黄原胶对盐胁迫下紫花苜蓿种子萌发及幼苗生长的影响

Effects of xanthan on seed germination and seedling growth of alfalfa under salt stress

摘要:

【目的】盐胁迫降低种子活力、抑制萌发出苗，严重制约盐碱地区紫花苜蓿的生产。黄原胶已被证明能有效促进植物生长，但其对植物耐盐性的影响尚不清楚。本研究旨在阐明不同浓度黄原胶处理对盐胁迫下紫花苜蓿种子萌发期和苗期盐害的减缓效果。【方法】以紫花苜蓿品种敖汉为试验材料进行水培试验，在 75 mmol/L NaCl胁迫下，采用不同浓度（0. 5、1. 0、1. 5、2. 0 和 2. 5 g/L）黄原胶处理紫花苜蓿种子，研究黄原胶对盐胁迫下紫花苜蓿种子萌发及幼苗生长的影响。【结果】1）75 mmol/ L NaCl胁迫可显著抑制紫花苜蓿种子的发芽率、发芽势和发芽指数，并抑制幼苗的根长和苗长生长，降低其鲜重、干重、叶片相对含水量及叶绿素含量，同时显著升高叶片相对电导率（P＜0. 05）。2）添加 1. 5、2. 0 和 2. 5 g/L 黄原胶均能显著提高该胁迫下紫花苜蓿种子的发芽势、发芽率和发芽指数。3）该胁迫下，添加 0. 5~2. 5 g/L 黄原胶均能显著促进紫花苜蓿幼苗和根系的生长（P＜0. 05），显著提高幼苗的鲜重、干重、叶片相对含水量及叶绿素含量（P＜0. 05），并显著降低叶片相对电导率（P＜0. 05）。 【结论】黄原胶能够缓解 75 mmol/L NaCl 胁迫对紫花苜蓿的毒害，1. 5 g/L 黄原胶对盐胁迫下紫花苜蓿的缓解效果最佳。本研究为开发利用缓解盐碱地种植紫花苜蓿的生物源制剂提供了理论基础。

Abstract:

【Objective】Salt stress can reduce seed vitality，inhibit germination of seedlings，and seriously restrict the production of alfalfa in saline-alkali areas. Xanthan，a type of microbial polysaccharide，has been known to be effec- tive in promoting plant growth. But its effects on salt-tolerance of alfalfa are unknown. In this study，the alleviating effect of different concentrations of xanthan to salt damage on the germination and seedling stages of alfalfa under salt stress has been investigated.【Method】 The effects of xanthan （0. 5，1. 0，1. 5，2. 0 and 2. 5 g/L） on seed germination and seedling growth of alfalfa under 75 mmol/L NaCl stress were studied by hydroponic experiments using alfalfa 'Aohan' as experimental material.【Result】 The germination rate，germination potential and germination index of al- falfa seeds were significantly inhibited by 75 mmol/L NaCl stress，The root length，seedling length，fresh weight and dry weight of seedlings，relative water content and chlorophyll content of leaves were also inhibited by the stress， while the relative electrical conductivity of leaves was significantly increased （P＜0. 05）. Another part of the results showed that the addition of 1. 5，2. 0 and 2. 5 g/L xanthan could significantly increase the germination potential，ger- mination rate and germination index of alfalfa under the stress. Furthermore，under this stress，the addition of 0. 5~ 2. 5 g/L xanthan could significantly promote the growth of alfalfa seedlings and roots （P＜0. 05），significantly in- crease the fresh weight，dry weight，relative water content and chlorophyll content of leaves （P＜0. 05），and signifi- cantly decrease the relative electrical conductivity of leaves（P＜0. 05）.【Conclusion】 Xanthan can significantly allevi- ate the toxicity of 75 mmol/L NaCl stress on alfalfa. According to the comprehensive evaluation of membership func- tion，1. 5 g/L xanthan gum has the best effect on alfalfa under salt stress. This study provides a theoretical basis for the development and utilization of biogenic preparations for alfalfa cultivation in saline-alkali soil.