Nine beans, nine zucchini, and nine lettuce seeds were cultivated in indoor pots. Each type of plant was then watered at three different salinities: three of each type at 30g of salt per liter, three at 15g of salt per liter, and three of each type as controls with normal fresh water. After about ten days of testing, all the experimental plants were dead. Consequently, four beans, four lettuce, and four zucchini plants were re-grown, maintaining the regular watering of the healthy controls. Two of each plant were watered with 5g of salt per liter, and two at 10g of salt per liter; the plants progress was observed every day.
At 15g and 30g of salt per liter, the plants died relatively quickly. The lettuce were the less tolerant plants as they died first, followed by the zucchini and beans at 30g of salt per liter, and finally the zucchini and beans at 15g of salt per liter. The bean plants survived longer than both the zucchini and lettuce. In the second set of testing, though reaction time decreased drastically, all plants at 10g per liter of salt and 5g per liter of salt showed salt spots by one week and a half. They then continued to become floppy by the end of the second week.
From the original test, the results showed that zucchini, beans, and lettuce plants could not tolerate a level of salinity greater than or equal to 15g of salt per liter of water. The second experiment showed that plants could not survive healthily when 5g of salt per liter was watered into the soil everyday. It would be difficult to effectively grow these plants, and probably others similar, in salty soil without them dying; however, some plants are more tolerant than others, as the bean plant seemed the hardiest towards salt in the first test.
The science project tests to determine salts affect on plant growth.
Science Fair Project done By Helen C. Jackson