| To investigate the morphological and physiological bases in its salt tolerance, a silver leaf sunflower ARG1807（Wt）was used as the test materialand, two other oil sunflower inbred lines, HA and HL, were used as the control materials.Salt stress treatment was carried out with 250 mmol·L-1 of NaCl solution for 7 days. The morphological changes before and after salt stress, as well as the differences in physiological indexes including levels of chlorophyll, proline, malondialdehyde content and SOD activity in leaves were measured. The results showed that: (1) It was noticed that plant height, leaf area, and biomasses of root, stem, and leaf of Wt after salt stress were lower than those of the HA and HL by 24.53%, 38.21%, 2.59%, 5.50%, and 3.42%, respectively.(2) It was further found that under salt stress, the intercellular carbon dioxide concentration (Ci) of each sunflower was decreased significantly, while limiting value of stomata (Ls) elevated significantly, indicating that the decrease in photosynthetic rate of HA,HL and Wt sunflowers were mainly due to stomatal factors.（3）The activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT),the contents of proline (Pro) and malondialdehyde (MDA) in three sunflower varieties were significantly changed after salt stress. Among them, the proline content, SOD activity, POD activity and CAT activity of Wt were increased by 279.94%, 65.09%, 211.111% and 55.91%,respectively, higher than those increased in the HA and HL, whereas the MDA content increased by 231.10% after salt treatment, lower than that increased in HA and HL. (4) With time going, the water loss rate in leaves of the three sunflower varieties increased significantly. Among them, the water loss rate of Wt is always lower than that of HA and HL. At 150 min, water loss rate in HA and Wt was the highest and the lowest, reaching levels of 84% and 69%, respectively, implying that Wt maybe more advantageous in water retention. (5) Through the observations on phenotypes of sunflower leaves, it was worth mentioning that the length and density of trichome of Wt leaves were richer than those of HA and HL. It is reasonable to speculate that this may be the reason why the water retention of Wt was stronger than that of HA and HL. Taken together, our analyses showed that in terms of both morphological and physiological indicators under salt stress, silver leaf sunflower exhibited good performance and prominent superiority. In short, silver leaf sunflower has an ultimate ability to adapt against salt. |