Effects on production potential and economics of direct seeded rice sowing dates and weed management techniques

摘要

Plant height, tillers/m row length, leaf area index (LAI), crop growth rate (CGR), net assimilation rate (NAR) and dry matter accumulation in plants were significantly higher in plots getting weed free environment closely followed by pre-emergence application of butachlor 1.5 kg/ha fb 1 HW. However, yield attributes i.e. panicles/m2 and fertile grains/panicle and finally yield were significantly higher in weed free check with butachlor fb 1 HW closely on its heel. Among the nutrient concentration, itwas only P in straw which was very marginally higher in weed free check and butachlorfb 1 HW. However, sowing date of 22nd June showed significantly higher N, P and K uptake by grain and straw. Weed population and weed dry matter were significantly higher in 12th July sown crop but least weed population, dry matter and good weed control efficiency were accounted with weed free check and butachlor fb 1 HW though the nutrient concentration were affected significantly both due to sowing date and weed management practices. Nutrient uptake due to weed was higher in 12th July sowing date. Amongst the weed management methods, the nutrient uptake of weeds were least in weed free check followed by butacholar fb 1 HW and Sesbania broadcast fb 2,4-D 0.5 kg/ha at30 DAS. Similar results were also recorded in the case of gross return, net return and B :C ratio in case of 22nd June.