Physiology of salinity tolerance in Bromus danthoniae genotypes originated from saline and non-saline areas of West Iran

Abstract

Genetic resources of halophytic grass species are vital factors to be explored for improvement in pasture and rangeland productivity and to elucidate mechanisms of salinity tolerance. The objective of the present study was to understand the adaptive strategies of Bromus danthoniae to a hyper-saline environment by using 80 genotypes originated from saline and non-saline areas in West Iran. Salinity treatments of 0 and 350 mm NaCl were applied for 4 weeks, and plant growth, leaf water status, ionic status, oxidative stress and salt-excretion responses were evaluated. Analysis of variance showed significant genotypic (G) variation for all traits as well as significant salinity stress (S) and G × S effects for most of the traits. Dry matter was positively correlated with K+/Na+ (r = 0.69) and Ca2+/Na+ (r = 0.66) ratios, and negatively correlated with Na+ concentration (r = –0.72). In addition, a coincidence of low concentrations of Na+ in the leaf tissues and the excretion of salt crystals on the sheath leaves and leaf blades was observed in the hyper-salinity tolerant genotypes. These observations open up new avenues for elucidating potential strategies and pathways used by halophytic grasses to avert the excess Na+ in their plant tissues.