Vol. 4 No. 2
Effect of herbicides on weeds and soil microbes in wheat under Terai agro-ecological region of West Bengal.
Author(s): S. RAHAMAN AND P.K. MUKHERJEE
Abstract: A field experiment was conducted during rabi season of 2005-06 and 2006-07 at instructional farm of Uttar Banga Krishi Viswavidyalaya to find out the effective and ecologically suitable herbicides in wheat (Sonalika) grown under different tillage systems. The dominant weeds were Polygonum pensylvanicum, Polygonum orientale, Polygonum persicaria, Stellaria media, Oldenthnadia diffusa, Spilanthes paniculata, Hydrocotyl renunculoides, Physalis minima and Eclipta alba (broadleaved weeds) and Cynodon dactylon, Setaria glauca and Digitaria sanguinalis (grasses). Among the herbicides, pendimethalin 0.50 kg ha-1 in conventional tillage showed highest weed control efficiency (82.2% and 77.42%) in both the years. The treatment 2,4-D 0.50 kg ha-1at 35 DAS found effective in controlling weeds in first year of the experiment. However, isoproturon became ineffective in controlling weed especially broadleaved. Among the herbicides highest yield was recorded in pendimethalin (22.4 q/ha and 26.7 q/ha) under conventional tillage and it was statistically at par with complete weed-free situation (23.04 q/ha and 27.19 q/ha) during both the years. Timely sowing of the crop during second year increased yield of wheat. Highest net return was obtained in 2,4-D 0.50 kg ha-1 at 35 DAS (Rs.5921/-) in conventional tillage system in first year and pendimethalin 0.50 kg ha-1 (Rs. 9111/ -) in second year. However, poor yield of wheat in second year was due to shifting of weed flora triggered by 2,4-D application. Pendimethalin 0.50 kg ha-1 in conventional tillage at initial stage showed antagonistic effect on soil microbes. Isoproturon showed little growth promoting activity in terms of increasing height of wheat. Performance of wheat was comparatively higher in conventional tillage than zero tillage.
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