Physiological response and ion accumulation in two grasses, one legume, and one saltbush under soil water and salinity stress

A glasshouse–pot trial using four levels of soil moisture (>100%, 90%, 75%, and 60% field capacity) and three levels of salinity (1.0 dSm –1 , 3.5 dSm –1 , and 6.0 dSm –1 ) was done to evaluate Na + , K + , and Cl − accumulation capacity and the physiological responses (net photosynthetic rate, stomatal conductance, intercellular CO 2 concentration, quantum efficiency of PSII, and non‐photochemical quenching) in Melilotus siculus , Tecticornia pergranulata , Cynodon dactylon , and Thinopyrum ponticum . Results reveal that the combined effects of soil water and salinity had a significant effect on Na + and Cl − accumulation and not on that of K + . Concentrations of Na + and Cl − and non‐photochemical quenching increased significantly whereas, the net photosynthetic rate ( P n), stomatal conductance (g s ), and intercellular CO 2 concentration decreased significantly in the tested plants, because of salinity. Salinity had no significant effect on the maximum quantum yield and relative water contents in shoots. Soil moisture had a significant effect on Na + , K + , and Cl − accumulation and the physiological responses in tested plants. T. pregranulata accumulated the highest concentrations of Na + and Cl − and had the lowest P n. C. dactylon accumulated the lowest concentrations of Na + and Cl − , whereas P n was the highest. No strong positive correlation between P n and g s was evident in tested plants. We indicate that the reduced physiological performance was because of non‐stomatal activities. Na + and Cl − accumulation capacity in the tested plants was in the following order: T .  pergranulata > M .  siculus > T .  ponticum > C .  dactylon . C. dactylon , a C4 plant, accumulated lower salt ions than the other three C3 plants. Copyright © 2015 John Wiley & Sons, Ltd.