关键词: 国兰, 光合特性, 光化学效率

Abstract: The photosynthetic characteristics of five species of Cymbidium were studied by gas exchange and analysis of chlorophyll fluorescence. According to the light saturation points, the light compensationpoints, the CO₂ saturation points and the CO₂ compensation points, the five species of cymbidium have the characteristics of C3 plants. The photosynthetic rates were between 3.0 - 5.9μmol·m^{- 2} ·s^{- 1}. The results also demonstrated that the photosynthetic rateswere largely affected by the concentrations of the CO₂ while the CO₂ concentrationswere below 2 000 μmol·mol^{- 1}. And there were also some differences among the photosynthetic capacities, the apparent quantum yields and the carboxylation efficiencies in leaves of the five species.
The light saturation pointswere between 350 - 650 μmol·m^{- 2} ·s^{- 1} indicating that all five species of Cymbidium were shade acclimated plants, among which C. goeringii and C. ensifolium have relatively lower shade endured capacities; while C. sinense and C. longibracteatum have relatively higher shade-endured capacities; and C. faberi has relatively moderate shade-endured capacity. The light activation of photochemical reaction
and photochemical efficiencies after the activations in the five species exhibitd obvious differences, which maybe correlate with the originally ecological conditions, the acclimations and the evolutions of different species of cybidium.

Key words: Cymbidium, Photosynthetic characteristics, The efficiency of photochemistry