Effect of weed management practices in a rice-mustard-mungbean cropping system on weeds and yield of crops.

摘要

A field experiment was conducted during 1997-99 in New Delhi India, involving 5 weed control treatments: weedy control, hand weeding, chemical, cultural, and chemical+cultural, in a rice-Indian mustard-mung bean cropping system. Twenty-five days old seedlings of rice cv. Pusa 834 were transplanted at a spacing of 15x10 cm on 10 July and harvested on 15 October; Indian mustard cv. Pusa Bold was sown at a spacing of 30x10 cm on 26 October and harvested on 25 March; and mung bean cv. PS 16 was sown at a row spacing of 25 cm on 5 April and harvested on 15 June each year. Anilofos at 0.500 kg/ha, fluchloralin at 75 kg/ha and pendimethalin at 1.0 kg/ha were sprayed on rice, Indian mustard and mung bean, respectively. Anilofos was applied 4 days after transplanting and fluchloralin and pendimethalin a day after sowing (DAS) using a spray of 600 l/ha. Hand weeding in rice was performed at 30 days after transplanting, while in Indian mustard and mung bean at 20 DAS. In the cultural treatment, a hand-driven wooden hand plough was run between the line 35 DAS. Weed competition in the rice-Indian mustard-mung bean cropping system lowered the total grain productivity by 32%. The maximum decrease in grain productivity of rice, Indian mustard and mung bean was 35.3, 19.3 and 45.6%, respectively. The most potent weed species that competed were Echinochloa colonum and E. crus-galli in rice, Phalaris minor in Indian mustard and Trianthema portulacastrum in mung bean. The competitive effect of other weed species on grain yield was nominal as their population was sparse. In all the 3 crops, in all weed control treatments, weed population and weed dry weight were recorded significantly lower compared to the weedy control. Chemical+cultural, hand weeding and chemical treatments resulted in a marked decrease in weeds, the decreases being higher in the former 2 treatments. Weed control treatments caused a significant increase in grain yield of crops in both years. Chemical+cultural and hand weeding caused a significant increase in grain yield of rice, while hand weeding and chemical treatments in mustard and mung bean.