盐碱胁迫下文冠果生理响应机制研究

目的 研究文冠果（Xanthoceras sorbifolia Bunge）盐碱条件生理响应机制，为其在盐碱区造林及管理提供科学依据。 方法 以1年生文冠果实生苗为材料，采用盆栽浇盐法，分别设置70、140、210、280 mmol·L?1中性盐（NaCl）及35、70、105、140 mmol·L?1碱性盐(Na2CO3)处理，分析其相对电导率、脯氨酸含量和超氧化物歧化酶（SOD）活性等生理指标。 结果 随盐碱浓度的增大，相对电导率、脯氨酸含量和可溶性蛋白含量均升高，且高浓度胁迫显著高于对照；在NaCl浓度为210 mmol·L?1、Na2CO3浓度为105 mmol·L?1 胁迫12 d后丙二醛含量比CK显著增多，且在NaCl浓度为280 mmol·L?1、Na2CO3浓度为105 mmol·L?1时达到峰值；SOD活性随处理时间延长而升高，但处理浓度增大其呈先升后降规律。双因素方差分析表明: 时间和浓度对2种类型处理下的相对电导率、脯氨酸含量有极显著交互效应（P < 0.01）。相关性分析显示: 盐碱胁迫下各生理指标均存在显著正相关（P < 0.05）。对指标标准化后进行主成分分析，2种盐类型处理分别提取出特征值大于1的1个主成分，NaCl、Na2CO3处理下累计方差贡献率分别为82.423%、77.725%。 结论 文冠果在盐碱胁迫下主要通过大量积累渗透调节物质、增大抗氧化酶活性来保护细胞膜系统的完整性，抵抗盐碱胁迫。在抗氧化酶系统中，低浓度胁迫时SOD活性较高，高浓度胁迫会破坏SOD活性，具有一定阈值。

Study on Growth and Physiological Response Mechanism of Xanthoceras sorbifolia Bunge under Salt-alkali Stress

Objective To explore the physiological response mechanism of Xanthoceras sorbifolia Bunge under saline-alkali conditions, so as to provide reference for silviculture in saline-alkali land. Method The relative conductivity, the activity of proline and superoxide dismutase (SOD) were studied to observe the change of physiological indicators. The influences of different concentrations of NaCl (70, 140, 210, 280 mmol·L?1) and Na2CO3 (35, 70, 105, 140 mmol·L?1) on the growth and physiological characteristics of one-year-old X. sorbifolia seedlings were observed by pot experiment. Result With the increase of saline-alkali concentration, the relative conductivity, the contents of proline and soluble protein changed significantly. The experimental data was larger than that of control group under high concentrations stress. Compared with the CK, the content of malondialdehyde increased significantly after 12 days of treatment with 210 mmol·L?1 salt and 105 mmol·L?1 alkali, and reached a peak with the concentrations of NaCl and Na2CO3 were 280 mmol·L?1 and 105mmol·L?1 respectively. Moreover, the SOD activity continued to increase under the stress, while the activity increased and then declined with the strengthen of the treatment concentration. Additionally, Two-way ANOVA showed that the time duration and concentration had extremely significant correlated with relative conductivity and proline content (P < 0.01). Correlation analysis demonstrated that the five physiological indicators measured in the leaves of seedlings under salt-alkali stress had significant positive correlation (P < 0.05). Principal component analysis was also applied after standardization of all index data. A principal component with eigenvalue greater than 1 was extracted under two different salt treatments. The cumulative variance contribution rate under NaCl treatment reached 82.423%, and the cumulative variance contribution rate under Na2CO3 treatment was 77.725%. Conclusion Under salt and alkali stress, X. sorbifolia Bunge mainly protects the integrity of the cell membrane system by accumulating a large amount of osmotic adjustment substances and increasing the activity of antioxidant enzymes. In the antioxidant enzyme system, the activity of SOD is higher under low-concentration stress than that of control group. However, the enzyme activity is destroyed under high concentration stress, which shows an obvious phenomenon of threshold value.