Evaluating of Potassium Uptake and Utilization Efficiency in Cotton Genotypes

Identification and selection of efficient genotypes for uptake and utilization of potassium (K) can help to increasing potassium fertilizers and available soil potassium use efficiency in K-deficient soils. Therefore, efficiency of of potassium uptake and utilization 25 cotton genotypes was studied in deficient (0.025 mM) and sufficient (2.5 mM) potassium levels in a hydroponics experiment. Potassium efficiency of cotton genotypes were classified based on three criteria including; shoot dry weight in K-deficient level, the dry weight ratio (dry weight in K deficient : dry weight at K sufficient), and K use efficiency. Potassium deficiency decreased dry weight, K concentration and K uptake by root and shoot of cotton genotypes, while K use efficiency increased in deficient K level. Very high and significant correlation (r = 0.98**) was observed between root and soot dry weight of genotypes. Correlations between root and shoot dry weight with K uptake and K use efficiency were also significant. Grouping of potassium efficiency of cotton genotypes identified six efficient genotypes based on soot dry weight and dry weight ratio, whereas only four efficient genotypes were identified based on K use efficiency. In conclusion, cv. Golestan, Sajedi and genotype N2G80 were selected as efficient genotypes for potassium uptake and utilization.