-Aldrich (USA). Completely randomized design was followed in all experiments with three replicates.

Root shoot length

After uprooting the plant from pots, roots and shoots were carefully separated. A meter rod was used to measure the root and shoot length of the harvested plants.

Root shoot fresh and dry weight

After harvesting, the root and shoot fresh weight was determined using electrical weight balance. For dry weight measurement, the samples were dried at 75 °C for 48 h using laboratory oven.

Photosynthetic pigments

A leaf sample of 0.5 g was homogenized in 10 mL of 90% acetone at 4 °C. Supernatant from each sample was obtained after centrifugation at 12,000 rpm for 5 min. Absorbance was recorded using a UV-Spectrophotometer (Hitachi U-2001, Japan) at 480, 645, and 663 nm. Calculations of photosynthetic pigments were done using [ 20 ] method.

Estimation of enzymatic antioxidants

A leaf sample weighing 0.5 g was taken, ground in liquid nitrogen, and then mixed with EDTA (0.5 mM) and NaCl (0.2 mM) in 5 mL of sodium phosphate buffer (50 mM, pH 7.00). The resulting homogenate underwent a centrifugation process at 12,000 × rpm for 15 min at 4 °C. The activity of the enzymes, superoxide dismutase (SOD) and peroxidase (POD) was assessed using the collected supernatant.

A reaction mixture of 3 mL containing 50 mM sodium phosphate buffer (pH 7.0), 55 mM NBT (nitro blue tetrazolium), 10 mM methionine and 100 µL enzyme extract prepared to calculate the SOD activity. Then guaiacol was employed as the substrate to measure POD activity according to methodology reported [ 21 ]. The absorbance of SOD and POD was noted using a UV-visible spectrophotometer (Hitachi U-2001, Japan) at 560 and 470 nm, respectively.

For CAT activity was estimated by methodology reported by Hatch [ 22 ] by maintaining H 2 O 2 concentration in a reaction mixture as reported, and absorbance changes were measured at 240 nm. A 100 µL of enzyme extract, 100 µL of 250 mM H 2 O 2 , 2.5 mL of 50 mM phosphate buffer, and 2 mM EDTA (pH 7.0) made up the reaction mixture. The activity of APX was assessed using the method described by Asada and Takahashi [ 23 ]. A 100 µL of enzyme extract, 100 µL of 7.0 mM ascorbate, 100 µL of 250 mM H 2 O 2 , and 2.5 mL of 25 mM potassium phosphate buffer with 2 mM EDTA (pH 7.00) made up the reaction mixture. At 290 nm, the absorbance was measured. The unit of measurement for enzyme activity was mg -1 protein.

Non-enzymatic antioxidants and oxidative stress indicators estimation

An ethanol extract was made to assess non-enzymatic antioxidants and osmolytes. After being homogenized in 10 mL of 80% ethanol, a 50 g sample of air-dried leaves was filtered through Whatman filter paper No. 41. Once more extracting the filtrate residues, the filtrate was mixed to create a final amount of 20 mL.

Estimation of phenolic contents

Julkunen-Tiitto’s [ 24 ] method was used with little modification for estimation of total phenolic contents. In this procedure, 2 ml of 80% acetone was used to homogenize 0.5 g of fresh leaf material. The homogenate was centrifuged at 12,000 × g for 10 min. After separating the supernatant (100 l), 1 ml of the Folin-Ciocalteu phenol reagent and 2 ml of distilled water were added. Following this, 3 ml of 20% N 2 CO 3 was added before the final volume of 10 ml of distilled water was added. It was vigorously Shaked. To measure absorbance at 750 nm, a UV-vis spectrophotometer (Hitachi U-2001, Japan) was used.

Determination of anthocyanin content

Using methods described by Hodges & Nozzolillo, anthocyanin content was measured. In this protocol, Fresh leaves (0.1 g) are ground in 2 ml of acidic methanol (Methanol + 1% HCL). After completion of a homogenous mixture of samples, transferred it to the test tubes. Then tubes were boiled at 100 o C for 30 min. Centrifugation at 12,000 × sample (g) for 15 min. Absorbance was observed using a spectrophotometer at 536 nm and 600 nm [ 25 ].

Determination of flavonoids content

The flavonoid contents were determined by the method of Karadeniz [ 26 ]. The 0.1 g sample of fresh plant leaves grinding was performed in 80% acetone. Add 0.3 ml of 5% NaNO 2 and 3 ml of distilled water to the clean plant leaf extract. The reaction mixture was then mixed, and it was left to reset for five minutes at room temperature. After that, add 0.6 ml of 10% AlCl 3 and 2 ml of a solution of 1 M NaOH to the reaction mixture. distilled water was added to the mixture to get the volume up to 10 milliliters. Uv-Vis spectrophotometer was used to measure absorbance at 510 nm (Hitachi U-2001, Japan).

Reducing sugars estimation

Dinitro alicyclic acid (DNS) reagent was used for the determination of reducing sugars. For the preparation of reagent Wood and Bhat (1988) method was used [ 27 ].

Proline contents

Proline contents were estimated by following procedure [ 28 ]. A sample of 0.2 g fresh leaves was grinded in 8 mL of 30% aqueous sulphosalicylic acid. A new test tube was filled with 1 mL of supernatant after the lysate had been centrifuged for 10 min at 12,000 × rpm. This tube was filled with 1 mL of acidic ninhydrin and 1 mL of glacial acetic acid, heated for 10 min at 100 ℃, and then cooled in the ice bath. Following the addition of 5 mL of toluene, the test tube was vortexed for 30 s and then cooled. To measure the absorbance, a UV-visible spectrophotometer was used at 520 nm (UV-2550; Shimadzu, Kyoto, Japan). Using a standard curve, the amount of proline was determined and expressed in µmol g -1 FW.

MDA estimation

Using a modified version of procedure, the degree of lipid peroxidation, the MDA content was calculated [ 29 ]. In 20 mL of 50 mM phosphate buffer with a pH of 7.8, A frozen leaf sample of 2 g was homogenized. The resultant homogenate was centrifuged at 4 ℃ and 12,000 × rpm for 10 min. Supernatant was collected and mixed 5 mL supernatant with 1.5 mL of 0.5% TBA. The resultant mixture was chilled in an ice bath after being heated for 20 min at 95 ℃ in water bath. Using a spectrophotometer, the supernatant absorbance was recorded at 532, 600, and 440 nm wavelengths (UV-2550; Shimadzu, Kyoto, Japan). The MDA content was estimated as follows and expressed as nmol g -1 FW.

H 2 O 2 content estimation

For H 2 O 2 estimation, in 20% H 2 SO 4 , 3 mL of the leaf extract mixture and 1 mL of titanium sulphate were added. For 10 min, this reaction mixture was centrifuged at 8000 rpm. Supernatant was employed at a wavelength of 410 nm to measure absorbance. The H 2 O 2 concentration was calculated by an extinction coefficient of 0.28 -1  cm -1 and was expressed as µmolg -1 FW [ 30 ].

Electrolyte leakage

Electrolyte leakage (EL) was determined following [ 31 ] procedure using a fully stretched top second leaf. 10 mL of distilled water and the leaves were put in a test tube after being uniformly chopped into 5 mm pieces. The first electrical conductivity (EC1) was determined after two hours of incubation. The samples were autoclaved at 121 ℃ for 15 min before being chilled to 27 ℃ for evaluating their final electrical conductivity (EC2).

Gas exchange characteristics

The net photosynthetic rate (Pn), stomatal conductance (gs), and transpiration rate (E) of the second youngest leaf from the top of each plant were measured using the photosynthesis measuring-system CI-340 portable infrared gas analyzer (Analytical Development Company, Hoddesdon, USA). All these parameters were recorded from 9:00 to 11:00 AM. Atmospheric pressure was approximately 99.9 kPa, water vapors pressure ranged from 6.0 to 8.9 mbar, maximum PAR at leaf surface was up to 1711 molm -2 s -1 , leaf temperature was between 28.4 and 32.4 ℃, ambient temperature was between 22.4 and 27.9 ℃. Three plants from each replicate of each treatment were used to measure the said parameters.

Water use efficiency

The formula for calculating water use efficiency was (Pn/E), where Pn = net photosynthetic rate.

Nutrient analysis

For sample digestion, the Wolf (1982) method was used, and 5 mL of concentrated H 2 SO 4 and 0.5 g of dried, material was introduced to the digestion tube. The extract was used to measure potassium (K), calcium (Ca), and phosphorous (P) after being filtered.

Estimation of K +

Using a flame photometer (Jenway PFP 7), potassium (K + ) was measured.

Determination of P

A spectrophotometer was used to measure the amount of phosphorus [ 32 ].

Calcium (ca) and magnesium (mg) determination

Using an atomic absorption spectrophotometer (Hitachi Z-2000), calcium (Ca) and magnesium (Mg) concentrations were determined.

