水盐梯度下克里雅河流域芦苇光合响应特征

选择新疆克里雅河流域地下水埋深不同的样点芦苇为材料,采用Li-6400便携式光合系统仪对各样点芦苇的光合响应特征进行实地测定,探讨其适应干旱胁迫和盐胁迫环境的光合机理。结果显示:(1)在干旱区,当地下水位大于2m时,芦苇的光饱和点、表观量子效率、光呼吸速率随地下水位的下降显著降低,而水分利用效率却随着地下水位的下降呈上升趋势;随着地下水位的下降,芦苇的羧化效率、最大净光合速率、CO2饱和点显著下降,水分利用效率随之增大;1.6m地下水位的芦苇相对于2.7m地下水位下芦苇的最大净光合速率、光饱和点、光补偿点、暗呼吸速率分别下降19.98%、40.61%、37%、74.56%。(2)在盐胁迫下芦苇的光合参数整体低于受干旱胁迫的参数;盐胁迫下的芦苇水分利用效率大于受干旱胁迫环境。(3)与陆生环境下的芦苇相比,渍水条件下芦苇的最大净光合速率、光饱和点、光补偿点分别下降41.32%、14.56%、55.55%。研究表明,提高空气CO2供应量可降低水分利用效率从而缓解芦苇盐胁迫伤害,并且可通过调节气孔开闭程度显著增加水生芦苇最大净光合速率,这种变化是植物自身对环境因素变化的生理性反馈和适应性选择对策的结果。

Reed Photosynthetic Response under Water-salt Stress in Keriya River Watershed

The aim of this field experiment was to find out the photosynthetic response of reed along the water table gradient in Keriya river watershed using Li-6400 portable photosynthesis system.The results showed that:(1)When water table was 2 m below,reed showed a decreasing light saturation point (LSP) and a increasing light compensation point (LCP),suggesting the reduction of potential in the use of light intensity.Meanwhile the decreases in maximum net photosynthetic rate(A_max),light respiration(LR),CO₂ saturation point (CSP),carboxylation efficiency and apparent quantum efficiency were observed with decreasing water table(P<0.05),while water use efficiency(WUE) tended to increase.(2)Under salt stress,the photosynthetic parameters were all lower than that under water stress with A_max 19.98%,LSP 40.61%,LCP 37% and dark respiration (RD) 74.56% lower,respectively.Reed WUE under salt stress was lower than that under drought stress.(3)Compared with reed at dry land,water logged plant showed decreas in A_max,LSP and LCP with 41.32%,14.56%,55.55% lower,respectively.We also found that atmospheric CO₂ enrichment can improve reed salt tolerance through decrease in plant WUE under salt stress,and the A_max of water logged plant.It can be concluded that in arid area,reed has developed counter mechanisms in response to long-term drought and salt stress.