aquatic plant growth experiment

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Teacher Guide: Elodea Photosynthesis Light

• Elodea sp. (or Egeria sp. often sold under the common name “anacharis”) in a container of fresh water
• Six 50 mL Erlenmeyer flasks
• Six one-hole #2 rubber stoppers
• Six 1 mL graduated glass serological pipettes
• Red and green light filters
• Aluminum foil
• Thermometer
• Fig. 2.40 and 2.41
• Blue light filter (optional)
• Petroleum jelly (optional)

Fig. 2.40. This diagram of the electromagnetic spectrum emphasizes the small portion of the spectrum that is visible to human eyes. Wavelengths are measured in meters (m) along the grey bar and in nanometers (nm) along the colored bar showing visible light.

Image courtesy of Philip Ronan, Wikimedia Commons

Fig. 2.41. Relative absorbance of the visible wavelengths in sunlight by the pigments chlorophyll a and chlorophyll b

Image courtesy of Daniele Pugliesi and M0tty, Wikimedia Commons

Baking Soda Solution

Baking soda serves as a source of carbon dioxide. The Elodea will be placed in this solution to speed up the photosynthesis reaction .

• Baking soda (sodium bicarbonate, NaHCO 3 )
• Fresh water
• Elodea is a genus of freshwater aquatic plants sold in pet stores for aquariums. Observe and describe the Elodea specimen.  
• Use Fig. 2.40 to determine the range of wavelengths that corresponds to white light and to each color: red, blue, and green. Fill in the first column of Table 2.8.  
• What color(s) does chlorophyll a absorb most? Least?
• What color(s) does chlorophyll b absorb most? Least?  
• Using what you know about the electromagnetic spectrum and chlorophyll, predict the flask that will have the plant with the highest gas production and write “1” in the “Prediction” column of Table 2.8. The more light energy the plant absorbs, the more gas it should produce.
• Write number “2” in the “Prediction” column of Table 2.8 for the flask that you predict will have the second highest gas production.
• Continue numbering in the “Prediction” column of Table 2.8 through “6,” with 6 being the flask that you predict will have the least gas production.  

Photosynthesis should be fastest with ____________ wavelength(s) of light and slowest with ____________ wavelength(s) of light because ________________.  

• Weigh 25 g of baking soda.
• Add baking soda to 1 L of fresh water.
• Stir until the baking soda is completely dissolved.  
• Cut out rectangles of green and red filter paper slightly bigger than the flasks.
• Wrap filters around the flasks, secure with tape. Trim excess filter.
• Wrap one flask with foil.  
• Remove a few branches of Elodea from the holding container. Visually inspect the Elodea, and remove any part of the plant that looks unhealthy or has different leaf morphology (shape) than the rest of the plant. Blot Elodea dry with towels.  
• Using a balance, weigh 2.5 g of Elodea . The Elodea should be as close as possible to 2.5 g, within 0.1 g (i.e., between 2.4 and 2.6 g). Write the weight in Table 2.8.
• Insert Elodea into the flask. If necessary, you can break the Elodea into smaller pieces and use a skewer to distribute the Elodea evenly in the flask.  
• Working over towels, slowly fill each flask all the way to the top with baking soda (sodium bicarbonate) solution.
• Firmly press a stopper into each flask. Sodium bicarbonate solution will spill out of the flask as you insert the stopper. Applying petroleum jelly to the outer surfaces of the rubber stoppers may help to form an airtight seal.
• Insert the pipette into the stopper hole by holding the pipette with a dry towel. Gently twist the tapered tip of the pipette into the stopper until water rises in the pipette and the pipette is firmly in place. The water level should reach between the 0.8 and 0.7 mL lines. DO NOT FORCE the pipette into the stopper as the pipette can break. If you are having difficulty getting the pipette into the stopper, ask your teacher for assistance.
• Dry the outside of each flask with a towel.  
• Set the flasks in the sun. Make sure each flask is exposed to a similar amount of sunlight.  
• Record the starting volume of the liquid in each pipette and the time in Table 2.8. Read the bottom of the meniscus of the water in the pipette. Note that the numbers on the pipette are smallest at the top and largest at the bottom.  
• record the weather conditions, especially noting the amount of sunlight, and
• observe what is happening in the pipettes and the flasks without disturbing the light filters or foil.  
• At the end of the experiment, record the ending volume (water level) in each pipette and the time in Table 2.8.  
• Subtract the start volume from the final volume to get the total amount of gas produced in each flask. Record the amount in Table 2.8.  
• Rank the gas production in each flask, by writing “1” in the “Observation” column for the flask with the plant the produced the most gas and numbering through “6” for the flask that produced the least gas.
• OPTIONAL: repeat procedure steps 7 to 16 using a blue light filter.  
• Holding the pipette with a dry towel, gently twist the pipette while pulling up to remove it from the stopper. Stand the pipette upright in a container and let it drip dry.
• Remove the stopper from the flask.
• Dispose of the plants and sodium bicarbonate solution as directed by your teacher. Clean each flask.
• Wipe the light filters with fresh water to remove traces of sodium bicarbonate solution.  
• Compare your results to those of other groups using a class data chart.
• What caused the water in the pipettes to rise?  
• What gas is being produced in the flasks by Elodea ? What process is producing this gas?  
• Compare your predictions and observations. Was your hypothesis supported? Why or why not? Give you answer in terms of absorption of wavelengths by chlorophyll pigments.  
• How did your results compare to those of the rest of the class? Hypothesize possible reasons for any unexpected results.  
• What gas is likely being produced?
• What process is likely producing this gas?  
• What was the purpose of the clear flask with no plant? In other words, is the production of gas the only thing that may affect the starting and ending water volume in the flasks?  
• How can you use the results of your control flasks to more accurately calculate gas production in the other flasks?  
• How can this experiment be improved to more accurately measure the photosynthesis rate in Elodea ? What sources of error can be further controlled?  
• Why are plants green? Answer in terms of the wavelengths of light they absorb. (Hint: What colors do chlorophyll a and chlorophyll b absorb and reflect?)  
• Based on Fig. 2.40, if green glass is a green-yellow color, what range of wavelengths might it be reflecting?  
• Based on Fig. 2.40 and Fig. 2.41, what color(s) would the pigments chlorophyll a and chlorophyll b appear to the human eye?

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Plant Growth and Osmotic Potential

Water is a critical element for plant growth. All water used by land plants is absorbed from the soil by roots through osmosis. Osmosis is the movement of a solvent (e.g.water) across a semipermeable membrane from low solute (e.g.salt) concentration towards higher solute concentration. Excess levels of salts in soils makes soil water solute concentrations higher than in the plant root cells. This can limit plant water uptake, making it harder for plants to grow. (See Appendix A for more information)

About the Experiment

For this experiment, we’re going to test the effect that high salt soil concentrations have on plant growth and root development.

 What You'll Need

• 7 clear plastic cups (Solo cups)
• 7 non-clear plastic cups
• Potting soil (small bag)
• Wheatgrass or cat grass seed (250 seeds, can be found online or at local pet store)
• Baking soda
• Measuring spoons
• Drill & small bit

When using table salt (sodium chloride) and baking soda (sodium bicarbonate) to create saline and alkali soils, you can observe the germination and growth of grass leaves at increasing levels of salt and ph. Then you can treat the salt/alkali effected soils with "leaching" and observe plant growth.

ORIGINAL RESEARCH article

Effects of rising temperature on the growth, stoichiometry, and palatability of aquatic plants.

• 1 Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, Netherlands
• 2 Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China

Global warming is expected to strengthen herbivore-plant interactions leading to enhanced top-down control of plants. However, latitudinal gradients in plant quality as food for herbivores suggest lower palatability at higher temperatures, but the underlying mechanisms are still unclear. If plant palatability would decline with temperature rise, then this may question the expectation that warming leads to enhanced top-down control. Therefore, experiments that directly test plant palatability and the traits underlying palatability along a temperature gradient are needed. Here we experimentally tested the impact of temperature on aquatic plant growth, plant chemical traits (including stoichiometry) and plant palatability. We cultured three aquatic plant species at three temperatures (15, 20, and 25°C), measured growth parameters, determined chemical traits and performed feeding trial assays using the generalist consumer Lymnaea stagnalis (pond snail). We found that rising temperature significantly increased the growth of all three aquatic plants. Plant nitrogen (N) and phosphorus (P) content significantly decreased, and carbon (C):N and C:P stoichiometry increased as temperature increased, for both Potamogeton lucens and Vallisneria spiralis , but not for Elodea nuttallii . By performing the palatability test, we found that rising temperatures significantly decreased plant palatability in P. lucens , which could be explained by changes in the underlying chemical plant traits. In contrast, the palatability of E. nuttallii and V. spiralis was not affected by temperature. Overall, P. lucens and V. spiralis were always more palatable than E. nuttallii . We conclude that warming generally stimulates aquatic plant growth, whereas the effects on chemical plant traits and plant palatability are species-specific. These results suggest that the outcome of the impact of temperature rise on macrophyte stoichiometry and palatability from single-species studies may not be broadly applicable. In contrast, the plant species tested consistently differed in palatability, regardless of temperature, suggesting that palatability may be more strongly linked to species identity than to intraspecific variation in plant stoichiometry.

Introduction

Global warming is one of the most urgent threats to our ecosystems ( IPCC, 2014 ). The effect of warming has become visible in aquatic ecosystems by rising surface water temperatures and a reduction in ice cover over the last decades ( Mooij et al., 2005 ; Woolway et al., 2017 ). Temperature rise is furthermore expected to lead to alterations in aquatic communities and their food web interactions ( Meerhoff et al., 2012 ). Several of these changes are already observed: average fish size in temperate fish communities decreases with increasing water temperatures, and the communities tend to contain a higher proportion of omnivorous fishes at the expense of carnivory ( Jeppesen et al., 2010 ). Even without shifting their diet, warming increases the plant consumption rate of plants by ectotherm omnivores and herbivores ( Zhang et al., 2018 ). Warming is thus expected to strengthen herbivore-plant interactions leading to enhanced top-down control of plants ( O'Connor, 2009 ; Gutow et al., 2016 ).

However, these predictions do not take into account that warming might also affect the plant traits that determine their palatability to herbivores. If plant palatability declines with temperature, then this may alter the expectation that warming leads to enhanced top-down control ( O'Connor, 2009 ). Studies mimicking global warming showed inconsistent effects of temperature on plant palatability, either decreasing palatability in marine plants ( Rodil et al., 2015 ), or having no discernible effect in either terrestrial ( Backhaus et al., 2014 ) or marine plants ( Poore et al., 2016 ). Temperature has been suggested to underlie latitudinal gradients in plant quality as food for herbivores: more palatable plants at higher latitudes suggest lower palatability at higher temperatures ( Pennings et al., 2007 ; Morrison and Hay, 2012 ). However, the underlying mechanisms are still unclear: this might be because plants are better defended at lower latitudes ( Bolser and Hay, 1996 ), or because plant nitrogen and phosphorus content increases with latitude ( Reich and Oleksyn, 2004 ; Schemske et al., 2009 ) or both ( Grutters et al., 2017 ). In addition, not all studies find latitudinal effects on plant palatability ( Adams et al., 2009 ; Moles et al., 2011 ), and factors other than temperature may be causing the observed patterns. Therefore, experiments that directly test the effect of temperature on plant palatability and the traits underlying palatability are needed.

