干旱胁迫对多裂叶荆芥幼苗形态和不同部位生理生化指标的影响

Effects of Drought Stress on Morphology,Physiological and Biochemical Indexes in Different Parts of Nepeta multifida L.Seedlings

为探究干旱对多裂叶荆芥生长的影响,以多裂叶荆芥1年生幼苗为试验材料,采用盆栽称重控水法模拟干旱的方法,设置CK、轻度、中度和重度4个水分梯度,对0、7、14、21 d下多裂叶荆芥幼苗的株高、叶面积和根冠比等形态指标,以及根、叶的生理生化指标进行统计学分析。结果表明,不同程度干旱胁迫对多裂叶荆芥幼苗株高和叶面积的影响较小,而根冠比对干旱胁迫的响应较为敏感;不同干旱处理下叶片含水量差异不显著,但0~7 d的叶绿素含量差异显著。整体来看,多裂叶荆芥根、叶中脯氨酸、可溶性糖、丙二醛含量均随时间增加呈先减后增的趋势,在21 d达到最高;而可溶性蛋白含量呈现递减(叶)或先增后减(根)的趋势,21 d时含量最低,此时不同处理下的差异显著;SOD活性在14~21 d最高,且在21 d时中、重度干旱下与CK差异显著;POD活性在21 d降到最低,且重度干旱下与CK差异显著,说明多裂叶荆芥幼苗在短时间内对轻度干旱有一定的抵抗能力和适应性,胁迫21 d时,为应对干旱胁迫通过对渗透物质积累的调节,协调自身抗氧化酶活性,从而清除活性氧对细胞膜带来的伤害,维持植物的正常生长。相关性分析表明,根、叶的脯氨酸、可溶性糖与丙二醛含量三者均呈极显著正相关,与可溶性蛋白含量呈极显著负相关,与SOD呈极显著负相关,此外,SOD与POD活性呈极显著负相关。

To investigate effects of drought stress on growth of Nepeta multifida L.,taking annual seedling of Nepeta multifida L.as material tested,soil water contents at CK,mild,moderate and severe using pot weighing method to simulate drought were set.The morphological indexes including plant height,leaf area,root-shoot ratio and physiological-biochemical indexes of root and leaf of seedling at 0,7,14,21 d were statistically analyzed.The results showed that drought stress had little effect on plant height and leaf area,but root-shoot ratio had sensitive response to drought stress.There was no significant difference in leaf water contents under different treatments,but difference in chlorophyll content between drought stress treatments and CK at 0-7 d was significant.On the whole,the contents of proline,soluble sugar and malondialdehyde in root and leaf of Nepeta multifida L.decreased firstly and then increased with treatment time,and reached the highest at 21 st d.The content of soluble protein decreased(in leaf)and it increased firstly and then decreased(in root),and reached the lowest at 21 st d.There was significant difference between indexes above in drought stress treatments and CK at 21 st d.SOD activity was the highest during 14-21 d,and it had a significant difference between moderate,severe drought stress treatments and CK at 21 st d.POD activity was the lowest at 21 st d,and it also had a significant difference between severe treatment and CK.These results indicated that the Nepeta multifida L.seedlings had certain resistance and adaptability to mild drought in a short period.And Nepeta multifida L.seedlings withstood drought at 21 st d by regulation of osmotic substances accumulation and antioxidant enzyme activity to remove damage caused by ROS to cell membrane and maintain plant growth.Correlation analysis showed that there was significantly positive correlation among the contents of proline,soluble sugar and malondialdehyde in root and leaf.The former three indexes were significantly negatively correlated with soluble protein content and SOD activity.And SOD activity was significantly negatively correlated with POD activity.