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Allelopathic water extracts are the solutionsthat are obtained from the allelopathic crops like sorghum, sunflower and brassica which have the potential to control weeds, especially when applied in combination with reduced rates of herbicides. Aim of this experiment was to study the effectiveness of herbicide, sorghum extract and their application times on weed dynamics and yield of wheat. Sorghum extract with three concentrations (1:3, 1:4, 1:5), herbicide (affinity) with three different levels (1/3, 1/ 2, 2/3 of the recommended dose) and along with three application time (emergence, tillering, 50% at tillering time and 50% at emergence time) were applied. Herbicide sole, un-weeded and weeded plots were considered for comparative study. Among all the treatments, herbicide sole had higher effect followed by hand-weeded plots for minimizing weeds density, weed dry weight, fresh weight and increased grain yield and yield contributing constitutes of wheat. Sorghum application time and sorghum extract concentration considerably increased yield and yield components and decreased weed density in wheat. Sorghum extracts spurted at 1:5 gave more grain spike-1 (45), increased spike m-2 (257), high thousand grain weight (59.0 g)and higher harvest index (36.8 %), while taller plants were noted with 1:4 (92.4 cm). Herbicide (affinity) at the rate of 1317g ha-1 resulted in significantly increased spike m-2 (256), increased grain spike-1 (45), higher thousand grain weight (58.3 g), and higher harvest index (37.4 %), Sorghum extract concentration with combination of herbicide sprayed at tillering stage gave more spike m-2 (255), increased grain spike-1 (44.8), while more harvest index (36.4 %) were found when treatments applied 50% at emergence + 50% at tillering or tillering stage. Thousand grain weight were found non-significant. It is concluded that sorghum extract concentration 1:5 with 1317g ha-1 of herbicide affinity used at tillering stage is proposed for effective weeds control, high yield and high net return of wheat crop.
Keywords: Allelopathy; Affinity; Harvest index; Sorghum extract; Wheat