Root organic acid estimation

Using high-performance liquid chromatography (HPLC), organic acids were measured (PerkinElmer, MA, USA). The procedure developed by [ 33 ] was used to analyze the root organic acids. Briefly, three plants each, from different treatments were washed with tap water and transferred to a rhizo box-like system containing 200 g autoclaved humid soil. A nylon net was used in the rhizoboxes to avoid root penetration into the soil. After 36 h, plants were taken out of the rhizoboxes and rinsed with10 ml of double distilled water for 30s. The collected exudates were passed through 0.45 mm syringe filters. (BioRad USA) and poured into 15 ml falcon tubes. For organic acid analysis, samples were mixed with 0.01 M NaOH. The root exudates were stored at -80 °C for further analysis.

As level estimation in roots and shoots

To estimate the amount of As present in the root and shoot, the obtained samples were dried in an oven (Esco OFA-32-8 Singapore) at 70 ℃ for 24 h while ash was produced in a muffle furnace at 550 ℃ for 20 h. It received a treatment of 17.5% (v/v) H 2 O 2 and 31% (m/v) HNO 3 at 70 ℃ for two hrs before being given distilled water. To estimate As contents, an atomic absorption spectrophotometer (Hitachi Z-2000) was employed.

Statistical analysis

Using CoStat software version 6.303, a three-way analysis of variance (ANOVA) was conducted using the LSD test at p <  0.05 to measure differences in variables among the various treatments. The LSD test was then used to compare treatment means. Using R Studio, the principal component analysis and Pearson’s correlation were also computed.

Different biotic and abiotic stresses tend to reduce plant growth and metabolism. Different metabolic changes take place when plants encounter stress conditions, and these alter the expression of different genes relative to production of different chemicals beneficial for the plant’s health. Stress reduced the plant growth by reducing root and shoot length significantly as reported in the results. It also increased the H 2 O 2 and MDA content which is indicator that the plant is undergoing stress. Different types of root exudates were released to reduce metal uptake shows the plant capability to defend themselves against the stress conditions. But plant’s simple own defense mechanism can’t mitigate the stress conditions that’s why Se have been reported to increase the secondary metabolite production like flavonoids and anthocyanins which have been reported to increase plants defense mechanism. Similar results are presented in next sections showing increased plant defense under Se application.

Growth parameters

The findings of this work demonstrated that As toxicity significantly ( p <  0.001) reduced growth attributes of both bell pepper varieties. Decrease in growth parameter was observed which might be due to many different defense mechanisms like ROS scavenging and osmolyte disturbance. The most notable reduction in shoot length (27%) fresh weight (13%) and dry weight (18%) was recorded in var. HSP-181 A under 50 µM As stress as compared to control. Under 100 µM As stress, the same cultivar experienced a maximum reduction in shoot length (45%), fresh weight (29%), and dry weight (36%). The var. PS09979325 showed the most minimal drop in shoot length (8 and 18%), fresh weight (7 and 12%), and dry weight (6 and 10%), respectively, under 50 µM and 100 µM As stress.

Under control conditions, the shoot length, shoot dry weight, and shoot fresh weight of cv. HSP-181 A increased up to 13, 7, 14, 25, 23, and 36%, respectively, following the application of Se (5 µM and 10 µM) in nutrition media. While greater increases in shoot length (5 and 33%), shoot fresh weight (7 and 25%), and shoot dry weight (8 and 26%) were observed in cv. HSP-181 A by Se application (5 µM) under As stress (50 µM, 100 µM), and maximum increases in shoot length (14%) were observed in variety HSP-181 A by Se application (10 M) under As stress (Fig.  1 ).

Effect of Se on growth attributes of bell pepper ( Capsicum annuum L.) varieties under As stress. Shoot length ( a ), root length ( b ), shoot fresh weight ( c ), shoot dry weight ( d ), root fresh weight ( e ) and root dry weight ( f ). T0 = Control, T1 = control + Se (5µM), T2 = control + Se (10µM), T3 = As (50µM), T4 = As (50µM) + Se (5µM), T5 = As (50µM) + Se (10µM), T6 = As (100µM), T7 = As (100µM) + Se (5µM), T8 = As (100µM) + Se (10µ)

Under As stress, both vars. of bell pepper experienced significant ( p <  0.01) reductions in root length, dry weight, and fresh weight. However, the response varied between the varieties. As compared with control, the var. HSP-181 A experienced the greatest decrease in root length (27%), fresh weight (18%), and dried root weight (25%). When plants were treated with 100 µM As, maximum drop in root length (45%), fresh weight (44%), and dry weight (36%) was observed. Under untreated control, the Se application (5 µM and µ10 M) enhanced root length (13% and 25%), root fresh weight (25 and 52%), and root dry weight (4 and 28%), respectively. When applied to HSP-181 A under As (50 µM and 100 µM) stress, 5 µM Se increased root length (5 and 33%), fresh weight (5 and 27%), and dry weight (6 and 29%), respectively. In the same cultivar, 10 µM Se also enhanced root length (14 and 34%), fresh weight (11 and 37%), and dry weight (21 and 32%), respectively, under As (50 and 100 µM) stress. So, based on our findings, plants produced more biomass when Se was applied under As stress (Fig.  1 ).

Pigments and photosynthetic parameters concentrations

Figure  2 depicts the effects of As stress with or without the application of Se on the contents of Chl a , b , Total Chl., and Car in both vars. of bell pepper. Under As (50 µM) stress, Chl a (27%), b (20%), T. Chl (24%) and Car. (17%) contents decreased significantly ( p <  0.01) in the leaves of the HSP-181 A. However, at 100 µM As stress, the var. HSP-181 A showed maximum drop in Chl a (47%) Chl b (35%) Total Chl (42%) and Car (32%). Furthermore, by applying Se 5 µM under control conditions, Chl a , b , Total Chl, and Car levels increased up to 3, 5, 4, and 7%, respectively in this variety. While application of 10 µM Se increased these contents up to 15, 30, 22, and 56% in the same variety under same conditions. When Se was applied (5 µM) under As stress of 50 µM and 100 µM, a greater increase in Chl a (5 and 31%), Chl b (7 and 24%), T. Chl (6 and 28%), and carotenoids (5 and 19%) was observed in the var. HSP-181 A (Fig.  2 ).

Effect of Se on pigments and photosynthesis attributes of bell pepper ( Capsicum annuum L.) varieties under As stress. Chlorophyll a ( a ), chlorophyll b ( b ), total chlorophyll ( c ), carotenoids ( d ), net photosynthetic rate ( e ), stomatal conductance (f), transpiration rate ( g ) and water use efficiency ( h ). T0 = Control, T1 = control + Se (5µM), T2 = control + Se (10µM), T3 = As (50µM), T4 = As (50µM) + Se (5µM), T5 = As (50µM) + Se (10µM), T6 = As (100µM), T7 = As (100µM) + Se (5µM), T8 = As (100µM) + Se (10µM)

Under As stress, gaseous exchange attributes were significantly decreased ( p <  0.01) as compared with control. The var. HSP-181 A under As stress (50 µM) demonstrated reductions in Pn (23%), gs (60%), E (30%), and WUE (7%). The greatest decreases in Pn (33%), gs (80%), E (48%), and WUE (16%) were observed when plants were exposed to nutritional solution containing 100 µM As. Additionally, under control conditions, with Se application of 5 µM, the var. HSP-181 A exhibited an increase in Pn, gs, E and WUE values up to 19, 17, 9, and 10% while 10 µM increased these attributes up to 35, 38, 28, and 28 respectively. With 5 µM Se application under As stress (50 and 100 µM), var. HSP-181 A showed an increase in Pn (14 and 16%), WUE (1 and 12%), gs (18 and 51%), and E (15 and 10%), respectively. Additionally, 10 µM Se treatment increased Pn (21 and 28%), gs (37 and 70%), E (20 and 33%), and WUE (9 and 17%) under 50 µM and 100 µM As stress, respectively (Fig.  2 ).

Antioxidants, osmolytes and stress indicators profile

In the present investigation, enzymatic antioxidant activity increased significantly ( p <  0.01) under As exposure in both bell pepper varieties. When var. HSP-181 A was exposed to As stress (50 µM), the greatest increase in SOD (26%), POD (53%), CAT (51%), and APX (68%) was recorded as compared to As non-treated plants. But under 100 µM As stress, var. HSP-181 A showed the highest increases in SOD (43%), POD (61%), CAT (57%), and APX (77%). In addition, SOD, POD, CAT and APX in cv. HSP-181 A increased under control conditions by Se application (5 µM and 10 µM) up to 3, 39, 28, 42% and 12, 67, 69, 62%, respectively. At the same time, a greater increase in SOD (51 and 60%), POD (53 and 58%), CAT (51 and 57%), and APX (71 and 81%) was recorded in var. HSP-181 A by 5 µM Se application under As stress (50 and 100 µM) as well as SOD (77 and 67%), POD (55 and 61%), CAT (52 and 59%) and APX (74 and 86%) were increased in var. HSP-181 A with Se application (10 µM) under As 50 and 100 µM stress (Fig.  3 ).

