目的通过对决明子萌发及幼苗生理特性的研究,寻找提高决明子及幼苗在盐胁迫条件下抗性能力的途径。方法测定盐胁迫下决明子在经过不同质量浓度的外源性5-氨基乙酰丙酸(ALA)处理后,种子的发芽势、发芽率、发芽指数和活力指数,并对决明幼苗叶片叶绿素量、叶绿素荧光参数、原生质膜透性、叶片丙二醛(MDA)量、可溶性糖量、可溶性蛋白量及脯氨酸量及超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性进行测定。结果 100 mmol/L盐胁迫下的决明子萌发受到显著抑制,但是经过不同质量浓度的ALA处理后,萌发指标均有升高。结果表明,外源性ALA处理显著提高了决明子发芽势、发芽率、发芽指数和活力指数,提高了叶片叶绿素a、叶绿素b和总叶绿素量,显著提高了最大光化学效率(Fv/Fm),PSII有效光化学效率(Fv′/Fm′),PSII实际光化学效率(ΦPSII),光化学淬灭系数(qP),降低了原生质膜透性、叶片的MDA量及非光化学淬灭系数(NPQ),提高了盐胁迫下幼苗叶片可溶性糖、可溶性蛋白和脯氨酸量,显著提高了叶片SOD、POD、CAT活性。结论外源性ALA通过提高决明子的萌发指数,提高幼苗光合效率、渗透调节物质量及抗氧化酶活性,有效地减缓盐胁迫对决明子及幼苗产生的伤害,提高种子及幼苗的抗盐能力。

Objective In order to improve the salt resistance activity of seeds and seedlings for Cassia obtusifolia under NaCl stress,seed germination and physiological characteristics of C. obtusifolia seedlings were investigated. Methods Several physiological indexes of C. obtusifolia seeds treated by exogenous 5-aminolevulinic acid (ALA) under NaCl stress, such as germination vigor,germination rate, germination index, and vigor index, were measured. And other indexes, contents of photosynthetic pigment,chlorophyll fluorescence parameters, membrance permeability, contents of malondialdehyde (MDA), soluble sugar, soluble protein and proline, activities of superoxide (SOD), peroxidase (POD), and catalase (CAT) were also measured. Results The germination indexes of C. obtusifolia seeds under NaCl stress (100 mmol/L) have an obvious inhibition. But after the treatment of ALA, all germination indexes were increased. The results showed that the treatment of exogenous ALA obviously improved the germination vigor,germination rate, germination index, and vigor index, increased the content of chlorophyll a, chlorophyll b, and total chlorophyll,improved the photochemical efficiency of photosystem II (Fv/Fm), photochemical efficiency (Fv′/Fm′), PSII actual photochemical efficiency (ΦPSII), and photochemical quench coefficient (qP), decreased the membrance permeability, the contents of MDA and non-photochemical quenching coefficient (NPQ), increased the content of soluble sugar, soluble protein and proline. Meanwhile, the results also indicated that ALA improved the activities of SOD, POD, and CAT significantly. Conclusion Exogenous ALA with appropriate concentration could significantly alleviate the damages to the seeds and seedlings of C. obtusifolia under NaCl stress and promote the salt resistance of the seeds and seedlings through improving the germination indexes, the photochemical efficiency, and the antioxidase activities of the seedlings.

国家林业公益科研专项项目(201004064)