Effect of submergence periods and herbicides on the control of red sprangletop (Leptochloa chinensis (L.) Nees) in transplanted rice.

摘要

A field experiment was conducted to determine the effect of submergence periods and herbicides on the control of red sprangletop (Leptochloa chinensis (L.) Nees) in transplanted rice on a loamy sand soil during summer 2003 and 2004 at Punjab Agricultural University, Ludhiana. The experiment was a split plot design with three submergence periods (one, two and three weeks after transplanting rice) in the main plots and four herbicides (butachlor 1.5 kg ha-1, anilofos 0.375 kg ha-1, pretilachlor 0.75 kg ha-1 and pyrazosulfuron 0.015 kg ha-1) along with unweeded control in the sub plots. The two and three week submergence periods, though statistically similar, gave significantly better control of L. chinensis than one-week submergence leading to improved growth and yield of transplanted rice. The one week submergence period resulted in 10.3 and 10.7 times more dry matter accumulation by L. chinensis and 19.7 and 20.7% less effective tillers of rice than two and three week submergence periods, respectively. All the herbicides applied gave statistically similar weed control and were significantly better than the unweeded control but only when the field was kept submerged for at least two weeks. The herbicides gave poor weed control under one week submergence. The herbicide application reduced weed count by 91% on average over the unweeded control. The submergence period of two and three week gave 46.7 and 48.1% increase in grain yield of rice over the one week submergence.