Effect of Seed Rate, Spacing and Herbicide Use on Weed Management in Direct Seeded Upland Rice (Oryza sativa L.)

A field experiment was conducted during kharif 2006 at the Students’ Research Farm, Department of Agronomy, Punjab Agricultural University, Ludhiana on loamy sand soil to study effect of seed rate, spacing and herbicide use on weed management in direct seeded upland rice. Increasing seed rate from 40 to 60 kg/ha and row spacing from 15 to 20 cm, respectively, did not reduce the total weed population and weed dry matter at maturity. Seed rate and row spacing did not influence the grain yield significantly. However, all the weed control treatments i. e. application of pretilachlor 0.75 kg, pendimethalin 0.75 kg and thiobencarb 1.5 kg/ha significantly reduced the total weed population and weed dry matter production resulting in higher weed control efficiency as compared to weedy check. All weed control treatments produced significantly higher yield attributes which ultimately resulted in higher grain yield of paddy as compared to weedy check. Among different herbicidal treatments, thiobencarb 1.5 kg/ha produced highest grain yield of 5.51 t/ha which was at par with other weed control treatments. All weed control treatments reduced nitrogen uptake by weeds making it available to be used by the crop.