干旱胁迫对青藏高原4种灌木生理指标的影响

以江孜沙棘(Hippophae rhamnoides)、锦鸡儿(Caragana sinica)、砂生槐(Sophora moorcroftiana)、唐古特莸(Caryopteris tangutica)4种青藏高原灌木树种为试材进行干旱胁迫模拟盆栽试验,通过对比干旱胁迫后4种灌木叶片中丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化物酶(POD)活性、脯氨酸含量、可溶性蛋白质含量的变化,对供选树种进行抗旱性能分析与评价,为青藏高原地区造林筛选优良耐旱灌木。研究表明,4种供试植物在轻度干旱时体内MDA含量缓慢升高,重度干旱时达到最大值,唐古特莸MDA含量峰值和增幅较另3个树种最小,其次是锦鸡儿和江孜沙棘,而砂生槐的MDA峰值和增幅都最大。SOD和POD活性的变化规律都为"单峰曲线",其中唐古特莸和锦鸡儿遭受干旱胁迫时SOD活性峰值出现最迟,值也最大,SOD活性降低最少,充分反映出该2种树种对干旱环境有较强的适应性及自我调节能力,江孜沙棘和砂生槐则相反。在干旱胁迫过程中,唐古特莸的POD活性始终维持在较低活性水平,而且增加的幅度最大,达到805.23%,增加幅度远高于另外3个供试树种,表现出超强的抗旱能力,而其余3个树种POD活性增幅较小,对干旱的适应性差。4树种的脯氨酸含量都呈增加趋势,唐古特莸增幅最大,与正常水分条件相比增加了10.86倍。苗木可溶性蛋白质含量的变化规律为先增大后减小,其中唐古特莸增幅最大为213.44%。通过综合评价结果表明,水分胁迫条件下,抗旱性强弱顺序均为:唐古特莸>锦鸡儿>江孜沙棘>砂生槐。

The Impact of Drought Stress on Physiological Indicators of Four Shrub Species on the Qinghai-Tibet Plateau

Four shrub species, Hippophae rhamnoides, Caragana sinica, Sophora moorcroftiana, and Caryopteris tangutica from Qinghai-Tibet Plateau were used to simulate the drought stress on potted seedlings. By comparing the changes of malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, peroxidase (POD) activity, praline content, and soluble protein content, the drought resistance performance of selected tree species were analyzed and evaluated in order to find the superior drought tolerant shrub species suitable for the afforestation on Qinghai-Tibet Plateau area. The results indicated that the MDA content rose slowly when the four selected plants were under light drought stress and reached the maximum when under heavy drought stress. Both the peak and increase of MDA content of Caryopteris tangutica were the least compared with the other three species, followed by Caragana sinica and Hippophae rhamnoides, and the peak and increase of MDA of Sophora moorcroftiana were the largest. The change rule of SOD and POD activity followed a single-peak curve, with Caryopteris tangutica and Caragana sinica's SOD activity spiked the latest and the value was also the largest. The SOD activity decreased to the minimum, which fully reflected that the two species had stronger adaptability and self-regulation under drought environment, while the Hippophae rhamnoides and Sophora moorcroftiana were the opposite. During the process of drought stress, the POD activity of Caryopteris tangutica maintained at a low level, but with the greatest increase (up to 805.23%), the increase rate was much higher than that of the other three species, and showed a superior ability of drought tolerance. But for the rest three species, the increase rate of POD activity was small and the adaptability to drought proved to be bad. The proline content of the 4 species showed an increasing trend and the increase rate of Caryopteris tangutica was the highest, 10.86 times compared with that under normal water condition. The seedling's soluble protein content increased at initial and then decreased, the soluble protein's increase of Caryopteris tangutica was the largest which was up to 213.44%. The comprehensive evaluation results showed that under water stress, the seedlings' resistance strength sequences were Caryopteris tangutica>Caragana sinica>Hippophae rhamnoides>Sophora moorcroftiana.