Sodic-alkalinity is a serious limiting factor in agricultural productivity. This study was conducted to examine the contribution of acclimation to the adaptation of rye (Secale cereale) to sodic-alkalinity. Effects of acclimation were determined in two sets of experiments: One experiment for mineral accumulation, antioxidative capacity, and other physiological parameters; and a vivo experiment for root Evan's Blue and Na+ influx from medium to root. Being exposed to sodic-alkalinity, acclimation did not affect plant dry weight. However, acclimation significantly reduced Na+ concentration and maintained a lower Na+/K+ ratio in all the tissues, increased the Ca2+ and Mg2+ concentrations in the root tissues, and increased the water uptake ability in comparison to the non-acclimated plants. Acclimation increased the antioxidant capacity represented by the increased activities of the enzymes SOD, GR, CAT, and GPOX in the leaf tissues of acclimated plants in comparison to the non-acclimated plants. Moreover, acclimation increased the root cell viability inhibited the Na+ influx to the root tissues in comparison to the non-acclimated plants. Together, these results suggest that rye can acclimate to sodic-alkalinity by increasing root cell viability, and therefore limited Na+ influx to root tissues and increased water uptake and antioxidant capacities without any change in the plant growth.
Keywords: antioxidant capacity; ionic homeostasis; osmotic stress; root cell viability; sodium.