Effect of Se on enzymatic antioxidants of bell pepper ( Capsicum annuum L.) varieties under As stress. SOD ( a ), POD ( b ), CAT ( c ) and APX ( d ). T0 = Control, T1 = control + Se (5µM), T2 = control + Se (10µM), T3 = As (50µM), T4 = As (50µM) + Se (5µM), T5 = As (50µM) + Se (10µM), T6 = As (100µM), T7 = As (100µM) + Se (5µM), T8 = As (100µM) + Se (10µM)

The As stress significantly ( p <  0.01) enhanced the phenolics, flavonoids, MDA, and anthocyanin contents in both bell pepper varieties. The maximum accumulation of phenolics (62%), flavonoids (65%), MDA (6%), and anthocyanin (52%) contents was recorded in var. HSP-181 A under 50 µM As stress. However, under 100 µM As stress, a maximum increase in phenolics (73%), flavonoids (71%), MDA (27%), and anthocyanin (72%) contents was observed in var. HSP-181 A. In addition, maximum increase in phenolics, flavonoids, and anthocyanin contents of var. HSP-181 A was recorded under 10 µM Se applications. MDA content decreased with 5 and 10 µM Se application by 16 and 29% respectively under control condition. At the same time, more increases in phenolics (72 and 60%), flavonoids (53 and 78%), and anthocyanin (51 and 77%) were recorded in var. HSP-181 A with Se application (5 µM) under As stress (50 and 100 µM) and more decrease in MDA contents were observed in HSP-181 A with Se application (5 µM) under As stress (50 and 100 µM) by 8 and 18% respectively. Moreover, a maximum increase in phenolics (79 and 67%), flavonoids (58 and 81%), and anthocyanin (55 and 80%) contents were observed, more decrease in MDA contents (12 and 25%) were observed in var. HSP-181 A with Se application (10 µM) under As (50 µM and 100 µM) stress, respectively (Fig.  4 ).

Effect of Se on non-enzymatic antioxidants and oxidative damage indicators of bell pepper ( Capsicum annuum L.) varieties under As stress. Phenolics ( a ), flavonoids ( b ), anthocyanin ( c ) reducing sugar ( d ), proline ( e ), MDA ( f ), H2O2 ( g ) and electrolyte leakage ( h ). T0 = Control, T1 = control + Se (5µM), T2 = control + Se (10µM), T3 = As (50µM), T4 = As (50µM) + Se (5µM), T5 = As (50µM) + Se (10µM), T6 = As (100µM), T7 = As (100µM) + Se (5µM), T8 = As (100µM) + Se (10µM)

Ion concentrations

In the present study Ca 2+ , Mg 2+ , K + and P were decreased significantly ( p <  0.001) in both bell pepper varieties under stress. The maximum adverse effect of As (50 µM) was exhibited by var. HSP-181 A in Ca 2+ (28%), Mg 2+ (29%), K + (16%) and P (23%) contents under control condition. Maximum reduction in Ca 2+ (46%), Mg 2+ (46%) K + (53%) and P (37%) were observed in var. HSP-181 A under 100 µM As stress. In addition, Ca 2+ , Mg 2+ , K + , P in var. HSP-181 A increased under control conditions with Se (5 and 10µM) application up to 17, 20, 9, and 7%, and 35, 38, 38, and 23%, respectively. At the same time, a higher increase in Ca 2+ (13% and 9%), Mg 2+ (13 and 34%) K + (2 and 36%) and P (3 and 25%) was recorded in var. HSP-181 A with Se application (5 µM) under As stress (50 and 100µM) level as well as Ca 2+ (18 and 31%), Mg 2+ (17 and 40%), K + (6 and 49%), and P (11 and 32%) was increased maximum in var. HSP-181 A with Se (10 µM) application under 50 and 100 µM As stress (Fig.  5 ).

Effect of Se on ionic contents and organic acids of bell pepper ( Capsicum annuum L.) varieties under As stress. Calcium ( a ), magnesium ( b ), potassium ( c ), phosphorus ( d ), malic acid ( e ), citric acid ( f ), acetic acid ( g ) and oxalic acid ( h ). T0 = Control, T1 = control + Se (5µM), T2 = control + Se (10µM), T3 = As (50µM), T4 = As (50µM) + Se (5µM), T5 = As (50µM) + Se (10µM), T6 = As (100µM), T7 = As (100µM) + Se (5µM), T8 = As (100µM) + Se (10µM)

Root exudates profile

Analysis of variance revealed that malic acid, citric acid, acetic acid, and oxalic acid significantly ( p <  0.01) increased. The adverse effect of As (50 µM) was recorded in var. HSP-181 A for malic acid (38%), citric acid (21%), acetic acid (23%), and oxalic acid (32%) contents increment as compared to As non-treated plants. While under 100 µM As stress, maximum increment in malic acid (40%), citric acid (35%), acetic acid (46%), and oxalic acid (38%) was observed in var. HSP-181 A as compared to control. A maximum increase in malic acid (5 and 50%), citric acid (14 and 27%), acetic acid (17 and 37%), and oxalic acid (12 and 28%) was observed in var. HSP-181 A with Se application (10 µM) under 50 µM and 100 µM As stress, respectively (Fig.  5 ).

Our result revealed that As in root and shoot increased substantially ( p <  0.01) in both bell pepper varieties under As treatment. A maximum increment in As levels in root and shoot were observed in var. HSP-181 A under 100 µM As stress. In addition, As contents in root and shoot increased under control conditions with Se application (5 and 10 µM) up to 5, 32, and 13, 28%, respectively. While the greater decrease in As contents of root and shoot were recorded in var. HSP-181 A with Se application (5 µM) under both levels of As stress. A maximum reduction in As contents of root/shoot was recorded in var. HSP-181 A with 10 µM Se application under 50 and 100 µM As stress (Table  1 ).

Plant development, biomass, photosynthetic pigments, gaseous exchange characteristics, antioxidants, root exudates, and mineral intake were correlated, according to PCA analysis. Figure  6 describes that Mg, WUE, P, Ca, K, RDW, RFW, SDW, SFW, SL, RL, Chl. a , Chl. b , T. Chl, Car, Elec, and H 2 O 2 negatively correlate with MDA, Ma, As R, Oxa, Ace, As S, Cit, POD, CAT, APX, SOD, Anth, FL, RS, Pro, and Phe. However, Mg, WUE, and P are closely positively correlated. Oxa, As S, and Ace are closely positively correlated. POD, CAT, and Anth are also closely positively correlated. Among the extracted components, the significant contribution of Dim 1 (66.5%) was followed by Dim 2 (13.8%), with a cumulative donation of 80.3%. Pearson’s correlation shows the relationship between plant growth, biomass, photosynthetic pigments, gaseous exchange attributes, antioxidants, root Exudates, and mineral intake (Fig.  6 ). MDA has a highly negative correlation with SL, SFW, SDW, RL, RFW, RDW, Chl. b , Chl. a , T. Chl, Car, RS, Pn, C, E, WUE, Ca, Mg, K, P strongly correlates with SOD, POD, CAT, Pro, Elec, H 2 O 2 , and Anth. Ma, Cit, Ace, As R, and As S has a highly negative correlation with SL, SFW, SDW, RL, RFW, RDW, and Chl. b , Chl. a , T. Chl, Car, Pn, C, E, WUE, Ca, Mg, K, P, and it has a highly positive correlation with MDA. POD and CAT negatively correlate with SL, SFW, SDW, RL, RFW, RDW, and Chl. b , Chl. a , T. Chl, Car, Pn, C, E, WUE, Ca, Mg, K, P strongly correlates positively with SOD, CAT, APX, Phe, FL, and Anth.

Principal component and correlation analysis of the all studied attributes of bell pepper ( Capsicum annuum L.) varieties under As stress. Different abbreviations used in this figure are as follow: RL, root length; SL, shoot length; SFW, shoot fresh weight; SDW, shoot dry weight; RFW, root fresh weight; RDW, root dry weight; Chl. a, chlorophyll a; Chl. b, chlorophyll b; T. Chl, total chlorophyll; Car, carotenoids; SOD, superoxide dismutase; POD, peroxidase activity ; CAT, catalase ; APX, ascorbate peroxidase; MDA, malondialdehyde content; Anth, anthocyanin, FL, flavonoids; Phe, phenolics; H2O2, hydrogen peroxide; Pro, proline, Elec, electrolyte leakage; RS, reducing sugar; Ca, calcium; Mg, magnesium; K, potassium; P, phosphorus; Ma, malic acid; Cit, citric acid; Ace, acetic acid, Oxa, oxalic acid; As R, arsenic contents in roots; As S, arsenic contents in shoots

Like all other heavy/toxic metals, when discharged into the environment As is hazardous to living things being incorporated and accumulated through food chain [ 34 , 35 ]. The first tissue to come into contact with As from polluted soil is the root system. It inhibits root development and extension [ 36 ] by delaying or preventing cell development and biomass creation as it passes through shoots and may significantly limit plant growth [ 37 ]. Numerous chemicals are used to combat heavy metal toxicity. Due to its metabolic functions in the living system, Se application has become one of the most efficient methods for reducing heavy metal toxicity [ 38 ]. By using it, heavy metals are restricted from being absorbed by roots and passed on to shoots. Its supplementation is expected to increase the quantity of pectin as well as the cell wall thickness enhancing plant growth [ 39 ]. In the present study root and shoot biomass was significantly reduced in both bell pepper varieties under As stress although the observed biomass reduction was dose and cultivar specific. The var. HSP-181 A was found to be more vulnerable to As stress while Se application significantly restored the development attributes in both varieties under investigation.

