摘要： 为了挖掘外源硅（Si）在盐分逆境胁迫应答中的作用，探讨外源Si对盐分逆境胁迫响应机制，以棉花品种新陆早45号为供试材料，分别对其实施不同程度的盐分逆境处理（盐分（NaCl）、硅（Si）2因素随机组合，分别为盐分（NaCl：0，100，200 mmol/L）、硅（K₂SiO₃：0，262.3 mg/L），总计6个处理），研究施用外源Si后，棉花幼苗生长、渗透调节系统、活性氧、丙二醛（MDA）含量和电解质渗出率的变化，探讨外源Si缓解盐分逆境胁迫对棉花幼苗各测量指标的抑制效应及其机制。结果发现：与对照（CK）相比，随着NaCl浓度的增加，棉花幼苗叶片鲜质量、叶片干质量、茎鲜质量、茎干质量、根干质量、根冠比、根系活力、苹果酸和柠檬酸均呈下降趋势；游离脯氨酸（Pro）、过氧化氢（H₂O₂）、丙二醛（MDA）含量、电解质渗出率和氧自由基（O₂^·）产生速率均呈上升趋势；可溶性糖（SS）和游离氨基酸含量呈先上升后下降的趋势。相同浓度盐分处理施加外源硅后，棉苗生物量及渗透调节物质含量明显增加，氧自由基产生速率、电解质渗出率、过氧化氢和丙二醛含量明显减少。综合分析表明，盐胁迫对棉花幼苗生长有抑制作用，且随盐浓度的增加，其生长受抑制和渗透胁迫程度加剧，外源硅通过提高棉花幼苗渗透调节物质积累量并降低活性氧积累，缓解盐胁迫对棉花幼苗生长的抑制作用，提高棉花幼苗抗盐性。

关键词: 硅, 盐胁迫, 棉花幼苗, 渗透调节, 活性氧, 丙二醛

Abstract: In order to excavate the role of exogenous silicon(Si) in salt stress response and explore the regulation mechanism of salt stress response, the cotton variety Xinluzao 45 was used as test material, and was treated with 3 levels of salt(NaCl:0, 100, 200 mmol/L) and 2 levels of silicon(K₂SiO₃:0, 262.3 mg/L). The changes of seedling growth, osmotic regulation, reactive oxygen, malondialdehyde(MDA) content and electrolyte leakage rate were measured after the treatment of exogenous Si, and the effect of silicon in relieving the inhibitory effect of NaCl on cotton seedlings were studied. The results showed that, compared to CK, the fresh leaf weight, dry leaf weight, stem fresh weight, stem dry weight, root dry weight, root cap ratio, root activity, malic acid and citric acid of cotton seedlings all showed a downward trend along with the increase of NaCl levels, while the contents of free proline(Pro), hydrogen peroxide(H₂O₂) and malondialdehyde, the rate of electrolyte leakage and the oxygen free radical(O₂^·) production presented a upward trend, and SS and free amino acid contents increased first and then decreased. The biomass and osmotic regulator of cotton seedlings increased obviously in the same salt treatment after application of exogenous silicon, while the rate of O₂^· production, electrolyte leakage rate, the contents of hydrogen peroxide and malondialdehyde in cotton seedlings decreased obviously. Comprehensive analysis showed that the salt stress could inhibit the growth of cotton seedlings, and with the increase of salt concentration, the inhibition effect and osmotic stress degree aggravated. The exogenous silicon increased the accumulation of osmotic regulation substances and reduced the accumulation of active oxygen in cotton seedlings, so it could alleviate the inhibiting effect of salt stress on cotton seedling growth and improve the salt resistance of cotton seedlings.

Key words: Silicon, Salt stress, Cotton seedlings, Osmotic adjustment, Active oxygen, Malondialdehyde

中图分类号: 

• S562.01