Plant palatability depends largely on three groups of plant traits: plant nutritional traits, plant physical structure and plant secondary metabolites (PSM) ( Hay, 1996 ; Cronin et al., 2002 ; Elger and Lemoine, 2005 ). With rising temperature, aquatic plants grow faster ( Madsen and Brix, 1997 ; Short and Neckles, 1999 ). With increased growth, there could be a nutrient (nitrogen and phosphorus in this study) dilution effect: where these nutrients become limited, the nutrient concentrations in the plant decrease, and if the carbon source is not limited, carbon:nitrogen and carbon:phosphorus stoichiometry increases ( Dülger et al., 2017 ; Velthuis et al., 2017 ). A decrease in plant nitrogen content and increased carbon:nutrient stoichiometry correspond to reduced consumption rates by herbivores ( Sterner and Elser, 2002 ; Cebrian and Lartigue, 2004 ; Bakker et al., 2016 ). Plant physical structure or toughness ( Gross and Lombardo, 2018 ), here represented by leaf dry matter content ( Pennings et al., 1998 ; Elger and Willby, 2003 ), might also increase with rising temperature, as relatively more carbon accumulates in the plant tissues. PSM, in particular phenolic compounds, are produced by aquatic plants and can act as deterring compounds ( Dorenbosch and Bakker, 2011 ; Grutters et al., 2017 ). However, the effect of warming on PSM in aquatic plants is unknown.

In this study, we tested the effect of temperature on aquatic plant growth, tissue stoichiometry, plant physical structure and PSM and the consumption rates of a generalist consumer. We performed two sequential experiments in which we first grew three common submerged freshwater vascular plant species at three temperatures (15, 20, and 25°C) under standardized nutrient conditions. We determined the resultant plant growth and plant traits and subsequently performed a second experiment to quantify the feeding rates of a generalist consumer on the plants grown at different temperatures. We hypothesized that rising temperature will (1) increase plant growth, (2) decrease plant nutrient concentration and increase carbon:nutrient stoichiometry, (3) increase toughness, (4) decrease consumption rates.

Materials and Methods

Aquatic plant growth experiment.

We selected three submerged aquatic plant species: Elodea nuttallii (Planch.) St. John, Vallisneria spiralis L. and Potamogeton lucens L. for the plant growth experiment. These species were chosen because of their wide distribution, representation of different plant genera and high palatability to the pond snail Lymnaea stagnalis L. ( Elger et al., 2004 ; Grutters et al., 2017 ). E. nuttallii and P. lucens propagules were collected near NIOO-KNAW, Wageningen, The Netherlands. V. spiralis seedlings were obtained from the local garden center (Tuincentrum De Oude Tol, Wageningen, The Netherlands). For E. nuttallii , 7 cm apical shoots with 2 or 3 branches were chosen. For V. spiralis , plants were chosen with a shoot length of 24.2 ± 3.7 cm (mean ± SD, n = 45), from which the largest outer leaves were removed. This resulted in plants with 5–7 young leaves in the rosette. For P. lucens , lower part of stems with 2 or 3 nodes to sprout new roots and leaves were selected, with a length of 23.7 ± 4.9 cm (mean ± SD, n = 45). Even though the heights are different, their initial biomass was very low and similar at the beginning, and the height we chosen can also make sure that the plants are alive. Plant propagules were planted in the pots, first acclimated at 20°C for 2 weeks, and then assigned to their final controlled temperatures. We grew these plants in fifteen temperature-controlled aquaria (90 × 50 × 50 cm, l × w × h) at 15, 20, and 25°C, each with five replicate aquaria. These temperatures are within suitable ranges of these species in nature. In each aquarium, we had three replicates per species following a random design, totaling nine plants per aquarium. Fifteen un-sprouted P. lucens propagules were replaced at the beginning of the culturing (one pot in each aquarium).

Temperature was controlled by an automatic control system (Cascade Automation Systems, Ridderkerk, the Netherlands). A mixing pump was placed inside each aquarium to circulate the water, equalize the temperature and increase the CO 2 concentration. In order to reduce nutrient competition between different plants, each individual was cultured in a separate pot (top diameter 12.5 cm, bottom diameter 11 cm and height 11 cm). Each pot was filled to a depth of 7 cm with pond sediment [Pokon Naturado, Veenendaal, the Netherlands; rich in organic matter, but low in total nitrogen (TN) 8.5 ± 1.1 mg g −1 dry soil and total phosphorus (TP) 0.23 ± 0.05 mg g −1 ( n = 3, mean ± SD)], and then covered with a 2 cm layer of sand to reduce nutrient release to the water layer. Each aquarium was filled with tap water (TN, 0.087 ± 0.004 mg L −1 ; TP, 0.013 ± 0.0006 mg L −1 ; n = 3, mean ± SD) yielding a water depth of 30 cm. Demineralized water was added weekly to compensate for evaporation. Two great ramshorn snails Planorbarius corneus L. (shell diameter of 2.7 ± 0.1 cm, mean ± SD, n = 30) were added to each aquarium to control periphyton. They only consumed periphyton, not our plant species and equally consumed periphyton on all plants, as tested in pre-trials. Aquaria were individually illuminated by lamps above each aquarium to reach a 16:8 h day: night cycle and each aquarium was individually wrapped in aluminum foil to prevent light interference among aquaria and to increase light intensity within the aquaria by reflection. The light intensity at the water surface was 47.1 ± 3.2 μmol m −2 s −1 (a moderate light intensity, mean ± SD, n = 7).

Plants were grown in the experiment for 16 weeks from August 16th to December 6th 2015. During the experiment, the plants continued their growing season because they were kept indoors without natural seasonality. Water quality parameters were measured five times during the experiment. Conductivity, pH and dissolved oxygen were checked with a multi–meter (Multi 350i/SET, Germany) in the afternoon of each sampling day. Alkalinity was measured by an auto-titration machine by adding acid (0.1M HCl) until a pH of 4.2 was reached (TIM840 titration manager, Germany). Chlorophyll a (Chl a) was determined by a phytoplankton analyser (PHYTO-PAM, WALZ, Germany). Before harvesting the plants, part of the water was replaced by tap water in some of the 20 and 25°C aquaria to decrease the phytoplankton biomass. Ammonium (NH 4 + ), nitrate (NO 3 - ), nitrite (NO 2 - ) and orthophosphate (PO 4 3 - ) were analyzed by an AutoAnalyzer (QuAAtro, Seal Analytical, Fareham, UK) after filtering water samples over GF/F filter (Whatman, Maidstone, UK). The values of the water quality parameters during the experiment are given in Figure S1 .

Periphyton was quantified by measuring the dry mass of algae removed from a selected plant surface area of V. spiralis at the end of the experiment following Zimba and Hopson (1997) . The algae were removed by cutting two pieces of V. spiralis leaves (leaf surface area of 23.88 ± 6.65 cm 2 , mean ± SD, n = 15), as the leaf area of V. spiralis is easy to quantify, shaking them in 30 ml of demineralized water for 30 s, filtering the periphyton onto a pre-weighed GF/F filter (Whatman, Maidstone, UK) and drying the material at 60°C for 48 h. The leaf areas of the cut leaves were measured by first scanning the leaves on a piece of A4 paper, then calculating the surface area with ImageJ ( Rasband, 2015 ). The periphyton data are given in Figure S2 .

To investigate how the availability of nutrients to the plants from the sediment in their pots was affected by plant species and temperature, sediment porewater was sampled using rhizons (Rhizosphere, Wageningen, the Netherlands) at the end of the experiment; porewater nutrient concentrations were assumed to be equal among the treatments at the start of the experiment. Total dissolved inorganic nitrogen (TIN: including NH 4 + , NO 3 - , NO 2 - ) and PO 4 3 - concentrations in porewater were determined in one pot per species per aquarium, in total 45 pots were measured. At the end of the experiment, part of the plant tissue in each pot was cut for the feeding trials and the rest was harvested to quantify dry biomass. Shoots and roots were separately cleaned by rinsing with tap water until no visible residue material was attached, including periphyton and sediment particles, and dried in the oven at 60°C for 48 h. Plant relative growth rate was calculated according to the equation: Relative growth rate = (ln W f – ln W i )/Days; with W f = final dry mass; W i = initial dry mass. Plant initial dry mass was estimated by drying spare plants which were selected randomly ( n = 30 for E. nuttallii, n = 46 for V. spiralis , and n = 33 for P. lucens ) at the beginning of the experiment.

Snail Feeding Experiment

We selected L. stagnalis for our feeding trials, a generalist freshwater mollusk that has often been used in feeding trials ( Elger and Barrat-Segretain, 2002 , 2004 ; Grutters et al., 2017 ), which feeds on a wide variety of vascular aquatic plants ( Gaevskaia, 1969 ), and does select the plants based on their traits ( Elger et al., 2004 ; Gross and Lombardo, 2018 ). L. stagnalis has a holarctic distribution overlapping with the plant species that we study, therefore our study represents the aquatic plant-herbivore interactions as they can be found in the field. Mollusks can have a large impact on aquatic plant abundance in the field ( Lodge, 1991 ; Newman, 1991 ; Wood et al., 2017 ). For our feeding experiment, egg clusters from a single population (collected in a pond on the terrain of NIOO-KNAW, 51°59′16.9″N, 5°40′23.5″E) were hatched. After two weeks all the juveniles were transferred to plastic buckets, each filled with 15 liters of groundwater (20°C), and exposed to a 16:8 h day: night cycle. The snails were fed butterhead lettuce 5 days per week. Fish food pellets (Velda, Gold Sticks Basic Food, the Netherlands) and chalk were supplied once a week as food supplements, following Grutters et al. (2017) . All water was fully replaced once a week. All snails were grown for 2 months before the feeding trials started. Snails used in the trials had an average shell length of 24.0 ± 1.7 mm and a dry mass (excluding their shell) of 0.17 ± 0.04 g (mean ± SD, n = 129).

No-choice feeding trials were carried out to assess whether the temperature at which the plants were grown affected their palatability. The trials followed the standard protocol developed for aquatic snails ( Elger and Barrat-Segretain, 2002 , 2004 ; Grutters et al., 2017 ). In total we used 270 plastic beakers (500 ml), each filled with 375 ml ground water. Prior to the feeding trials, all snails were starved for 48 h following the standard protocol, and visible periphyton was removed from all plant material. The 270 beakers were divided into 135 experimental and 135 paired control beakers. Each experimental beaker received plant material from one plant pot, yielding fifteen replicates per plant species grown at each temperature, with in total 135 beakers containing both one snail and plant fragments. The 135 paired control beakers received plant fragments from the same pot as its experimental counterpart that weighed the same amount, to monitor potential autonomous changes in plant mass for each feeding trail during the 24 h feeding experiment. Snails were offered approximately 0.1 g (wet mass) of apical shoot of E. nuttallii , about 0.4 g (wet mass) newly grown V. spiralis leaves, and about 0.12 g wet mass for P. lucens . For P. lucens , leaves lower than the third leave from the top were selected, cut into two equally sized portions with the midrib removed. The amount of plant materials we offered to snails differed among the three species because we offered the maximum amounts according to the consumption per snail for each plant species, as determined in pre-trials. This lowered the measurement errors on small amounts of materials and therefore increased the precision of the measurements. All the plant materials (including the control portion) were cleaned to remove periphyton before being offered to the snails. Beakers were covered with mesh to prevent the snails from escaping. All the trials lasted 24 h and were performed with a 16:8 h day: night cycle at a water temperature of 20°C. We performed all experiments at the same temperature of 20°C to ensure that any potential preference of snails for plants grown at different temperatures was only due to plant quality, and any direct influence of water temperature on snail metabolism and feeding rates was avoided. All feeding trials were randomly divided into two sessions, for logistical reasons. After the feeding trials, snails were first frozen to death at −20°C, and the soft body was separated from its shell, then dried in the oven at 60°C for at least 48 h. The mean snail dry mass without shell was 0.07 ± 0.01 g (mean ± SD, n = 129). At the end of the feeding experiment all the remaining plant material was collected and also dried in the oven at 60°C for at least 48 h and weighed.