A considerable decrease in the production of chlorophyll and carotenoids has been recorded in the present study possibly due to disagreement between the adaptive alterations in photosystems II and I under elevated As stress as has been reported previously [ 40 ]. Another explanation for the decreased pigment level could be that the As stress prevents the absorption of N and Mg, two crucial elements of the chlorophyll molecule [ 41 ]. In the current study, the same reduced uptake behaviour was observed for both Mg and N, resulting in reduced chlorophyll content. As a result of severe As stress, the external supply of Se protects chloroplasts and aids in the maintenance of photosynthetic pigments. The findings of the current investigation showed that Se application considerably boosted the bell pepper’s pigment content as previously reported in Brassica juncea [ 42 ]. The As is absorbed by plants and interacts with different metabolic pathways to produce peroxides thus increasing ROS levels in plant cells. According to [ 38 ], ROS production creates enzymatic antioxidants under stress conditions. These antioxidants are regarded as the first line of defence since they scavenge ROS from various cellular compartments [ 43 ]. In contrast to As-stressed plants, the current study showed that Se treatments boosted SOD, POD, CAT, and APX activity in bell pepper and similar findings has been reported in past [ 44 ]. The SOD oversees neutralising ROS and changing O 2 into H 2 O 2 . Later, utilising ascorbate, POD and CAT scavenge the H 2 O 2 produced by dismutation and transform it into H 2 O and O 2 [ 45 ]. The enzyme APX, which is a part of the (ASA)-Glu cycle, inhibits the buildup of H 2 O 2 in tissue by converting it to H 2 O. Several enzymes may function individually or in groups via crosstalk, as may be appropriate in different plant species, to prevent oxidative damage and toxicity inside plants [ 42 ].

In response to As stress, the anthocyanin contents increased. Anthocyanin synthesis under stress may result from glutathione-S-transferase activation, whereas violaxanthin, a xanthophyll, serves as a precursor for the manufacture of abscisic acid, It is also connected with the protection of oxidative stress [ 46 ]. Numerous investigations have shown that the enzyme’s gene expression in anthocyanin synthesis pathways that scavenge reactive oxygen species is closely related to anthocyanin accumulation by Se administration [ 47 ]. The flavonoids content increased during the early stages of As stress; it is also regarded as a polyphenolic molecule with antioxidant properties. As stress was followed by an increase in radical scavenging, demonstrating the beneficial function flavonoids play in removing free radicals [ 48 ]. Phenolics have hydroxyl and carboxyl groups with metal-binding properties. Plant phenolics also act as antioxidants. The high phenolic content in this study may have performed a strong antioxidant effect. According to previous studies, use of Se in plants under Stress boosted the activity of enzymes involved in the phenylpropanoid production pathway [ 49 , 50 ] and same is thought to be happened in the present study however, the varietal differences may be due to variation in level of genes expression for candidate enzymes of the metabolic process.

The findings of the present study revealed that as As concentration increased in various plant tissues, oxidative damage as indicated by MDA level, also increased. As a result, Se accumulation’s impact on oxidative damage because of which oxidative stress increased. The supply of Se thereby mitigated oxidative harm because the MDA level in the Se application was equivalent to that of the non-stressed plants. In previous study [ 51 ] it has been found that Se can potentially deactivate ROS produced by As toxicity in oilseed rape.

The increase in the concentration of As in the solution of nutrients resulted in reduction of gaseous exchange attributes. However, the main effect of As stress is that it hinders the electron transport chain (ETC), reduces the photosynthesis rate, and causes ultrastructure disruption of chloroplast [ 52 ]. As metal reduce produce secondary metabolite which destroy the PS-II and PS-I structure and reduce the plant growth and defense mechanism [ 53 ]. As inhibits key enzymes of ETC like cytochrome c oxidase and thus disrupting plant metabolism [ 53 ]. One of the initial coping mechanisms of stressed plants is closure of stomata, which reduces leaf transpiration and, as a result, the regular CO 2 flow into the carboxylation site. The principal factor decreasing photosynthesis in plants grown under stress is stomatal conductance [ 54 ]. Additionally, In the respiratory chain, Se increased respiration and electron transport, which improved chlorophyll biosynthesis. By boosting chlorophyll content and preserving chloroplast ultrastructure, the Se treatment may help stressed plants recover their ability to photosynthesize [ 55 ]. In the current investigation, the exact same response was noted in both varieties of bell pepper.

Leaf Ca 2+ , Mg 2+ , K + , and P contents in bell pepper varieties were decreased with increasing As stress level in our study because stress reduced mineral nutrient retention, as is evident in previous study [ 56 ]. Such consequences could result from increased stress accumulation, which displaces mineral nutrients from binding sites, limiting their translocation and uptake [ 57 ]. Under stress, for example, a decrease in K + concentration may be related to xylem obstruction and suppression of root growth of plant [ 58 ]. A similar result shows that the As stress lowered plant Ca 2+ levels resulting in poor rice growth [ 58 ]. Metalloid stress reduced uptake of Mg 2+ in tomato shoots and roots, decreasing chlorophyll production [ 59 ]. For instance, [ 39 ] reported the beneficial effect of Se treatment on ion homeostasis in Chinese cabbage under heavy metal stress.

The As significantly boosted the root exudation of citric, acetic, maleic, and oxalic acids in the current study. The metabolism of root cells, which is related to the buildup and release of different organic acids, is disrupted by toxic chemicals. As observed in Solanum nigrum L. the current study showed the exudation of various organic acids from stressed plant roots, which may be crucial in lowering As toxicity through metal detoxification, nutrient stabilisation, and improved plant growth [ 33 ]. According to prior research on poplar roots under metal stress, organic acid exudation occurs via anion channels [ 60 ], and their release ought to be balanced by the efflux of cations/protons [ 61 ].

Applying Se under As stress increased the metal content of plant organs, increased mineral uptake, and impacted the exudation of organic acids from plant roots [ 62 ]. Despite the genetic variations among the species, our study revealed the same results in bell pepper varieties under investigation. This study found that 100 µM As caused greater As accumulation in the roots. Ions are transported across the cell membrane by transporters, which are unique proteins. Only a small part of the total ions reaches the plant root. The majority of such ions are physically takes in by the negative-charged -COO compartment, which oversees cell wall surface absorption. This compartment prevents ions from entering the cell in the plant shoot [ 63 ]. The As competes for transport channel and gets stored in different non-essential parts disturbing the osmotic conditions in the plant. It disrupts normal metabolic machinery and competitively reduce the other ions concentrations as reflected by the results presented in the study [ 64 ]. The competition might be between specific and non-specific transporters contributing towards the stress symptoms appearance [ 65 ]. These substances build up in cellular vacuoles and become more concentrated, which inhibits them from moving to the shoot. Because of this, the level of this element has a greater impact on the root than the shoot [ 66 ]. All these components are accumulated in the root and shoot, Se decreased the deleterious impact of As stress [ 63 ].

Conclusions

The As had a significant impact on plant mineral uptake, biomass accumulation, photosynthesis, and the antioxidant profile of both cultivars (HSP-181 A and PS09979325). The As stress had significantly reduced the physicochemical and biochemical parameters by changing secondary metabolism, disrupting the normal osmotic balance, reducing ions exchange, uptake and translocating. The Se application proved to have positive effect on reducing stress conditions caused by As stress and improved plant growth and all physiological and biochemical parameters. According to the findings of the present study, it is proposed that var. PS09979325 responded more effectively overall under As stress as compared to var. HSP-181 A. The organic acid exudations, oxidative stress markers, and As levels in plant organs also increased as the toxicity level did. The Se supplementation, however, promoted greater plant growth and biomass, decreased the production of ROS, maintained minerals, and decreased the concentration of As in plant organs. Different industrial effluents are used for irrigation purposes because these crops are cultivated in suburban regions of the big cities. Contaminated water is used for irrigation of vegetables grown near urban regions and it poses a threat to plants’ health and tends to modulate gene expression as well as metabolite production. So, it is essential to know the varietal response against different heavy metals including As present in industrial wastewater. The var. PS09979325 showed a more effective response against As toxicity, which might be due to its genetic makeup. Based on these observations this var. may be considered as potential candidate for future variety development program. Further molecular studies are required to elaborate on its distinguished behavior of As toxicity tolerance. Additionally, after Se supplementation, balanced organic acid exudation confers typical activities of metabolites in both kinds even under As stress. Thus, to fully comprehend the cellular and molecular mechanisms of As toxicity avoidance/tolerance, long-term field research should be conducted to draw parallels between plant/crop root exudations, metal stress, Se fertigation regimes, nutrient uptake, and plant biomass accumulation.

Data availability

All data generated or analysed during this study are included in this published article.

Zemanová V, Pavlíková D, Hnilička F, Pavlík M. Arsenic Toxicity-Induced physiological and metabolic changes in the shoots of Pteris cretica and Spinacia oleracea. 2021.

Chattopadhyay A, Singh AP, Kasote D, Sen I, Regina A. Effect of Phosphorus Application on Arsenic Species Accumulation and Co-Deposition of Polyphenols in Rice Grain: Phyto and Food Safety Evaluation. Plants 2021, Vol 10, Page 281. 2021; 10:281.

