Abstract:

Aiming at the limited cultivated soil resources in southern Xinjiang， the effects of mixed salt on cotton seed germination were studied， and the tolerance of cotton to saline-alkali soil environment was discussed.To simulate the complex saline-alkali environment in southern Xinjiang， NaCl， Na₂SO₄， NaHCO₃ and Na₂CO₃ were mixed in molar ratios of 1∶0∶0∶0 （S1）， 9∶1∶0∶0 （S2）， 0∶0∶9∶1 （S3） and 9∶1∶9∶1 （S4）. 5 salt levels （40， 80， 120， 160 and 200 mmol·L^-1） were set to stress the germination period of cotton seeds for varieties Tahe 2 and Xinluzhong 62. The seed germination potential， germination rate， germination rate， salt tolerance critical salinity concentration， and early seedling fresh weight and dry weight were analyzed by using distilled water as control （CK）. The results showed that all 4 salt stresses significantly reduced the germination potential of cotton seeds. At 40 mmol·L^-1， there was no significant difference in germination rate between S1~S4 treatments and CK， but as the salt level increased （≥80 mmol·L^-1）， the germination rate of cotton seeds significantly decreased. At the same salt level， the germination rate of both cotton varieties in the S4 treatment was higher than that in the S1， S2 and S3 treatments. The 4 salt stresses caused a delay in the initial germination time of cotton seeds， and the germination rate significantly decreased. The S1， S2 and S3 treatments at 40 mmol·L^-1 promoted the accumulation of fresh weight and dry weight of cotton seedlings，and with the increase in salt level the fresh weight and dry weight of cotton seedlings gradually decreased， and all levels of the S4 treatment reduced the fresh weight and dry weight of cotton seedlings. Correlation analysis and principal component analysis indicated that germination rate was an important indicator for evaluating the salt tolerance of cotton during the germination period. Under 4 salt stresses， the salt tolerance critical salinity concentration of cotton seed germination rate was as S4>S2>S1>S3. In summary， during the germination period of cotton seeds， there was a certain level of tolerance to 40 mmol·L^-1 of the 4 salt stresses， but as the salt level increased， the 4 salt stresses resulted in a delayed germination time， decreased germination potential， germination rate and germination rate. Xinluzhong 62 showed strong tolerance to NaCl， and Tahe 2 exhibited strong tolerance to mixed salts. Above results provided a theoretical basis for the breeding of cotton germplasm in southern Xinjiang and evaluated important indicators of salt tolerance during the germination period of cotton seeds.

Key words: cotton, complex salts, salt stress, germination, seed

摘要：

针对南疆地区栽培土壤资源有限问题，研究混合盐对棉花种子萌发的影响，探讨棉花对盐碱土壤环境的耐受能力。为模拟南疆地区复杂的盐碱环境，将NaCl、Na₂SO₄、NaHCO₃和Na₂CO₃按照摩尔比1∶0∶0∶0（S1）、9∶1∶0∶0（S2）、0∶0∶9∶1（S3）、9∶1∶9∶1（S4）进行混合，设置5个盐水平梯度（40、80、120、160和200 mmol·L^-1）对塔河2号和新陆中62号棉花种子萌发期进行胁迫，以施用蒸馏水作为对照（CK），分析棉花种子的发芽势、发芽率、萌发速率、耐盐半致死浓度及早期幼苗的鲜重和干重。结果表明，4种盐胁迫显著降低了棉花种子的发芽势。在40 mmol·L^-1时，S1~S4处理棉花种子发芽率与CK无显著差异，但随盐水平（≥80 mmol·L^-1）的升高，棉花种子的发芽率显著降低。在相同盐水平下，2个品种棉花在S4处理的发芽率高于S1、S2和S3处理。4种盐胁迫造成了棉花种子初始萌发时间延迟，萌发速率显著降低。40 mmol·L^-1的S1、S2和S3处理促进了棉花幼苗鲜重和干重的积累，但随着盐水平的升高棉花幼苗鲜重和干重逐渐降低；各水平的S4处理均降低了棉花幼苗的鲜重和干重。相关性分析和主成分分析显示，发芽率是评价棉花萌发期耐盐碱能力的重要指标。在4种盐胁迫下棉花种子发芽率的耐盐半致死浓度依次为S4>S2>S1>S3。综上，棉花种子萌发期对40 mmol·L^-1的4种盐胁迫表现出一定的耐受能力，但随着盐水平的增加，4种盐胁迫导致了棉花种子萌发时间推迟，发芽势、发芽率和萌发速率降低。新陆中62号对NaCl的耐受能力较强，塔河2号对复合盐的耐受能力较强。以上研究结果为南疆棉花种质的选育及评价棉花萌发期耐盐碱能力的重要指标提供理论依据。

关键词: 棉花, 复合盐, 盐胁迫, 萌发, 种子