Hypothesis by huanghengdong


									        The Effect of NaCl on Poa Pratensis


                 A Science Paper

                   Presented to

The Shawnee Mission South High School Science Fair


                Oliver L’Esperance



Water has been one of the most vital aspects of life everywhere on the planet. Every single cell

of every single living being on this planet requires some form of water to survive. This includes

plants. With drinkable water supplies dwindling, the amount of water that can be spared for

agriculture shrinks as well. If it were possible to grow plants in salty water, a large amount of

stress would be taken off of water-starved parts of the globe. If it were to become possible to

grow plants in salt water, we would first have to investigate exactly how the salinity affects

plant growth and to what extent. To what extent do NaCl-H2O solutions with varying

concentrations of NaCl affect the growth of Kentucky Bluegrass (poa pratensis)?


If a solution containing NaCl and H20 are used to water Kentucky Bluegrass in the place of tap

water for 3 weeks, then the growth of the plant will decrease geometrically relative to the

amount of NaCl in the solution.


      Five pots about 3” in diameter

      Measuring cup

      Measuring spoons
       2 cups potting soil

       Tap water

       NaCl (table salt)

       Ruler

       2 Tbsp Kentucky Bluegrass seed

       5 1-gallon jugs


The experiment took place at my house. The plants were placed on a windowsill on the

southern side of my house in order for the plants to obtain the most sunlight. All of the plants

were placed in as close to the same conditions as possible throughout the experiment. The jugs

of solution were kept at room temperature in my kitchen throughout the experiment and were

remixed before each watering.


       Control: The plant that is not being exposed to NaCl

       Independent: The amount of NaCl in the solutions

       Dependent: The growth of the Kentucky Bluegrass
   Controls: The amount of solution each plant is being exposed to, amount of sunlight

    received by each pot, temperature of each solution, temperature and humidity of

    growing conditions, soil type, seed type.


    1. Fill each of the pots up halfway with potting soil

    2. Divide the seed into five equal amounts

    3. Sprinkle the seed into the pots

    4. Use the rest of the soil to cover the seeds equally in every pot

    5. Label the pots CONTROL, P1, P2, P3, and P4

    6. In each of the jugs, mix a solution of tap water and NaCl as in the following:

            a. In the first, add just one gallon of tap water

            b. In the second, mix 4400 mg of NaCl and one gallon of water (275mg per cup)

            c. In the third, add 8800 mg of NaCl and one gallon of water (550mg per cup)

            d. In the fourth, add 17600 mg of NaCl and one gallon of water (1100mg per


            e. In the fifth, add 35200 mg of NaCl and one gallon of water (2200mg per cup)

    7. Label the first jug CONTROL, the second SOL1, the third SOL2, the fourth SOL3, and

       the fifth SOL4

    8. Add 3 tbsp of the CONTROL solution to the CONTROL PLANT, 3 tbsp of SOL1 to P1,


    9. Record the height of the tallest blade of grass for each plant
         10. Repeat steps 8 and 9 once daily for 20 days

         Data Collection

            CONTROL P1           P2        P3        P4
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7
Day 8
Day 9
Day 10
Day 11
Day 12
Day 13
Day 14
Day 15
Day 16
Day 17
Day 18
Day 19
Day 20

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