长期深淹对三峡库区三种草本植物的恢复生长及光合特性的影响

硬秆子草（Capillipedium assimile）、双穗雀稗（Paspalum distichum）和狗牙根（Cynodon dactylon）在经受与三峡水库水位运行节律基本一致的水淹时间和水淹持续时期，但淹水深度（0、5、15和25m）不同的处理后，对其进行了恢复生长和光合特性研究。结果表明：（1）3种草本植物之间相比，狗牙根的存活率最高，所有处理植株存活率达到了100％；硬秆子草和双穗雀稗随着水淹深度的增加，存活率呈降低趋势，5in深处理存活率达到了100％，15in和25m深处理存活率在80％以上。（2）3种草本植物恢复生长后的叶片净光合速率Pn、蒸腾速率Tr、气孔导度Gs、水分利用效率WUE和表观CO2利用效率CUEapp与未淹对照相比没有显著差异；不同物种相同水淹处理之间比较，狗牙根的各光合指标显著高于硬秆子草和双穗雀稗。（3）结合三峡库区消落带植被恢复物种筛选的基本条件和本试验不同处理植株的恢复生长及其光合特性的研究，结果表明，硬秆子草、双穗雀稗和狗牙根是能够忍耐长期深淹胁迫的、适宜于三峡库区消落带植被恢复与重建的优良物种。三者之间的耐淹能力从大到小依次为：狗牙根〉硬秆子草〉双穗雀稗。

Effect of Long-time and Deep Submergence on Recovery Growth and Photosynthesis of Three Grass Species in Three Gorges Reservoir Area

Vegetation reconstruction and restoration in the newly formed water-level-fluctuation zone （WLFZ）, an anthropogenic-impacted ecosystem, is of great significance in ecological safety in the Three Gorges Reservoir Area of the Yangtze River. Selection of appropriate plant species that are adaptive to long-time and deep submergence is crucial for vegetation reconstruction and restoration in the water-level-fluctuation zone （WLFZ）. In this study, a split-plot design was used. Three grass species （ Cynodon dactylon, Cap 15 and 25 illipedium assimile and Paspalum distichum） and four treatments（submerged at depths of 0,5, m） were arranged as the main-plot and sub-plot, respectively. The indices of recovery growth ability and photosynthetic characteristics of each treatment were examined, including photosynthetic rate （ Pn）, transpiration rate （ Tr）, stomatal conductance （ Gs ）, water use efficiency （WUE） and apparent CO2 use efficiency （CUEapp）. The important findings were as follows： （1）Cynodon dactylon had the highest survival rate,and its survival rate was 100% in all of the three submerged depths. However, the survival rates of Capillipedium assimile and Paspalum distichum decreased with the increase in submerged depth, and their survival rates were 100% at the submerged depth of 5 m and more than 80% at the submerged depths of 15 m and 25 m. （2）Compared with the unsubmerged control group, each grass specie showed no significant differences in the indices of net photosynthetic rate （Pn） ,transpiration rate（Tr）, stomatal conductance（Gs） ,water use efficiency （WUE） and apparent CO2 use efficiency （CUEapp） among the three submerged depths. Howerer, Pn, WUE and CUEapp of Cynodon dactylon were much higher than those of Capillipedium assimile and Paspalum distichum when compared with the treatments at the same submergence depth among the three grass species. （3）According to the recovery growth abilities and photosynthesis of three grass species, which we