EFFECT OF INTEGRATED WEED MANAGEMENT ON YIELD AND NUTRIENT-UPTAKE BY RAIN-FED RICE (ORYZA-SATIVA) IN ACID SOILS OF NAGALAND

An experiment conducted during 1989 and 1990 showed that 2, 4-D (c) ap plied @ 0.8 kg ai/ha, butachlor @ 2.0 kg ai/ha and fluchoralin @ 1.5 k g ai/ha at 1 day; theobencarb @ 1.5 kg ail ha at 1 and 7 days after tr ansplanting and hand-weeding at 25 and 45 days after transplanting wer e found superior to other treatments in controlling weeds. The highest yield of rice (Oryza sativa L.) was obtained when fluchoralin was app lied @ 1.5 kg ai/ha at 1 day after transplanting and minimum under wee dy check. The highest weed population (71.4/m2 in 1989 and 64.5/m2 in 1990) and dry weight of weeds (819 kg/ha in 1989 and 775 kg/ha in 1990 ) was found under the weedy check. All the herbicides tried gave signi ficant control of weed when applied 1 day after transplanting. Higher yield was obtained due to significant influence of weed-control treatm ents on grains/panicle and tillers/hill. The maximum uptake of N, P an d K (on an average 92.1, 13.8 and 68.6 kg/ha of N, P and K respectivel y) was observed when fluchoralin was applied @ 1.5 kg ai/ha at 1 day a fter transplanting.