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USING PEA AND SOYBEAN IN DEVELOPMENTAL TESTS FOR NON-TARGET PLANT EFFECTS
Citation:
Olszyk, D M., T G. Pfleeger, E H. Lee, E. S. Davis, AND M. Plocher. USING PEA AND SOYBEAN IN DEVELOPMENTAL TESTS FOR NON-TARGET PLANT EFFECTS. Presented at Society for Environmental Toxicology and Chemistry, Portland, OR, November 14-18, 2004.
Description:
Current tests required for pesticide registration do not investigate the potential effects of chemical exposure on plant development. The tests investigate only seedling emergence and early growth. Previous research has shown that significant impacts can occur to plant development with little or no visible injury or effect on vegetative growth. Plant reproduction has significant economic and ecological effects, but is not evaluated under current test requirements. We are developing plant seed reproduction tests that use pea (Pisum sativum) or soybean (Glycine max). Pea and soybean were chosen because they are economically important, easy to culture, and produce an easily measured seed reproduction endpoint. In a series of experiments, peas and soybeans were grown in pots in a greenhouse and outside. Below field application rates (0.1 to as low as 0.0056 and 0 x field application rate or f.a.r.) of herbicides (Oust?, Roundup?, Atrazine 4F, Beacon?, Accent?, Banvel? or Stinger?) were applied to the plants at 14 DAE or at flowering (~18-20 DAE for peas and ~26-45 DAE for soybeans). Peas were harvested ~ 35 DAE and soybeans 114+ DAE. Pod numbers and weight, and seed number and dry weight were measured for both species as well as seed fresh weight for peas. Soybean dry seed weight was reduced with Stinger? and Atrazine 4F at 0.1 and Banvel? at 0.018 x f.a.r. Pea fresh seed weight was reduced with Beacon? and Banvel? at 0.1 and Oust? at 0.001 x f.a.r. For pea, the correlation between seed production and herbicide exposure occurred for plants grown for only 35 DAE. Thus, pea provides a development test lasting only one week longer than the current vegetative vigor test, and gives regulators a new tool to evaluate the risks associated with new chemicals prior to their release into the environment.