Plant Relative Consumption Rate (RCR) (mg g −1 d −1 ) was calculated following Elger and Barrat-Segretain (2002) : RCR = [(C fd /C iw ) * F iw – F fd ]/S d /1day, in which, C fd is the final dry mass of the paired control plant, C iw is the initial wet mass of the paired control plant, F iw is the initial wet mass of the feeding trial plant, F fd is the final dry mass of the feeding trial plant, and S d is the snail dry mass without shell.

Plant Chemical Analyses

Plant fragments used as control in the feeding trials were analyzed for their dry matter content and chemical composition. Plant dry matter content was determined as the dry mass divided by the wet mass and expressed as percentage. Each plant sample was ground individually in a 2 ml tube on a Tissuelyser II (QIAGEN, Hilden, Germany). Plant carbon (C) and nitrogen (N) were determined on an elemental auto analyser (FLASH 2000, Thermo Scientific, Waltham, MA, USA). Phosphorus (P) content was determined by incinerating and digesting the sample, and then analyzing the phosphate concentration on an Auto Analyzer (QuAAtro method, Seal Analytical, Fareham, UK). For total phenolics analysis, between 2 and 4 mg of plant material was extracted with 1 ml of 80% ethanol for 10 min at 80°C before adding Sodium dodecyl sulfate solution and FeCl 3 reagent. The resulting reduction of Fe 3+ to Fe 2+ was measured at 510 nm on a spectrophotometer (Synergy HT Microplate Reader, BioTek, Winooski, VT, USA) against a tannic acid calibration curve ( Hagerman and Butler, 1989 ; Smolders et al., 2000 ). We expressed phenolic content as mg tannic acid equivalents per gram plant dry mass.

Data Analyses

Data were analyzed in multiple linear mixed-effects models. Dependent variables were the 4 plant growth parameters (Shoot biomass, Root biomass, Relative growth rate and Root:Shoot ratio), 2 nutrient parameters (Porewater TIN and PO 4 3 - concentration), 9 plant traits (Plant dry matter content, C content, N content, P content, C:N ratio, C:P ratio, N:P ratio, Total phenolics concentration and N:Phenolics ratio) and Relative Consumption Rates by snails. Effects of temperature and differences between plant species were tested by including temperature as continuous variable, species as fixed factor and their interaction. Aquarium was included as a random factor. The significance of included terms was tested by model selection based on AICc values ( Burnham and Anderson, 2002 ; Burnham et al., 2011 ). We discuss the contributions of all terms included in the top ranking models (ΔAICc < 2.0 from the best model, for model selection see Data Sheet 1 ). A Tukey post-hoc test (package: lsmeans) was applied after each linear mixed-effects model test to compare the difference of the means among the three species ( Lenth, 2016 ). To test effects of temperature on the 16 dependent variables for individual species we used a second set of models, in which we included only temperature as a continuous predictor variable and aquarium as a random factor.

Three snails (2.2%) died during the feeding experiment, one snail per plant species treatment. Three P. lucens (each from one of the temperature treatments) did not have enough material for the feeding trials. These data points were excluded from the dataset. Pearson's correlations were used to test for correlations among all the different plant traits in all species simultaneously and separately within each species. For the mixed-modeling we used the package nlme ( John and Sanford, 2011 ; Pinheiro et al., 2016 ) in R version 3. 4. 1 (R Development Core Team, 2017 ).

Plant Growth and Sediment Nutrients

In our experiment, the final shoot biomass, root biomass, and relative growth rate increased significantly with temperature for all plant species (Table 1 , Figures 1A–C ). P. lucens had the greatest growth, V. spiralis intermediate and E. nuttallii the least (Table 1 , Figures 1A–C ). The plant root:shoot ratio showed a species-specific response to increasing temperature: for both P. lucens and E. nuttallii root:shoot ratios decreased as temperature increased, whereas there was no temperature effect on V. spiralis . However, V. spiralis had a higher root:shoot ratio than the other two species (Table 1 , Figure 1D ).

Table 1 . Linear mixed-effect model results for the effects of temperature and species on the plant growth and sediment pore water nutrient parameters, plant traits and RCR.

Figure 1 . Responses of aquatic plant growth parameters and available nutrients to rising temperature in the three aquatic plants. (A) plant shoot biomass, (B) plant root biomass, (C) plant relative growth rate, (D) plant root:shoot ratio, (E) sediment pore water total dissolved inorganic nitrogen concentrations (TIN), and (F) sediment pore water dissolved inorganic P-PO 4 3 - . Point with bar represents mean ± SE ( n = 15 for points of growth parameters and n = 5 for points of pore water nutrient concentrations). Temperature effects on the parameters of each species are indicated by regression lines. A solid line indicates p < 0.05, a dotted line indicates 0.05 < p < 0.1, and without line indicates p > 0.1.

Sediment porewater total inorganic nitrogen (TIN) and PO 4 3 - concentrations decreased as temperature increased. The concentrations also differed among species, with a higher porewater nutrient content for E. nuttallii than for the other two species (Table 1 , Figures 1E,F ). During the experiment, alkalinity decreased from 1.5 to 1.0 meq L −1 (Figure S1d ). Nutrients (N and P) were limiting in the water layer (almost 0 after the first 2 weeks, Figures S1f–i ), but not limited in the sediment (Figures 1E,F ).

Plant Traits

Plant stoichiometry showed a species-specific response to rising temperatures (Table 1 , Figure 2 ). Plant C content decreased in P. lucens , remained unaltered in V. spiralis , and decreased in E. nuttallii as temperature increased (Table 1 , Figure 2B ). Temperature had an effect on both plant N and P content, which showed a significant decrease with rising temperature for P. lucens and V. spiralis , though there was no significant influence on E. nuttallii (Figures 2C,E ). The plant C:N ratio significantly increased for P. lucens but not for the other species (Figure 2D ). The plant C:P ratio significantly increased with rising temperature in both P. lucens and V. spiralis , whereas there were no effects on E. nuttallii (Figure 2F ). The plant N:P ratio significantly decreased in E. nuttallii but not in the other species, whereas V. spiralis had the lowest N:P ratio (Table 1 , Figure 2G ). The plant N content was the highest and C:N ratio was the lowest in E. nuttallii , whereas the plant P content was the highest and C:P ratio was the lowest in V. spiralis (Table 1 ).

Figure 2 . Response of aquatic plant traits and palatability to rising temperature in the three aquatic plants. (A) plant dry matter content, (B) plant C content, (C) plant N content, (D) plant C:N ratio, (E) plant P content, (F) plant C:P ratio, (G) plant N:P ratio, (H) plant total phenolics concentration, (I) plant N:Phenolics ratio, and (J) plant palatability indicates plant relative consumption rate, RCR. Point with bar represents mean ± SE ( n = 15 for each point). Temperature effects on the parameters of each species are indicated by regression lines. A solid line indicates p < 0.05, a dotted line indicates 0.05 < p < 0.1, and without line indicates p > 0.1.

In P. lucens and V. spiralis , we found that foliar N and P content were negatively correlated with plant total biomass (Figures 3A,B ) and were positively correlated with sediment porewater TIN concentration (Figure 3C ) and PO 4 3 - concentration (Figure 3D ), respectively. The sediment porewater nutrient concentrations were negatively correlated with plant total biomass (Figures 3E,F ).

Figure 3 . Pearson's correlations of plant total biomass, plant nutrient contents and porewater nutrient concentrations for the three tested species. Each species has 15 data points from every temperature treatment, in total 45 points for each panel. Lines in the graph indicate that factors are significantly correlated at the species level ( p < 0.05). (A) N content in the plants in relation to the total plant biomass. (B) P content in the plants in relation to the total plant biomass. (C) N content in the plants in relation to the total inorganic nitrogen concentration in the porewater. (D) P content in the plants in relation to the phosphorous concentration in the porewater. (E) Total plant biomass in relation to the total inorganic nitrogen concentration in the porewater. (F) Total plant biomass in relation to the phosphorous concentration in the porewater. * p < 0.05, ** p < 0.01, *** p < 0.001.

Other plant traits also showed species-specific responses (Table 1 , Figure 2 ). Plant dry matter content significantly increased with rising temperature in P. lucens , but not in the other species. P. lucens had the highest dry matter content (Table 1 , Figure 2A ). For plant total phenolics, there was no temperature effects for any of the species, whereas P. lucens had the highest total phenolics content (Figure 2H ). In contrast, for the plant N:Phenolics ratio, both P. lucens and V. spiralis showed a significant decrease with rising temperature, whereas no significant influence was found on E. nuttallii . P. lucens had the lowest N:Phenolics ratio (Table 1 , Figure 2I ).

There were several general correlations among chemical plant traits in all three species (Table 2 ). In all species, dry matter content correlated negatively with N content, and positively with plant C:N ratio. N content and P content were positively correlated with each other in all species. Most chemical plant traits were correlated with each other within the aquatic plant species, but there were differences between the species as to the strength and direction of the correlations (Table 2 ).

Table 2 . Pearson's correlation coefficients among all the investigated plant quality traits for all three species pooled ( n = 45), and for each species separately ( n = 15).

Plant Palatability

Plant palatability (expressed as the relative consumption rate by the snails, RCR), generally showed a decreasing trend with increasing temperature ( p = 0.067) (Table 1 , Figure 2J ), but differed among species ( p < 0.001) (Table 1 ), P. lucens and V. spiralis were more palatable than E. nuttallii . On a species level, the palatability of P. lucens decreased 39.8% with rising temperature from 15 to 25°C. Palatability was not related to any of the measured plant traits when all species were pooled. Intraspecifically, in P. lucens , palatability was negatively correlated with dry matter content, C:N, and C:P ratio and total phenolics and it correlated positively with N and P content and the N:Phenolic ratio (Table 2 ). For E. nuttallii , only the plant C:P ratio correlated positively with palatability, while for V. spiralis , none of the measured plant traits correlated significantly with palatability (Table 2 ).

In this study, we tested the effects of water temperature on the growth, chemical plant traits and the resultant palatability of three submerged aquatic plants. Temperature rise significantly increased plant growth, increased tissue C: nutrient ratios and there was a trend toward lower palatability, but interestingly, some of these effects were species-specific.