Kofroňová M, Hrdinová A, Mašková P, Tremlová J, Soudek P, Petrová Š, et al. Multi-component Antioxidative System and Robust Carbohydrate Status, the Essence of Plant Arsenic Tolerance. Antioxid (Basel). 2020;9:283.

Article   Google Scholar  

Praveen A, Pandey A, Gupta M. Protective role of nitric oxide on nitrogen-thiol metabolism and amino acids profiling during arsenic exposure in Oryza sativa L. Ecotoxicology. 2020;29:825–36.

Article   PubMed   Google Scholar  

Solórzano E, Corpas FJ, González-Gordo S, Palma JM. Reactive oxygen species (ROS) metabolism and nitric oxide (NO) content in roots and shoots of Rice (Oryza sativa L.) plants under Arsenic-Induced stress. Agronomy. 2020;10:1014.

Fayiga A, Geoderma US-. 2016 undefined. Arsenic hyperaccumulating fern: Implications for remediation of arsenic contaminated soils. ElsevierAO Fayiga, UK SahaGeoderma, 2016•Elsevier.

Richards L, Casanueva-Marenco MJ, Magnone D, Sovann P, Dongen B, Polya D. Contrasting Sorption Behaviours Affecting Groundwater Arsenic Concentration in Kandal Province, Cambodia. Geosci Front. 2019;10.

Rabbani U, Mahar G, Siddique A, Fatmi Z. Risk assessment for arsenic-contaminated groundwater along River Indus in Pakistan. Environ Geochem Health. 2017;39:179–90.

Article   CAS   PubMed   Google Scholar  

Shah Saqib An, Waseem A, Khan Af, Mahmood Q, Khan A, Habib A et al. Arsenic bioremediation by low-cost materials derived from Blue Pine (Pinus wallichiana) and Walnut (Juglans regia). Arsenic bioremediation by low-cost materials derived from Blue Pine (Pinus wallichiana) and Walnut (Juglans regia). 2013; 51:88–94.

Ali H, Khan E, Sajad MA. Phytoremediation of heavy metals—concepts and applications. Chemosphere. 2013;91:869–81.

Nwaobiala CU, Ogbonna MO, editors. Adoption determinants and profitability analysis of okra farming in Aninri Local Government Area (LGA) of Enugu State, Nigeria. DISCOURSE JOURNAL OF AGRICULTURE AND FOOD SCIENCES.

Khan MTI, Qamar Ali QA, Muhammad Ashfaq MA, Muhammad Waseem MW. Economic analysis of open field chilli (Capsicum annuum L.) production in Punjab, Pakistan. 2017.

Rodríguez-Ruiz M, Aparicio-Chacón MV, Palma JM, Corpas FJ. Arsenate disrupts ion balance, sulfur and nitric oxide metabolisms in roots and leaves of pea ( Pisum sativum L.) plants. Environ Exp Bot. 2019;161:143–56.

Thakur S, Choudhary S, Majeed A, Singh A, Bhardwaj P. Insights into the molecular mechanism of Arsenic Phytoremediation. J Plant Growth Regul. 2020;39:532–43.

Article   CAS   Google Scholar  

Pezzarossa B, Remorini D, Gentile ML, Massai R. Effects of foliar and fruit addition of sodium selenate on selenium accumulation and fruit quality. J Sci Food Agric. 2012;92:781–6.

Feng R, Wei C, Tu S. The role of selenium in protecting plants against abiotic stresses. Environ Exp Bot. 2013;87:58–68.

Tran TAT, Zhou F, Yang W, Wang M, Dinh QT, Wang D, et al. Detoxification of mercury in soil by selenite and related mechanisms. Ecotoxicol Environ Saf. 2018;159:77–84.

Wang C, Rong H, Zhang X, Shi W, Hong X, Liu W, et al. Effects and mechanisms of foliar application of silicon and selenium composite sols on diminishing cadmium and lead translocation and affiliated physiological and biochemical responses in hybrid rice ( Oryza sativa L.) exposed to cadmium and lead. Chemosphere. 2020;251:126347.

Ali S, Chaudhary A, Rizwan M, Anwar HT, Adrees M, Farid M, et al. Alleviation of chromium toxicity by glycinebetaine is related to elevated antioxidant enzymes and suppressed chromium uptake and oxidative stress in wheat (Triticum aestivum L). Environ Sci Pollut Res Int. 2015;22:10669–78.

Arnon DI. Copper enzymes in isolated chloroplasts. Polyphenoloxidase in Beta Vulgaris. Plant Physiol. 1949;24:1–15.

Article   CAS   PubMed   PubMed Central   Google Scholar  

Sakharov IY, Ardila GB. Variations of peroxidase activity in cocoa (Theobroma cacao L.) beans during their ripening, fermentation and drying. Food Chem. 1999;65:51–4.

Hatch MD, Glasziou KT. Sugar Accumulation Cycle in Sugar Cane. II. Relationship of invertase activity to Sugar Content & Growth Rate in Storage tissue of plants grown in controlled environments. Plant Physiol. 1963;38:344–8.

Asada K. Production and scavenging of active oxygen in chloroplasts. Mol Biology free Radical Scavenging Syst. 1992;173–92.

Julkunen-Tiitto R. Phenolic constituents in the leaves of Northern willows: methods for the analysis of certain phenolics. J Agric Food Chem. 1985;33:213–7.

Hodges DM, Nozzolillo C. Anthocyanin and anthocyanoplast content of cruciferous seedlings subjected to mineral nutrient deficiencies. J Plant Physiol. 1996;147:749–54.

Karadeniz F, Burdurlu HS, Koca N, Soyer Y. Antioxidant activity of selected fruits and vegetables grown in Turkey. Turkish J Agric Forestry. 2005;29:297–303.

CAS   Google Scholar  

DuBois M, Gilles KA, Hamilton JK, Rebers PA, Smith F. Colorimetric Method for Determination of Sugars and related substances. Anal Chem. 1956;28:350–6.

Bates LS, Waldren RP, Teare ID. Rapid determination of free proline for water-stress studies. Plant Soil. 1973;39:205–7.

Heath RL, Packer L. Photoperoxidation in isolated chloroplasts: I. kinetics and stoichiometry of fatty acid peroxidation. Arch Biochem Biophys. 1968;125:189–98.

Jana S, Choudhuri MA. Glycolate metabolism of three submersed aquatic angiosperms: effect of heavy metals. Aquat Bot. 1981;11:67–77.

Dionisio-Sese ML, Tobita S. Antioxidant responses of rice seedlings to salinity stress. Plant Sci. 1998;135:1–9.

Jackson ML. Soil chemical analysis constable. London: Ltd Co; 1958. p. 498.

Google Scholar  

UdDin I, Bano A, Masood S. Chromium toxicity tolerance of Solanum nigrum L. and Parthenium hysterophorus L. plants with reference to ion pattern, antioxidation activity and root exudation. Ecotoxicol Environ Saf. 2015;113:271–8.

Zvobgo G, Lwalaba JLW, Sagonda T, Mapodzeke JM, Muhammad N, Shamsi IH, et al. Alleviation of arsenic toxicity by phosphate is associated with its regulation of detoxification, defense, and transport gene expression in barley. J Integr Agric. 2019;18:381–94.

Karakaya O, Uygulamalı S, Üniversitesi B, Ateş U, Çelik SM, Faizy AH. Biochemical properties and antimicrobial and antioxidant activity of blackberry growing naturally in Kelkit valley. researchgate.net. 2022; 2022:2687–3818.

Kumar V, Vogelsang L, Schmidt RR, Sharma SS, Seidel T, Dietz K-J. Remodeling of root growth under combined arsenic and hypoxia stress is linked to nutrient deprivation. Front Plant Sci. 2020;11:569687.

Article   PubMed   PubMed Central   Google Scholar  

Alam MZ, Hoque MA, Ahammed GJ, McGee R, Carpenter-Boggs L. Arsenic accumulation in lentil (Lens culinaris) genotypes and risk associated with the consumption of grains. Sci Rep. 2019;9:9431.

Wang C, Rong H, Zhang X, Shi W, Hong X, Liu W, et al. Effects and mechanisms of foliar application of silicon and selenium composite sols on diminishing cadmium and lead translocation and affiliated physiological and biochemical responses in hybrid rice (Oryza sativa L.) exposed to cadmium and lead. Chemosphere. 2020;251:126347.

Zhao Y, Hu C, Wang X, Qing X, Wang P, Zhang Y, et al. Selenium alleviated chromium stress in Chinese cabbage (Brassica campestris L. Ssp. Pekinensis) by regulating root morphology and metal element uptake. Ecotoxicol Environ Saf. 2019;173:314–21.

Shah Fahad Sönmez, Osman S, Shah W, Depeng W, Chao. Kātibī M ʻAdnān. et al Heavy Met Stress Plants De?F Responses. 2021;October:57–82.

Handa N, Kohli SK, Sharma A, Thukral AK, Bhardwaj R, Alyemeni MN, et al. Selenium ameliorates chromium toxicity through modifications in pigment system, antioxidative capacity, osmotic system, and metal chelators in Brassica juncea seedlings. South Afr J Bot. 2018;119:1–10.

