巨尾桉在岩溶石山生境中的适应性研究（Ⅰ）：春季光合生理生态学特性

Study on the adaptability of Eucalyptus grandis× E.urophylla in karst hills(Ⅰ):photosynthetic physiological ecology characteristics in spring

关键词:  巨尾桉  光合作用  日变化  通径分析  光曲线  岩溶石山

Key words:  Eucalyptus grandis×E.urophylla  photosynthesis  diurnal change  path analysis  light curve  karst hills

摘要:

以岩溶石山生境的3年生巨尾桉人工林为研究对象，采用LI 6400型便携式光合仪测定巨尾桉在春季的叶片净光合速率（Pn）及其他生理生态因子日变化，同时测定巨尾桉光合-光响应曲线，并通过相关分析和通径分析探讨净光合速率与其他生理生态因子的关系。结果表明：巨尾桉光合-光响应曲线符合Walker的非直线双曲线模型。巨尾桉的光饱和点为1 340 μmol•m 2•s 1，光补偿点为14.68 μmol•m 2•s 1，表观量子效率（AQY）为0.06mol•mol 1，具有阳生植物的特点。净光合速率日变化呈现“单峰型”的特点。蒸腾速率（Tr）、气孔导度（Gs）和大气CO2浓度（Ca）是影响巨尾桉叶片净光合速率日变化的重要因子。巨尾桉有较高的水分利用效率，说明巨尾桉具有适应岩溶石山干旱的特征或避旱策略。

Abstract:

Diurnal changes of net photosynthetic rate(Pn)，other physiological and ecological factors，and photosynthesis and photo response curve of E.grandis×E.urophylla were measured with the LI 6400 photosynthesis system in spring in karst hills. The relationship between Pn and other physiological and ecological factors were analyzed using correlation analysis and path analysis. The results showed that the photosynthesis and photo response curve of E.grandis×E.urophylla were complied with the Walker’Nonlinear Hyperbolic Model. The 1ight saturation point(LSP)and 1ight compensation point(LCP)of E.grandis×E.urophylla were 1 340 μmol•m 2•s 1 and 14.68 μmol•m 2•s 1 respectively，which conformed the characteristic of heliophyte. The apparent quantum yield (AQY) was 006 mol•mol 1.The diurnal change of Pn of E.grandis×E.urophylla was a “single peak” curve. Transpiration rate(Tr)，stomatal conductance(Gs)and atmospheric CO2 concentration(Ca)were the main factors influencing the Pn of E.grandis×E.urophylla. That the high water use efficiency(WUE)of E.grandis×E.urophylla indicated that E.grandis×E.urophylla had the characteristic being suitable to the karst hills or the tactics avoiding drought.