罗布泊腹地人工植被梭梭的光学特性及其对干旱胁迫的响应

Photosynthetic Characteristics and Response of Haloxylon ammodendron to Drought Stress in Hinterland of the Lop Nur

在罗布泊高温、高盐碱、干旱的极端环境条件下,研究植物的光合进程以及植物对环境的适应性,对于评价植物的耐旱性有重要意义。研究设置3个干旱处理,轻度干旱、中度干旱以及重度干旱。结果表明：（1）重度干旱处理中,梭梭的光补偿点（LCP）为118.75μmol·m-2·s-1,光饱和点（LSP）为6174.79μmol·m-2·s-1,是3个处理中对光能利用范围最广的。说明在重度干旱情况下,梭梭通过增大可利用光能的范围来提高对环境资源的利用率。（2）在轻度和中度干旱处理中,灌水后梭梭的最大净光合速率分别为35.06μmol·m-2·s-1和49.51μmol·m-2·s-1,比灌水前增加了48.81%和22.83%,可见水分状况是影响植物生长的一个重要因素。（3）在3个干旱处理下,梭梭均出现光合午休现象,且持续时间较长,这可能是梭梭对罗布泊腹地环境的一种适应。（4）轻度干旱与中度干旱处理间的光合日过程差别不大,且灌水后各项光合生理指标均迅速回升,故考虑到节水灌溉,在确立灌溉制度时可以选择中度干旱时所使用的灌水制度。

It is important to understand the photosynthetic process of Haloxylon ammodendron growing in the hinterland of the Lop Nur and its adaptation to environment. In this study,the photosynthetic characteristics and response of planted H. ammodendron to drought stress were revealed,and a suitable irrigation period was established.Three drought treatments were designed： i. e. the slight,moderate and heavy drought treatments. The results are as follows：（1） Under heavy drought,LCP and LSP of H. ammodendron were 118. 75 μmol·m-2·s-1 and 6174. 79μmol·m-2·s-1 respectively,which were the largest use of light energy in these three treatments. It means that,in an adverse environment,H. ammodendron expanded the scope of available light energy to improve the efficiency of using environmental resources;（2） In the slight and moderate drought treatments after irrigation,the Pnmax values of H. ammodendron were 35. 06 μmol·m-2·s-1 and 49. 51 μmol·m-2·s-1,increased by 48. 81% and 22. 83%,respectively,and higher than those in drought. It could be seen that water supply is an important factor affecting plant growth in this region;（3） There was a long-duration midday depression of photosynthesis of H. ammodendron under drought stress,which might be an adaption to environment;（4） The difference of daily photosynthetic process between slight and moderate drought treatments was not significant,and the physiological indexes of photosynthesis were rapidly increased after irrigation. Considering to saving water,the moderate drought is the most suitable irrigation schedule.