Salinity can be defined as ‘the measurement of salts in soil or water’ (Department of sustainability). This experiment will be performed in order to determine the tolerance and growth of bean plants on different salinity levels from water containing salt.
According to ‘The basics of Salinity and Sodicity effect on the physical properties of soil ‘, in the root zone of the plant, excess salt can hinder or prevent the plant from withdrawing water from surrounding soil. The irrigation of saline water improves soil structure, but can negatively affect plant growth and crop yield. The reason why is because salinity acts like a drought on plants, preventing the roots from performing their cosmetic activity where water and nutrients move from an area of low concentration, to an area of high concentration, causing the plant to use extra energy to draw water with it’s roots. Excess energy use in plant may eventually lead into plant stress and cause vegetation to become unhealthy and die. A high salt level in the water or soil may then interfere with the germination of new seeds. Some causes of salinity in the water or soil is due to Natural processes such as the weathering of rocks, wind, and rain. Salinity also may occur when long rooted plants are replaced with short rooted plants which will then cause the water table to rise and bring the salt to the surface.
Although that may be one of the effects of salinity in water, plants are able to adapt by producing a quantitative trait loci that increases survivability against salinity. Stretches of DNA are connected and linked to genes that contain the phenotype of being able to survive the salinity. This was tested in Dvorak and Zhang’s study in 1992 that showed the difference in resistance to salinity between Chinese spring wheat and cultivated wheat. Mesembryanthemum crystallinum or the ice plant has also shown its adaptation to salinity. They used a CAM pathway, or a day and night cycle which only opens the stomata at night. This saves water that they intake and increases their water use efficiency to support tolerance against salinity stress. Plants have adapted to survive against salinity through facilitation of water intake. In this experiment bean plants will be used to determine the tolerance and growth of the plants of different salinity levels from water containing salt as said previously before.
The technique that will be used to perform this experiment is receive a total of 400 bean plants planted in plastic cups containing natural unfertilized soil. By having a control group of 100 bean plants that will have only tap water as well as 3 experimental groups with different salinity levels of 2%, 5% and 20%, and will have 100 bean plants for each experimental group. The tolerance of the bean plants as well as the growth of the experimental plants compared to the controlled plants will be tested. The plants will all be receiving the same amount of sunlight, the same type of environment, and same type of soil to grow in.
How the data will be recorded is by first allowing the plants to sprout and grow. The seed to seedling development takes about two weeks. The bean begins to absorb water when planted in warm, moist soil, and the absorption of water signals the metabolic start of growth. Pressure builds inside the seed until the seed coat bursts. A small root called the radicle forms and a hooked stem grows. Then the seeds split and two small leaves, or cotyledons, appear. Afterwards, 3-4 sets of true leaves cause rapid new growth. The roots deepen into the soil, and side shoots grow and the stem thickens. The plant develops special bacteria to regulate the amount of nitrogen within the plant. After another 35-45 days, the flowering begins. The bean plants can fertilize themselves, but cross pollination makes fertilization more successful. The ovary contains 3-7 chambers called ovules that develop into pinto bean seeds, which mature in the bean pod. After hardening and drying, they become pinto beans. The bean plants will be observed each day until the plant begins to grow out of the roots, and each day the number of leaves and height of the plant will be recorded. The data will be collected for one month after the seeds sprout.
B. Purpose/ Objective
As the salinity of the water increases, the bean plants’ health will disintegrate as the tolerance of the bean plants weaken through the increase of salinity in each experimental group, the salinity in the experimental groups or ‘excess salt’ ,is an example of real life natural occurrences.
D. Parts of the Experiment
The dependent variable in this experiment is plant growth, measured in height of the plant and number of leaves of the plant.
The independent variable is the salinity of the water that the different plant groups are being watered with.
The control group is the bean plants that are being watered with tap water with no salinity.
The experimental group is the bean plants that are being watered with salt in them.
Some constants are the type of bean, the amount of water that they are being watered with, the sunlight they are exposed to, the temperature they are being grown in, and the moisture of where they are being grown
In this experiment, the required materials will be needed:
400 plastic party cups to cultivate the bean plants in
400 bean seeds / seedlings
1 box of iodine table salt
1 tbsp to measure the salt
1 cup measurer
1 measuring ruler
Regular Tap water
1-5 measuring beakers, depending on how many bean seeds may be fit into each beaker.
The night before planting the beans, soak the beans in a measuring beaker(s) overnight to make it easier to sprout.
Label 100 cups as the control group
Label 100 cups as 2% salinity, 100 as 5%, and 100 as 20%
Line up the cups in 20 rows of 20
The first 5 rows will be the control group, next 5 rows will be 2%, next 5 will be 5%, and final five rows will be 20%
Place one cup of soil in each party cup.
Place one bean in each cup, about one inch deep.
Water each control group with 200 mL of water, slowly poured on the surface of the soil.
For the 2% salinity, mix 5 g of table salt in 200 mL of water, and water each 2% salinity plant with 200 mL of the 2% saline water.
For 5% salinity, repeat the procedure in step 9, but with 60 g of table salt.
For 20% salinity, repeat the procedure again from step 9, with 90 g of table salt.
Every day, water each plant with 100 mL of water, with no salt in the control group’s water, 2 g of salt in the 2% salinity, 5 g in 5%, and 20 g in 20%.
Observe and record observations each day in the lab journal until the beans sprout
When beans sprout, measure each sprout with a ruler every 3 days.
When the first leaves grow, measure the height of the plant each day and record the number of leaves on each plant.
Keep all measurements in a data table and make calculations on excel.
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