Evaluation of Bentazone as Post-emergence Against Weed Flora of Direct Seeded Rice (Oryza sativa L.)

Abstract

In direct-seeded rice (DSR) production systems, both rice seedlings and weeds emerge at the same time, as there is no flood water to prevent weed germination, growth, and development when the rice crops begin to sprout. Consequently, weeds are the primary obstacle to successful DSR, often leading to a significant reduction in yield. This research aimed to develop a strategy for effective weed management in DSR, focusing on enhancing growth and production through the use of herbicides. Therefore, a field experiment was conducted at the Breeder Seed Production Unit, Adhartal, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur (M.P.) during the Kharif season of 2016 to evaluate the effectiveness of various doses of Bentazone herbicide in direct-seeded rice. The experimental soil was clayey with a neutral pH of 7.2, medium organic carbon content (0.62%), available nitrogen (365 kg/ha), available phosphorus (16.34 kg P2O5/ha), and high available potassium (327.16 kg K2O/ha). Weed control treatments included Bentazone at 600, 800, 1000, 1200, 1600, 1800, and 2000 g/ha; 2,4-D at 380 g/ha; two hand weedings at 20 and 40 days after sowing (DAS); and an unweeded control. These treatments were arranged in a randomized block design with three replications. The primary weeds in the experimental field were monocots (Echinochloa colona, Dinebra retroflexa), sedges (Cyperus iria), and broad-leaved weeds (Mollugo pentaphylla, Alternanthera philoxeroides). The post-emergence application of Bentazone at 1600 g/ha was found to be the most economically effective for controlling dicot weeds in direct-seeded rice, resulting in the lowest weed index. This treatment also improved growth parameters (such as plant height, number of tillers per square meter, and plant dry weight), yield attributes (such as grains per panicle), and grain yield compared to other weed control treatments. Therefore, Bentazone at 1600 g/ha is recommended to farmers for achieving higher economic returns and effective weed control in direct-seeded rice.