Evaluation of physiological and morphological responses associated with cotton subjected to drought stress conditions

Drought is an abiotic stress that affects performance and growth of cotton genotypes. Therefore, the identification of tolerant genotypes to drought is of utmost importance in cotton for germplasm selection and further improvement. The experiment was conducted in three genotypes of cotton (GossypiumhirusutumL.) cvs. Pratima, Anjali and Bunny Bt under pot culture technique by using gravimetric method for study of drought tolerance in cotton. A factorial completely randomized design with three replications was used. The research trials were carried out during the period from August 2012 to April 2013 with pot culture experiment in the glasshouse, Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore. The stress imposed with four watering treatments viz., 100, 75, 50 and 25% of field capacity at squaring stage to understand the effects of water deficit in terms of physiological and morphological parameters studied. The total chlorophyll content (SPAD) values were highest in control as that of with drought stress condition. Gas exchange attributes such as photosynthetic rate, stomatal conductance and transpiration rate were found to be remarkably higher in cotton variety Bunny Bt compared to Pratima and Anjali during water deficit. The morphological characters plant height, number of leaves and angle of branching were reported to be reduced in cotton genotypes with different watering treatments. The study concludes that both physiological and morphological parameters were found to be reduced under drought stress conditions. The drought stress imposed conditions revealed that Bunny Bt was considered as more tolerant and stable genotype.