Salt Water Intrusion and the Tolerance of Freshwater Plants
Research Question: How does the salinity of water affect the growth and longevity of basil plants?
Background: All organisms must maintain a proper chemical balance in and around their cells. Too
much or too little of a chemical can upset the positive and negative feedback mechanisms which
maintain a healthy balance. Salt is chemical which is both necessary for life but can also be extremely
toxic in large quantities.
Hypothesis : If salinity is increase, then both the longevity and growth of the basil plant will be
negatively affected.
Variables:
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Independent Variable: Salinity of water from 1.5% to 4.5% solutions
Dependent Variable: Longevity and growth of basil plants
Control: Use of distilled water with 3 basil plants
Control of Variables: Factors that can be controlled which affect the growth of plants are amount of
light, temperature, size of container, soil and amount of water. In this investigation, all plants were kept
under the same controls. Selected plants were all initially 20 centimeters in height and 8 leaves. Each
plant received 8 hours of light from indoor grow lights and kept at room temperature. All plants were
given 80 mL of solution and watered every three days. All plants were kept in 1 pint containers, and
planted in _____potting soil. Salinity solutions were increased by 1 percentage point each from 1.5% to
4.5%.
Sampling: Sampling for data was derived from the 15 basil plants purchased from local greenhouse. 3
control plants and 12 plants with varying salinity.
Materials
15 potted plants 10cm in height
1 bag of potting soil
15 1 pint pots
Kosher Salt
15 liters of distilled water (for solutions below)
3 liters of each salt water solution: 0%, 1.5%, 2.5%, 3.5% and 4.5%
25-100ml Graduated cylinder
Grow lights with timer
Methods (Procedures)
1.
2.
3.
4.
5.
Select 15 plants of 20 centimeters in height and 8 leaves
Transplant using potting soil into 1 pint pots with good drainage on the bottom.
Label 3 plants each : control, 1.5%, 2.5%, 3.5%, 4.5%
Place plants under grow lights and set timer for 8 hours of light.
Add 80 ml of solution to corresponding plant once every 3 days. (soil should be moist and well
drained)
6. Using charts for each solution amount collect the following data for 1 month every three days:
see example below:
Date
Height
±.05 cm
Basil Plant 1.5 Salt Solution
# of Leaves
Color
Amount of added solution
±.05 ml