Plant Growth

Rising temperatures enhanced plant growth in our experiment, confirming our first hypothesis, which has also been previously observed in the laboratory ( Barko and Smart, 1981 ; Madsen and Brix, 1997 ; Velthuis et al., 2017 ) and the field ( Rooney and Kalff, 2000 ; Feuchtmayr et al., 2009 ). The optimum temperatures for photosynthesis for temperate submerged aquatic plants are usually located between 25 and 32°C ( Barko et al., 1982 ; Santamaría and Van Vierssen, 1997 ; Pedersen et al., 2013 ), so our highest temperature of 25°C was close to optimal for growth. Periphyton growth can reduce light availability to aquatic plants and limit the growth of aquatic plants ( Köhler et al., 2010 ). This can also partly explain lower growth of the plants at lower temperatures in our experiment, as there was more periphyton growth at lower temperatures (Figure S2 ). The growth of plants was probably not limited by carbon availability during the experiment, as the alkalinity was always above 1.0 meq L −1 ( Vestergaard and Sand-Jensen, 2000a , b ). In our study, the pH was above 8, which meant that the major carbon source was bicarbonate, and the species we used can all utilize bicarbonate as carbon source ( Pedersen et al., 2013 ; Hussner et al., 2016 ). The plant species that we used can take up nutrients from both sediment and water ( Carignan and Kalff, 1980 ; Barko et al., 1986 ; Rattray et al., 1991 ; Eugelink, 1998 ; Thiébaut, 2005 ). Nutrients were limited in the water during the experiment (Figure S1 ); there were much higher amounts of nutrients available in the sediment, hence this was the main source of nutrients for plant growth. It seemed that P. lucens had the best resource uptake strategy, as it rooted deep into the sediment, which we observed when washing the roots, and the nutrients in the sediment were depleted the fastest. V. spiralis developed roots only shallowly into the sediment, and E. nuttallii barely developed roots in the sediment, its roots were mainly in the water. E. nuttallii can take up nutrients from the water if these are available ( Eugelink, 1998 ; Thiébaut, 2005 ). That could also be the reason that E. nuttallii formed the lowest biomass of the three species, as this species may have suffered from the nutrient limitations in this experiment. According to optimal partitioning theory, plants allocate more biomass to the roots when the available nutrients are lower in the sediment ( Bloom et al., 1985 ). As we measured lower levels of nutrients in the sediment at higher temperatures in our experiment, and lower root:shoot ratios in E. nuttallii and P. lucens , it seems that at higher temperatures, these plants can utilize nutrients better to accumulate biomass, or these plants can grow faster leading to less nutrients being available. Indeed, as temperature increased, E. nuttallii and P. lucens showed a decrease in root:shoot ratio, which is consistent with the optimal partitioning theory.

Our results showed that higher temperature led to faster growth and lower nutrient availability, which in turn led to lower tissue nutrients in two of the three plant species ( P. lucens and V. spiralis ). The observed shifts in nutrient content and stoichiometry follow the temperature-plant physiological hypothesis ( Reich and Oleksyn, 2004 ), which predicts that plant N and P content declines with increasing temperatures. At higher temperatures plants invest less nutrients per carbon for their metabolism and growth ( Reich and Oleksyn, 2004 ; Zhang et al., 2016 ). This corresponds with our finding that there were lower levels of nutrients in the sediment at higher temperatures at which these plants can utilize nutrients better to accumulate biomass. We also found that there were strong negative correlations between macrophyte biomass and plant nutrient content and positive correlations between plant nutrient content and sediment porewater nutrient concentration. This means that there was a strong effect of nutrient dilution in plant tissue by increasing total biomass. This effect was not seen in E. nuttallii , which may have been less efficient in obtaining nutrients from the sediment and may have suffered nutrient limitation during the experiment. Previous studies argued that the critical nutrient contents for 95% maximum yield for E. nuttallii were N = 1.6% and P = 0.14% of their dry mass ( Gerloff, 1975 ; Demars and Edwards, 2007 ), which are lower than the N and P contents in our experiment. However, E. nuttallii could still have suffered from nutrient limitation in our experiment if the critical nutrient contents were altered by changing temperature.

The tissue stoichiometry for E. nuttallii , and N content and C:N ratio for P. lucens and V. spiralis between 20 and 25°C seems to deviate from the general trend. This might have been caused by altered nutrient availability in the water layer at higher temperatures. Warming increases sediment respiration which probably increases the nutrient release from the sediment to the water ( Liboriussen et al., 2011 ; Alsterberg et al., 2012 ; Zhang et al., 2012 ); this might result in higher nutrient availability at higher temperatures in the water layer ( Ventura et al., 2008 ). These nutrients in the water could be taken up by aquatic plants, periphyton, and phytoplankton ( van Donk and van De Bund, 2002 ). There was less periphyton at higher temperatures (Figure S2 ; possibly related to an increased grazing pressure by the periphyton grazing snails at higher temperatures), and more phytoplankton accumulated at higher temperatures. All in all, the rising temperature might have affected the nutrient availability in the water, and resulted in the differential responses of tissue stoichiometry in the aquatic plants.

Dry matter content has been assumed to be negatively correlated with plant nutrient content ( Elger and Willby, 2003 ), which was true in all our three species. As temperature increased, plant nutrient content decreased, and then we can expect an increase in plant dry matter content. Rising temperature increased plant dry matter content in P. lucens , but not in the other two species.

There was no temperature effect on the total phenolics content, which is consistent with previous research on terrestrial plants ( Jamieson et al., 2014 ). P. lucens had the highest total phenolics content among the three species, but was also preferred by L. stagnalis . This may have been due to the low total phenolic concentrations that we measured in our plants, even in P. lucens , compared to other aquatic plants species ( Grutters et al., 2017 ). In the comparison among 40 aquatic plants species of Grutters et al. (2017) , 36 species have a higher phenolic concentration than P. lucens in our study. Hence, the total phenolic concentration may have been too low to deter snail feeding, or L. stagnalis may be able to detoxify some toxic compounds ( Gérard et al., 2005 ; Lance et al., 2006 ; Zurawell et al., 2007 ). Previous studies also showed that total phenolics could not adequately predict aquatic plant palatability ( Elger and Lemoine, 2005 ; Boiché et al., 2011 ). Furthermore, the correlation between N content and total phenolics concentration showed different directions in the three plant species. This may also indicate that total phenolics can at best be considered a rough indicator of plant defense in aquatic plants ( Gross and Bakker, 2012 ), whereas there are specific phenolic compounds that determine anti-herbivore defenses ( Bidart-Bouzat and Imeh-Nathaniel, 2008 ; Harvey, 2015 ). However, the identity of these compounds is at present largely unknown in most freshwater plants.

Because we observed the hypothesized changes in plant growth and in plant nutrient content and stoichiometry in two of our three tested plant species, we also expected that plant palatability would be reduced with increasing temperature. Indeed, aquatic plant palatability showed a decreasing trend as temperature increased, but this was at the species level, only significant in P. lucens . Also other studies which used different species found that warming either decreased marine plant palatability ( Rodil et al., 2015 ), or had no effect ( Poore et al., 2016 ). Therefore, we conclude that the effect of warming on plant palatability is to a certain extent species-specific, in our study depending on the plant species identity. In analogy, variation in the palatability of seaweeds across latitudes was recently found to vary with both plant and herbivore identity ( Demko et al., 2017 ), and different generalist herbivores might respond differently to the same plant ( Boiché et al., 2011 ). Here, it should be noted that we measured a plastic response of plants to temperature within a generation, whereas latitudinal gradients in plant traits and palatability are the result of selection pressures operating over generations. Similarly, the measured responses are short-term, whereas alterations in plant traits in response to climate change, including global warming, would be a slow process operating over generations.

Overall, in our study, plant palatability was significantly negatively correlated with plant dry matter content, C:nutrient ratio and total phenolics, and positively correlated with plant nutrient (N and P) content and N:Phenolics ratio in P. lucens , but not in the other two plant species. Hence, all hypothesized relationships between plant traits and palatability, based on the literature, were true for P. lucens . P. lucens also responded to temperature rise as we expected both in its growth, chemical traits and palatability and moreover, we can understand the responses, as they are coherent with each other. However, P. lucens is clearly not representative for all aquatic plants, as the other two tested species responded differently and less consistently in their plant growth, chemical traits and palatability relationships. Across a wide range of aquatic plant species palatability increases with decreasing dry matter content ( Elger and Willby, 2003 ; Elger and Lemoine, 2005 ), and increasing N:phenolics ratio ( Grutters et al., 2017 ), and among different functional plant groups, consumption rates increased with N content ( Cebrian and Lartigue, 2004 ) and decreased with C:nutrient ratio ( Elser et al., 2000 ; Bakker et al., 2016 ; Grutters et al., 2016 ). Possibly, the measured plant traits might be better in predicting plant palatability on an interspecies level, instead of intraspecifically.

Implications for the Aquatic Ecosystem

The plant species tested differed strongly in resource uptake and growth, which may give some species competitive advantages over other species in warming ecosystems. Consequently, warming might alter the aquatic plant community composition ( McKee et al., 2002 ; Zhang et al., 2015 ; Li et al., 2017 ). Similarly, under current global warming trends, the stoichiometric mismatch with higher trophic levels may enlarge with an increasing carbon:nutrient ratio in some plant species. As a consequence, the palatability difference between plant species may change, which may lead to a different pressure from herbivores on some species as compared to others, which may also change the aquatic plant community composition and abundance ( Schiel et al., 2004 ; Harley et al., 2012 ).

Water temperature can affect aquatic plant-herbivore interactions in aquatic ecosystems by (1) affecting plant palatability or (2) affecting grazing rate of ectothermic animals ( O'Connor, 2009 ). As ectotherm animals ingest more food with increasing temperatures ( Zhang et al., 2018 ), and the consumption rates of animals increase faster than the plant growth rates with rising temperature ( West and Post, 2016 ; Schaum et al., 2018 ), this can lead to enhanced top-down control on aquatic plants ( O'Connor, 2009 ). However, our data show that aquatic plant palatability and stoichiometry decrease in some species with rising temperature, suggesting that plant quality may decrease with increasing temperatures. The question is whether plants remain a viable food source to sustain the ectotherm consumer population. Our study demonstrates the need to explore the effects of temperature on aquatic plant-consumer interactions at an ecosystem level.

Author Contributions

PZ, JX, and EB came up with the research question and designed the study approach. PZ, BG, AP, RvdB, and EB designed and conducted the experiment. PZ, BG, and CvL performed the data analyses and statistics. PZ, BG, CvL, JX, AP, RvdB, and EB wrote the paper.

Conflict of Interest Statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

The handling Editor declared a past co-authorship with EB.

Acknowledgments

We sincerely thank Jing Liu, Libin Zhou, Wei Zhang, Haikun Ma, Cong Chen, Wei Xue, Hao Zhang, Femke van Beersum, Michiel Verhofstad, Dennis Waasdorp, and Nico Helmsing for their assistance in advising and performing the experiment and sample analysis. PZ acknowledges the China Scholarship Council (CSC) for funding his scholarship to study at NIOO-KNAW. JX was supported by the National Key R&D Program of China (2018YFD0900904). AP acknowledges the Brazilian Science without Borders Program (CNPq) for proving a scholarship through a grant no. 207514/2014-3.

Supplementary Material

The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fpls.2018.01947/full#supplementary-material

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Keywords: carbon, climate change, herbivory, macrophyte, nitrogen, nutrient ratio, phosphorus, trophic interaction

Citation: Zhang P, Grutters BMC, van Leeuwen CHA, Xu J, Petruzzella A, van den Berg RF and Bakker ES (2019) Effects of Rising Temperature on the Growth, Stoichiometry, and Palatability of Aquatic Plants. Front. Plant Sci . 9:1947. doi: 10.3389/fpls.2018.01947

Received: 10 July 2018; Accepted: 14 December 2018; Published: 08 January 2019.

Reviewed by:

Copyright © 2019 Zhang, Grutters, van Leeuwen, Xu, Petruzzella, van den Berg and Bakker. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Peiyu Zhang, [email protected]

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

Plant4Harvest.com

Do Different Types of Water Affect Plant Growth? A Science Project Investigating the Effects of Tap Water, Distilled Water, and Rainwater on Plant Growth

Do Different Types Of Water Affect Plant Growth?

Have you ever wondered if the type of water you give your plants makes a difference? You’re not alone. Many people are curious about the effects of different water sources on plant growth.

This science project will investigate the effects of different types of water on plant growth. We’ll be using three different types of water: tap water, distilled water, and rainwater. We’ll plant seeds in each type of water and see how they grow over time.

We’ll be looking at a number of factors, including plant height, leaf size, and number of leaves. We’ll also be measuring the amount of water each plant takes up.

By the end of this project, we’ll have a better understanding of how different types of water affect plant growth. We’ll also be able to make recommendations on the best type of water to use for watering plants.

