Evaluating potassium-use-efficiency of five cotton genotypes of pakistan

Potassium (K) deficiency in Pakistani soils has been recently reported as the major limiting factor affecting sustainable cotton production. The present study was conducted to envisage how K nutrition affect the growth, biomass production, yield and K-use-efficiency of five cotton genotypes, NIBGE-3701, NIBGE-1524 (Bt-transgenic), Sadori, Sindh-1 and SAU-2 (non-Bt conventional), commonly grown in Pakistan. All five genotypes were raised at deficient and adequate K levels, i.e. 0 and 60 kg K/sub 2/O ha-1, respectively. The experiment was performed in plastic pots following a completely randomized factorial design with three repeats. Adequate K nutrition significantly increased various plant growth traits and yield of all cotton genotypes under study, viz. number of sympodia (21%), number of leaves (34%), leaf dry biomass (30%), shoot dry biomass (31%), number of bolls (50%) and yield of seed cotton (92%). Substantial variations were observed among cotton genotypes for their K-use-efficiency and K-response-efficiency. Sadori and SAU-2 were screened as most K-use-efficient cotton genotypes, while Sindh-1 and SAU-2 were ranked as the most K-responsive cotton genotypes. Interestingly, Sadori did not respond to K nutrition. Moreover, Bt cotton genotypes accumulated more K as compared to non-Bt genotypes. The cotton genotype SAU-2 was identified as efficient-response genotype for better adaptation for both low- and high-K-input sustainable cotton agriculture systems. (author)