POST EMERGENCE CHEMICAL WEED CONTROL IN DIRECT SEEDED FINE RICE

Direct seeding of rice is a promising resource conservation technology for rice-wheat cropping system but its adoption is impeded due to heavy weed infestation. A field study was conducted during summer 2008 to 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, University of Agriculture, Faisalabad. Bispyribac sodium, ethoxysulfuron ethyl and penoxuslam were used as early post emergence (15 days after sowing; DAS) at label dose of 30, 30 and 15 g a.i. ha-1, respectively. A weedy check and manual weeding (15 and 25 DAS) were maintained for comparison. Bispyribac sodium suppressed both weed 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 herbicide in all rice cultivars. Despite of its effectiveness against weeds and scoring higher rice yields, manual weeding was uneconomical primarily due to higher costs involved. Post emergence application of bispyribac sodium appeared to be a viable strategy for weed control in direct seeded rice with higher economic returns.