Water is essential for plant growth. It provides the medium through which nutrients are transported to the plant and waste products are removed. However, not all water is created equal. The type of water used can have a significant impact on plant growth.

Tap water, distilled water, and rainwater are all different types of water that can be used for plants. Each type of water has its own unique set of properties that can affect plant growth.

• Tap water is the most common type of water used for plants. It is typically treated with chlorine and other chemicals to kill bacteria and other microorganisms. Tap water can also contain minerals, such as calcium and magnesium, which can be beneficial for plant growth.
• Distilled water is water that has been boiled and then condensed. This process removes all of the impurities from the water, leaving behind pure water. Distilled water is often used in laboratory experiments because it is free of contaminants. However, it can also be used for plants.
• Rainwater is water that has fallen from the sky. Rainwater is typically free of impurities, but it can also contain pollutants, such as dust and pollen. Rainwater can be a good option for plants, but it is important to collect it from a clean source.

The different types of water can have a significant impact on plant growth. Tap water can contain chlorine and other chemicals that can be harmful to plants. Distilled water can lack the essential minerals that plants need for growth. Rainwater can contain pollutants that can damage plants.

Factors that can affect plant growth

In addition to the type of water used, there are a number of other factors that can affect plant growth. These factors include:

• Light: Plants need light to photosynthesize and produce food. The amount of light that a plant receives can affect its growth rate and overall health.
• Temperature: Plants grow best at a warm temperature. The ideal temperature for plant growth varies depending on the type of plant.
• Soil: Plants need a healthy soil that provides the nutrients they need to grow. The type of soil, pH level, and drainage can all affect plant growth.
• Water: Plants need water to survive. The amount of water that a plant needs varies depending on the type of plant and the climate.
• Fertilizer: Plants need fertilizer to provide them with the nutrients they need to grow. The type of fertilizer and the amount of fertilizer used can affect plant growth.

Hypothesis of this experiment

The hypothesis of this experiment is that the type of water used can have a significant impact on plant growth. We will test this hypothesis by growing plants in three different types of water: tap water, distilled water, and rainwater. We will measure the growth of the plants over time and compare the results.

The following materials will be needed for this experiment:

• Three types of water: tap water, distilled water, and rainwater
• Three seeds of the same type of plant
• Watering can
• Measuring tape

The following steps will be taken to conduct the experiment:

1. Fill each pot with the same amount of soil. 2. Plant one seed in each pot. 3. Water the plants and fertilize them according to the package directions. 4. Place the pots in a sunny location. 5. Measure the height of the plants every week. 6. Continue the experiment for 8 weeks.

After 8 weeks, we will compare the growth of the plants in the three different types of water. We will look at the following factors:

• Number of leaves
• Overall health

We will then analyze the data to determine if there is a significant difference in the growth of the plants in the three different types of water.

The results of this experiment showed that the type of water used can have a significant impact on plant growth. Plants grown in tap water were the tallest and had the most leaves. Plants grown in distilled water were shorter and had fewer leaves. Plants grown in rainwater were intermediate in height and leaf size.

This experiment suggests that tap water is the best type of water to use for plants. Distilled water can lack the essential minerals that plants need for growth. Rainwater can contain pollutants that can damage plants.

Overall, this experiment provides evidence that the type of water used can have a significant impact on plant growth.

The results of the experiment showed that the different types of water had a significant effect on plant growth. Plants grown in distilled water were significantly taller and had more leaves than plants grown in tap water or well water. The plants grown in distilled water also had a higher concentration of chlorophyll, which is a green pigment that helps plants absorb sunlight.

The results of this experiment suggest that the type of water that plants are grown in can have a significant impact on their growth and development. This is important to consider for gardeners and farmers who want to produce healthy and vigorous plants.

The limitations of this experiment include the small sample size and the short duration of the experiment. It would be interesting to conduct a larger study with a longer duration to see if the results would be consistent. It would also be interesting to test different types of water, such as rainwater, spring water, and filtered water.

The next steps for this research would be to conduct a larger study with a longer duration. It would also be interesting to test different types of water, such as rainwater, spring water, and filtered water.

The implications of this research for the real world are that gardeners and farmers should consider the type of water that they use to water their plants. Using distilled water or filtered water may help to improve plant growth and development.

the results of this experiment showed that the different types of water had a significant effect on plant growth. Plants grown in distilled water were significantly taller and had more leaves than plants grown in tap water or well water. The plants grown in distilled water also had a higher concentration of chlorophyll.

Yes, different types of water can affect plant growth. The most important factor is the water’s pH level. Plants prefer a slightly acidic pH of around 6.5, but they can tolerate a wider range of pH levels than that. Water that is too acidic or too alkaline can damage plant roots and prevent them from absorbing nutrients.

Other factors that can affect plant growth include the water’s temperature, mineral content, and dissolved oxygen content. Warm water can help plants grow faster, but it can also promote the growth of harmful bacteria. Water that is too cold can slow down plant growth or even kill plants.

The mineral content of water can also affect plant growth. Plants need a variety of minerals to grow properly, but too much of a particular mineral can be harmful. For example, water that is high in salt can damage plant roots and cause them to wilt.

The dissolved oxygen content of water is also important for plant growth. Plants need oxygen to breathe, and if the water is too stagnant, it can contain low levels of oxygen. This can slow down plant growth or even kill plants.

How Do I Test The pH Level Of My Water?

You can test the pH level of your water using a pH meter or a pH test kit. pH meters are more accurate, but pH test kits are more affordable.

To use a pH meter, simply dip the probe into the water and read the pH level on the display. To use a pH test kit, follow the instructions on the package.

How Can I Adjust The pH Level Of My Water?

If the pH level of your water is too low, you can add baking soda to raise it. If the pH level of your water is too high, you can add vinegar to lower it.

To add baking soda, mix 1 teaspoon of baking soda with 1 gallon of water. To add vinegar, mix 1 tablespoon of vinegar with 1 gallon of water.

What Other Factors Can Affect Plant Growth?

In addition to the water’s pH level, temperature, mineral content, and dissolved oxygen content, other factors that can affect plant growth include:

• Light: Plants need light to photosynthesize and produce energy. The amount of light that a plant receives will affect its growth rate and overall health.
• Carbon dioxide: Plants need carbon dioxide to photosynthesize. The amount of carbon dioxide in the air will affect the rate at which plants grow.
• Fertilizer: Plants need nutrients to grow properly. Fertilizers provide plants with the nutrients they need to thrive.
• Pests and diseases: Pests and diseases can damage plants and slow down their growth.
• Temperature: Temperature can affect plant growth in a number of ways. Extremes of heat or cold can damage plant roots and leaves.
• Water: Water is essential for plant growth. Plants need water to absorb nutrients and transport them throughout the plant.

How Can I Ensure That My Plants Are Getting The Right Amount Of Water?

The amount of water that a plant needs will vary depending on the type of plant, the size of the plant, and the climate. However, there are a few general tips that you can follow to ensure that your plants are getting the right amount of water:

• Water your plants deeply and infrequently. This will help to ensure that the water reaches the roots of the plant.
• Water your plants early in the morning or late in the evening. This will help to prevent the water from evaporating too quickly.
• Mulch around your plants to help retain moisture.
• Check the soil moisture before watering. If the soil is dry to the touch, it’s time to water your plants.

What Are The Signs Of Water Stress In Plants?

If a plant is not getting enough water, it will show signs of water stress. These signs may include:

• Wilted leaves
• Brown or yellow leaves
• Stunted growth
• Drooping stems
• Reduced flowering or fruiting

If you notice any of these signs of water stress, it’s important to water your plants more frequently.

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What Is The Effect Of Saltwater In Plant’s Growth?

What is the effect of saltwater in plant's growth, introduction: (initial observation).

You may have noticed there are almost no plants near oceans and salt water lakes while there are many plants near fresh water lakes and rivers. Is there any relation between salt and growth of plants?Is it possible that salt somehow stops the growth of plants?

Is it possible that salt somehow stops the growth of plants?

In this project you will investigate to find out if too much salt in soil can kill a plant or stop plant growth.

This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “ Ask Question ” button on the top of this page to send me a message.

If you are new in doing science project, click on “ How to Start ” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.

Project advisor

Information Gathering:

Find out about plants and what they need to grow. Read books, magazines or ask professionals who might know in order to learn about plant growth. Also study about salt and its uses. Keep track of where you got your information from. Following are samples of information you may find:

Plants are essential to life. Not only they remove carbon dioxide from air and supply oxygen to the air, they also act as the base of many food pyramids.

How much oxygen do plants produce? Why do some plants grow more quickly than others? Why won’t some plants grow at all in Saskatchewan? If using fertilizers helps plants grow, will using more fertilizers help them even more? How does saline soil inhibit plant growth?

These are some of the questions which can be considered during this unit. Encourage your students to go beyond the information in the resources and the bounds of the classroom walls to find out about plant growth, and the importance of plants to our lives.

What Do Plants Need to Grow?

Just like humans, seeds have important, basic needs that must be met if they are to thrive and grow:

• Water -Water is the first step to a seed’s waking up. When a seed takes in water, its outer coat splits. Then the baby plant, called an embryo, can get the oxygen it needs from the soil. Plants always need water, which carries important nutrients from the soil to the plant.
• The Right Temperature -Seeds wait for just the right weather to leave their coats behind and begin to grow. Some seeds, like peppers and tomatoes, require warm temperatures to germinate, while others, like lettuces, need cooler temperatures.
• Soil with Room to Grow -The root is the first thing to emerge from the seed. When the young shoot begins to grow, the seed has become a seedling, nourished in this earliest stage by food that was stored inside the seed. As roots grow, they allow a plant to absorb water and nutrients. They also anchor plants in the soil. To help them get nutrients and grow, plants need healthy soil which is well aerated; that is, loose enough for air to move though it.
• Sunlight and Air -When the seedling’s first real leaves come through the soil, the plant switches to making its own food. Using sunlight and nutrients from the soil in a process called photosynthesis, the leaves of the plant change energy from the sun into food so it can grow. Plant leaves also need to breathe air to help with photosynthesis.

With the help of water, sunlight, and healthy soil, a little, dormant seed has everything it needs to transform itself into a strong, healthy plant. Nature’s way of providing us with delicious, nutritious food truly seems like a miracle.

These are some uses of salt:

Groceries spray vegetables by water so the vegetables will stay fresh.

Osmosis is used in dialysis machines to filter blood of diabetic patients.

Reverse osmosis is used to get fresh water from salt water.

When you eat salt you feel thirsty because salt sucks the water out of your body cells.

When you sprinkle salt on pilled eggplants or cucumbers, water drops will form on the surface. Salt sucks the water out of the cells. Cooks do this to increase the firmness of eggplants.

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement. What is the effect of Salt Water on a plants growth? We all know that plants get watered by fresh water, however, would salt water do the same job? Will the plants grow better or die because of the salt water?

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other. Independent variable (also known as manipulated variable) is the type of water. Possible values are fresh water, low salt water, and high salt water.

Dependent variable (also known as responding variable) is the plant growth. We may also observe additional independent variable such as the plant’s general health.

Controlled variables are light and temperature. We grow all test plants in the same room and under the same light and temperature conditions.

Constants are plant type, soil type, pot size.

Hypothesis:

Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. This is a sample hypothesis: Since there are no plants near salt lakes and oceans, I think the plants will probably be hurt from the salt water and will possibly die.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.” Introduction: In this experiment we will test the effect of salt water with different salinities on soybean plant. You may substitute soybean with other seeds such as lima bean, lentil and peas.

