Phenotypic and physiological responses of two willow varieties to salt stress

Willows are one of the most important landscaping, biofuel, and raw timber tree species in the world. Cultivating fast-growing, salt-tolerant willow varieties is an effective way to balance wood supply and demand in China. This paper presents a comparative evaluation of the phenotypic development and physiological responses of two willow varieties, Salix L0911 (L0911) and Salix matsudana (SM), to salt stress. L0911 developed more biomass than SM and demonstrated higher tolerance to long-term exposures to NaCl-salinity. The two varieties demonstrated similar trends of physiological changes under salt stress, but the extent of the induced responses were higher in L0911, suggesting the involvement of specific responses in the salt-tolerant mechanism. Specifically, the activities of superoxide dismutase, peroxidase, soluble proteins and proline contents were higher in L0911 compared to SM, and the content of malondialdehyde and Na+ and Na+/K+ ratios were lower, demonstrating that the improved tolerance to salinity in L0911 is based on antioxidant response and improved ion selectivity.