SCREENING OF HERBICIDES FOR EFFICIENT CONTROL OF BROADLEAF WEEDS IN WHEAT (Triticum aestivum L.)

Broadleaf weeds constitute major proportion of weed flora in wheat. A field study to find out suitable herbicides for controlling broadleaf weeds in wheat crop was conducted during winter, 2014. Ten premixed herbicides viz., bromoxynil + MCPA at 450 g a.i. ha^-1, fluroxypyr + clopyralid + tribenuron at 330 g a.i. ha^-1, fluroxypyr + MCPA at 450 g a.i. ha^-1, bromoxynil + MCPA + tribenuron methyl at 475 g a.i. ha^-1, fluroxypyr + MCPA at 375 g a.i. ha^-1, fluroxypyrmethyl + MCPA at 144 g a.i. ha^-1, clopyralid at 525 g a.i. ha^-1, tribenuron + fluroxypyr at 140 g a.i. ha^-1, triasulfuron at 30 g a.i. ha^-1 were applied 25 days after sowing (DAS) (1st irrigation). A weedy control was also kept for comparison. The highest weed control was given by bromoxynil + MCPA at 450 g a.i. ha^-1, triasulfuron at 30 g a.i. ha^-1, and fluroxypyr + MCPA at 450 g a.i. ha^-1 as they gave highest values of weed control efficiencies (81.3, 81.2 and 79.7%) and herbicide efficiency indices (3.31, 3.27 and 3.25), respectively. Fluroxypyr + MCPA at 450 g a.i. ha^-1 produced the highest grain yield (4.07 t ha^-1) of wheat which was followed by triasulfuron at 30 g a.i. ha^-1 (3.97 t ha^-1) and bromoxynil + MCPA at 450 g a.i. ha^-1 (3.95 t ha^-1). The improvement in grain yield of wheat by herbicides seem to be resulted due to better weed control as grain yield showed significant negative relationship with total weed density (R^2=0.68) and total weed biomass (R^2=0.85). Regression analysis also revealed a significant positive dependence of grain yield on number of tillers m^-2 (R^2=0.93), spike length (R^2=0.91), grains spike-1 (R^2=0.83) and grain weight (R^2=0.95). It is concluded that fluroxypyr + MCPA, triasulfuron and bromoxynil + MCPA are the best herbicides for the control of broadleaf weeds like Chenopodium album, Chenopodium murale, Convolvulus arvensis, Euphrobia helioscopia and Fumaria indica in wheat.