Influence of extreme K: Na ratios and high substrate salinity on plant metabolism of crops differing in salt tolerance

The effect of a range of NaCl concentrations (up to 340 meq/1) on growth of cotton varieties (Dandara and Giza 45), as well as effects of extreme K: Na ratios (60 meq/1 total concentration) on the mineral distribution were studied in water culture experiments. During high NaCl salinization growth of Dandara was more depressed than of Giza 45. Furthermore, leaf development of Dandara was inhibited, whereas that of Giza 45 did not differ from the untreated control. At low external K+/Na+ accumulation of Na+ and Cl‐ in leaves of Giza 45 was significantly lower than in leaves of Dandara, while larger amounts of these ions were retained in the roots. K+ in leaves of Dandara declined more than in leaves of Giza 45. Divalent cations of both cultivars were similarly affected. The results show that Dandara is a salt sensitive and Giza 45 a salt tolerant cotton variety. The considerable genotypic difference in salt tolerance of cotton is negatively correlated with sodium and chloride accumulation in the leaves during initial salinity stress.