Weed and nitrogen management effects on weed flora and productivity of transplanted rice (Oryza sativa) in North-Eastern region of India

A field study was conducted during rainy (kharif) season of 2017 at Barapani, Meghalaya, to find out the effects of weed and nitrogen management on weed flora and yield of transplanted rice (Oryza sativa L.) in North-Eastern region of India. The experiment was taken in split-plot design with 3 replications. In the main plot, 4 weed management practices, viz. unweeded control; oxadiargyl 0.08 kg/ha followed by (fb) bispyribac-Na 0.02 kg/ha; oxadiargyl 0.08 kg/ha fb hand weeding (HW) at 40 days after transplanting (DAT), and 2 HW at 20 and 40 DAT was taken, while 4 N levels, viz. 0, 30, 60 and 90 kg N/ha were taken in sub-plots. At 60 DAT, total weed population and weed density were remained at par in HW at 20 and 40 DAT, oxadiargyl 0.08 kg/ha fb HW at 40 DAT and oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha. The grain yield also followed the same trend and remained at par in HW at 20 and 40 DAT, oxadiargyl 0.08 kg/ha fb HW at 40 DAT and oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha. However, in terms of net returns, application of oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha recorded the highest followed by oxadiargyl 0.08 kg/ha fb HW at 40 DAT. Application of N at higher level reduced the total weed population at 60 DAT and a reverse trend was found with weed dry weight. Application of 90 kg N/ha recorded higher grain yield, net returns and benefit: cost ratio. It may be concluded that oxadiargyl 0.08 kg/ha fb bispyribac-Na 0.02 kg/ha with 90 kg N/ha could be an alternative for HW to enhance the productivity in transplanted rice for North-Eastern region of India.