Effects of salinity on photosynthetic pigments, respiration, and water content in two barley varieties.

Salinity (NaCl Stress) was applied with 50, 100, 200, 300 and 400 mM NaCl. The shoot and root respiration of two barley cultivars (Hordeum vulgare L. variety Afzal and variety EMB82-12) were determined in various concentrations ofNaCl. Chlorophyll a, b and total chlorophyll content were significantly decreased, but carotenoids content increased under salinity. Decrease of chlorophyll content in EMB82-12 was higher than Afzal, but carotenoids content in Afzal variety was higher than EMB82-12. Relative Water Content (RWC) was used to indicate the degree of stress. Oxygen uptake declined in shoot and root with increasing NaCl concentrations. Decrease of oxygen uptake in shoot and root of EMB82-12 variety was higher than Afzal variety. RWC decreased with increasing NaCl concentrations. Lowering of RWC reduced growth and increased shoot/root ratio. Decrease of water content in EMB82-12 plants was higher than Afzal plants. Shoot/root ratio in EMB82-12 variety was higher than Afzal.