三种固沙植物对高温胁迫的生理响应及其抗热性研究

Physiological Response and High-temperature Resistance of Three Species of Psammophytes under High-temperature Stress

通过实验测定热胁迫过程中多枝柽柳、梭梭和头状沙拐枣三种植物叶或同化枝外部形态、相对含水量(RWC)、质膜透性、膜脂过氧化物(MDA)、可溶性蛋白、可溶性糖、过氧化物酶(POD)、超氧化物酶(SOD)和过氧化氢酶(CAT)含量的变化,研究三种植物对沙地高温逆境环境的生理适应机理。结果表明:随高温胁迫强度增加,三种植物叶片相对含水量下降,膜透性及膜脂过氧化作用增强,渗透调节物质积累,同时植物保护酶系统活性上升,但在变化趋势和幅度上有显著差异。三种固沙植物中,多枝柽柳具有最强的耐热性,梭梭次之,头状沙拐枣最差。

The study area （39°06′N, 83°40′E） is located in the hinterland of the Taklimakan Desert, where the annual air temperature is 12.4℃, the monthly temperatures in July and December, the hottest month and coldest month, are 28.2 ℃ and - 8.1 ℃, the extremely maximum and minimum air temperatures are 45.6 ℃ and -22.2 ℃, respectively, the annual precipitation varies in a range of 10-50 mm only, but the annual evaporation is as high as 3638.6 mm, and the annual average wind speed and the maximum wind speed are 2.5 m/s and 20.0 m/s respectively. In this paper, the physiological adaptability mechanism of Tamarix hohhenacker, Calligonum caputmedusae and Haloxylon ammodendron under high - temperature stress in sandy environment is discussed. The changes of relative water content in plant leaves （RWC）, membrane permeability, activity of superoxide dismutase （SOD）, catalase （CAT） and peroxidase （POD）, and the contents of soluble protein and malonaldehyde （MDA） in plant under temperature varying from 30℃ to 60℃ were measured. The results are that, with increasing the high - temperature stress, RWC of these three species of psammophytes are decreased, the membrane permeability and lipid peroxidation are increased, the osmoregulation matters are accumulated, and the activity of protective enzyme system is increased. However, there are the distinct differences in degrees. So these three species of psammophytes have the different high - temperature resistances. The high - temperature resistance of Tamarix hohhenacker is the highest, then that of Haloxylon ammodendron, and that of Calligonum caputmedusae is the lowest, viewing from the change trends of membrane permeability, contents of MDA and soluble protein, and the activity of SOD, CAT and POD.