Ahmed B, Dwivedi S, Abdin MZ, Azam A, Al-Shaeri M, Khan MS, et al. Mitochondrial and chromosomal damage induced by oxidative stress in Zn2 + ions, ZnO-bulk and ZnO-NPs treated Allium cepa roots. Sci Rep. 2017;7:40685.

Ahmad P, Alyemeni MN, Al-Huqail AA, Alqahtani MA, Wijaya L, Ashraf M, et al. Zinc oxide nanoparticles application alleviates arsenic (as) toxicity in soybean plants by restricting the uptake of as and modulating key biochemical attributes, antioxidant enzymes, ascorbate-glutathione cycle and glyoxalase system. Plants. 2020;9:825.

Skalickova S, Milosavljevic V, Cihalova K, Horky P, Richtera L, Adam V. Selenium nanoparticles as a nutritional supplement. Nutrition. 2017;33:83–90.

Das K, Roychoudhury A. Reactive oxygen species (ROS) and response of antioxidants as ROS-scavengers during environmental stress in plants. Front Environ Sci. 2014;2:53.

Choudhury FK, Rivero RM, Blumwald E, Mittler R. Reactive oxygen species, abiotic stress and stress combination. Plant J. 2017;90:856–67.

Liu D, Li H, Wang Y, Ying Z, Bian Z, Zhu W et al. How exogenous selenium affects anthocyanin Accumulation and Biosynthesis-related gene expression in Purple Lettuce. Pol J Environ Stud. 2017;26.

Sachdev S, Ansari SA, Ansari MI, Fujita M, Hasanuzzaman M. Abiotic Stress and Reactive Oxygen Species: Generation, Signaling, and Defense Mechanisms. Antioxidants 2021, Vol 10, Page 277. 2021; 10:277.

Padhi EMT, Liu R, Hernandez M, Tsao R, Ramdath DD. Total polyphenol content, carotenoid, tocopherol and fatty acid composition of commonly consumed Canadian pulses and their contribution to antioxidant activity. J Funct Foods. 2017;38:602–11.

Skrypnik L, Styran T, Savina T, Golubkina N. Effect of selenium application and growth stage at harvest on hydrophilic and lipophilic antioxidants in lamb’s lettuce (Valerianella locusta L. Laterr). Plants. 2021;10:2733.

Wu Z, Yin X, Bañuelos GS, Lin Z-Q, Liu Y, Li M, et al. Indications of selenium protection against cadmium and lead toxicity in oilseed rape (Brassica napus L). Front Plant Sci. 2016;7:1875.

Albornoz F, Lieth JH, González-Fuentes JA. Effect of different day and night nutrient solution concentrations on growth, photosynthesis, and leaf NO3-content of aeroponically grown lettuce. Chil J Agric Res. 2014;74:240–5.

Singh R, Singh S, Parihar P, Singh VP, Prasad SM. Arsenic contamination, consequences and remediation techniques: a review. Ecotoxicol Environ Saf. 2015;112:247–70.

Jiang Y, Ding X, Zhang D, Deng Q, Yu C-L, Zhou S, et al. Soil salinity increases the tolerance of excessive sulfur fumigation stress in tomato plants. Environ Exp Bot. 2017;133:70–7.

Liu H, Xiao C, Qiu T, Deng J, Cheng H, Cong X et al. Selenium Regulates Antioxidant, Photosynthesis, and Cell Permeability in Plants under Various Abiotic Stresses: A Review. Plants 2023, Vol 12, Page 44. 2022; 12:44.

Liu X, Feng H, Fu J, Chen Y, Liu Y, Ma LQ. Arsenic-induced nutrient uptake in As-hyperaccumulator Pteris vittata and their potential role to enhance plant growth. Chemosphere. 2018;198:425–31.

Gupta P, Kumar V, Usmani Z, Rani R, Chandra A, Gupta VK. A comparative evaluation towards the potential of Klebsiella sp. and Enterobacter sp. in plant growth promotion, oxidative stress tolerance and chromium uptake in Helianthus annuus (L). J Hazard Mater. 2019;377:391–8.

Srivastava D, Tiwari M, Dutta P, Singh P, Chawda K, Kumari M et al. Chromium Stress in Plants: Toxicity, Tolerance and Phytoremediation. Sustainability 2021, Vol 13, Page 4629. 2021; 13:4629.

Hayat S, Khalique G, Irfan M, Wani AS, Tripathi BN, Ahmad A. Physiological changes induced by chromium stress in plants: an overview. Protoplasma. 2012;249:599–611.

Zhu XF, Zheng C, Hu YT, Jiang TAO, Liu YU, Dong NY, et al. Cadmium-induced oxalate secretion from root apex is associated with cadmium exclusion and resistance in Lycopersicon Esulentum. Plant Cell Environ. 2011;34:1055–64.

Magdziak Z, Gąsecka M, Waliszewska B, Zborowska M, Mocek A, Cichy WJ, et al. The influence of environmental condition on the creation of organic compounds in Pinus sylvestris L. Rhizosphere, roots and needles. Trees - Struct Function. 2021;35:441–57.

Guo X, Ji Q, Rizwan M, Li H, Li D, Chen G. Effects of biochar and foliar application of selenium on the uptake and subcellular distribution of chromium in Ipomoea aquatica in chromium-polluted soils. Ecotoxicol Environ Saf. 2020;206:111184.

Azizi I, Esmaielpour B, Fatemi H. Effect of foliar application of selenium on morphological and physiological indices of savory (Satureja hortensis) under cadmium stress. Food Sci Nutr. 2020;8:6539–49.

Gulz PA, Gupta SK, Schulin R. Arsenic accumulation of common plants from contaminated soils. Plant Soil. 2005;272:337–47.

Jayakumar M, Surendran U, Raja P, Kumar A, Senapathi V. A review of heavy metals accumulation pathways, sources and management in soils. Arab J Geosci 2021. 2021;14:20.

Ramos I, Esteban E, Lucena JJ, Gárate A. Cadmium uptake and subcellular distribution in plants of Lactuca sp. Cd–Mn interaction. Plant Sci. 2002;162:761–7.

Download references

Acknowledgements

The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through large group Research Project under grant number RGP2/486/45.

Not applicable.

Author information

Authors and affiliations.

Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan

Muhammad Nawaz, Eram Shahzadi, Aqsa Yaseen & Muhammad Rehan Khalid

Office of Academic Research, Office of VP for Research & Graduate Studies, Qatar University, Doha, 2713, Qatar

Muhammad Hamzah Saleem

Department of Biochemistry, Faculty of Science, University of Tabuk, Tabuk, 71491, Saudi Arabia

Adel I. Alalawy & Awatif M. E. Omran

Department of Biology, Applied College, King Khalid University, Mohayil Asir Abha, 61421, Saudi Arabia

Fatma Mohamed Ameen Khalil

Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, Taif, 21944, Saudi Arabia

Meshari A. Alsuwat

Department of Horticulture, Agricultural Faculty, Ataturk University, Erzurum, 25240, Türkiye

Sezai Ercisli

Department of Biomedical Sciences, Institute of Health, Jimma University, Jimma, 378, Ethiopia

Tabarak Malik

Department of Plant Sciences, Quaid-i-Azam University, Islamabad, 45320, Pakistan

Adjunct Faculty, Division of Research and Development, Lovely Professional University, Phagwara, Punjab 144401, India

School of Science, Western Sydney University, Penrith 2751, Australia

You can also search for this author in PubMed   Google Scholar

Contributions

MN, ES, AY: Conceptualization, Data curation, Writing – original draft, Formal analysis, Investigation, Methodology; MRK, MHS, AIA, AMEO, FMAK, MAA, SE,, TM: Formal analysis, Validation, Visualization Resources, Writing – review & editing; BA: Data Curation, Formal analysis, Software, Visualization, Writing – original draft, Writing – review & editing. All authors contributed significantly, have read and agreed to the published version of the manuscript.”

Corresponding authors

Correspondence to Muhammad Nawaz , Tabarak Malik or Baber Ali .

Ethics declarations

Ethics approval and consent to participate.

Capsicum annuum L. (HSP-181A and PS09979325) seeds taken from the Ayub Agricultural Research Institute, Faisalabad, Pakistan. All the experiments were performed in accordance with relevant guidelines and regulations”.

Consent for publication

Competing interests.

The authors declare no competing interests.

Additional information

Publisher’s note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/ .

Reprints and permissions

About this article

Cite this article.

