Author(s): G.C.MISHRA, A.K.RATH, B.S.RATH, J. SAHOO AND P.K.MOHAPATRA

Abstract: A field experiment was conducted in sandy loam soil during wet season of 2000 and 2001 at Central Research Station, O.U.A.T, Bhubaneswar in a factorial randomised block design comprising of eighteen weed management treatment combinations of 2 seed rates (normal seed @ 75 kg/ha and higher seed @ 20% excess to normal), 3 intercultures (no interculture, interculture at 20 DAS and interculture at 30 DAS) and 3 herbicides (pre emergence spraying of butachlor @ 1kg/ha, early post emergence application of clomazone @ 0.15 kg/ha + propanil @ 0.30 kg/ha and no herbicide) in direct seeded upland rice. The weed panorama in the experimental field revealed that upland rice was associated with 67% monocot and 33%dicot weeds during critical period of crop weed competition. Use of higher seed rate effectively reduced the weed population, its dry weight, and the depletion of N, P and K by weeds. It also enhanced the tillering, LAI, CGR, grain (24.21 q/ha) and straw (24.22 q/ha) yield and nutrient uptake (40.68 kg N, 9.28 kg P and 45.55 kg K/ha). Interculture in upland rice at 20 DAS reduced the density, dry matter accumulation and nutrient removal by weeds which ultimately reflected in better crop growth, yield attributes and grain (24.29 q/ha) and straw (24.00 q/ha) yield along with higher uptake of 40.18kg N, 9.45 kg P and 46.02 kg K/ha. Similarly application of butachlor drastically lowered down the weed density, biomass and removal of nutrients by weeds and resulted in the highest grain (25.92 q/ha) and straw (25.39 q/ha) yield. Considering the economics, integration of higher seed rate with butachlor and interculture at 20 DAS registered the maximum net return in upland rice under rainfed condition.

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