Effects of High Temperature Stress on Physiological Characteristics on Jujube Seedlings

【Objective】 To explore the adaptation mechanism of sour and hui jujube seedlings to high temperature stress.【Method】Sour jujube and hui jujube seedlings were used as the materials, plug experiments were conducted to investigate the effects of 45℃ high temperature treatment at different time (0, 1, 3, 5 d) on relative conductivity, malonaldehyde, osmotic substances content, antioxidant enzyme activity and the photosynthetic pigments in leaves of sour jujube and huizao jujube seedlings.【Result】Leaf relative conductivity of sour jujube seedlings increased significantly only on the 5th-day high temperature treatment compared with the control treatment, which was 18.1% higher than that of the CK, but no significant differences were observed in leaf MDA content among all the treatments. The relative electrical conductivity and MDA content in leaves of Zizyphus jujuba seedlings increased significantly, and the cell membrane system was damaged seriously. As the high temperature treatment time prolonged, the soluble sugar content in leaves of sour jujube seedlings first decreased and then increased, proline, SOD and CAT activity significantly increased, the soluble sugar, SOD activity of hui jujube seedlings first decreased and then increased, proline and CAT activity significantly increased. High temperature treatment had no significant effect on leaf soluble protein, POD activity of sour jujube and hui jujube seedlings. The photosynthetic pigment content in the leaves of jujube and gray jujube seedlings was significantly decreased by high temperature treatment, and the decrease rate of photosynthetic pigment content in the leaves of wild jujube seedlings was smaller than that of gray jujube seedlings.【Conclusion】With the extension of high temperature stress time, soluble sugar, proline content, SOD and CAT activities in leaves of sour and hui jujube seedlings increased, and the content of photosynthetic pigments decreased. Moreover, the cell membrane stability of the leaves of jujube was stronger than that of the seedlings of Zizyphus jujuba, which showed that sour jujube seedlings had stronger heat resistance.