EVALUATION OF HERBICIDES FOR WEED CONTROL IN GREENGRAM [Vigna radiata (L.) Wilczek]
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Date
1996
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AAU, Anand
Abstract
The study indicated that integrated weed management practices of pre-emergence application of pendimethalin 0.5 kg/ha + IC at 30 DAS and fluchloralin 0.5 kg/ha + IC at 30 DAS were most effective in controlling weeds and were comparable with twice manual weedings (20 and 45 DAS). These integrated treatments reduced the dry weight of weeds by 87.1 to 89.1 X as compared to unweeded control (3533 kg/ha) and found equally effective and selective to greengram. For every kilogram of dry matter produced by weeds, there was 0.230 kg reduction in grain production. Of the different weed control treatments, the higher grain yield was obtained under the integrated treatment pendimethalin 0.5 kg/ha coupled with IC at 30 DAS (1681 kg/ha), followed by fluchloraln 0.5 kg/ha coupled with IC at 30 DAS (1656 kg/ha) and hand weeding twice (1641 kg/ha). The yield differences among these treatments were not significant. Plant growth as well as yield attributing characters were higher under these treatments. The lower grain yield (947 kg/ha) of greengram was recorded under weedy check with 42.2 % weed index. Oxadiazon herbicide proved phytotoxic to the crop showing suppression of growth leading to reduction in yield. Weed control treatments had no marked influence on the protein content of grains. Weed control practices restricted the nutrient removal by weeds substantially compared with the unweeded check. Weeds removed 49.46, 21.02 and 47.51 kg N, P2O5 and K2O kg/ha, respectively. Weed control proved helpful in arresting nutrients depletion to the extent of 81 per cent. Bacterial population in the soil was significantly reduced immediately after application of oxadiazon at both levels and at higher level (0.75 kg/ha) of fluchloralin and pendimethalin herbicides. Whereas, all herbicides proved ineffective in changing fungal population. The highest net returns (Rs. 20,727) was obtained by the pre-emergence application of pendimethalin 0.5 kg/ha + IC at 30 DAS, followed by fluchloralin 0.5 kg/ha + IC at 30 DAS (Rs.20,569) and twice manual weedings treatment (Rs.20,382). The benefit : Cost ratio were also higher in these treatments (3.54 to 3.61). The present study thus indicated that the integrated weed management involving pre-emergence herbicides at reduced dosage followed by one intercultivation (30 DAS) offers a viable alternative to conventional method of weed management.
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AGRONOMY, AGRICULTURE, EVALUATION