Ecologically sustainable integrated weed management in dry and irrigated direct-seeded rice

Abstract

Weeds are one of the major biological constraints in direct seeded rice farmer’s field and cause a substantial rice yield loss owing to greater diversity in weed flora due to alternate wetting and drying. Sometimes more than three flushes of weed infest the direct seeded rice (DSR) in whole life cycle of crop. In India, weeds are mainly controlled manually in rice. However, manual weeding is becoming less cost effective because of labour crisis at critical times or increased labour costs. Herbicides are replacing manual weeding at a faster rate in rice as they are easy to use but there are concerns about the sole and repeated use of herbicides, such as evolution of resistance in weeds, shifts in weed flora, cost of weed management to farmers and concerns about the environment. Therefore, there is an urgent need to effectively integrate different aspects of ecological weed management strategies especially preventive measures like stale seedbed technique, summer tillage, precession land leveling, crop rotation and sowing methods, cultural methods like competitive varieties, herbicide resistance varieties, seed rate, crop residues/straw mulching, cover crops and live mulching, brown manuring, water and nutrient management (specially organic amendments), manual and mechanical method, bio-control agent to achieve effective and sustainable weed control in DSR systems. This paper describes different approaches, including preventive, cultural approaches, mechanical approach and biological approach to manage weeds in dry seeded rice as well as irrigated DSR culture systems.