Analysis of Growth and Physiological Response Characteristics of Suaeda salsa Under Compound Stress

This investigation examines the physiological and ecological adaptation mechanisms of Suaeda salsa, a halophytic plant, in response to multifaceted environmental stresses prevalent in coastal saline-alkali wetlands. Using a three-factor, three-level orthogonal experimental design, we evaluated the combined effects of temperature (15°C, 20°C, 25°C), light intensity (25, 50, 100 μmol m^-2 s^-1), and salinity (0, 200, 400 mM NaCl) on plant performance. Temperature emerged as the dominant factor influencing growth, photosynthetic efficiency, and betacyanin accumulation. The highest growth rate and betacyanin content were observed under low temperature (15°C), high light (100 μmol m^-2 s^-1), and moderate salinity (200 mM NaCl). Chlorophyll content was highest under moderate temperature (20°C) and low light (25 μmol m^-2 s^-1). Y(II) and qP peaked under low temperature (15°C) and high light (100 μmol m^-2 s^-1). Notably, chlorophyll content was highest under moderate temperature and low light, whereas betacyanin accumulation was highest under low temperature and high light. Positive correlations were observed between betacyanin content and both photosynthetic efficiency (Y(II), qP, F_v/F_m) and AGR. The interactive effects among the three factors were predominantly additive under the tested conditions, indicating that the main effects of temperature, light, and salinity largely acted independently on most physiological traits. Temperature consistently exhibited the largest effect size for all measured traits ( ${\eta }_p^2$  = 0.588-0.773). Overall, this study provides a physiological basis for optimizing S. salsa restoration in coastal saline-alkali wetlands.