乐东拟单性木兰光合、蒸腾及水分利用效率研究

运用Li-6400光合测定仪对乐东拟单性木兰的光合蒸腾特性进行了初步研究。结果表明：（1）乐东拟单性木兰的光补偿点为65.5μmol•m-2•s-1，光饱和点为1467μmol•m-2•s-1，表观量子效率为0.024；（2）乐东拟单性木兰在晴天条件下光合日变化为双峰曲线，分别在10和16时达到峰值，而在14时到达谷底，表现出午休现象。相关分析表明其影响因子主要是蒸腾速率、气孔导度和光合有效辐射；（3）乐东拟单性木兰蒸腾速率日变化近似单峰型，其主要影响因子为大气温度、叶面温度和光合有效辐射；（4）乐东拟单性木兰水分利用效率日变化为倒单峰型曲线变化。

Study on photosynthesis, transpiration and water use efficiency of Plarakmeria lotongensis (Chun et C. Tsoong) Law

Using Li-6400 portable photosynthesis system, the photosynthesis, transpiration and water use efficiency (WUE) of Plarakmeria lotongensis (Chun et C. Tsoong) Law) were explored in this paper. The results showed as follows: (1) light compensation point (LCP) of Plarakmeria lotongensis (Chun et C. Tsoong) Law) was 65.5μmol•m-2•s-1, light saturation point (LSP) was 1467μmol•m-2•s-1, and its apparent quantum efficiency (AQE) was 0.024; (2) Under sunlight condition, the diurnal variation of photosynthesis showed double-peak curve, and the peak value reached at 10︰00 and 16︰00, respectively, which revealed midday depression. And correlation analysis showed that the factors mainly affecting photosynthesis were transpiration rate (Tr), stomatal conductance (Gs) and photosynthetically active radiation (PAR); (3) The diurnal variation of transpiration was close to single peak curve, and its mainly affecting factors were atmospheric temperature (Ta), leaf temperature (Tl) and photosynthetically active radiation (PAR); (4) the diurnal variation of water use efficiency (WUE) showed inverse single peak curve.