Crop phenology, thermal requirement, yield and fiber properties of cotton (Gossypium hirsutum) genotypes as influenced by different environments

A field experiment was conducted during 2012–2013, and 2013–2014 with two dates of sowing as main plot and six genotypes as sub-plot treatments. Late sowing resulted in significant reduction in the days to 50 % flowering, days to 50 % boll bursting and days to maturity as well as number of GDDs for boll bursting and maturity compared to normal sowing. The fiber quality parameters, viz., 2.5 % span length, uniformity ratio, micronaire value, fiber strength, elongation and fiber maturity exhibited significant decline under late sowing. However, short fiber index increased under late sowing. Late sown crop could not develop a full canopy surface area as evidenced by reduced plant height, sympodia, leaf area and LAI at different growth stages. The Bt hybrid, Ankur-3028 BG-II recorded significantly higher plant height, sympodia, number of bolls, boll weight, seed cotton yield, seed and lint index and fiber properties like 2.5 % span length, fiber strength. The Bt hybrid G.Cot.Hy.-8 BG-II was early in terms of days to 50 % squaring, flowering, boll bursting and maturity and required less GDDs to attain a particular growth stage. The genotype Ankur-3028 BG-II took significantly higher number of GDDs during flowering to boll opening stage.