Abstract: Salt tolerance of Psathyrostachys juncea at the germination and seedling growth stages was evaluated using 6 different accessions planted in saline-alkali soil. Seeds of the 6 accessions were treated with 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8% and 2.0% NaCl solutions, and pure water was used as the Control. The germination rate, germination potential, root length and shoot lengths were measured under salt stress. The seedlings germinated under the high 1.8% and 2.0% NaCl solution concentrations were transplanted into nursery pots. After these transplanted seedlings reached the three-leaf stage, 0.6% NaCl solution was added to the growth media, representing medium salt stress. Leaf length was measured. The soluble sugar, free proline, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and other antioxidant enzyme activity and malondialdehyde (MDA) contents were also measured. The general salt tolerance of the six P. juncea accessions at the germination and seedling growth stages was evaluated by subordinate function analysis. The results showed that germination rate, germination potential, seedling vigor index and relative growth rate all decreased with increase in salt concentration. The contents of free proline, soluble sugar, MDA and relative electric conductivity of leaves were increased by exposure to medium salt stress in seedling stage. The changes in SOD, POD and CAT activities varied in different materials. Principal component analysis showed that germination related indexes under salt stress were the key indicators of P. juncea salt tolerance. Antioxidant enzyme activity and MDA level were also identified as salt-tolerance indicators by the second principal component.

Key words: Psathyrostachys juncea, salt stress, seed germination, physiological characteristics