Effect of salinity in growth, photosynthesis, mineral status and oxidative compounds in two ecotypes of the Thellungiella salsuginea

This study investigates the physiological and biochemical responses of two Thellungiella salsuginea ecotypes Yukon and Shandong under varying salt treatments. The results revealed that low salt concentrations stimulated plant growth in both ecotypes, whereas high salinity significantly reduced dry biomass compared to the control. This reduction in growth was accompanied by increased Na⁺ accumulation and decreased levels of K⁺ and Ca2⁺. Under moderate salt stress (100, 200, and 300 mM NaCl), both chlorophyll a and b levels increased, particularly in the Yukon ecotype. However, at higher salinity levels, chlorophyll content declined. Interestingly, at 100 mM NaCl, both ecotypes exhibited a sharp reduction in certain growth parameters. Despite morphological differences, both Yukon and Shandong ecotypes demonstrated a capacity to tolerate high salinity, reinforcing the halophytic nature of the species. The Shandong ecotype consistently showed greater resilience than the Yukon ecotype. One key defense mechanism observed was the accumul2ation of Na⁺ in older, mature leaves, protecting younger tissues. Additionally, the maintenance of photosynthetic stability under salinity stress was evident. At moderate salinity, Shandong displayed higher stomatal conductance, intercellular CO₂ concentration, and net photosynthesis rates. However, these parameters declined under severe salt stress.