Effect of herbicides on the growth, yield attributes and yield of raya under late sown conditions

Field experiment was conducted dUring 1996–97. The weed control treatments, in general, significantly increased the crop dry weight, number of primary and secondary branches without having any significant effect on plant height with a few exceptions. There was a marked increase in yield attributes due to different weed control treatments except isoproturon. Chemical treatments which proved at par with hand weeding twice (20 and 40 DAS) in terms of seed yield of raya were, trifluralin 0.75 & 1.0 kg/ha as pre-planting incorporation, trifluralin + isoproturon @ 0.375+0.5 kg/ha as pre-emergence application, pendimethalin + isoproturon @ 0.375 + 0.5 kg/ha as pre-emergence application and pendimethalin @ 1.0 kg/ha as pre-emergence application. Variation in doses and time of application of pendimethalin had no significant effect on seed and stover yield of raya. Highest values of harvest index and attraction index were recorded with hand weeding twice foUowed by combination of isoproturon with trifluralin or pendimethalin while lowest values were recorded in unweeded control plots. Pre-plant application of trifluralin 1.0 kg/ha proved to be the best chemical treatments in suppressing the intensity of weeds and consequently offsets the yield losses caused by weeds.