混合盐碱胁迫对紫花苜蓿的生长和生理指标的影响

以混合盐碱模拟盐碱胁迫环境,设置0.0%（对照）、0.3%、0.6%、0.9%、1.2%浓度梯度的混合盐碱溶液胁迫紫花苜蓿(Medicago sativa)幼苗,通过对株高、根系等生长及叶片脯氨酸等生理指标的测定、分析,研究紫花苜蓿在混合盐碱胁迫下的生长和生理变化规律。结果表明,随着盐浓度的增加,苜蓿株高、地上和地下生物量先增后降,均在0.3%盐浓度处理下最高,0.6%、0.9%、0.0%下依次降低,1.2%处理下最低,且各处理间差异显著。根粗、根长均在1.2%盐浓度处理下最低,显著低于其他处理。生理指标在苜蓿品种间变化不同,但在1.2%处理下,多数品种叶片脯氨酸、可溶性糖、MDA含量最高,与其他处理差异显著。有的品种叶片叶绿素含量在0.3%处理下最高、1.2%处理下最低,有的品种变化无规律。苜蓿叶片抗氧化酶SOD、POD、CAT活性在1.2%处理下显著高于对照。由此得出苜蓿苗期相对耐盐碱,当盐浓度为1.2%时,生长和生理指标与对照相比变化较大,此浓度可作为苜蓿苗期耐盐碱性鉴定的适宜浓度。

Effects of Mixed Saline-alkali Stress on Growth and Physiology of Alfalfa

In this study, mixed saline-alkali solution was used to simulate the saline-alkali stress, and pot experiments were carried out on alfalfa (Medicago sativa). The experiment set mixed saline-alkali solution gradients of 0.0% (control), 0.3%, 0.6%, 0.9% and 1.2% to stress the seedling stage alfalfa, and to study the effects of mixed saline-alkali stress on plant height, root growth, leaf proline and other growth and physiological indicators. The results showed that with the increase of saline-alkali concentration, the plant height of alfalfa, and the biomass of the aboveground and underground parts all increased first and then decreased, the highest value appeared under the stress of 0.3% concentration, followed by that under the concentration of 0.6%, 0.9% and 0.0%, and the lowest value was observed under 1.2% concentration. There were significant differences among the treatments. The root thickness and root length were the lowest under 1.2% concentration stress, which was significantly lower than those of other treatments. Physiological indicators varied greatly among varieties. The content of proline, soluble sugar and MDA in leaves of most alfalfa varieties were the highest under the 1.2% concentration, which were significantly different from those under other treatments. The chlorophyll content of some varieties was the highest under 0.3% concentration and the lowest under 1.2% concentration, and others had irregular changes. The activities of antioxidant enzymes SOD, POD and CAT under 1.2% concentration were significantly higher than those of control. It is concluded that alfalfa at seedling stage has stronger tolerance to saline-alkali stress than that at germination stage. When the saline-alkali concentration is 1.2%, the growth and physiological indicators of alfalfa change greatly compared with those of CK, so this concentration can be used as the appropriate one to identify the saline-alkali stress tolerance for alfalfa at the seedling stage.