Effects of Salt Stress on Vegetative Growth and Ion Accumulation ofTwo alfalfa (Medicago sativa L.) Cultivars

Salt stress is one of the most chalanging abiotic stresses affecting natural productivity and causing significant crop losses worldwide. a greenhouse experim ent was conduct ed to evaluate the response of two alfalfa cultivars (bami and hamed ani) to 6 levels of salinity (0 as control, 25, 50, 75, 100, 125 mm nacl) at the college of agriculture,shiraz university, shiraz, iran in 2008. plant dry weight per pot in both cultivars decreased with increasing salinity levels. however, bami as compared to hamedani , with the lowest na+sequestration, produced the greater dry matter weight. leaf area per pot was significantly affected by salt stress with bami cultivar showing a higher leaf area than hamedani. na+ accumul ation also increased by increase in the salinity level in either one of the cultivars; however,na+ sequestration of bami as compared to hamedani , was lower due to na+exclusion mechanisms occurring in this cultivar. although cr accumulation increased with increasing salinity level in either one of the cultivars, craccumul ation was higher in hamedani than in the other cultivar. similar to k+ina+ ratio, ca2+ina+ ratio alsodecreas ed by an increase in salt stress levels and there were highly significant difference s observed between 25 and125 mm of naci in either one of the cultivars. there was a strong positive relationship observed between plant dry matter weight and leaf relative water content for both bami (r2=0.94) and hamedan i (r2=0.96) cultivars under salt stress conditions. all in all, it 'appear s that less adverse effect of salinity on. bami cultivar has made it suitable for growth in saline soils as compared to hamedani in saline areas prevailent in south iran.