干旱胁迫下美国薄荷幼苗形态与生理特性研究

Research on morphological and physiological responses of Monarda didyma seedlings to drought stress

[目的]探究干旱胁迫下,美国薄荷幼苗各组织生理生化指标的变化,旨在探讨干旱胁迫中美国薄荷植株不同部分的形态和生理变化的表现。[方法]用称重控水法,分4个水分梯度进行试验。[结果](1)形态变化:在胁迫水平加剧以及试验进行的条件下,植株叶片的叶面积扩展量、株高增量均较同期对照相应降低,且在胁迫21d时达到显著水平。根冠比总体随胁迫程度加剧增大。(2)生理变化:光合色素的含量在试验的14d之前为先增加后减少,在试验21d时表现为减少,脯氨酸的含量在整个试验处理中为上升趋势。可溶性蛋白的含量在第7天时同胁迫程度呈正相关;在处理21d的时候,可溶性蛋白的含量在叶和根中减少,茎中的含量先升后降。丙二醛含量在处理的14d之前为持续增加,胁迫21d时为先升后降;超氧化物歧化酶的活性在处理的前7d趋于稳定状态,在处理14d的时候地上部分呈先升后降的趋势,地下部分趋于下降的趋势;在胁迫21d的时候呈下降趋势。[结论]美国薄荷通过调整形态特征来降低植株水分消耗,调整植株内部的光合色素、渗透调节物质的含量以及保护酶的活性来维持体内生理平衡。

[Objective]The aim of this study was to determine the morphological and physiological plant responses to drought stress in different tissue of Monarda didyma.[Methods]One-year-old Monarda didymaplants were used as experimental material.Studies were conducted by adjusting water content of in potting soil to four different levels in the greenhouse,and the effect of drought stress on the plants tissues were determined by measuring plant morphological and physiological indexes at certain time interval.[Results](1)Morphological changes were occurred in all treatments.The leaf area expansion and plant height increment rates were reduced with the increase of water stress level compared to control group,and significant difference was observed in 21 d post treatment,while root-shoot ratio positively responded to the increase of stress level.(2)Plant physiological response to drought stress displayed as following:the content of photosynthetic pigment was positively impacted by the stress before 7 dposttreatment,and then it was decreased afterward until the end of experiments when plants suffered from medium or high drought stress..The content of praline was increased in all treatments.The content of soluble protein in 7 dwas positively correlated with stress level,when stress 14 d,first after rising downward trend,the content of soluble protein content in leaf and root is on the decline in 21 d,and the content in the stem was first rises fall.MDA content was enhanced during first 14 days post-treatment stress 21 dat the trend of first rise after fall.The activity of SOD wasn't significantly affected by the stress in the first 7 d,but that of ground part was boost at 14 days post-treatment and was declined afterward.The activity of SOD in the underground part was decreased.[Conclusion]Monarda didymacan adapt to drought stress by adjusting the morphological characteristics to reduce plant water consumption,and by modifying the content of photosynthetic pigment,osmotic regulation substances,and protective enzyme activity of plant to maintain the physiological balance.