岩溶植物青冈和九龙藤叶片光学特性日变化研究

Study on the Daily Course of Photosynthesis of Plant in Southwest Karst Area

关键词:  喀斯特地区  青冈  九龙藤  光合速率  蒸腾速率  气孔导度  水分利用效率

Key words:  karst area  C.glauca  B.championii  photosynthetic rate  transpiration rate  stomatal conductance  water use efficiency

摘要:

采用LI-6400便携式光合测定系统测定分析喀斯特生态系统重要乔木植物青冈(Cyclobalanopsis glauca)和藤本植物九龙藤(Bauhinia championii)的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、水分利用效率(WUE)等生理特性指标。结果表明:净光合速率日变化在青冈为双峰型,九龙藤则为单峰型,其中日均Pn、Tr值九龙藤(3.58μmol CO₂·m^-2·s^-1、2.06 mmol H₂O·m^-2·s^-1) > 青冈(2.13μmol CO₂·m^-2·s^-1、1.08mmol H₂O·m^-2·s^-1),WUE值青冈(2.40mmol·mol^-1) > 九龙藤(1.83mmol·mol^-1)。比较而言,乔木树种青冈为低Pn、弱Tr、高WUE的树种,而九龙藤则属高Pn、高Tr树种。

Abstract:

Photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs)and water use efficiency (WUE)of Cyclobalanopsis glauca and Bauhinia championii in Southwest karst area were measured with LI-6400 portable photosynthesis system.The results showed that the diurnal variation of the Pn for the C.glauca and B.championii were ‘double peak curve’ and ‘single peak curve’ respectively.Pn and Tr of the two species were 3.58μmol CO₂·m^-2·s^-1, 2.06 mmol H₂O·m^-2·s^-1 for B.championii and 2.13μmol CO₂·m^-2·s^-1, 1.08 mmol H₂Om^-2s^-1 for C.glauca, respectively.The WUE of the two species were C.glauca (2.40mmol·mol^-1) > B.championii (1.83mmol·mol^-1).Comparatively, C.glauca is an arbor species with low Pn, Tr and high WUE, while B.championii with high Pn and Tr.