Comparisons of chlorophyll content in bread wheat (Triticum aestivum L.) cultivars with contrasting of shoot sodium concentration under salinity stress

To assess the effects of sodium exclusion on leaf chlorophyll content and biomass production, three bread wheat cultivars with contrasting of sodium concentration and different salt tolerance were grown at 2 salinity levels (0 and 150 mM NaCl) under hydroponics and greenhouse conditions in 2017 year. Salinity decreased yield, shoot dry weight, shoot K+/Na+ ratio and chlorophyll content and increased shoot Na+ compared to control. In this experiment, shoot K+ was not affected by salinity. Shoot Na+ concentration was more in salt tolerant cultivar (Kavir) than Mahdavi and Tajan under salinity stress and there was no relationship between Na+ exclusion and salt tolerance in cultivars. Leaf Na+ concentration were much lower in Mahdavi than two other cultivars. Chlorophyll content showed the most decreases in Tajan (75%) than Kavir and Mahdavi under salinity stress. Yield and shoot dry weight was reduced to the same extent (40% and 37% respectively) by 150 mM NaCl in each cultivar, despite greater chlorophyll content by Kavir cultivar. Results showed that Kavir had the highest ability to tolerate high leaf tissue concentrations of Na+. Despite different sodium concentration, the reduction in shoot biomass under salt stress was the same for all cultivars. It seems that the major effect of salinity on shoot biomass and yield was due to the osmotic effect of salt, not due to Na+-specific effect within the plant.