干旱胁迫对新疆大叶苜蓿幼苗形态及生理的影响

The effects of drought stress on the morphology and physiology of Medicago sativa cv.Xinjiangdaye

摘要:

【目的】 研究不同浓度的PEG胁迫对新疆大叶苜蓿形态和生理指标的影响，为深入开展苜蓿抗旱机制研究提供理论依据。【方法】 以新疆大叶苜蓿为材料，采用不同浓度（0%、5.0%、10.0%、 15. 0%、20. 0%）的PEG模拟干旱胁迫条件，测定苗期各浓度胁迫下的根长、株高、鲜重、干重、叶绿素含量、脯氨酸、丙二醛（MDA）、超氧化物歧化酶（SOD）和过氧化物酶（POD）活性变化。【结果】 随着干旱胁迫处理浓度的升高，新疆大叶苜蓿根长、株高、鲜重、干重变化差异达到显著（P＜0.05）水平，且在 PEG 10% 浓度下达到峰值，较0% 分别增长了41.21%、12.59%、48.29%和101.80%。叶绿素含量随胁迫浓度的升高表现为逐渐降低；MDA和脯氨酸含量则表现为不断升高，且在2、4、6 d PEG 20% 处理下叶绿素含量较0%分别下降31.57%、28.94%、30.02%；MDA和脯氨酸在2、4、6 d PEG 20% 处理下较0%分别上升94.20%、85.57%、93.97% 和172.58%、482.84%、400.04%。SOD、POD活性随胁迫浓度和处理时间的增加，呈先升高后降低的趋势，不同处理时间下各胁迫浓度达到峰值的时间有所差异，第2天时在15% 的PEG处理下，第4、6天在10% 处理下SOD、POD活性达到最大值。【结论】 短时间的干旱胁迫下新疆大叶苜蓿抵御干旱胁迫的能力更强，适度的（低浓度、短时间）干旱对新疆大叶苜蓿的生长具有积极影响，因此，在苜蓿栽培管理中采取合理的灌溉频率更有利于其生长。

Abstract:

【Objective】 This study aims to investigate the effects of PEG stress at different concentrations on the morphology and physiological indicators of Medicago sativa cv. Xinjiangdaye.【Method】 Using M. sativa cv. Xinji angdaye as the material，different concentrations （0%，5. 0%，10. 0%，15. 0% and 20. 0%，） of PEG were used to simulate drought stress conditions，and changes in plant height，root length，fresh weight，dry weight，chlorophyll con tent，SOD and POD activity were measured under each concentration of stress during the seedling stage.【Result】 With the increase of drought stress treatment concentration，the root length，plant height，fresh weight，and dry weight of alfalfa changed significantly，and reached their peak at PEG 10% concentration，increasing by 41. 21%， 12. 59%，48. 29%，and 101. 80% respectively compared to the control. The chlorophyll content gradually decreased with the increase of stress concentration，while the malondialdehyde and proline content showed a continuous in crease. Under 2，4，and 6 d PEG20% treatment，the chlorophyll content decreased by 31. 57%，28. 94%，and 30. 02% compared to the control，while the malondialdehyde and proline content increased by 94. 20%，85. 57%， 93. 97%，172. 58%，482. 84%，and 400. 04% compared to the control under 2，4，and 6 d PEG20% treatment. The activities of SOD and POD showed a trend of first increasing and then decreasing with the increase of stress concen tration and treatment time. The peak values reached at different stress concentrations varied at different treatment times. The enzyme activity reached its maximum value at 15% PEG treatment on day 2，and at 10% treatment on days 4 and 6.【Conclusion】 The results showed that M. sativa cv. Xinjiangdaye have a stronger ability to resist drought stress in the short term than in the long term. Moderate （low concentration，short duration） drought has a positive impact on plant growth. Therefore，adopting a reasonable irrigation frequency in alfalfa cultivation and man agement is more conducive to its growth.