Studies on the influence of integrated weed management practices in direct wet seeded rice + dhaincha dual cropping

Abstract

A field experiment was conducted at wetland farm, Tamil Nadu Agricultural University, Coimbatore during rabi, 2016-17 to study the influence of integrated weed management practices in wet seeded rice + dhaincha dual cropping using the variety CO(R)51. The experiment was laid in randomized block design with three replications. The treatments comprised of application of bispyribac sodium 25 g/ha at 20 DAS/30 DAS with cono weeding at 40 DAS, 2, 4-D Na salt 0.5 kg/ha at 20 DAS/30 DAS with cono weeding at 40 DAS, chlorimuran ethyl + metsulfuron methyl 4 g/ha at 20 DAS/30 DAS with cono weeding at 40 DAS, cono weeding twice at 20/30 DAS and 40 DAS, hand weeding twice at 20 and 40 DAS and unweeded check. The results revealed that lower weed dry weight and higher weed control efficiency were recorded with hand weeding twice at 20 and 40 DAS which was comparable with application of bispyribac sodium 25 g/ha at 20 DAS + cono weeding at 40 DAS. Biomass addition of dhaincha ranged from 8.25 t/ha to 19.10 t/ha and nitrogen addition ranged from 43.69 kg/ha to 73.93 kg/ha. Efficient control of weeds along with green manure addition resulted in higher growth parameters and yield attributes of rice and recorded higher grain yield in hand weeding twice at 20 and 40 DAS (6535 kg/ha) and it was comparable with application of bispyribac sodium 25 g/ha at 20 DAS + cono weeding at 40 DAS (6244 kg/ha). Higher net return of Rs.55,556/ha was recorded with hand weeding twice at 20 and 40 DAS and it was closely followed by application of bispyribac sodium 25 g/ha at 20 DAS + cono weeding at 40 DAS (Rs.55,161/ha). However, the BC ratio was higher (2.59) with application of bispyribac sodium 25 g/ha at 20 DAS + cono weeding at 40 DAS due to less cost involved for weeding.