Abstract:

To study the changes in growth traits and physiological responses of Fraxinus hybrid seedling under salt stress and understand the salt tolerance of different hybrid seedlings, seven kinds of Fraxinus hybrid seedlings and two new varieties of Fraxinus were used as test materials to study their physiological responses to salt stress (0‰, 4‰, 8‰, 12‰), and the salt tolerance of nine kinds of Fraxinus seedlings was comprehensively evaluated by membership function method. The results showed that with the increase of salt stress intensity, the growth of hybrid seedlings was inhibited. The plant height and ground diameter of ‘327’ and ‘325’ decreased less, and the effect of salt damage was not obvious, while the inhibition of salt stress on the growth of ‘Qingbi’ and ‘344’ was more obvious. Compared with other combinations, the conductivity and MDA content of ‘327’ and ‘325’ changed more smoothly under salt stress, the chlorophyll content decreased less, the SOD activity in leaves increased more, and the proline content and soluble sugar content increased more than other hybrid seedlings. The conductivity and MDA content of ‘Qingbi’ and ‘344’ increased significantly, the chlorophyll content decreased greatly, and the SOD enzyme activity, proline content and soluble sugar content in leaves increased less. It indicated that under salt stress, ‘327’ and ‘325’ had stronger antioxidant enzyme protection system, more complete cell membrane structure, lower membrane lipid peroxidation, lower chlorophyll loss, more photosynthetic accumulation of photosynthetic products, faster plant growth and higher salt tolerance, while ‘Qingbi’ and ‘344’ had poor salt tolerance. The salt tolerance of 9 kinds of Fraxinus seedlings was comprehensively evaluated by membership function method, and the order of salt tolerance was ‘327’>‘325’>‘Lula 6’>‘318’>‘317’>‘346’>‘342’>‘344’>‘Qingbi’.

Key words: Fraxinus, salt stress, physiological response, salt tolerance, comprehensive evaluation