香蒲叶功能性状对模拟增温和CO_(2)浓度倍增的响应

Response of leaf Hydraulic Traits of Typha orientalis to Simulated Warming and Elevated CO_(2)Concentration

为探讨高原湿地植物对增温和CO_(2)浓度升高的响应策略,以高原地区常见的挺水植物香蒲(Typha orientalis)为研究对象,通过构建封顶式人工生长室模拟增温2℃和CO_(2)浓度倍增的气候变化,检测其叶片功能性状,结果表明:(1)与对照组相比,CO_(2)浓度倍增处理下,香蒲的净光合速率、气孔导度、胞间CO_(2)摩尔分数和蒸腾速率都显著降低(P<0.05);增温处理下,香蒲的净光合速率和气孔导度也显著降低(P<0.05),表明增温和CO_(2)浓度倍增显著降低了香蒲的光合碳同化能力。(2)与对照组相比,CO_(2)浓度倍增处理下,香蒲叶脉密度显著增加;增温处理下叶脉密度和气孔密度显著增加,而维管束面积和导管面积显著降低(P<0.05),反映了香蒲在增温和CO_(2)浓度升高条件下香蒲水分输送和蒸腾散失能力增强,其水分利用效率显著降低。(3)与对照组相比,增温和CO_(2)浓度倍增处理下香蒲叶光合参数间的相关性减弱,净光合速率与叶结构性状间的紧密关系显著增强。研究结果证明了增温和CO_(2)浓度升高显著增强香蒲叶功能性状间的功能协同和权衡关系。

In order to explore the response strategies of plateau wetland plants to increasing temperature and CO_(2)concentration,Typha orientalis,a common emergent plant in plateau areas,was selected as the research object to detect its leaf functional traits,and the simulated climatic change of increasing 2℃temperature and CO_(2)concentration doubling were designed by constructing a capping artificial growth chamber.The results showed that:(1)The net photosynthetic rate,stomatal conductance,intercellular CO_(2)molar fraction and transpiration rate of T.orientalis under the CO_(2)concentration doubling treatment were significantly reduced(P<0.05);while the net photosynthetic rate and stomatal conductance of T.orientalis were also significantly reduced under the warming treatment(P<0.05)compared with the control group.The results indicated that the photosynthetic carbon assimilation capacity of T.orientalis was significantly reduced under the temperature increasing and CO_(2)concentration doubling conditions(P<0.05).(2)The vein density of T.orientalis leaves increased significantly under the CO_(2)concentration doubling treatment;while the vein density and stomatal density increased significantly,but the vascular bundle area and catheter area decreased significantly(P<0.05)under the warming treatment compared with the control group.The results reflected the enhancement of water transport and transpiration loss capacity but the reducing of water use efficiency of T.orientalis under the conditions of warming and CO_(2)concentration increasing.(3)The correlations among leaf photosynthetic parameters were looser,while the correlations between net photosynthetic rate and leaf structure traits were stronger under warming and CO_(2)concentration doubling treatments than control group.The results showed that the functional synergistic or trade-off effects of leaf functional traits of T.orientalis were enhanced significantly by increasing temperature and CO_(2)concentration.