Efficacy of Isoproturon in Relation to Irrigation and Top Dressing of Nitrogen in Wheat

A field experiment was conducted at the Agronomy Farm of HPKY, Palampur during rabi 1993–94 and 1994–95 to study the effect of irrigation and time of top dressing of nitrogen on efficacy of isoproturon in controlling weeds in wheat. Application of isoproturon 1.5 or 1.0 kg/ha before irrigation (25 DAS) fb top dressing of nitrogen (35 DAS) resulted in significantly lowest dry matter accumulation of weeds and highest number of effective tillers/metre row length and spikelets/spike. The values of spike length and 1000-grain weight were also higher in these treatments which ultimately resulted in significantly highest wheat grain yield compared with the remaining treatments. Irrigation (25 DAS) fb top dressing of nitrogen (30 DAS) fb isoproturon 1.0 kg/ha (35 DAS) and irrigal ion (25 DAS) fb isoproturon 1.0 kg/ha fb top dressing of nitrogen being statistically at par were the least effective in controlling weeds and recorded significantly lower values of all the yield attributes and yield.