Eco friendly weed management practices in transplanted rice

Abstract

Mundakan season, Virippu ,Punja Season, Summer Ploghings, Microclimate An investigation was underta:z~i;atthe State Seed Farm, Kottarakkara dur- ing Virippu 1998 to evolve ecofriendly weed management practices in transplanted rice. The experiment was laid out as factorial randornised block design with three replications. The treatments included, two levels each of summer ploughings, stale seed bed technique, and nitrogen application along with four controls (complete weed free, weedy check, hand weeded twice and pre-emergent herbicide followed by hand weeding). Two summer ploughings enhanced the growth characters of rice such as plant height, tiller count and 'lA!. Dry matter production and nutrient uptake of rice were also enhanced by two summer ploughings. Yield attributes and grain yield was significantly improved by two summer ploughings. The count of grasses, sedges and BLW and the total weed population was reduced by this practice. The dry matter production of weeds and NPK uptake by weeds were reduced by two summer ploghings. Weed control efficiency was also increased at all stages. Adoption of stale seed bed technique enhanced the plant height, tiller count, LAI, dry matter production and nutrient uptake of rice. The yield attributes and grain yield were significantly increased by the practice and the weed index was significantly reduced. The total weed population was also reduced at all observa- tions, The count of grasses and BLW reduced up to 40 DAT, while sedge popula- I tion was unaffected by the adoption of stale seed bed practice. Relative density of grasses and sedges were also reduced by this technique. The v, ced dry matter production, and nutrient uptake were reduced and weed control efficiency was increased by the stale seed bed practice. Delaying the basal application of nitrogen up to 10 DAT had no influence on the crop-weed competition and yield. The treatment combinations enhanced the growth and yield. T7 and T" re- corded the higher dry matter production and nutrient uptake of rice. These treat- ments also resulted in higher grain yield and lower weed index than other combi- nations. They also recorded the lowest total weed count, weed frequency and weed density at all stage of observations. Moreover, the combinations of summer ploughing, stale seed bed and nitrogen application helped to reduce the weed dry matter production and nutrient uptake. Compared to existing hand weeding practice all treatments showed their superiority in increasing the net income especially. T7 and Tg. T, registered the highest benefit cost ratio. The benefit cost ratio of treatment combinations was comparable to herbicide application