Abstract: A field study on diurnal variation of net photosynthetic rate (Pn), light response curve and CO₂ response curve in leaves of Musa AAA Group Cavendish Williams was conducted using Li-6400 portable photosynthetic gas analysis system. Some photosynthetic parameters were estimated using non-rectangular hyperbola model combined with nonlinear regression of SPSS software. The results indicated that diurnal variation in Pn presented a single peak curve, with no apparent midday depression, and the peak value of Pn appeared at about 10:20 am. The light saturation point (LSP), light compensation point (LCP), apparent quantum efficiency (AQY), CO₂ saturation point(CSP), CO₂ compensation point(CCP) and carboxylation efficiency (CE) were 778.19 μmol/m²·s, 61.09μmol/m²·s, 0.0414, 608.97μmol/mol, 72.13μmol/mol and 0.094, respectively. The main environmental factors influencing on Pn were also discussed, and it showed that under sufficient soil water supply, photosynthetic active radiation rather than stomatal conductance (Gs) limited the Pn.

Key words: Banana (Musa AAA Group Cavendish Williams), net photosynthetic rate, diurnal variation, light response curve, CO₂ response curve

摘要： 用Li-6400型便携式光合作用测定系统研究大田威廉斯香蕉叶片光合日变化、光响应曲线和CO₂响应曲线,运用非直角双曲线模型并结合SPSS软件的非线性回归估算其光合作用参数。结果表明,香蕉叶片光合日进程呈单峰曲线,没有明显的午休现象,最大净光合速率出现在10:20左右;光饱和点与光补偿点分别为778.19和61.09μmol/m²·s,表观量子效率为0.0414;CO₂饱和点与补偿点分别为608.97和72.13μmol/mol,羧化效率为0.094。此外,对影响香蕉光合速率的主要环境因子分析表明,在土壤供水充分的条件下,限制光合速率的因子是光合有效辐射而非气孔导度。

关键词: 威廉斯香蕉, 净光合速率, 日变化, 光响应曲线, CO₂响应曲线