Post emergence chemical weed control in direct seeded fine rice.

Abstract

Direct seeding of rice isa promising resource conservation technology for rice -wheat cropping system but its adoption is impeded due to heavy weedinfestation.A fieldstudy was conductedduring summer 2008to evaluate the efficacy of post emergence herbicides in three fine rice cultivars viz. Super Basmati, Basmati 385 and Shaheen Basmati under direct seed rice culture at Agronomic Research Area, Un iversity of Agriculture, Faisalabad. Bispyribac sodium, ethoxysulfuron ethyl and penoxuslam were used as early post emergence (15 days after sowing; DAS) atlabel dose of30 and 15 g a.i. ha -1 , respectively . A weedy check andmanual weeding (15 and 25DAS) were maintained for comparison. Bispyribac sodiumsuppressed bothweed density(75%)and dry weight(80%) over control that was highest among all herbicides.Higher rice grain yield and maximum marginal rate of return was also associated with this her bicidein all ricecultivars. Despite of its effectiveness against weeds and scoring higher rice yields, manual weeding was uneconomicalprimarily due to higher costs involved .Post emergence application of bispyribac sodium appearedto be a viable strateg yfor weed control in direct seeded rice with higher economic returns.