Abstract:
Greenhouse studies were carried out to determine the suitable time of QYR301 application and rainfastness, examine influence of temperature and light intensity on its efficacy targeted by barnyard grass (
Echinochloa crus-galli) and paddy (
Oryza sativa). QYR301 showed high safety for paddy at different leaf stages, with 0% dry weight inhibition for over-2 leaf stage of the paddy at 360 g a.i./hm
2. Meanwhile, the growth stage of barnyard grass significantly influenced the efficacy of QYR301 and barnyard grass at 2-3 leaf stages was most sensitive to QYR301 with 95%-98% dry weight inhibition at 30 g a.i./hm
2. QYR301 had ability to quickly penetrate into the leaf tissues and remained effective on 8 h of simulate rainfall after application with 75%-93% dry weight inhibition at 30-120 g a.i./hm
2. QYR301 exhibited relatively stable efficacy against barnyard grass under temperature of 20-35 ℃ with GR
50 of 44.6-51.4 g a.i./hm
2. Compared with middle (45%) and low (4%) light intensity, QYR301 showed significant higher efficacy against barnyard grass under high light intensity (100%) conditions. In conclusion, the growth stage of weeds, rainfall, temperature and light intensity significantly influenced the efficacy of QYR301 and the optimum time, temperature and light intensity for barnyard grass control were 2-4 leaf stage of the weeds and over-2 leaf stage of the paddy, 20-35 ℃ and 100% light intensity, respectively. The application needs to be reconducted if the rain occurs within 8 hours after application.