Title: Bio-efficacy of sulfonylurea herbicides on mixed weed flora in transplanted rice.
Abstract: A field experiment was conducted during kharif season of 2003 and 2004 to study the bio-efficacy of different rates of sulfonylurea herbicides for the management of mixed weed flora in transplanted rice. In experimental field, Echinochloa colona, E. crusgalli and Paspalum distichum among grasses, Caesulia axillaris among broadleaf weeds and Cyperus spp. among sedges were the dominant weed species which constituted 18.8,12.4,11.7,32.95 and 9.5 per cent, respectively of total weed population under weedy check at 60 days after transplanting. The lowest total weed density (1.40 m−2), dry matter production (1.37 g m−2) and weed control efficiency irrespective of weed species was recorded under two hand weeding followed by metsulfuron methyl at 8.0 g ha−1, metsulfuron methyl + chlorimuron ethyl (ready mixture of metsulfuron methyl and chlorimuron ethyl in 1:1 ratio) at 8.0 g ha−1 and 2,4-D at 500.0 g ha−1 at all the stages of crop growth during both the years. Morpho-physiological crop characteristics viz., number of shoots m−2, crop dry weight (g m−2), leaf area index (LAI) and crop growth rate (g day−1) were found to be lowest in weedy plot and maximum in weed-free plot and there was an increasing trend from 30 days stage upto harvest except number of shoots (m−2) and leaf area index. Among herbicides, metsulfuron methyl at 8.0 g ha−1 and metsulfuron methyl + chlorimuron ethyl at 8.0 g ha−1 recorded highest values for number of shoots m−2, crop dry weight (g m−2), leaf area index (LAI) and crop growth rate (g day−1) in 2003 and 2004, respectively. Weeds caused 30.5 per cent reduction in the grain yield of rice in comparison to weed-free condition. Yield contributing characters like number of panicles, number of grains panicle-1, weight of grains panicle−1, 1000-grain weight, maximum weight of panicle and grain weight plant−1 observed highest under metsulfuron methyl at 8.0 g ha−1 and metsulfuron methyl + chlorimuron ethyl at 8.0 g ha−1 among the herbicides during both the years. Consequently, metsulfuron methyl at 8.0 g ha−1 (53.5 q ha−1) and metsulfuron methyl + chlorimuron ethyl at 8.0 g ha−1 (53.84 q ha-1) not only yielded higher among herbicides but their effectiveness for suppressing mixed flora of weeds was statistically comparable to weed-free condition (55.15 q ha−1) and two hand weeding treatment (53.6 q ha−1) during both the years.
Publication Year: 2012
Publication Date: 2012-03-01
Language: en
Type: article
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Cited By Count: 6
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