香附子光合生理对三峡库区消落带陆生环境的响应

摘要

植物在消落带水淹结束后的陆生环境中能否合成和储存足够的碳水化合物,对其在消落带长期定居、存活和扩散具有重要影响.香附子是能够适应三峡库区消落带生境的少数多年生草本植物之一.该试验通过对消落带水淹结束后生长在深水(22~27m)、浅水(2~7m)和未淹区段香附子光合生理的定期观测,研究其在陆生环境下的光合生理变化及其形成机制.结果表明:(1)生长在深水区段香附子的净光合速率(Pn)显著高于浅水区段与未淹区段.(2)随着香附子在陆生环境中生活时间的延长,其Pn、气孔导度、表观水分利用效率、表观光能利用效率、表观CO2利用效率增加.(3)与未淹区段相比,浅水淹没区段香附子的光饱和点显著升高,而光补偿点显著降低.研究发现,淹水胁迫后积极的自我调节能力和光合补偿机制是香附子能够适生于三峡库区消落带的重要原因.%Whether plants can synthesise and stored abundant carbohydrate in the terrestrial environment in hydro-fluctuation belt after water flooding have important influence on their long-term settlement, survival and spread of the plants living in hydro-fluctuation belt.Cyperus rotundus is one of the few perennial herbs that able to adapt to the habitat of hydro-fluctuation belt in the Three Gorges Reservoir area.In order to study the changes of C.rotundus photosynthetic physiology and its formation mechanism in the terrestrial environment, we regularly observed the photosynthetic physiology of C.rotundus which grow in the deep water (22-27m), shallow water (2-7m) and non-flooded zone in hydro-fluctuation belt of Three Gorges Resevoir area after water flooded.The results as follows: (1) the net photosynthetic rates (Pn) of C.rotundus growth in deep water and shallow water were significantly higher than that in non-flooded area;(2) the Pn, stomatal conductance, apparent water use efficiency, apparent light use efficiency and apparent CO2 use efficiency increased with the extension of C.rotundus living in terrestrial environment;(3) the light saturation point of C.rotundus which grow in shallow water was significantly rose, while the light compensation point was significantly decreased.Positive self-adjustment ability and the photosynthetic compensation mechanism of C.rotundus after water flooded stress are important reasons for its adaptation to hydro-fluctuation belt in the Three Gorges Reservoir area.