棉花幼苗对盐胁迫的生理响应与耐盐机理

为探究不同耐盐性棉花品种幼苗对盐胁迫的生理响应特征,以棉花耐盐品种中9806和盐敏感品种中S9612为材料,采用水培法,设置4个NaCl浓度梯度(0、100、150、200 mmol·L^-1)来模拟不同强度盐胁迫条件。结果表明:随着盐浓度的增加,各棉花品种的可溶性糖(SS)含量上升,抗氧化酶活性呈先上升后下降的趋势;盐处理下,耐盐品种可溶性蛋白(SP)、脯氨酸(Pro)含量增加量高于盐敏感品种;S1处理(100 mmol·L^-1 NaCl)中盐敏感品种丙二醛积累量较低,但在S2和S3处理(150、200 mmol·L^-1 NaCl)中,耐盐品种丙二醛含量增幅(5.35%~6.83%)低于盐敏感品种(36.93%~77.34%),超氧化物歧化酶(SOD)、过氧化物酶(POD)活性增加量较大;低盐浓度(S1处理)下,盐敏感品种地上部分能够保持较少的Na⁺,高盐浓度(S2和S3处理)下,耐盐品种根中Na⁺增加量小于盐敏感品种,茎中K⁺、K⁺/Na⁺较高。综上表明,耐盐品种棉花通过增强渗透调节,提高抗氧化酶活性缓解膜脂过氧化,维持较高K⁺/Na⁺,从而提高棉花幼苗的耐盐性。

Physiological response and salt tolerance mechanism of cotton seedlings to salt stress

To study the physiological response characteristics of cotton seedlings with different salt tolerance under salt stress, the salt-tolerant variety Zhong 9806 and salt-sensitive variety Zhong S9612 were used as test materials, four different concentrations (0, 100, 150, 200 mmol·L^-1) of NaCl were set to simulate different conditions of salt stress by hydroponic method. The results showed that with the increase of salt concentration, soluble sugar content of each cotton variety increased, and the antioxidant enzyme activity increased first and then decreased. Under salt treatment, the soluble protein and proline content of salt-tolerant cultivar increased more than those of salt-sensitive cultivar; Under S1 treatment (100 mmol·L^-1 NaCl), the accumulation of malondialdehyde content was lower in salt-sensitive cultivar, but under S2 and S3 treatments (150, 200 mmol·L^-1 NaCl), the increase of malondialdehyde content of salt-tolerant cultivar (5.35%-6.83%) was lower than those of salt-sensitive cultivar (36.93%-77.34%), and the activities of superoxide dismutase and peroxidase increased greatly. Under low salt concentration stress, the above-ground part of the salt-sensitive cultivar could maintain less Na⁺, and under high salt concentration stress, the increase of Na⁺ in the root of salt-tolerant variety was less than that of the salt-sensitive cultivar, and K⁺, K⁺/Na⁺ in the stems were relatively high. In summary, it had been shown that under salt stress, salt-tolerant cultivars of cotton could increase the content of osmoregulation substance, increase the activity of antioxidant enzymes to relieve membrane lipid peroxidation, and maintain a higher K⁺/Na⁺ ratio, thereby improving salt tolerance of seedlings.