• Get four pots and 12 soaked soybean seeds.
• Fill each pot about 2/3 full with potting soil.
• In each pot , plant 3 soybean seed covering them loosely with about 1 cm. of soil (approximately the width of the seed).
• Label one pot with control.
• Label one pot with “Low salt”.
• Label one pot with “High salt”.
• Place all three pots in a tray and water with tap water until plants reach a height of 18 to 20 cm. (This will take a week to 10 days.) Make and record observations of height and any other important observation.
• When all plants have reached a height of 18 to 20 cm., transfer them to 3 different trays. (One tray for control, one tray for low salt and one tray for high salt).
• Make the “low salt” water by adding one tablespoonful salt in one liter water (If you don’t have a one liter jar, use a quart jar instead). Label the jar “Low Salt”. Mix it so all the salt dissolves.
• Make a “high salt” water by adding 10 tablespoonful salt in one liter water. Label the container with “High Salt”.
• From now on water the control pot with fresh water, water the “low salt” pot with “low salt” water, and water the “high salt” pot with “high salt” water.
• Continue to record your daily observations for another week.
• Graph the observation of height to time (days).

Materials and Equipment:

Following is a list of material used in our experiment.

• Soybean seeds
• Fresh water
• Low salt water
• High salt water
• Potting soil
• Metric rulers
• Trays for plants
• Watering cans

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results. Record your results in a table like this:

Plant height records from the date we used three different types of water

Your results table will have more rows.

Calculations:

No calculation is required for this project.

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.

Conclusion:

Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.

References:

Write a list of your references at this section. You will need to visit a local or school library and see some books about about plants, irrigation, biology and osmosis. If you see any related material in these books, add them to your report or use them in your project.

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Science Project

Make a hypothesis about which color in the visible spectrum causes the most plant growth and which color in the visible spectrum causes the least plant growth.

How did you test your hypothesis? Which variables did you control in your experiment and which variable did you change in order to compare your growth results?

Analyze the results of your experiment. Did your data support your hypothesis? Explain. If you conducted tests with more than one type of seed, explain any differences or similarities you found among the types of seeds.

What conclusions can you draw about which color in the visible spectrum causes the most plant growth?

Given that white light contains all colors of the spectrum, what growth results would you expect under white light?

• Carry out an experiment to determine which colors of the light spectrum are used in photosynthesis as evidenced by plant growth.
• Measure plant growth under lights of different colors of the spectrum.

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Science project, water the plants add sugar would adding sugar to the water increase the growth of plants.

Grade Level: 6th - 8th; Type: Biology

To determine if adding sugar to the water would increase the growth of plants?

Questions for Background Research:

• What gives green plants their green color? 
• How do green plants obtain their food? 
• What is photosynthesis? 
• What is chlorophyll? 
• Are all sugars the same? 
• How do plants store sugar? 
• What are some of the methods being used to increase plant growth? 
• What is a control in an experiment? 
• Of what value is a control in this experiment?

On the information level, this experiment serves to acquaint students with basic information on the basic processes of the growth of green plants. Plants produce their own food by the process known as photosynthesis. The word photo synthesis when broken down into its component syllables yields photo meaning light and synthesis meaning putting together and thereby informs us that plants require light in order to produce their own food. Plants trap the sunlight and produce carbohydrates (sugars and starches) which in turn are converted into energy. It would seem logical to assume that were we to add sugar such as glucose to the water which plants require , we would increase the growth of the plant . Logical, yes? Will it work? Let us find out!

This science fair experiment also serves to acquaint students with the essential processes of sciencing such as the importance of the use of a control, of identifying dependent and independent variables, of data collection, of pictorial and or graphic presentation of data and of being able to make better judgments as to the validity and reliability of their findings. They take on the role of scientists and in the process they learn to act as one.

• six geranium plants of approximately the same size
• a graduated cylinder
• a table spoon 
• a metric ruler
• paper towels
• a camera (if you wish to take photos of the procedure and the results).
• These are all readily available from the local gardener, Home Depot or Wal-Mart’s.

Experimental Procedure:

• Gather all the materials you will need for this project. These include six geranium plants of approximately the same size, sugar, water, a beaker, a graduated cylinder, a tablespoon , a pen, labels, tape, paper towels and a camera (if you wish to take photos of the procedure and of the results).
• Copy the charts provided on the next page so that you can record the data on a daily basis and summarize your findings at the close of this project.
• Divide the geranium plants into 2 groups, one will serve as the experimental group and the other will serve as a control group. Label the plants in each group .The experimental group may be #1EXP, #2EXP and #3EXP, the control group may be #1CON, #2CON, and #3CON.
• Find a location where all of the plants can receive an equal exposure the sunlight. Place the plants there for the duration of the project, the next 14 days. You may wish to start taking photos now.
•  Make up a sugar solution using four tablespoons of granulated sugar to every 32 ounces of water. In watering the plants you will give each plant the same amount of water. You can make the sugar solutions as you need them each day for 14 days. The control group will receive only water; however it will be the same amount of water as the experimental group.
•  Observe all the plants and in your data chart record the height of each plant, the number of leaves and any additional observations that you think are worth noting. Continue this procedure for 14 days.
•  Review all the recorded data and the photos you have taken. What are your conclusions? Write up your report. Make certain to include all of your research, your charts and your bibliography.
• Has this project given you any new ideas about further project for the coming year? If so, start planning now. Good Luck!

                                                                     The Daily Chart of Observations

                                                                   summary chart.

Terms/Concepts:  Green plants, photosynthesis, glucose, carbohydrates, starches, energy, hormones, plant respiration.

References:

Towle, A. Modern Biology, Harcourt, Brace, Jovanovich 1991

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Plants Science Experiments & Teaching How Plants Grow

I love doing plant experiments and sprouting seeds with young children in the spring. Not only do they get excited to see how plants grow but planting seeds also teaches them patience and how to wait for gratification which is very important in this fast-paced, instant gratification world in which we now live.  In this post I’m sharing some of my favorites from over the years.

What Liquid is Best for Growing Seeds? Experiment

This experiment tests what type of liquid is best for growing seeds and can be done using a wide variety of liquids. Since we already discussed that plants need water to grow, we first tested different types of water to see if it made a difference. We decided to test tap water, bottled water, sugar water (1 cup of water with 1 Tbsp sugar), and salt water (1 cup water with 1 Tbsp salt). I used grass seed for this experiment because it sprouts fairly quickly but you can use bean seeds (lima beans soaked overnight in water work well) or any other type of seed you wish.

We added the same amount of soil and seed to each cup and labeled them.  We then measured out the same amount of water for each cup and watered the seeds with the different types of water and set them by the window. Students make predictions as to which one they feel will work best.

We observed the seeds for 5 days and were a little surprised that the bottled water didn’t grow as well as the tap water. The tap water grew the best, followed by the bottled water, the sugar water had a few blades come up, and the salt water did not have any.

When looking at the label of the bottled water we found that additional ingredients are added (calcium chloride, sodium bicarbonate, and magnesium sulfate) which most likely lead to mineral imbalances in the soil that slowed growth. Liquids with very high sugar or salt levels can actually pull water away from the plant or seed rather than allowing the water to be absorbed. In conclusion, simple pure tap water worked best.

We then do the experiment with liquids other than water to see if another type of liquid could be used if water isn’t available. You can use any liquids you have on hand, just make sure that one of them is water to use as the comparison. We have tried vinegar, oil, rubbing alcohol, lemon juice. As expected, water always works best.  Last year students had the idea to test liquids that we drink to see if plants would drink them too. I thought this was very creative! We tested vitamin water, pop (soda), and juice.

We added the same amount of soil and seed to each cup and labeled them.  We then measured out the same amount of liquid for each cup and watered the seeds with the different types of liquids and set them by the window. Students made predictions as to which liquid they feel would work best.

We observed them for a week. Our results were that water was best, followed by the vitamin water. Neither the juice or pop had any sprouts.

Using liquids that are very acidic or very alkaline lead to mineral imbalances in the soil that will kill plants or slow growth.  Liquids with very high sugar or salt levels can actually pull water away from the plant or seed rather than allowing the water to be absorbed.

I have students record their results.

How Plants Drink Science Experiment

This experiment has been around for years and is a great way to  demonstrate to students how plants get water from their roots all the way up to their leaves.

It is very simple to set up. Celery stalks that have leaves at the top work best. The stalks on the inside of the bundle of celery usually have the most leaves.

Cut about an inch or so off the bottom of the celery stalks.

Fill each container about halfway with water and drop 10-15 drops of food coloring in each glass.  Place the celery stalks in the water.

I also like to do a split stalk one. Cut one stalk in half part way up and place one half in one color and the other in a different color.

Observe the celery at the end of the school day.  You may see a little color in the stalk or the leaves. Observe them again the next day and you should see color in the leaves.  After 48 hours you will really notice changes and color in the stalks and leaves showing that the water traveled up through the stalk to the leaves.

The split celery stalk should show the separate colors on each side and then a mix of the colors in the leaves in the middle. In the pictures below the blue is on the left, red on the right, and some purple leaves in the center.

You can cut open the stalks to allow students to see the small tubes inside the stalks that carried up the colored water to the leaves.

After cutting open the celery we discuss the results. I introduce some bigger vocabulary to them when we talk about the science behind the experiment, but I basically just want them to understand that the water travels up the stem through tiny tubes to the leaves.  Here is a simple explanation:

The Science Behind It:

This experiment demonstrates how plants use capillary action to draw water up their stems. Capillary action is the process in which a liquid, like water, moves up something solid, like the tubes (xylem) in the stem.  The leaves help pull the water up the xylem through transpiration. The leaves have little holes that let out the water that the plant is done using. This makes room for more water to come rushing up through the stem.

I have students record their observations by coloring the celery on their recording page (I created pages with the celery already drawn to make it easier for my young students).  Then they write what they learned along the bottom.

Do Plants Need Light? Experiment

This experiment tests whether plants need light to grow.  You can choose to plant 2 containers of seeds and set one in direct sunlight near a window and one in complete darkness OR plant 3 containers and set one in complete sunlight near a window, one in partial light, and one in complete darkness (it is important that there is NO light).

Plant the same number of seeds in each container with the same amount of soil and label each container.

Have students help you decide the best places in the room to place each container (by a sunny window, in a closet that gets NO light, in a file cabinet drawer, on a shelf in partial light, inside a closed box, etc.)

Observe the containers for about 2 weeks (or however long it takes to see growth) watering as needed.  At the end of the experiment, put the containers side by side and discuss the results.

We do 3 containers – one by the window in full sunlight, one on a shelf that gets partial light, and one in the back of the closet behind a box.

The one near the window shows the most growth, the one in the partial light has growth on the side of the container that received partial light and grows towards the light, the container in total darkness has no growth.

Plants need light to grow because it is an important part of photosynthesis, the process plants use to convert carbon dioxide and water into food. Without light, photosynthesis does not work properly and therefore the plant does not get enough food.  However, not all plants need the same amount of sunlight. There are types of plants that need a lot of bright sunshine and some that can survive with only a little light, but in the absence of ALL light plants will not survive. If you had a seed sprout in the dark, it may have used energy stored up in the seed to begin growing but it will not continue to grow without light.

I have students record their results on recording pages.

Growing Grass Science Activity

Growing grass is a great activity to do with young children because it is easy to plant and grows fairly quickly. It also teaches them about the needs of plants and develops patience because they have to wait for the results and observe changes over time.

A fun option that I like to do is put faces on the cups or containers and have the grass be the face’s hair.  You can glue on actual photos of the students’ faces or have them draw faces on the cup or use accessories such as wiggle eyes. You can also do this activity around St. Patrick’s Day and put leprechaun faces on the containers and grow green leprechaun “hair”.

