降雨量对科尔沁沙地3种沙生植物生长和生理的影响

对降水格局变化的响应是植物适应环境的重要方面。通过野外增减雨试验，研究了降水变化对科尔沁沙地3种沙生植物生长特性和生理特征的影响。结果表明：（1）6月植被平均密度最大，7月平均盖度最大，降雨量增加60%时，植被盖度最大，为58.0%。（2）增雨区的主要植物为雾冰藜（Bassia dasyphylla）和猪毛菜（Salsola collina），减雨区主要植物为蒺藜（Tribulus terrestris），降雨量减少60%时，蒺藜在6、7、8月密度分别为70%、80%、79%，显著高于其他植物。（3）降雨量减少时，3种沙生植物的相对含水量（RWC）减少，而细胞膜透性增加；蒺藜RWC高于雾冰藜和猪毛菜，但是丙二醛（MDA）正好相反；蒺藜的耐脱水能力和细胞膜的耐伤害程度强于雾冰藜和猪毛菜。（4）随着降雨量的增加，3种植物的光能转化效率（F_v/F_m、ΦPSⅡ）逐渐增加，但随干旱天数的增加而减小。

Effects of Precipitation on Growth and Physiology of Three Psammophytes in the Horqin Sandy Land,China

The response of plant to the change of precipitation pattern is one of the important contents of the study on the mechanism of plant adapting to environmental changes, while the comparative study on the response of plant to the change of precipitation gradient in arid and semi-arid regions is rarely reported. Effects of precipitation on growth and physiology of three psammophytes were conducted with a precipitation-addition-reduction device in Horqin Sandy Land. The results showed that (1) The average density reached the maximum in June, but the average coverage reached the maximum value in July, and the coverage reached the highest of 58.0% under +60% treatment. (2) The main vegetation in precipitation addition region were Bassia dasyphylla and Salsola collina, while the main vegetation in precipitation reduction region was Tribulus terrestris. Under -60% treatment, the density of T. terrestris in the period from June to August was 70%, 80% and 79%, which was significantly higher than other plants. (3) The relative water content (RWC) of the studied species decreased and the membrane permeability increased as precipitation decreased. RWC of T. terrestris was higher than those of B. dasyphylla and S. collina, but the malondialdehyde (MDA) was opposite, which indicated that the ability of T. terrestris to withstand dehydration and damage was stronger than those of B. dasyphylla and S. collina. (4) F_v/F_m and ΦPSⅡof three psammophytes gradually increased with the increase of precipitation, but decreased with the increase of drought days.>