Abstract: Three 3-month-old shrub seedlings, Hedysarum multijugum, Clematis fruticosa and Buddleja alternifolia were selected as the test materials. The shrub seedlings were divided into two groups, which were irrigated with water and 150 mM NaCl solution, and then treated with natural drought after the soil moisture was saturated. The physiological responses of the three shrub seedlings to drought under low salt and no salt conditions were determined, and the drought tolerance of the three shrub seedlings were further comprehensively evaluated with the subordinate functions. Results showed that, with the prolongation of drought stress duration, the height and leaf area of three shrub seedings increased, but the increase decrease, the leaf relative water content all decreased to certain extent, and the malondialdehyde first increased and then decreased in H. multijugum and C. fruticosa, and significantly increased in B. alternifolia, while the antioxidant enzyme system in B. alternifolia was less varied. The photosynthetic pigment content gradually decreased in H. multijugum and C. fruticosa, and first increased and then decreased in B. alternifolia. In comparison with the salt-free treatment, the height and leaf area of three shrub seedings under low salt treatment increase relatively large, the leaf relative water content, MDA contents and photosynthetic pigment content of the three shrub seedings under low salt treatment were smaller, and the accumulation of osmotic regulation substances and anti-oxidant enzyme activities were higher. Subordinate function analysis revealed that the drought tolerance of the three shrub seedlings from strong to weak was B. alternifolia, C. fruticosa and H. multijugum. Low-salt environment significantly promoted drought resistance of three shrubs.

Key words: seedling, drought stress, subordinate function methodI