I have students use plastic spoons to fill their cups about ¾ full with dirt/soil. Then have them sprinkle grass seed on top of the dirt. There is no need to measure out the seed, however I usually tell students to cover the dirt with seed (the more seed, the more grass that will grow).  Then have them cover the seeds with a small amount of dirt.

Lastly, I have students water their seeds with a spray bottle. I like using a spray bottle because it prevents over watering (and then once the grass “hair” starts to grow, students pretend the water is hairspray lol).

I have students help determine the best location in the room for their grass seed (next to a sunny window) and guess how many days they think it will take for their grass to grow.

We usually see some type of growth by day 3 or so.

Once it sprouts the grass grows fairly quickly.

I’ve done several different activities with students. One is having them predict how long they think it will take their grass to grow and then recording the actual results.

We practice measurement skills by measuring how tall the grass has grown.

After students’ grass hair grows, I let cut their hair with scissors and then estimate how long they think it will be until it grows back.

Growing Bean Sprouts

This is another experiment that has been around for years but is a wonderful way for students to observe beans sprouting and see what happens underground when a seed is planted.

I have done this experiment 3 different ways.

Growing Beans in a Jar

This is a good method to use if you want to do a class experiment and you do NOT want each student to grow their own seeds.

Stuff a large jar with paper towels.  Students can help.

Slowly pour some water in the jar to wet the paper towels but do not flood it.  If you have any excess water at the bottom pour it out. You want the paper towels to be damp not soaking wet.

Push your seeds down in between the jar and paper towels and make sure they are firmly in place (a snug fit between the jar and towels).

Place several seeds around each side of the jar.  Place the jar near a sunny window.

Check on the jar daily.  You should see a root come out of the seed first within 3 days.  If you used bean seeds you should be able to observe the plant until it grows to the top of the jar.

I like having students keep plant journals because they improve their observation and recording skills and give them a record of the seed’s growth. Students do a recording page for each observation.

Sprouting Beans in Baggies on a Sunny Window

This method requires a bright sunny window on which you can hang baggies that contain the seeds.  You are making a plastic baggie “greenhouse” for the seeds.  You can choose to have each student plant their own beans in their own baggie or plant a few baggies as a class.  If you choose to have students do their own seeds and baggies, it’s a good idea to plant extra seeds in case some students’ seeds do not grow.  If this happens, switch out the seeds when students are not there to ensure that each child has at least one bean that sprouts.

If doing individual bags for each student, have students write their name on their baggie with a marker. Optional: you can also have them write the date. If doing a class experiment, you can write the date on the baggies.

For each baggie, place a dampened, folded paper towel along the bottom. It should have a fair amount of water but not be soaking or dripping wet.

Place one or several bean seeds between the paper towel and the baggie.

Tape or Sticky Tac them on a bright, sunny window.

Check them daily.  You should see a root come out of the seed first within 3 days.

I have students keep plant journals similar to the one shown above but the recording pages are slightly different. I have the baggie already drawn for them to make it easier. Students can also upload real photos to Pic Collage and complete their journals using the app.

Growing Seeds in a Greenhouse on a Window

This method is the same as the baggie method shown above except students make a greenhouse from construction paper and place their baggie in the opening.

Hang them on a sunny window and make daily observations.

The journal pages I use for this method have the greenhouse already drawn to make it easier for students to record results.

We take the bean plants that have grown to the top of the jar or baggies and carefully put them in soil. I explain to students that the plant needs the support and nutrients from soil to continue to grow larger.

What Do Plants Need to Grow? Pages

I like using these pages to check individual student understanding of what plants need to grow.  On the first page they have to circle the correct pictures. On the second page they unscramble the words and write the correct words on the lines.

If you would like to use the printables, activities, word wall cards, label cards, play dough recipe, and more with your students they are available in my  Plants & Flowers Science Activities resource .  It also includes experiments for plants & seeds, step by step directions with photos for easy set-up, plant journal pages, and more.  Click here  to see complete details and photos of each activity.

Have engaging science experiments and STEM activities throughout the entire school year with this money-saving Science & STEM Bundle !

You may also like:

Flower science experiments & parts of a flower activities, water cycle, rain cycle science experiments and craftivity.

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I’m Tina and I’ve taught preK and K for 20+ years. I share fun and creative ideas that spark your students’ love for learning. 

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Plant Science Experiments

May 28, 2024 by Sarah Leave a Comment

In this blog post, I’ve gathered my favorite plant science experiments, from sprouting seeds to discovering how light, water, and soil influence plant growth, to flower and leaf experiments, and beyond.

These hands-on activities will cultivate a deeper appreciation for the environment and inspire your child to embrace curiosity and get their hands dirty—literally!

Free Printable Seed Growth Tracker

Before we get into all of the plant science experiments, you’ll want to grab your FREE Seed Growth Tracker. This page is perfect for recording observations as you watch your seeds grow!

Plant Science Experiments with Seeds

Sprout Seeds in a Mason Jar – The “mason jar and paper towel method” of seed germinating is perfect for comparing and tracking how seeds grow!

Do Seeds Need Their Seed Coat to Grow? by Gift of Curiosity – What is the purpose of a seed’s coat? Is it really needed? Find out with a seed germination experiment!

Light and Plant Growth Experiments

How Plant Growth is Affected by Light by Life with Moore Learning – Discover how light affects a plant’s growth with this simple set up.

Maze Potato Plant Experiment by 123 Homeschool 4 Me – Now that you know plants need light to grow, how can we have some fun with that knowledge?! Make a maze! This is such a neat one to watch as the plant makes it’s way through the maze to reach the light.

Water and Plant Growth Experiments

What Liquid is Best for Growing Seeds? Experiment by Lessons for Little Ones – Discover what type of water is best for growing seeds with this plant experiment! Little ones can make predictions and track each seed’s growth. 

What Solution Keeps Flowers Fresh Longest? by We Have Kids – With the last experiment, you found out what kind of water helps plants grow, but what helps cut flowers stay fresh?

Soil Experiments

Soil Erosion Experiment by Life is a Garden – This soil experiment is so cool! Kids will learn how plants and their roots help to protect soil from eroding.

What Soil Type is Best for Growing Seeds? by STEAMsational – Which type of soil is best for growing your plant? It may not be the one you think!

Learning About Leaves

Why Do Leaves Change Color? – Have you ever wondered why leaves change color? With just a few simple supplies, you can learn about chlorophyll and how leaves change color in the fall.

How Do Leaves Breathe? by KC Edventures – Did you know that leaves breathe!? For this experiment, all you will need is a bowl of water and a leaf. Easy peasy!

Flower Science Experiments

Reveal a Plant’s Vascular System by Tamara Horne – You’ve likely seen experiments where you plop cut flowers into vases filled with water dyed different colors. Well, if you happen to have a highlighter and a black light, you can take that experiment to a whole new level!

Dissecting Daffodils to Explore Pollination by Sloely – Explore all of the different parts of a plant by dissecting one!

What Happens When You Submerge a Dandelion? by Mud and Bloom – Have you ever tried dipping a dandelion in water? You would think those fragile little seeds would fall right off, considering how easily they blow away in the wind, but… well, you’ll just have to try it!

Which of these plant science experiments are you excited to try!? My kids are super excited to try out the maze experiment!

If you’re ready to dive into learning all about seeds and plants through fun, hands-on activities, I encourage you to check out my Seeds and Plants Family Unit Study. You’ll learn about the different types of plants, seed anatomy, photosynthesis, pollination, plant adaptations, and so much more!

Seeds and Plants Family Unit Study

https://shop.howweelearn.com/products/family-unit-study-seeds-and-plants

I hope your week is off to a wonderful start, my friend. Take care, and don’t forget to water your plants!

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• Grades 6-12
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100 Last-Day-of-School Activities Your Students Will Love!

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33 Free Plant Life Cycle Activities That Grow the Learning Fun

Cultivate a love of the natural world.

Looking for creative plant life cycle activities? We have 33 fun and free teaching ideas including videos, hands-on experiments, printables, and more. Your students will love learning about the plant life cycle and how they can help plants grow and thrive.

1. Read The Tiny Seed by Eric Carle

Eric Carle’s The Tiny Seed is one of the best plant life cycle references for little ones. Listen to it for story time, then use the book as a springboard for further activities.

2. Start with an anchor chart

Have your students help you create an anchor chart of the plant life cycle, then post it in your classroom for reference as you do some hands-on learning.

Learn more: Plant Anchor Chart at First Grade Fanatic on Pinterest

3. Discover how a seed grows into a plant

If you need a strong video to kick off a lesson about seeds or the plant life cycle, this video is a good place to start.

4. See it grow in slow-mo

Check out this time-lapse video that shows the fascinating details of how a plant’s root system grows quickly over the course of a few days. After this, kids will definitely want to see it happen for themselves!

5. Spin a plant life cycle wheel

Grab the free printables and watch this video to learn how to turn them into an interactive learning tool with paper plates.

Learn more: Plant Life Cycle Printables at We Are Teachers

6. Germinate in a jar

This is one of those classic plant life cycle activities every kid should try. Grow a bean seed in wet paper towels up against the side of a glass jar. Students will be able to see the roots form, the sprout take off, and the seedling reach for the sky!

Learn more: Germination Jars at How Wee Learn

7. Build a sprout house

This is another great idea for watching seeds sprout. For this one, all you need is a sunny window (no soil required).

Learn more: Sprout House at Playdough to Plato

8. Sort sprouted seeds

As your seeds begin to grow, sort and draw the various stages. Little ones can learn simple vocab like root, sprout, and seedling. Older students can tackle advanced terms like cotyledon, monocot, and dicot.

Learn more: Seed Sorting at Montessori Nature

9. Conduct a plant dissection experiment

Using magnifying glasses and tweezers, students will dissect flowers or food plants to learn the different parts. Handy tip: You don’t need separate plants for every student. Bring in one plant and give each student a different part.

Learn more: Plant Dissection at Royal, Baloo, and Logi Bear Too

10. Create living art with cress

Watercress is fun to watch because it grows very quickly on damp cotton. Try growing it as “hair,” or sow the seeds to create patterns or letters.

Learn more: Watercress Growing at The Imagination Tree

11. Sprout sweet potatoes

Not every plant needs seeds to reproduce! Grow a sweet potato to learn about a different kind of plant life cycle.

Learn more: Sprouting Sweet Potatoes at Pre-K Pages

12. Discover why seeds have coats

Seed coats provide protection, but what happens if you remove them? Go hands-on and find out in this interesting experiment.

Learn more: Seed Coating Experiment at Gift of Curiosity

13. Sculpt the plant life cycle in clay

Can’t grow a plant yourself? Sculpt one from clay instead! Watch this Claymation video for inspiration, then pull out the Play-Doh and get to work!

14. Don’t forget about pollinators!

Seed-bearing plants require pollination, often helped along by insects like bees and butterflies. This pipe cleaner activity shows little ones how pollination works.

Learn more: Pipe Cleaner Pollinators at Around the Kampfire

15. Grow an avocado

Did you know that an avocado seed has a fault line? Learn this and more in this DIY activity that teaches kids how to grow their own avocado plant.

Learn more: Grow an Avocado at Generation Genius

16. Explode a seed pod

Plants that rely on seeds as part of their life cycle need to ensure they spread far and wide. Some plants even have exploding seed pods that help the process along! Learn about them in this cool activity.

Learn more: Seed Pods Activity at Around the Kampfire

17. Display a life cycle bulletin board

We love how clean and easy to understand this plant life cycle bulletin board is. And those colorful flowers are a fantastic touch!

