Salinization Lab

Salinization Lab
To design, implement, and evaluate an experiment to determine how the concentration of salt in water affects the
germination rate of seeds.
Background information:
Salt buildup is a potential problem on almost all of the irrigated farmland in the United States. Much of the world's unused
land is in arid or semiarid regions where irrigation would be necessary to grow crops. A small amount of salt in the soil will not
affect the germination and growth of crops. Eventually, however, if salt concentrations increase, negative impacts occur.
Eventually salt concentrations will affect the germination of seeds. Farmers need to know the relationship between the salt
concentration and the percent of seeds that will germinate.
Salt kills germinating seedlings by removing the H2O from their cells. There are several salts that are responsible but this lab
will involve only one, sodium chloride (NaCl). From your results you can assume that other salt concentrations would also
affect germination rate. NaCl has a solubility of 35.7g/100 mL of H2O. Ocean water has a concentration of 3.5% which is
3.5g/100 mL of H2O. Freshwater has a concentration of 0.005% salt which is 0.005g/100 mL of H2O.
You and your partners will act as a team of consultants hired by a group of farmers who are concerned about how increasing
salt concentrations in their soil will affect their crops. Design a controlled experiment to measure how increasing salt
concentrations interfere with the germination of crop seeds.
1. Formulate a hypothesis.
2. Identify your independent and dependent variables. Hint: What is the effect of the independent variable on the dependent
3. Identify your control. Identify the constants in your experiment.
4. Design a data table to record your data.
5. Label each pot with your period, group letter, and the solution in each. When adding water be sure to add the correct
solution. Make sure you are consistent with the amount of water you give your plants.
6. Keep accurate data tables and check on your experiment whenever we meet. When the experiment is completed, you’ll
turn in a lab report including a data table and a graph. Be sure to do an analysis of the data and a conclusion.
3 small pots and
potting soil
Dilutions of salt
Graduated cylinders,
Radish seeds
Analysis (answer as part of the conclusion):
1. Does there seem to be a relationship between the number of seeds which germinated and the concentration of the salt
water? If so, what is that relationship?
2. Does there seem to be a relationship between the % that germinated and the concentration of the salt water? If so, what?
3. Did your experiment support your hypothesis?
4. Can you think of any errors that might have occurred that would invalidate your results and how might they be corrected?
Note: some suggested concentrations: 0%, 0.01%, 0.1%, 0.5%, 1%, 2%, 3%, 4%
g/NaCl/1000mL: 0g, 0.1g, 1g, 5g, 10g, 20g, 30g, 40g