3种北美红枫对持续高温干旱胁迫的生理响应机制

对3种北美红枫幼苗进行持续高温干旱处理,通过测定幼苗渗透调节物质含量、保护酶活性、细胞质膜差别透性、丙二醛含量及叶绿素相对含量等生理生化指标和形态特征的变化,揭示了3种北美红枫幼苗对持续高温干旱胁迫的生理适应机制。研究发现,持续高温干旱处理2 d,植物叶片中的叶绿素、可溶性蛋白含量及超氧化物歧化酶、过氧化物酶、过氧化氢酶活性均有显著下降,十月光辉和秋火焰叶片开始受到热伤害,而酒红仍然生长良好。处理4—6 d时,叶片中仅可溶性蛋白含量变化不显著,其余生理指标均有显著变化:脯氨酸含量和电导率均持续显著上升,丙二醛含量呈下降趋势,此时植物体自身的生理调节机制开始发挥作用。处理6 d后,秋火焰整株叶片枯黄,十月光辉和酒红叶片的受害指数约为70%。处理10 d时,叶片中丙二醛、脯氨酸含量和电导率均达到最大值,3种北美红枫均整株枯死。3种北美红枫对持续高温干旱环境的耐受性具有一定差异,利用隶属函数的方法对试验测定的9个生理指标进行综合评价,发现秋火焰的耐受性最差,十月光辉次之,酒红的耐受性最强,这与其受害指数的变化情况是一致的。

Physiological response mechanism of three kinds of Acer rubrum L. under continuous high temperature and drought stress

Red maple (Acer rubrum L.), originated in North America, is one of the Aceraceae cultivated species. Red maple has high ornamental value for its beautiful treelike and gorgeous leaf color. Recently, many scholars have done researches about it in order to make more widespread in China. However, those studies are limited to breeding cultivation technology and color change mechanisms of leaves, while the studies of red maple''s physical response mechanisms to high temperature have not been reported. High temperature will affect the physiological growth of plants, and it may also influence colorful-leaf plants'' leaf color expression. While most cities in southern China get high temperature in summer, the climate has largely limited the introduction of the red maple. In order to explore physiological adaptive mechanisms of the red maple to adverse environments, continuous high temperature and drought stress was applied to three kinds of red maple (Acer rubrum L.) seedlings, including October Glory, Jeffersred and Brandywine. Measurements included contents of osmoregulation substance, activity of protective enzyme, cell membrane permeability, and malonaldehyde (MDA) content and relative amount of chlorophyll in the plant leaves and seedlings morphological characters. The results showed that after two days of the treatment, chlorophyll and soluble protein contents, and superoxide dismutase (SOD), peroxide enzyme (POD) and catalase enzyme (CAT) activities of plant leaves significantly decreased respectively, and the leaves of October Glory and Jeffersred began to be damaged, while those of Brandywine were still in good condition. After four to six days, there were significant changes in the physiological indices of the three species except for the contents of soluble protein. In the meantime, the contents of proline (Pro) and conductivity were keeping increasing while the contents of MDA showed a decline tendency, indicating that the plant biological controlling mechanisms began to function. Later, all the leaves of Jeffersred turned to yellow, and the injury index of the rest two species was approximate 70% respectively. The contents of MDA and Pro, and conductivity were at maximum and all the leaves in the three species died ten days after the treatment began. The results indicated that the resistances to continuous high temperature of the three species used in the experiment were different. According to a comprehensive evaluation based on subordinate function of fuzzy mathematics, Brandywine was the best among the three species in heat-resistance, compared with a lower heat-resistance in October Glory, and the lowest resistance in Jeffersred. This result is consistent with injury index.