Kulvir Singh, Pankaj Rathore and R K Gumber
Impact of Harvest-aid Defoliants on Yield of American Cotton and Their Monetary Evaluation
Field experiments were conducted during Kharif 2012 and 2013 to determine the effect of two harvest-aid defoliants i.e Dropp ultra® and Ethrel, their application rates and time of application on three American cotton cultivars. Pooled data revealed significantly higher seed cotton yield for Bt hybrids MRC7361BGII (3055.2kg /ha) and MRC7017BGII (2913.0 kg /ha) as compared to non Bt variety F1861 (2346.0 kg /ha). Among tested defoliants, Dropp ultra® @200ml/ha resulted in better SCY, lint and seed yield. This yield enhancement in case of Dropp ultra® @ 200 ml /ha further lead to significantly better net returns (? 85373/ha) and B:C ratio (2.31) over other treatments. Application of defoliants at 150DAS resulted in significantly improved net returns (? 79288/ha) as compared to earlier application (? 73632/ha) at 140 DAS. Improved water productivity and fertilizer use efficiency coupled with better B:C ratio for Dropp ultra® @ 200 ml /ha at 150 DAS clearly indicated its superiority among all treatments. Therefore Bt hybrids seems to be superior over the non Bt varieties and application of ethrel@2000ppm or dropp ultra® @ 200 ml /ha at 150 DAS should be adopted as useful production practice for enhancing cotton yield under semi-arid conditions of north-western India.
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