Potassium Substitution by Sodium in Root Medium Influencing Growth Behavior and Potassium Efficiency in Cotton Genotypes

ABSTRACT Potassium (K) deficiency affects cotton (Gossypium hirsutum L.) growth. Sodium (Na) can substitute K for some non-specific functions in plants. Four cotton genotypes were evaluated for their growth rates and K use efficiency grown at various K:Na. The cotton genotypes and treatments had significant (p < 0.01) effect on biomass production, growth rate related parameters, K use efficiency, and K: Na ratio. Maximum total dry matter (2.57 g plant-1) was accumulated by 'NIBGE-2' and minimum (1.91 g plant−1) was by 'FH-1000'. Maximum K:Na ratio in shoot was obtained by 'MNH-786' and minimum was by 'NIBGE-2'when 1/3rd K was replaced with Na. Genotypes and various treatments significantly (p < 0.05) influenced specific utilization rate (SUR) and K transport rate (KTR). There was a significant relationship (R2 = 0.84, n = 60) between shoot dry matter and K: Na ratio in shoot. Overall, the growth was better when K and Na were added in ratio of 3:1.