外源生长调节物质对甜高粱种子萌发过程中盐分胁迫的缓解效应及其生理机制

盐渍化土壤中盐胁迫是作物种子萌发和生长发育的主要限制因子, 探究盐分胁迫下提高种子萌发率的技术及机制对开发利用盐碱地有重要意义。本文以不同耐盐能力的高粱品种国甜2011和国甜106为材料, 研究了盐分对甜高粱种子萌发期生长过程的影响, 并比较了耐盐性差异。以耐盐性弱的国甜106为试材, 探究盐分胁迫下不同生长调节物质γ-氨基丁酸(GABA)、赤霉素(GA₃)、激动素(KT)和水杨酸(SA)]对甜高粱种子吸水萌发过程中生长特性的调节效应。表明, 盐分胁迫显著抑制种子的吸水萌发, 降低种子的吸水速率、发芽势、发芽率、发芽指数, 增加种子的相对盐害率和丙二醛(MDA)含量。外源生长调节物质可有效缓解盐害, 显著增加种子的吸水率、发芽率、可溶性糖含量、可溶性蛋白含量, 提高SOD (超氧化物岐化酶)、POD (过氧化物酶)、CAT (过氧化氢酶)的活性, 促进K ⁺、Ca ²⁺、Mg ²⁺离子的吸收, 降低Na ⁺和MDA含量。外源生长调节物质主要是通过提高保护酶活性、渗透调剂物质含量和维持体内离子平衡来提高耐盐性。GA₃和GABA对盐害的缓解效应较好, 而KT促进种子对Mg ²⁺的吸收效果较好。本研究表明外源生长调节物质(尤其是 GA₃和 GABA)可用于盐碱地高粱生产, 为减轻盐碱地对高粱的盐碱胁迫提供了理论依据。

Alleviation Effects of Exogenous Growth Regulators on Seed Germination of Sweet Sorghum under Salt Stress and Its Physiological Basis

Salinity is a major abiotic constraint affecting crop seed germination and growth. It is vital to exploit and utilize salinity soil by exploring the technologies for promoting seed germination under salt stress. In this experiment, two contrasting sorghum genotypes (Guotian 2011 and Guotian 106) were used to study the salt stress (0, 50, 100, 150, and 200 mmol L ^-1 NaCl solution) effect on seed germination, and different concentrations of exogenous growth substances of γ-aminobutyric acid (GABA), gibberellin (GA₃), kinetin (KT), and salicylic acid (SA) were used to regulate seed germination on salt-sensitive sorghum genotype Guotian 106. The seed germination was significantly inhibited under salt stress. Water uptake rate, germination potential, germination rate, germination index all decreased under salt stress, but relative salt damage rate and MDA (malondialdehyde) prominently increased in salinity condition. Exogenous growth regulators could effectively relieve the salt stress. With applied the exogenous growth substances, the seed uptake rate, germination rate, contact of soluble sugar and soluble protein, activities of SOD (superoxide dismutase), POD (peroxidase), and CAT (catalase) were all significantly increased, the absorption of K ⁺, Ca ²⁺, and Mg ²⁺ enhanced in the same time, but the contents of Na ⁺ and MDA decreased. Overall, GA₃ and GABA performed a better alleviating effect on salt stress, KT showed positive effect on promoting Mg ²⁺ absorption. These results suggested that the exogenous growth substances (especially GA₃ and GABA) can be applicated in sorghum production under salt condition, laying a foundation for improving and utilizing saline soil.