Nutrient Uptake by Red Sprangletop [Leptochloa chinensis (L.) Nees] and Transplanted Rice under Different Cultural and Weed Management Practices

摘要

The nutrient uptake by red sprangletop (Leptochloa chinensis) and transplanted rice was studied under three off-season land management practices (raising green manure, undisturbed land and frequent cultivations after wheat harvest) in main plots withthree crop plant densities (22, 33 and 44 hills/m~2) and two weed management practices (pyrazosulfuron 0.015 kg/ha and two hand weedings) alongwith an unweeded control in sub plots. The frequent cultivations were able to significantly reduce the nutrientremoval by the weed and increase the nutrient uptake by rice as compared to green manured and undisturbed land after wheat harvest, the latter two being at par. The increase in crop plant density from 22 to 44 hills/m~2 reduced the nutrient removal by the weed and increased the nutrient uptake by rice. Two hand weedings and pyrazosulfuron 0.015 kg/ha were equally effective in reducing the nutrient removal by the weed and increased nutrient uptake by rice and were significantly better than the unweededcontrol.