Salinity of Soil From Road Runoff and its Effects on Plant Life Grant Andrew Abe Blake

Background Info 2 major steps of photosynthesis are the light reactions and the Calvin cycle. The light reactions are the steps of photosynthesis that convert solar energy into chemical energy. Light energy is initially converted to chemical energy in the form of two compounds: NADPH and ATP. The Calvin cycle is the part of photosynthesis that produces sugar for the plant. It uses NADPH and ATP created from the light reactions along with C02 to create sugar, which provides energy for the plant. To put it simply, the more a plant photosynthesizes, the more energy it will create.

Background Info cont.  Salinity in plants can have a huge effect on the rate of photosynthesis.  Salinity stress is a recent emerging problem that has been developing and becoming more serious.  The effects of salt in plants is similar to drought in plants.  Because the salt absorbs the water, in a high enough quantity the salt can dry out plants which makes photosynthesis slow down at a very high rate or even make photosynthesis in plants cease all together.  If too much salt gets into the plant then the stomata, this allows carbon dioxide into the plant, may close up which will not allow and carbon dioxide in or oxygen out.

Purpose and Hypothesis The purpose of our experiment was to answer this question: Does a change in salt content of soil effect the rate of photosynthesis? We predicted that if we added salt to a plants soil, the photosynthesis of the plant will slow down.

Predictions Continued We also predicted that, if our hypothesis is correct, the plant would wither, or, in the higher salt percentages, the plant would die.

Basic Procedure  Gather the materials from the materials list  Punch four small holes in the bottom of the cup  Moisten the soil  Fill the four red cups each with the soil to about 3/4 of it's capacity  Add in four seeds, spaced in a square pattern, to each cup on top of the soil  Add an inch of soil on top of the seeds  Water the seeds with 150mL of water then

Procedure Cont.  Place the cups in a place with access to sunlight  Water the plants with the same amount every two days after that  When the plants have grown leaves, around two weeks, begin the treatment  watering Label one cup "Control" Label the rest of the cups by how much salt you will add to the watering of those cups (10g, 5g, 2g)  Measure out the salt amounts on a scale (10g, 5g, 2g)  Add each amount to four separate beakers of 150mL of water each  Add that water to the corresponding plant cups  Water the control normally  Perform floating leave disk assay and take data

Data

Continued P values: 2g of salt: For 2 grams of salt we would accept the Null Hypothesis. 5g of salt: For 5 grams of salt we would reject the Null Hypothesis. 10g of salt: 2.6e-6 or For 10 grams of salt we would reject the Null Hypothesis.

Qualitative Data

Limitations  Plant variety- only tested one type of plant  Time- we only had one week to treat the plants with our salt solutions  Inability to properly gauge whether our experiment was realistic or not. We did not have a way to get an average for the amount of salt placed on a square meter of road  Human error and absences

Limitations Continued The limitations had some less than desirable effects:  We only got two days of treatment in before we did the leaf disk assay  There were no repeated tests, and our data might not be valid because of it  Many people in our group were gone, so we struggled to keep up and we had to sacrifice some aspects of our experiment

Implications  It is standard practice in many areas of the world to salt roads in order to prevent ice related accidents  This salt can, based on our experiment and what other scientists have researched, destroy or adversely harm plant life that may get runoff from the roads  Watersheds, areas where water drains into along with any waste it brings with it, could be adversely effected if the water brings the road salt into the area

Work Cited  "Annals of Botany." Photosynthesis under Drought and Salt Stress: Regulation Mechanisms from Whole Plant to Cell. N.p., n.d. Web. 18 Mar  Campbell, Neil A., Jane B. Reece, and Lawrence G. Mitchell. Biology. fifth ed. Menlo Park: Addison Wesly Longman, Print.  Farabee, M J. "Water and Solute Movement." TRANSPORT IN AND OUT OF CELLS. Ed. M J. Farabee. N.p., 18 May Web. 20 Mar  Singer, S. J., and Nicolson, G.L The fluid mosaic model of the structure of cell membranes. Science 175,  Wachman, Monica. "Does Salt Affect Photosynthesis?" EHow. Demand Media, 01 Apr Web. 18 Mar

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