Variable Salinity Responses of 25 Alfalfa Genotypes and Comparative Salt-Response Ion Distribution

This study was carried out to evaluate the effects of salinity stress on ion distribution in different alfalfa genotypes and its relation with stress tolerance indices. The experimental treatments consisted of two levels of salinity stress including 0 (control) and 200 mM of NaCl and 25 alfalfa (Medicago sativa L.) genotypes. These were arranged as factorial based on a Completely Randomized Design with three replications. There was an increase in sodium (Na+) content and decrease in potassium (K+) content in salinity stress compared to the control condition in the shoot and root of all genotypes. However, the tolerant genotypes showed lower shoot and root Na+ content and higher K+ content and therefore higher potassium/sodium ratio (K+/Na+). The results of this study showed that the relation between Na+ exclusion and tolerance indices is very close, but the positive characteristics of some genotypes did not directly correlate with these indices.