Nawaz, M., Shahzadi, E., Yaseen, A. et al. Selenium improved arsenic toxicity tolerance in two bell pepper ( Capsicum annuum L.) varieties by modulating growth, ion uptake, photosynthesis, and antioxidant profile. BMC Plant Biol 24 , 799 (2024). https://doi.org/10.1186/s12870-024-05509-3

Download citation

Received : 26 October 2023

Accepted : 12 August 2024

Published : 24 August 2024

DOI : https://doi.org/10.1186/s12870-024-05509-3

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Ecotoxicology
• Metal stress
• Organic exudates
• Abiotic stress

BMC Plant Biology

ISSN: 1471-2229

• General enquiries: [email protected]

Advanced Decision-Making Irrigation Regulated by VPD Changed the Circadian Transpiration Pattern of Tomatoes

• Published: 22 August 2024

Cite this article

• Jiaxing He 1 ,
• Lele Ma 1 ,
• Wenxin Li 1 ,
• Chenxi Zhu 1 ,
• Minggao Liu 1 &
• Jianming Li 1  

Saturated vapor pressure deficit (VPD) is plant transpiration’s main driving force and regulates stomatal behavior. In theory, VPD can predict plant transpiration and determine irrigation. Still, the circadian transpiration of plants needs to be clarified for the rapid, short-term response of VPD. Here we set up two VPD environments (low VPD, high VPD) to irrigate three different varieties of tomatoes using our team’s advanced decision irrigation system. The study monitored the diurnal transpiration changes, morphological growth, leaf characteristics, water status, gas exchange, and photosynthesis of the tomatoes. The result showed that when that decision system was used for irrigation, the low VPD environment increased the water potential of roots, stems, and leaves during the daytime, alleviated the hydraulic restriction, and increased the proportion of nighttime transpiration of various tomato varieties. It was likely that the plants changed their circadian transpiration rhythm, and higher stomatal conductance, water use efficiency, and photosynthetic production performance during the daytime were obtained through higher nighttime transpiration. In addition, transpiration showed a response-ability to predict and adjust VPD in advance. There was a very high correlation between environmental factor VPD and plant transpiration during the daytime. Among them, when adding the time lag of −1 h and −0.5 h, the overall decision coefficient R 2 between the transpiration rate and VPD of each tomato variety was higher than without time delay. We use the daytime transpiration data of 30 min as fitting examples. The decision coefficients between transpiration and VPD accumulation within 30 min were 0.90, 0.81, and 0.89, respectively. But this correlation was insignificant at night. This study provided a new idea for the real-time and accurate prediction of irrigation for protected tomatoes using transpiration decisions.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Subscribe and save.

• Get 10 units per month
• Download Article/Chapter or eBook
• 1 Unit = 1 Article or 1 Chapter
• Cancel anytime

Price includes VAT (Russian Federation)

Instant access to the full article PDF.

Rent this article via DeepDyve

Institutional subscriptions

Similar content being viewed by others

Fine-Tuning Growth Conditions: Leaf-Level Vapor Pressure Deficit Control for Optimized Photosynthesis

Vapour pressure deficit control in relation to water transport and water productivity in greenhouse tomato production during summer

Spatio-temporal variation in transpiration responses of maize plants to vapor pressure deficit under an arid climatic condition

Explore related subjects.

• Environmental Chemistry

Anderson MC, Kustas WP, Norman JM (2003) Upscaling and downscaling—a regional view of the soil–plant–atmosphere continuum. Agron J 95:1408–1423. https://doi.org/10.2134/agronj2003.1408

Article   Google Scholar  

Buck AL (1981) New equations for computing vapor pressure and enhancement factor. J Appl Meteorol Climatol 20:1527–1532

Caird MA, Richards JH, Hsiao TC (2007) Significant transpirational water loss occurs throughout the night in field-grown tomato. Funct Plant Biol 34:172–177. https://doi.org/10.1071/fp06264

Article   PubMed   Google Scholar  

Claverie E, Schoppach R, Sadok W (2016) Nighttime evaporative demand induces plasticity in leaf and root hydraulic traits. Physiol Plant 158:402–413. https://doi.org/10.1111/ppl.12474

Article   CAS   PubMed   Google Scholar  

Coupel-Ledru A, Lebon E, Christophe A, Gallo A, Gago P, Pantin F, Doligez A, Simonneau T (2016) Reduced nighttime transpiration is a relevant breeding target for high water-use efficiency in grapevine. Proc Natl Acad Sci 113:8963–8968. https://doi.org/10.1073/pnas.1600826113

Article   CAS   PubMed   PubMed Central   Google Scholar  

Dayer S, Herrera JC, Dai Z, Burlett R, Lamarque LJ, Delzon S, Bortolami G, Cochard H, Gambetta GA (2021) Nighttime transpiration represents a negligible part of water loss and does not increase the risk of water stress in grapevine. Plant Cell Environ 44:387–398. https://doi.org/10.1111/pce.13923

Dodd AN, Salathia N, Hall A, Kevei E, Toth R, Nagy F, Hibberd JM, Millar AJ, Webb AAR (2005) Plant circadian clocks increase photosynthesis, growth, survival, and competitive advantage. Science 309:630–633. https://doi.org/10.1126/science.1115581

Gholipoor M, Choudhary S, Sinclair TR, Messina CD, Cooper M (2013) Transpiration response of maize hybrids to atmospheric vapour pressure deficit. J Agronomy Crop Sci 199:155–160. https://doi.org/10.1111/jac.12010

Gu Z, Qi Z, Ma L, Gui D, Xu J, Fang Q, Yuan S, Feng G (2017) Development of an irrigation scheduling software based on model predicted crop water stress. Comp Electron Agr 143:208–221. https://doi.org/10.1016/j.compag.2017.10.023

Huang R-C (2018) The discoveries of molecular mechanisms for the circadian rhythm: The 2017 nobel prize in physiology or medicine. Biomed J 41:5–8. https://doi.org/10.1016/j.bj.2018.02.003

Article   PubMed   PubMed Central   Google Scholar  

Huang Y, Zhao P, Zhang Z, Li X, He C, Zhang R (2008) Transpiration of cyclobalanopsis glauca (syn. Quercus glauca) stand measured by sap-flow method in a karst rocky terrain during dry season. Ecol Res 24:791–801. https://doi.org/10.1007/s11284-008-0553-6

Jiang S, Zhao L, Liang C, Hu X, Yaosheng W, Gong D, Zheng S, Huang Y, He Q, Cui N (2022) Leaf- and ecosystem-scale water use efficiency and their controlling factors of a kiwifruit orchard in the humid region of southwest china. Agric Water Manag 260:107329. https://doi.org/10.1016/j.agwat.2021.107329

Kangur O, Kupper P, Sellin A (2017) Predawn disequilibrium between soil and plant water potentials in light of climate trends predicted for northern Europe. Reg Environ Change 17:1–10. https://doi.org/10.1007/s10113-017-1183-8

Kebiao M, Jingming C, Zhaoliang L, Ying M, Yang S, Xuelan T, Kaixian Y (2017) Global water vapor content decreases from 2003 to 2012: An analysis based on modis data. Chin Geogra Sci 27:1–7. https://doi.org/10.1007/s11769-017-0841-6

Konno Y (2001) Feedback regulation of constant leaf standing crop in sasa tsuboiana grasslands. Ecol Res 16:459–469. https://doi.org/10.1046/j.1440-1703.2001.00421.x

Kukal MS, Irmak S (2022) Nocturnal transpiration in field crops: Implications for temporal aggregation and diurnal weighing of vapor pressure deficit. Agric Water Manag 266:107578. https://doi.org/10.1016/j.agwat.2022.107578

Kuwagata T, Ishikawa-Sakurai J, Hayashi H, Nagasuga K, Fukushi K, Ahamed A, Takasugi K, Katsuhara M, Murai-Hatano M (2012) Influence of low air humidity and low root temperature on water uptake, growth and aquaporin expression in rice plants. Plant Cell Physiol 53:1418–1431. https://doi.org/10.1093/pcp/pcs087

Leuschner C (2002) Air humidity as an ecological factor for woodland herbs: leaf water status, nutrient uptake, leaf anatomy, and productivity of eight species grown at low or high VPD levels. Flora 197:262–274. https://doi.org/10.1078/0367-2530-00040

Li Y, Ye J, Xu D, Zhou G, Feng H (2022) Prediction of sap flow with historical environmental factors based on deep learning technology. Comput Electron Agr 202:107400. https://doi.org/10.1016/j.compag.2022.107400

Litvak E, McCarthy HR, Pataki DE (2017) A method for estimating transpiration of irrigated urban trees in california. Landscape Urban Plann 158:48–61. https://doi.org/10.1016/j.landurbplan.2016.09.021

Liu X, Li Y (2016) Varietal difference in the correlation between leaf nitrogen content and photosynthesis in rice (Oryza sativa L.) plants is related to specific leaf weight. J Integr Agric 15:2001–2011. https://doi.org/10.1016/s2095-3119(15)61262-x

Luis R, Amal B, Lamia R, Juan MR (1997) Response of plant yield and leaf pigments to saline conditions: Effectiveness of different rootstocks in melon plants (cucumis melol.). Soil Sci Plant Nutr 43:855–862. https://doi.org/10.1080/00380768.1997.10414652

Ma LL, He JX, Li JM (2023) Temporal and spatial diurnal dynamics of the hysteresis of weighed transpiration and water transport in tomatoes. Environ Exp Botany 208:105238. https://doi.org/10.1016/j.envexpbot.2023.105238

Article   CAS   Google Scholar  

Makoto T, Tyree MT (2000) Plant hydraulic conductance measured by the high pressure flow meter in crop plants. J Exp Bot 51:823–828

McAdam SAM, Brodribb TJ (2016) Linking turgor with aba biosynthesis: Implications for stomatal responses to vapor pressure deficit across land plants. Plant Physiol 171:2008–2016

