Field experiment was conducted during 1996-97. The weed control treatments, in
general, significantly increased the crov 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 pendlmethalin had no
significant effect on seed and stover yield oi raya. Highest values of harvest index and attraction
index were recorded with hand weeding twice foUowed by Combination of isoproturon with trifluralin or pendlmethalin while lowest values were recorded in unweeded control plots. Pre-plant
application of trifluralln 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.