Abstract:In order to understand the effects of NaCl stress on the seedling growth of Salix spp., the survival rate, physiological response and anatomical structure of half-year-old Salix spp. seedlings were studied under salt stress by pot-culture method. The results showed that the growth of seedlings was well treated with 0.25% NaCl (light salt stress), while it was inhibited treated with more than 0.5% NaCl (moderate and severe salt stress). It was deduced that the salt tolerant threshold of Salix spp. was 0.5%. The relative water content, the content of Chl a, Chl a+b and Chl a/b decreased as salt stress enhanced, while the Chl b, proline and malondialdehyde (MDA) contents increased gradually. The activity of superoxide dismutase (SOD) and soluble protein content increased under light salt stress, but significantly declined under moderate and severe salt stress. The thickness, cuticle, palisade tissue of leaf and the diameter and periderm of root were the biggest treated with 0.25% NaCl, while under moderate salt stress, the cell length in palisade tissue of leaf decreased with loose arrangement and the cells in transfusion tissue of root was abnormal. Therefore, it was suggested that Salix spp. had tolerance to light salt stress, and undergrowth at moderate and severe salt stress.