CHEMICAL WEED CONTROL IN WHEAT UNDER DIFFERENT RICE RESIDUE MANAGEMENT OPTIONS

Rice residue management can influence weed dynamics and productivity of subsequent wheat crop. A field experiment was conducted at Agronomic Research Area, University of Agriculture, Faisalabad during Rabi 2010-11 to evaluate the influence of two broad spectrum post-emergence herbicides (isoproturon+carfentrazone and iodo+mesosulfuron) on wheat and associated weeds under different rice residue management options (residue incorporation, residue burning and zero tillage). The experiment was laid out in randomized complete block design under split plot arrangements. Residue management options were assigned to main plots while weed control treatments were maintained in sub-plots. Zero tillage was helpful in averting weed growth and recorded more wheat grain yield even under weedy check as compared to the rest of the residue management options. Residue incorporation resulted higher weed density and biomass than residue burning. Both the herbicides provided 80% suppression in weed density and dry biomass with upper limit (100%) recorded when isoproturon+carfentrazone was applied to zero tillage plots. The herbicide treatments also improved wheat leaf area indices, crop growth rate and dry matter accumulation over weedy check under all residue management options. Maximum grain yield (3742 kg ha-1) was obtained when isoproturon+carfentrazone was applied to zero tillage plots. Highest economic net benefits were also associated with the same treatment combination. Zero tillage seems more appropriate residue disposal method in rice-wheat cropping system than residue burning and incorporation.