Integrated weed management in direct seeded dry sown rice in lateritic belt of West Bengal.

摘要

The efficacy of various integrated weed management systems for the control of weeds of intercropped rice (cv. IR 36) was evaluated in Sriniketan, West Bengal, India, during the kharif of 2002 and 2003. The treatments were rice-cowpea intercropping + mechanical weeding at 35 days after sowing (DAS) (T1); T1 + butachlor (1.0 kg/ha) (T2); rice + black gram intercropping + mechanical weeding at 25 DAS (T3); rice-sesbania [Sesbania] green manure + mechanical weeding at 35 DAS (T4); T4 + fenoxaprop (60 g/ha) at 2 weeks after sowing (WAS) + 2,4-D (0.5 kg/ha) at 4 WAS + mechanical weeding (T5); butanil (4 litres/ha) + mechanical weeding at 35 DAS (T6); mechanical weeding at 25 and 45 DAS (T7); farmers' practice (hand weeding at 25 and 45 DAS; T8); and recommended practice (1.0 kg butachlor/ha + hand weeding at 30 DAS; T9). The predominant weeds were Digitaria sanguinalis, Ludwigia parviflora, Cyperus iria and Spilanthes acmella [Blainvillea acmella]. The rice-intercrop ratio was 2:1. In 2002 and 2003, weed population at 60 DAS were lowest under T2 (35 and 41/m2), T5 (34 and 32/m2), T6 (26 and 25/m2) and T9 (35 and 33/m2); these treatments also resulted in the lowest weed dry matter at 60 DAS (5.8 and 5.6, 3.4 and 3.9, 3.2 and 3.2, and 4.2 and 3.2 g/m2, respectively). The highest grain yields in 2002 and 2003 were obtained under T6 (3383 and 3583 kg/ha) and T5 (3317 and 3442 kg/ha). Weed infestation reduced the grain yield of rice by 69.5 and 78.8% over T6 in 2002 and 2003, respectively..