Have you ever wanted to plant a garden but were unsure of what chemicals have been used in that soil? How far does a herbicide spread through the ground? How long might it take before it's safe to plant in a soil once treated by herbicide? These are all questions that can be answered through an experiment to measure if seed germination is affected by herbicide residue in the soil. This plant science experiment, recommended by Cornell University's Horticulture Department, asks students to study seed germination bioassays to measure the effects of various levels of herbicides in the organisms. Lettuce seeds are one organism that's easy to conduct the experiment on because they are not only inexpensive, but also easy to culture.
Once again using lettuce seeds, college students can conduct a reference toxicity to see if the organism will respond in predictables way to various concentrations of certain chemical compounds. Questions that can be answered with this experiment are: what is the threshold concentration at which the organism dies; does diluting the chemicals affect seed germination; and what are the best conditions for the lettuce to germinate and grow? Students can choose any chemical, from household cleaning items to herbicides, to study in the experiment.
Ever wonder which plant fertilizer will help your garden grow? This experiment will help answer that question. Super Science Fair Projects suggests picking a certain vegetable to conduct this experiment on, such as radishes. Choose a variety of fertilizers to test and apply them as directed to the test plants. Also, use one plant as a control without any fertilizer. Watch and log how the plants grow and flourish. To further the experiment, analyze the ingredients in each fertilizer and determine why these chemicals may have aided in plant growth.
College students can experiment with the capillary system of a plant with this project. The basic version starts by splitting a white flowered plant's stem in half. Place one half in a glass of plain water, and the other in a glass of water dyed red. Watch the plant in the colored glass as it absorbs the hues through its capillary system. You will see how the water is spread through the plant. Students can continue this experiment in soil, and determine what effects chemicals or compounds can have on plants, or even how florists could use this method to create interesting bouquets.