Weed management in dry-seeded rice (Oryza sativa) cultivated in the furrow-irrigated raised-bed planting system

Dry seeding of rice (Oryza sativa L.) in the furrow-irrigated raised-bed planting system (FIRBS) represents a major shift in the production practices for attaining optimal water productivity in the rice-wheat system in the Indo-Gangetic Plains of South Asia. Information on weed management in dry-seeded rice in the FIRBS is lacking. Two experiments were conducted for 2 years, with an objective of identifying appropriate, effective, and economical methods of managing: (1) broadleaf weeds only; and (2) a mixed population of both grass and broadleaf weeds in dry-seeded rice cultivated in the FIRBS. The major weeds associated with dry-seeded rice in the FIRBS during both years were Echinochloa crus-galli (L.) P. Beauv., Echinochloa colona (L.) Link, Dactyloctenium aegyptium (L.) Willd., Leptochloa panicea (Retz.) Ohwl, Caesulia axillaris Roxb., Euphorbia hirta L., Lindernia sp., Commelina benghalensis L., Eclipta prostrata (L.) L., Trianthema portulacastrum L., and Portulaca oleracea L. Triclopyr at 500 g a.i. ha(-1), bensulfuron at 60 g a.i. ha(-1), ethoxysulfuron at 18 g a.i. ha(-1), and 2,4-D (ester) at 500 g a.i. ha(-1), all applied at 21 days after seeding (DAS), were equally effective in realizing higher rice grain yields by controlling broadleaf weeds. Among these, ethoxysulfuron at 18 g a.i. ha-1 was found to be least expensive but effective for controlling broadleaf weeds. Effective and economical herbicides identified for managing a mixed population of both grass and broadleaf weeds included fenoxaprop-p-ethyl + ethoxysulfuron at 50 + 18 g a.i ha(-1), applied at 21 DAS, and pendimethalin followed by (fb) chlorimuron + metsulfuron at 1000 fb 4 g a.i. ha(-1) applied at 3 fb 21 DAS. (c) 2005 Elsevier Ltd. All rights reserved.