The Effect of Salinity on the Germination and Root Length

of Zea mays (Corn)

Chris Lloyd-Davies

Period 4

Junior

Woodbridge Highschool

2/2/08

Purpose / Hypothesis

• The purpose of this experiment was to find what effect salinity had on the growth of germinating corn seeds.

• The hypothesis for this experiment is that the seeds soaking in the 0.2 M solution will not germinate and that the root length will increase as the concentration of sodium chloride decreases.

Background Information

• The plant in this experiment is Zea mays, also known as sweet corn, a very common crop plant used all over the world.

• Sodium chloride (NaCl) is the main salt in table salt and sea salt.

• Sodium chloride in the soil can have disastrous effects to plants, depleting them of necessary nutrients like potassium.

Background Continued

• Sodium chloride absorbs large amounts of water, creating dry arid areas where it is hard for plants to grow, like salt flats.

• Sodium chloride also produces osmotic pressure in the roots, forcing water out of the roots and plants, drying them up.

• If sodium chloride contacts a plant’s leaves, it can cause them to shrivel.

Background Continued

• A study by the U.S. Salinity Laboratory (1983)found that higher concentrations of sodium chloride caused a delay of the germination of corn.

• A research reported in the Soil Science Society of America Journal (1970) indicated that high salinity also reduced the amount of water that could be used by the plant.

Methods and Materials

• The manipulated variable is the different molarities of the sodium chloride solutions.

• The responding variable is the root lengths of the corn seeds.

• The controls are gravity, size of paper towel, size of zip lock bag, temperature, number of seeds, no sun light, time, and initial amount of water.

Methods and Materials

• Figure 1 shows all the materials used in the experiment.

• Calculation were done to get the right amount of salt to add to 200 mL of distilled water to achieve the molarities of .20 M, 0.10 M, 0.075 M, 0.050 M, and 0.025 M.

• The amounts of salt were added to 200 mL of distilled water and stirred till it dissolved.

Figure 1

• All the materials gathered for the experiment.

• Paper towels were soaked in each solution and wrung out.

• Eight seeds were placed in each paper towel, staggered as seen in Figure 2.

• Each paper towel was folded and placed in a plastic bag, sealed, and labeled.

• These plastic bags were kept in a temperature controlled environment with no light.

Methods and Materials

Figure 2

• Eight seeds were placed in each towel.

Methods and Materials

• On the fourth day, each towel was taken out, photographed, and each seed root was measured in length, carefully with a ruler

• This was repeated on the fifth and sixth day.

• Figure 3 shows what they looked like.

Figure 3

• The control group on day 4.

Results

• The control group had the longest average root length for each day.

• The 0.2 M group had the shortest average root length for each day.

• The average root length decreased with the increase of concentration of sodium chloride.

• This is a table of the average for each group.

Average (cm)

Day 4 Day 5 Day 6

0.2 M

1.047142857 1.50714285 1.79875

0.1 M

3.4525 3.7175 4.245

0.075 M

2.478571429 3.50857142 4.277142

0.050 M

2.7475 3.3675 3.87125

0.025 M

3.236666667 4.36 5.321666

Control

4.285 5.055 5.625

Figure 4

• This is a graph of the averages for each day.

Average Root Length (cm)

0

1

2

3

4

5

6

0.2 M 0.1 M 0.075 M 0.050 M 0.025 M Control

Salinity Groups

Ave

rag

e R

oo

t L

eng

th

(cm

) Day 4

Day 5

Day 6

Results

• The deviations were quite high, but that is to be expected when dealing with plants.

• The percent and average deviations were high as well.

• This is a table of the percent deviations.

PercentDeviation (%)

Day 4 Day 5 Day 6

0.2 M

27.5190021 24.671631 34.694232

0.1 M

13.2874728 18.728984 17.314487

0.075 M

32.2107863 29.862726 23.876324

0.050 M

15.7643312 21.455085 22.562156

0.025 M

44.9021627 40.290519 42.238229

Control

17.0750680 17.474447 18.488888

Discussion / Analysis

• The hypothesis was partially supported in the fact that the higher salinities had shorter root lengths while the control group had the longest root lengths.

• The hypothesis was also not supported because the 0.2 M group did germinate, going against the prediction that it would not.

Discussion / Analysis

• Drawing from this data, the best salinity for corn soil would be around 0.1 M or lower.

• The 0.2 M seeds were stunted greatly, but the 0.1 M seeds seemed to be relatively fine, with no great damage or retardation.

• Control had the best seeds, so a soil with no sodium chloride would be ideal, but 0.1M would be acceptable.

Discussion / Analysis

• Overall, the data showed what other experiments had shown, that the concentration of sodium chloride affects the root length of corn seeds.

• One of the problems was the small size of the sample and the mold that prevented the seeds from germinating.

Conclusion

• The hypothesis was supported, that increasing concentration of sodium chloride decreased the root length.

• The control group had the lowest concentration and the longest average root length while the 0.2 M group had the highest concentration and the shortest average root length.

• This lead to the conclusion that a salinity below 0.1 M would be best for the soil of a corn seed and that no sodium chloride in the soil would be ideal.

Further Research and Applications

• This experiment could be expanded by transplanting the seeds to pots and growing them by watering them with sodium chloride solutions.

• The experiment could be improved by having a larger sample, more concentrations, and some way to prevent mold from growing in the bags.

Literature • 1. Bar-Tal, A., S. Feigenbaum, D. L. Sparks. “Potassium-salinity

interactions in irrigated corn." Irrigation Science 12 (1991): 27-35.• 2. Bingham, F. T., M. J. Garber. "Zonal Salinization of the Root

System with NaCl and Boron in Relation to Growth and Water Uptake of Corn Plants." Soil Science Society 34 (1970): 122-126.

• 3. Maas, E. V., G. J. Hoffman, G. D. Chaba, J. A. Poss, and M. C. Shannon. "Salt sensitivity of corn at various growth stages." Irrigation Science 4 (1983): 45-57.

• 4. Perry, Leonard. “Salt Damage to Plants.” University of Vermont ExtensionDepartment of Plant and Soil Science. 10 Jan. 2008

<http://pss.uvm.edu/ppp/articles/saltl.htm>.• 5. SIEGEL, S. M., B. Z. SIEGEL, JANE MASSEY, PAMELA

LAHNE, JUNG CHEN. “Growth of corn in saline waters." Physiologia Plantarum 50 (2006): 71-73.

Credit / Acknowledgements• Thank you mostly to Mr. Antrim for being so understanding

and allowing me to do my research project over again when the first one failed. Thank you also for giving me an extension so that I could gather more data and be able to complete the project properly.

• Another big thank you to Karine Marois for helping me by writing down the measurements of the roots as I dictated them. Thank you for taking an hour out of your days to help me with this project.

• And also thank you to my parents for letting me run an experiment in their house and use the unused bedroom for my controlled environment.

• And a final thank you to my brother, who’s an environment scientist, for giving me the idea of testing on a crop plant and also offering help on the set up if I needed it.