Effect of Sowing Dates and Weed Control Methods on Weed Infestation, Growth and Yield of Direct-Seeded Rice

摘要

To evaluate the efficacy of different weed control methods and to determine an optimum sowing time for direct-seeded rice (DSR), a field trial was conducted during the summer season of 2012. Treatments comprised of two weed control methods viz; hand weeding (W-2) and chemical control (W-3) using pendimethalin at 1137 g a.i. ha(-1) (pre-emergence) and bispyribac Na at 30 g a.i. ha(-1) (post-emergence), 20 and 40 d after sowing (DAS) of rice and a weedy check (W-1) for comparison while crop was sown on various sowing dates viz; D-1=1st, D-2=10th, D-3= 20th and D-4=30th June. The experiment was laid out in split-plot design and replicated thrice. Data pertaining to weeds and yield traits revealed that all weed control methods and sowing dates substantially affected the weed flora, yield and related components of DSR over weedy check. The 20th June sowing proved to be an optimum sowing date, exhibiting highest paddy, straw and biological yield (4.50, 14.23 and 18.73 t ha(-1), respectively) in hand-weeded plots. Moreover, hand weeding and chemical weed control gave 97% and 84% weed control, respectively, over weedy check. Reduced weed intensity and biomass in hand-weeded plots resulted in better crop growth and ultimate yield.