Effects of glyphosate on germination and seedling growth of rice.

Abstract

Effect of glyphosate [N-(phosphonomethyl) glycine] on germination and seedling growth of rice was studied in the laboratory. A field on the material's residual status in the paddy levee and in water in the paddy field was also performed.In the laboratory experiments, glyphosate did not affect the germination of rice seeds up to a concentration of 50ppm. No difference was observed between Tainan No. 5 (Japonica-type) and Taichung No. 3 (Indica-type). The growth of rice seedlings in nutrient solution cultivated for 10-11 days was affected at concentrations of 1.0 and 2.5ppm for Tainan No. 5 and Taichung No. 3 cultivars, respectively, but the growth of root was affected at 0.5ppm for Tainan No. 5 and 1.0ppm for Taichung No. 3. In the field tests, no glyphosate was detected in soils collected in the paddy levee, even in a sample collected 1hr after application at the officially recommended rate. Residue in the paddy water was found only in first samples collected 1hr after application and was 1, 475ppb and 76ppb for the samples 30cm and 3m from the paddy levee, respectively.From the above evidence, application of glyphosate at the recommended rates not have a harmful effect on the germination of rice seeds or on nursery beds or young seedlings in paddy fields.