Production of weed-free mother bulb of onion (Allium cepa) through integration of herbicides and weeding

A field experiment was carried out during winter season of 2004 and 2005 to find out the appropriate and economic weed-management practice for production of weed-free mother bulb of onion (Allium cepa L.) required subsequently for seed production. There was reduction in the bulb yield (64.8%) and bulb diameter (24.8%) due to uncontrolled weed growth in the weedy check. Pre-emergence application of oxyfluorfen integrated with one hand-weeding at 35 days after transplanting (DAT) was significantly superior to pendimethalin, fluchloralin and alachlor when applied alone and also when supplemented with one hand-weeding at 35 DAT. All the weed-control treatments significantly reduced the weed density and dry weight of weeds, and in turn increased the bulb yield compared with the weedy check. Significantly lower bulb yield was recorded with alachlor (1.5 kg/ha) compared with pendimethalin, fluchloralin and oxyfluorfen at higher doses due to its inability to con-trol broad-leaf weeds, which had the maximum density in the experimental field. Maximum additional monetary returns (Rs 42,990 and 36,850 ha) and net monetary returns (Rs 37,350 and 31,750/ha) were recorded by oxyflurofen 0.15 kg/ha integrated with one hand-weeding at 35 DAT and oxyfluorfen 0.30 kg/ha, respectively.