Morris L, Neale F, Postlethwaite J (1957) The transpiration of glasshouse crops, and its relationship to the incoming solar radiation. J Agric Eng Res 2:111–122

Google Scholar  

Oogathoo S, Houle D, Duchesne L, Kneeshaw D (2020) Vapour pressure deficit and solar radiation are the major drivers of transpiration of balsam fir and black spruce tree species in humid boreal regions, even during a short-term drought. Agr Forest Meteorol 291:108063. https://doi.org/10.1016/j.agrformet.2020.108063

Pantin F, Simonneau T, Rolland G, Dauzat M, Muller B (2011) Control of leaf expansion: A developmental switch from metabolics to hydraulics. Plant Physiol 156:803–815. https://doi.org/10.1104/pp.111.176289

Resco de Dios V, Gessler A (2018) Circadian regulation of photosynthesis and transpiration from genes to ecosystems. Environ Exp Botany 152:37–48. https://doi.org/10.1016/j.envexpbot.2017.09.010

Rigden AJ, Salvucci GD (2017) Stomatal response to humidity and co2 implicated in recent decline in us evaporation. Glob Change Biol 23:1140–1151. https://doi.org/10.1111/gcb.13439

Shi L, Shi G, Qiu H (2019) General review of intelligent agriculture development in china. China Agr Econ Rev 11:39–51. https://doi.org/10.1108/CAER-05-2017-0093

Simonin KA, Burns E, Choat B, Barbour MM, Dawson TE, Franks PJ (2015) Increasing leaf hydraulic conductance with transpiration rate minimizes the water potential drawdown from stem to leaf. J Exp Bot 66:1303–1315. https://doi.org/10.1093/jxb/eru481

Spinelli GM, Shackel KA, Gilbert ME (2017) A model exploring whether the coupled effects of plant water supply and demand affect the interpretation of water potentials and irrigation management. Agr Water Manag 192:271–280. https://doi.org/10.1016/j.agwat.2017.07.019

Srivastav AL, Dhyani R, Ranjan M, Madhav S, Sillanpää M (2021) Climate-resilient strategies for sustainable management of water resources and agriculture. Environ Sci Poll Res 28:41576–41595. https://doi.org/10.1007/s11356-021-14332-4

Stuerz S, Asch F (2019) Responses of rice growth to day and night temperature and relative air humidity-dry matter, leaf area, and partitioning. Plants (basel). https://doi.org/10.3390/plants8110521

Tezcan AK, Büyüktaş K, Büyüktaş D, Baştuğ R (2019) Equations developed to estimate evapotranspiration in greenhouses. Yüzüncü Yıl Üniversitesi Tarım Bilimleri Dergisi 28(4):482–489

Ueda M, Nakamura Y (2007) Chemical basis of plant leaf movement. Plant Cell Physiol 48:900–907. https://doi.org/10.1093/pcp/pcm060

Xu K, Guo X, He J, Yu B, Tan J, Guo Y (2022) A study on temperature spatial distribution of a greenhouse under solar load with considering crop transpiration and optical effects. Energy Conv Manage 254:115277. https://doi.org/10.1016/j.enconman.2022.115277

Yang X, Short TH, Fox RD, Bauerle WL (1990) Transpiration, leaf temperature and stomatal resistance of a greenhouse cucumber crop. Agr Forest Meteorol 51:197–209. https://doi.org/10.1016/0168-1923(90)90108-I

Yu XM, Zhao MF, Wang XY, Jiao XC, Song XM, Li JM (2022) Reducing vapor pressure deficit improves calcium absorption by optimizing plant structure, stomatal morphology, and aquaporins in tomatoes. Environ Exp Botany 195:104786. https://doi.org/10.1016/j.envexpbot.2022.104786

Zhang D, Jiao X, Du Q, Song X, Li J (2018) Reducing the excessive evaporative demand improved photosynthesis capacity at low costs of irrigation via regulating water driving force and moderating plant water stress of two tomato cultivars. Agric Water Manag 199:22–33. https://doi.org/10.1016/j.agwat.2017.11.014

Church J, Clark P, Cazenave A, Gregory J, Unnikrishnan A (2013) Climate change 2013: The physical science basis. Contribution of working group i to the fifth assessment report of the intergovernmental panel on climate change. Computational Geometry.

Hall A E, Kaufmann M R (1975) Regulation of water transport in the soil-plant-atmosphere continuum. Perspectives of biophysical ecology: 187–202.

Download references

Acknowledgements

This work was supported by [National Key R&D Program of China] (Grant numbers [2019YFD1001903]

This work was supported by [Key R&D Program of Shaanxi Province] (Grant numbers [2022ZDLNY03-01].

Author information

Authors and affiliations.

College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China

Jiaxing He, Lele Ma, Wenxin Li, Chenxi Zhu, Minggao Liu & Jianming Li

You can also search for this author in PubMed   Google Scholar

Contributions

J.H. and J.L. conceived and designed the experiments. J.H., L.M., W.L., C.Z., M.L. performed the experiments. J.H. prepared the manuscript, and J.L. contributed extensively to its finalization. All authors reviewed the manuscript.

Corresponding author

Correspondence to Jianming Li .

Ethics declarations

Conflict of interest.

The authors declare that they have no conflict of interests.

Additional information

Handling Author: T. Casey Barickman.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

He, J., Ma, L., Li, W. et al. Advanced Decision-Making Irrigation Regulated by VPD Changed the Circadian Transpiration Pattern of Tomatoes. J Plant Growth Regul (2024). https://doi.org/10.1007/s00344-024-11461-1

Download citation

Received : 13 April 2023

Accepted : 19 July 2024

Published : 22 August 2024

DOI : https://doi.org/10.1007/s00344-024-11461-1

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Transpiration
• Advanced decision irrigation
• Vapor pressure deficit
• Find a journal
• Publish with us
• Track your research

How will you prove that chlorophyll is required for photosynthesis to take place?

Introduction photosynthesis is an important physiological activity of all green plants. for photosynthesis to occur in green plants the factors required are sunlight, chlorophyll and carbon dioxide. one factor that is more important for green plants to prepare their own food is the presence of chlorophyll pigment in their leaves.to prove the necessity of this factor there specific experiment to be done in the laboratory. so students must know clearly how this particular experiment will be done to prove the importance of this factor clearly and also must know why a particular step will be done for the success of this experiment with reasons. here is how oxygen is evolved by green plants in an experiment on photosynthesis aim of the experiment :- to prove that chlorophyll pigment in green leaves is necessary for the plants to prepare their carbohydrate (starch) food. requirements for the experiment: - a well watered variegated leaf plant, beaker, water, bunsen burner, mentholated spirit or rectified spirit or ethanol, iodine solution, a white porcelain tile. procedure for the experiments:- a variegated leaf plant is taken for this particular experiment to prove the necessity of chlorophyll for photosynthesis. a variegated leaf is a leaf in which different patches of colors are present in a croton or coleus or geranium plant. the place where green patches are present in the leaf, chlorophyll pigment is present while at the other color patches present in the leaf contain other pigments but not chlorophyll. before starting the experiment to prove chlorophyll is necessary for photosynthesis an important step has to be carried out is known as de-starching. de-starching is a step in which the starch present in the leaves of the plant will be removed by keeping the variegated leaves plant in a dark room or closed cup-board for about 48 hours. this step is done to ensure that previously synthesized starch in the leaves get consumed up because photosynthesis doesn't occur at that time as the plant is kept in dark place. after de-starching step the variegated leaf plant is kept in bright sunlight for about 6 hours. after this one of the variegated leaf is plucked out from the experimental plant. then iodine test is conducted for this experimental leaf to find out whether the leaf prepared starch through photosynthesis or not. steps to be followed for iodine test:- the plucked out experimental leaf is immersed in boiling water in the beaker for few minutes so that the cells of the leaf will be killed and at the same time metabolic activities of the leaf cells will be stopped. now the boiled leaf is taken out from the beaker with the help of a forceps. it is then placed in a test tube containing rectified spirit or ethanol. then the leaf is boiled in ethanol over a water bath by keeping it in boiling water for about 10 minutes. the leaf dissolves its chlorophyll by boiling it in rectified spirit and then become pale-white. next the pale-white leaf is removed from the test tube by forceps and then it is washed in under warm water to make it soft. then this leaf is spread over a white porcelain tile and iodine drops were placed over at different parts of the leaf. result of iodine test:- iodine is a purple colored reagent used to test the presence or absence of starch in the leaf conducted for photosynthesis process. in the presence of starch iodine solution will turn into blue-black color and in the absence of starch iodine added to leaf will turn into brown color. in this experimental leaf, the part of the variegated leaf which contain green patches will give a positive test for starch i.e. iodine when added to this part of the leaf will turn into blue-black color. the reason for this is, this part of the experimental leaf containing green patches include chlorophyll and thus prepare starch through photosynthesis. thus iodine added to this region will turn into blue-back color. but colored patches of variegated leaf doesn't include chlorophyll and thus don't prepare starch through photosynthesis. so iodine added in this region will change into brown color. thus this experiment proves chlorophyll is necessary for leaves to prepare starch through photosynthesis..

Prove that chlorophyll is necessary for photosynthesis.