IMPACT OF TEMPERATURE ON THE PHYTOTOXICITY OF IMAZAMETHABENZ AND FENOXAPROP TO WILD OAT (AVENA-FATUA)

Controlled environmental experiments were conducted to determine the e ffect of short- and long-term temperature stresses on the phytotoxicit y of imazamethabenz and fenoxaprop to wild oat. Short-term (16 h) temp erature stresses, imposed either before or after herbicide spraying, h ad no influence on imazamethabenz phytotoxicity. However, short-term t emperature stresses affected the phytotoxicity of fenoxaprop, with pre treatment high temperature (35-degrees-C) reducing the phytotoxicity a nd post-treatment high temperatures (25-35-degrees-C) enhancing the ph ytotoxicity. Imazamethabenz phytotoxicity was similar at long-term tem peratures between 20/15-degrees-C and 30/20-degrees-C. Constant low te mperature (10/5-degrees-C) reduced imazamethabenz phytotoxicity, where as such temperature had no effect if only imposed before or after spra ying. Among three constant temperature regimes, fenoxaprop was more ef fective at 20/15-degrees-C, followed by 10/5-degrees-C. Constant high temperature (30/20-degrees-C) greatly decreased fenoxaprop phytotoxici ty. The adverse effect of long-term low temperature on fenoxaprop phyt otoxicity was due mainly to the influence of post-treatment low temper ature, whereas long-term high temperature imposed either before or aft er spraying reduced the phytotoxicity of fenoxaprop.