Effect of time and method of isoproturon application on growth and yield of Indian mustard (Brassica juncea)

A field experiment was conducted during the winter season of 1993-94 and 1994-95 to study the effect of time and method of application of isoproturon on its selectivity in Indian mustard [Brassica juncea (L.) Czernj. & Cosson] in relation to soil-moisture levels. The phytotoxicity of isoproturon was the maximum when applied 35 days after sowing (DAS) compared with application at 25 DAS and at pre-emergence. Irrigation at 30 DAS and at flowering accentuated the isoproturon phytotoxicity with about 58% seed yield loss compared to 29% loss under no irrigation. Maximum seed yield (24.1 q/ha) was obtained with-preemergence application of pendimethalin @ 1.5 kg/ha. Irrigation did not alter the seed yield of Indian mustard treated with pendimethalin. Selective application of isoproturon as foliar spray, soil application or soil+foliar application revealed that the toxicity on Indian mustard was in order of soil + foliar > soil > foliar application. The-corresponding seed yield losses were 38, 281 and 22% at 0.5 kg/ha and 56, 41 and 35% at 0.75 kg/ha Isoproturon.