| Effects of 2,4-Epibrassinolide on physiological characteristics of Malus halliana under drought stress |
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| DOI：10.7606/j.issn.1000-7601.2022.03.05 |
| Key Words: Malus halliana 2,4-Epibrassinolide drought stress photosynthetic characteristics antioxidant enzyme |
| Author Name | Affiliation | | XIAN Xulin | College of Horticulture of Gansu Agriculture University, Lanzhou, Gansu 730070, China | | ZHANG De | College of Horticulture of Gansu Agriculture University, Lanzhou, Gansu 730070, China | | ZHANG Zhongxing | College of Horticulture of Gansu Agriculture University, Lanzhou, Gansu 730070, China | | WANG Shuangcheng | College of Horticulture of Gansu Agriculture University, Lanzhou, Gansu 730070, China | | GAO Yanlong | College of Horticulture of Gansu Agriculture University, Lanzhou, Gansu 730070, China | | WANG Yanxiu | College of Horticulture of Gansu Agriculture University, Lanzhou, Gansu 730070, China |
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| Abstract: |
| The effects of exogenous 2,4-Epibrassinolide (EBR) on the photosynthesis and physiological characteristics of Malus halliana seedlings under drought stress with seedlings of 7~8 leaf\|age Malus halliana as experimental materials were studied. The experiment used pot water control method of CK (normal water level) and drought stress as well as 6 brassinolide concentrations of T1 (0 mg·L-1), T2 (0.2 mg·L-1), T3 (0.4 mg·L-1), T4 (0.6 mg·L-1), T5 (0.8 mg·L-1) and T6 (1 mg·L-1). The contents of chlorophyll, photosynthetic characteristics, antioxidant enzyme activity, relative electrical conductivity and osmotic regulating substances in each treatment were measured, and the correlation and principal component analysis were computed. With the extension of drought stress time, Chl a, Chl b, Chl a+b, Chl a/b, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) decreased, and intercellular CO2 concentration (Ci), malonaldehyde (MDA), relative electrical conductivity (REC) increased. The activities of proline (Pro), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased first and then decreased. Additionally, compared with the control group, the increase and decrease of each index of Malus halliana leaves decreased to different degrees after spraying different concentrations of exogenous brassinolide, and there was a concentration effect. Among them, under 0.2 mg·L-1 (T2) treatment, Chl a, Chl b, Chl a+b, Chl a/b, Pn, Gs and TR decreased the least, significantly higher than those in T1, while MDA and REC increased the most, which were significantly higher than those in T1. Subsequently, correlation analysis of 14 indexes showed that Pn was significantly positively correlated with Chl a, Chl b, Chl a+b, Chl a/b and Gs (P<0.01) and Tr (P<0.05), and negatively correlated with REC and Ci (P<0.01). In addition, the 14 indexes were analyzed by principal component analysis, and the two principal components with eigenvalue >1 were extracted, whose eigenvalues were 9.765 and 3.747, respectively. The variance contribution rates were 69.747% and 26.766%, respectively, and the cumulative variance contribution rate reached 96.513%, which met the requirements. Finally, according to the ranking of principal component scores, the alleviating ability of exogenous brassinolide to drought stress of Malus halliana was T2>T3>T4>T5>T6>T. The 0.2 mg·L-1 brassinolide treatment had better results in improving the photosynthetic capacity, enhancing the activity of antioxidant enzymes, and promoting the stability of membrane to alleviate drought stress. |
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