Abstract
The differential weed-competitive abilities of eight rice genotypes and the traits that may confer such attributes were investigated under partial weedy and weed-free conditions in naturally occurring weed flora in dry direct-seeded rice during the rainy seasons of 2011 and 2012 at Ludhiana, Punjab, India. The results showed genotypic differences in competitiveness against weeds. In weed-free plots, grain yield varied from 6.6 to 8.9 t ha−1 across different genotypes; it was lowest for PR-115 and highest for the hybrid H-97158. In partial weedy plots, grain yield and weed biomass at flowering varied from 3.6 to 6.7 t ha−1 and from 174 to 419 g m−2, respectively. In partial weedy plots, grain yield was lowest for PR-115 and highest for PR-120. Average yield loss due to weed competition ranged from 21 to 46% in different rice genotypes. The study showed that early canopy closure, high leaf area index at early stage, and high root biomass and volume correlated positively with competitiveness. This study suggests that some traits (root biomass, leaf area index, and shoot biomass at the early stage) could play an important role in conferring weed competitiveness and these traits can be explored for dry-seeded rice.
Highlights
Dry-seeded rice (DSR) is an emerging rice production system in the northwestern Indo-Gangetic Plains amidst a looming water crisis and labor scarcity [1]
DSR production systems are subject to greater weed pressure than conventional production systems, in which weeds are suppressed by flooding and transplanted rice seedlings have a “head start” over germinating weed seedlings
Many options exist for weed control in DSR, perhaps the most common being the use of herbicides
Summary
Dry-seeded rice (DSR) is an emerging rice production system in the northwestern Indo-Gangetic Plains amidst a looming water crisis and labor scarcity [1]. Weeds are among the most important biological constraints to successful production of DSR and, the cultivation of DSR warrants intensive use of herbicides for weed control [2]. DSR production systems are subject to greater weed pressure than conventional production systems, in which weeds are suppressed by flooding and transplanted rice seedlings have a “head start” over germinating weed seedlings. Many options exist for weed control in DSR, perhaps the most common being the use of herbicides. In DSR, effective weed control requires proper herbicide application timing and method [4], which are often not met, resulting in poor weed control. Alternative weed management technologies are much needed [5]
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