Effect of chemical defoliation on boll opening percentage, yield and quality parameters of Bt Cotton (Gossypium hirsutum)
2011
, Rajni | Deol, J.S. | Brar, A.S.
A field experiment was conducted during kharif of 2008 and 2009 to study the effect of chemical defoliation on boll opening percentage (BOP), yield and quality parameters of Bt Cotton (Gossypium hirsutum L.). The experiment was laid out in a randomized complete block design with four replications comprising twelve treatments, viz. control, thidiazuron 100, 150 and 200 g/ha, ethrel 1.0 and 1.5 l/ha applied at 40 or 60 BOP and gramoxone (paraquat) 1.0 l/ha applied after first picking. Defoliation with ethrel 1.5 l/ha at 60 BOP resulted in higher number of picked bolls/plant and BOP when compared with control. However, maximum seed cotton yield was obtained with ethrel at 1.0 l/ha (2.27 and 1.96 t/ha) and it was followed by thidiazuron 100 g/ha (2.21 and 1.92 t/ha) applied at 60 BOP. Gramoxone (paraquat) application at 1.0 l/ha after first picking failed to exert any significant influence on seed cotton yield and yield contributing characters. The B:C ratio of thidiazuron 100 g/ha at 60 BOP was comparatively higher when compared with rest of the defoliation treatments. Seed index, lint index, ginning-outturn, oil content (%) in seeds and fibre quality parameters, viz. 2.5% span length, fibre bundle strength and fibre fineness were not significantly influenced by any of the defoliation treatment.
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