Effect of Weed Management Practices on Complex Weed Flora and Soil Microflora in Aerobic Rice under Rainfed Condition of Bihar

A Field experiment was conducted during the Kharif season of 2018 at Bihar Agricultural University, Sabour (Bihar) to evaluate the performance of different herbicides in aerobic rice (Oryza sativa L). Weed management had a positive influence on growth, yield attributes and yield of the aerobic rice. In experimental field, Cyperus rotundus, Cyperus iria, Cyperus difformis, Cynodon dactylon, Eleusine indica, Fimbristylis miliacea, Echinochloa colona, Echinochloa crus-galli, Commelina benghalensis, Caesulia auxillaris, Lippia nodiflora, Amaranthus spinosus, Oxalis acetosella, Amaranthus viridis, Eclipta alba, Phyllanthus niruri and Monochoria vaginalis were the dominant weed flora species. The results revealed that lowest weed population and weed dry weight were recorded in weed free situation which were significantly superior over rest of the herbicidal treatments. The maximum mean grain yield of aerobic rice (4.00 t/ha) was recorded by weed free which intern was statistically at par with the mean grain yield obtained from the herbicide Pyrazosulfuron fb one hand weeding (3.92 t/ha) followed by Pyrazosulfuron fb Bispyribac (3.88 t/ha), Bispyribac sodium (3.83 t/ha), Pyrazosulfuron+Ethoxysulfuron (3.62 t/ha), Bispyribac sodium+Pyrazosulfuron (3.61 t/ha) and Halosulfuron + Azimsulfuron (3.50 t/ha). Significantly lowest mean grain yield of (1.90 t/ha) was obtained from weedy check plots. The highest weed control efficiency (100%) was recorded under the treatment weed free which was followed by Pyrazosulfuron fb one hand weeding (85.96%), Pyrazosulfuron fb Bispyribac (84.77%), Bispyribac sodium (83.09%). All microflora (bacteria, fungi, actinomycetes) were recorded maximum number under the treatment weedy check. There were halosulfuron causes some phytotoxic effects at early stage on rice crop. The highest gross return (Rs.70,000/ha) was obtained by weed free which was statistically at par with Pyrazosulfuron fb one hand weeding (Rs.68,600/ha), Pyrazosulfuron fb Bispyribac(Rs.67,900/ha), Bispyribac sodium (Rs.67,025/ha), Pyrazosulfuron+Ethoxysulfuron (Rs.63,350), Bispyribac sodium+Pyrazosulfuron (Rs.58,800/ha) and significantly superior over rest of the treatments. However, the highest net return (Rs. 37,323/ha) was recorded by the treatment Pyrazosulfuron fb Bispyribac sodium which was found superior over rest of the treatments. The highest B:C ratio (Rs.2.22) was recorded by Pyrazosulfuron fb Bispyribac which was statistically at par with Bispyribac sodium (Rs.2.20), Pyrazosulfuron fb one hand weeding (Rs.2.19), Pyrazosulfuron+Ethoxysulfuron (Rs.2.13) and Bispyribac sodium+Pyrazosulfuron (Rs.1.91) all these were significantly superior over rest of the treatments.