外源H2O2对盐碱胁迫下万寿菊光合能力和抗性生理的影响

Effects of exogenous H2 O2 on photosynthetic capacity and resistance physiology of marigold under saline-alkali stress

摘要:

【目的】 探究外源H2 O2 对混合盐碱胁迫下盆栽万寿菊（Tagetes erecta）的光合特性和生理功能的影响，筛选抗盐碱性优异的外源H2 O2 浓度。【方法】 设置CK与混合盐碱胁迫加5种浓度外源H2 O2 处理，即T1（0 μmol/L）、T2（50 μmol/L）、T3（100 μmol/L）、T4（200 μmol/L）和T5（300 μmol/L）处理。 分别观察万寿菊表型变化，并测定其叶绿素含量、叶片渗透物质含量、相对电导率（REC）、丙二醛 （MDA）含量、叶片荧光参数、抗氧化酶活性和根系构型参数，并进行相关性和主成分分析。【结果】 随盐碱胁迫时间的延长，万寿菊叶片的REC、MDA、叶片渗透物质、根系构型参数呈上升趋势，叶绿素含量、叶片荧光特性参数呈下降趋势。外源H2 O2 处理后叶片各指标值均有减小，且存在明显的浓度效应。其中，T4（200 μmol/L）处理下叶绿素含量、叶片荧光参数和根系构型参数降幅最小。相反MDA 含量和REC升幅最小，而叶片渗透物质含量升幅最大。经综合评价分析得出，各处理排名为CK＞T4 ＞T3＞T2＞T5＞T1。【结论】 外源H2 O2 可以促进万寿菊根系生长，增强叶片的光合能力和渗透调节能力，同时提高抗氧化酶活性，从而减缓膜脂过氧化损伤，最终缓解盐碱胁迫对万寿菊的伤害，H2 O2 浓度以200 μmol/L效果最佳。

Abstract:

【Objective】 To investigate the effects of exogenous hydrogen peroxide （H2 O2 ） on the photosynthetic characteristics and physiological functions of potted marigolds （Tagetes erecta） under mixed saline‐alkaline stress， and to identify the optimal exogenous H2 O2 concentration for enhancing stress resistance.【Method】 Five concentra tions of exogenous H2 O2 were applied under control （CK） and mixed saline-alkaline stress conditions： T1 （0 μmol/L），T2（50 μmol/L），T3（100 μmol/L），T4（200 μmol/L） and T5（300 μmol/L）. Phenotypic observations were recorded，and physiological parameters including chlorophyll content，leaf osmotic substances，relative electrical conductivity （REC），malondialdehyde （MDA），chlorophyll fluorescence parameters，antioxidant substance content and root conformation parameters were measured. Correlation and principal component analyses were conducted for comprehensive analysis.【Result】 The results showed that the REC，MDA，leaf osmotic substances and root confor mation parameters of marigold leaves exhibited an increasing trend with the prolongation of saline and alkaline stress， while the chlorophyll content and leaf fluorescence parameters showed a decreasing trend. The magnitude of the changes of each index was reduced after exogenous H2 O2 treatment，with clear concentration-dependent responses. Among all treatments，T4（200 μmol/L） resulted in smallest decrease in chlorophyll content，leaf fluorescence param eters，and root conformation parameters，as well as the lowest increase in MDA and REC. T4 also showed the great est enhancement in leaf osmotic regulation. After comprehensive evaluation，the rankings of the treatments were CK ＞T4＞T3＞T2＞T5＞T1.【Conclusion】 It was shown that exogenous H2 O2 could promote the growth of the root system of marigold，enhance the photosynthetic and osmotic regulating ability of the leaves，and activate the activity of antioxidant enzymes，which could slow down the damage of membrane lipid peroxidation. Ultimately alleviate the damage of saline and alkaline stress on marigold with the most effective concentration being 200 μmol/L.