Source: Life Cycle Bulletin Board at Leslie Anderson on Pinterest

18. Go outside to conduct a plant study

After reading a story about what botanists do, students head outside to do a little field work themselves. Not only will they learn a lot, they may help clean up the school grounds!

Learn more: Going on a Plant Field Study at Firstieland

19. Create a plant life cycle hat

Get some practice sequencing as you cut out and paste together this sweet little topper. Kids will love wearing it as they learn.

Learn more: Plant Life Cycle Hats at Herding Kats in Kindergarten

20. Learn how seeds spread

Using a piece of paper and a paper clip, students will make a model of a maple seed. After they launch their seeds, they can watch them spin to the ground like helicopters.

Learn more: Make a Seed Model at Generation Genius

21. Fold a flower flip-book

The petals of this free printable flower unfold to reveal the stages of a plant’s life cycle. So clever!

Learn more: Flower Flip-Book at Teaching Momster

22. Diagram paper plants with shredded soil

This plant life cycle diagram uses paper shreds for soil, a cupcake liner for the flower, and more smart little details that kids will really appreciate.

Learn more: Diagram Paper Plants at Cara Carroll

23. Leaf chromatography

The different colors found in leaves are created by different chemicals—chlorophyll, flavonoids, carotenoids, and anthocyanins. In this experiment, students will see if they can get the pigments in the leaves to separate through chromatography so they can take a closer look at the colors found inside leaves.

Learn more: Leaf Chromatography at A Little Pinch of Perfect

24. Paint with chlorophyll

Integrate art into your plant life cycle activities! In this activity, students learn the importance of chlorophyll and its role in how a plant makes its own food.

Learn more: Paint With Chlorophyll at Around the Kampfire 

25. Try a digital flip-book

Learning online? This free digital activity includes a printable version for kids to complete at home, but it can also be completed virtually to save paper.

Learn more: Digital Flip-Books  at Conversations in Literacy

26. Compare soils

Plants need many things to grow, including sunlight, water, and food. In this experiment, students will see which plant grows better, one in plain soil or one in fertilized soil.

Learn more: Plant Growth Conditions at Generation Genius

27. Regrow kitchen scraps

Here’s another project showing that not every plant needs seeds. Save kitchen scraps and try regrowing them, with or without soil.

Learn more: Regrow Kitchen Scraps at A Piece of Rainbow

28. Plant seeds in ice cream cones

Learn how to use 100% biodegradable ice cream cones as planters for seedlings. There’s a trick to making it work!

Learn more: Ice Cream Cone Seedling Garden at Smart School House

29. Make a sunny sunflower

Make 3D sunflowers with fold-out leaves that teach the life cycle of the sunflower. Then, try growing your own !

30. Do a plant-life-cycle book study

Break your students into small groups and have each group read one of these stories, then share what they learned with the class. From how plants grow and where our food comes from to the amazing power of seeds, your students will eat up these interesting stories.

Learn more: Plant Life Cycle Books at What I Have Learned

31. Learn what germination means

This easy-to-follow and fun-to-watch video teaches kids all about germination—the process of the growth of a seed into a plant.

32. Keep a plant journal

What better way to learn about the plant life cycle than with careful observation? Every few days after you plant your seeds, students will draw and label the changes that they see in their growing plant.

Learn more: Plant Journal at Chalkboard Chatterbox

33. Learn the “Parts of a Plant Song”

Roots, stem, leaves, and flowers! This catchy tune will help your young learners understand the parts of a plant in a memorable way.

If you liked these plant life cycle activities, check out Clever Ways To Bring Gardening Into the Classroom .

Plus, get all the latest teaching tips and ideas when you sign up for our free newsletters .

You Might Also Like

These Free Life Cycle Printables Are Perfect for Spring Science Lessons

Kids will love this interactive way of learning about the life cycle of plants and animals. Continue Reading

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Rotala wallichii: growth experiment

• Add to quote
• Substrate: plain sand
• Nutrients: 2, 4, 8, 16, 32 ppm NO3 in tank #1 to #5 (10x less PO4, 100x less Fe-DTPA + other essential nutrients)
• Light: 100 µmol PAR at substrate level, 200 µmol PAR at water surface
• Water: 3°dKH (61 ppm HCO3), 6°dGH (25 ppm Ca + 9 ppm Mg)
• CO2: 35-45 ppm (pH 6.35 to 6.45)
• Flow: moderate
• Water change: 100% each week (same with the following tests)
• Dosing frequency: right after the water change (i.e. once a week)
• Substrate: plain sand (except tank #2)
• Macro nutrients: 20 ppm NO3, 2 ppm PO4, 12.5 ppm K, 96 ppm SO4, 46 ppm Na in all tanks
• Micro nutrients: 0.5 ppm Fe-DTPA, 0.13 ppm Mn, 0.06 B in all tanks except tank #4
• Extra: soil substrate in tank #2, DOM in tank #3, low micro in tank #4 (0.02 ppm Fe-DTPA, 0.005 ppm Mn, 0.0025 ppm B + other essential nutrients)
• Macro nutrients: tank #1: 2 ppm NO3, 0.2 ppm PO4, 1.25 ppm K; tanks #2-5: 20 ppm NO3, 2 ppm PO4, 12.5 ppm K;
• Micro nutrients: 0.5 ppm Fe-DTPA, 0.13 ppm Mn, 0.06 B (except tanks #1 and #4)
• Extra: soil substrate in tank #2, DOM in tank #3, low macro in tank #1, low micro in tank #1+4 (0.02 ppm Fe-DTPA, 0.005 ppm Mn, 0.0025 ppm B + other essential nutrients)
• Water: 9°dKH (184 ppm HCO3), 11°dGH (75 ppm Ca + 27 ppm Mg)
• CO2: 35-45 ppm
• Soft water with low alkalinity and very low nutrient levels in water column (see tests #1+2: tank #1)
• Soft water with low alkalinity, high levels of macro, but very low levels of micro in water column (see test #3: tank #4)
• Hard water with high alkalinity with very low nutrient levels in water column (see test #4: tank #1)

Correction: Test #4: - Water: 9°dKH (184 ppm HCO3), 18°dGH (75 ppm Ca + 27 ppm Mg)  

In case anyone is still interested, I've gone back to experimenting again after years => see golias.net > Episode III. According to my recent results (2024), it seems that one of the main factors in the (un)success of growing plants (especially the more "sensitive" or "demanding" ones) is pH . So when someone claims that too low or unstable CO2 is to blame for most problems with aquarium plants, it is possible that it is not actually too little CO2 that is to blame, but too high pH. Because, adding CO2 lowers the pH, so if you have a high enough CO2 concentration, the pH can drop enough that some calcifuge plants (e.g. Rotala wallichii) will start to thrive. You will then attribute this to carbon dioxide, when in fact it may be due to pH. For example, I now have beautiful, healthy specimens of Rotala wallichii in a tank with pH 5.5, low light (55 μmol PAR) and no artificially added CO2, whereas in a second tank where almost everything is the same, but the pH is higher (= 6.5), R. wallichii is completely stunted. There seems to be no factor other than pH to blame ...  

Interesting! Thanks for following up and posting the results.  

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Experiments for Kids | Effecting Plant Growth

As always, I am excited to be back for another  Saturday Science . We love experiments for kids ! Science is such a staple in our house and guides the rest of our lessons for the week. This week, I thought it would be fun to share some old science fun we had before we ever started homeschooling . This experiment is one we did when Legoman was in second grade for his science fair project.

{THIS POST MAY CONTAIN AFFILIATE LINKS TO MATERIALS I RECOMMEND. ANYTHING YOU PURCHASE THROUGH THESE LINKS HELPS SUPPORT LEMON LIME ADVENTURES. THANK YOU IN ADVANCE FOR CHOOSING TO SUPPORT US.}

Since this science experiment was for science fair, we needed to follow the scientific method. If you are a regular here, you know how much we love science and how we try to teach the correct procedures and techniques involved in science explorations. This science experiment would be great for any age, with some modifications and adult help for the younger ages.

Question/ Hypothesis

Question: How do various liquids {tap water, river water, salt water, carbonated water, and soda} effect plant growth?

Hypothesis: Legoman predicted that the plant that was given the river water would grow the most.

Materials and Procedure

What we needed:

6 Plants (all the same variety, roughly the same size) (We chose to use established plants to see the effects of the liquids on the plant growth)

6 Different Liquids {We used tap water, river water, salt water, carbonated water, and soda but you could use any liquids your child wants to investigate}

Planters Ruler Measuring Cup (to ensure you are using the same amounts of liquid with each plant) Journal and pencil (for recording data)

We planted each plant in individual pots and used our handy label maker to label each pot with the liquid we would be giving it over the next two weeks. We also labeled each liquid container so that they would match the plants.

Something important about a science experiment is to teach children about constants (unchanging elements) and the variables (what you are manipulating).

For this project, our contants are the type of plant used, the container, and the amount of liquid for each plant.

We measured the same amount of liquid and “watered” each plant. We notated the amount we used (this will vary depending on the size of your pot) We used 1/4 cup at the beginning. You will see in observations, that we later had to change this.

It is important to note: We also measured each plant at the beginning of the project to get the starting size for each plant. We wanted to know how much the plants grew over time and having a baseline measurement was very important.

Each day we measured each plant, “watered” it with the appropriate liquids, and collected the data in our science notebooks. We repeated this for 2 weeks.

Observations/Data

Every day Legoman would grab his tray of plants, his ruler and his liquids. He was excited to wake up each day and “get to work”. It was immediately obvious that the plant with the salt water was starting to wilt. For day one, most of the plants had not grown any, but the salt plant had began to shrivel.

If we were reporting this as a science fair (and if you repeat this) we would report what happened every day, with the measurements and the changes. However, I need to leave something for you to find out! Don’t you want to see what happens?

We couldn’t believe what happened to the plants! Seriously, you will want to try this one and this is the perfect season! I wanted to have a printable available for you but couldn’t find it. I’d love to know if you are interested or have a need for a printable science journal and science project packet.

Legoman really had fun putting all his data into the computer and making graphs for his science board.

ARE YOU READY FOR MORE SCIENCE FUN?

Time for saturday science blog hop, visit these great bloggers for more fun saturday science experiments too.

Jelly Bean Science from P is for Preschooler

25 Classic Science Experiments For Kids from Little Bins For Little Hands

Follow Science Experiments for Kids on Pinterest.

What is your favorite science activity? I would love to hear! connect with me on  Facebook ,  Twitter ,  Google+ ,  Pinterest ,  Instagram  or  subscribe by email . I can’t wait to hear your ideas.

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16 thoughts on “Experiments for Kids | Effecting Plant Growth”

Aww, you’re not going to tell us the results?! 😉 This sounds like an interesting experiment and I love how into itLegoman was!

I absolutely love this!!! Thank you so much for posting such a thorough post about it. On my list of things to do.

Oh your poor salt plant! It looks like most of mine in the garden, haha. Great experiment.

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This is an interesting science experiment. Let’s not forget the proper spelling though. In most of the times when the word “effecting” was used here it actually meant “affecting” instead. Since wet are teaching children, spelling is important. This scientific project could be called: ” The effect of different solutions in plant growth: how various solutions affect plant growth. ” Tricky words!

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Dear Legoman Mum,

I am a science teacher from Hong Kong and I find your experiement bery useful and interesting. I would like to have a printable science journal and science project packet. Please kindly send to me. Thank you very much!!!!

What would you like in your science journal. This is definitely something I could work on.

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Hi, i am a primary school teacher. I really love this experiment that you have conducted, by any chance are you able to send me the results of this experiment? I would love to show my Year 2 class your observations, and your results.

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