1Contribution of the Department of Agronomy, College of Agriculture, G.B. Pant University of Agriculture & Technology, Pantnagar.
To find out initial weedfree requirement, onion crop was kept weedfree for initial 15, 30, 45, 60, 75 and 90 days after transplanting. Keeping land weedfree for initial 45 days of transplanting gave bulb yield significantly superior to weedy check. Further increase in the period of weed free maintenance did increase bulb yield but the differences were not significant.
4-Nitro-2, 4-dichlorodiphenyl ether (nitrofen), N-methoxymethyl-L-chloroaceto-2, 6-diethyl anilide (alachlor), Amchem 70–25 and 4 amino-6-t.butyl-3- (methylthio)-as-triazine-5-(44)-one (metribuzin) were tested to control weeds and their effect on onion bulb yield, A treatment of one extra weeding was given 45 days after transplanting. Application of nitrofen at 2 kg/ha along with one extra weeding gave maximum bulb yield. Metribuzin proved toxic at all concentrations.
