Abstract:
An experiment was conducted at the College of Agriculture, Vellayani during the first crop season of 1992 to study the effect of time of sowing and weed management on the performance of dry sown rainfed rice using Onam variety. Split plot experiment in randomised block design with time of sowing as major treatments and weed management as minor treatments was adopted and the treatments replicated thrice. May 16, May 23 and May 30 were the first, second the third dates of sowing respectively. The weed management treatments included combination of butachlor with 2, 4-D, butachlor with hand weeding, hand weeding twice 20 and 40 DAS, complete weed free and un weeded control. Sowing on May 23 resulted in greater plant height, panicle weight, grain and straw yield, nutrient uptake, grain protein and lesser uptake of phosphorus and potash by weeds when compared to May 16 and May 30. The second best sowing date was May 16. When compared to un weeded control, hand weeding twice, combination of butachlor with hand weeding and butchlor with 2, 4-D gave higher plant height, tiller number, productive tiller number, panicle weight, thousand grain weight, grain yield, straw yield, nutrient uptake and grain protein out of which hand weeding was the best. Hand weeding also resulted in the lowest weed population, weed dry weight, nutrient uptake by weeds, weed index and the highest weed control efficiency. Initially, butachlor alone was ineffective in reducing weed population and its dry weight. However, the combination of butachlor with 2,4-D and butachlor with hand weeding was effective in later stages. The combination of butachlor with hand weeding resulted in higher weed control efficiency than butachlor with 2,4-D. The rice grains contained no applied weedicide residues. Hand weeding, combination of butachlor with hand weeding and butachlor with 2,4-D resulted in greater profit and benefit – cost ratio than un weeded control. However, the highest profit was obtained with hand weeding twice.
