Photosynthetic performances of transplanted Cypripedium flavum plants

To explore the conservation and cultivation of Cypripedium flavum at comparatively lower altitudes, a study on variations in photosynthetic characteristics was conducted on C. flavum plants from the high mountains of the eastern Himalayas. Plants of same size (6 leaves, 35-40 cm height) were selected from Tianshengqiao (alt. 3,450 m) and planted at the gardens at Zhongdian (alt. 3,200 m) and Kunming (alt. 1,900 m). The leaves of C. flavum at Tianshengqiao and Zhongdian exhibited higher photosynthetic rate, stomatal conductance, transpiration rate, apparent quantum yield, and carboxylation efficiency than their counterparts at Kunming. The optimal temperatures for photosynthesis of C. flavum plants growing at Tianshengqiao, Zhongdian, and Kunming were 18, 19 and 21°C, respectively. The optimal temperature also increased with increasing photosynthetically active radiation (PAR). However, the photosynthetic responses of C. flavum to PAR were similar at the three sites. The photosynthesis reached light saturation at the PAR of 746-832 μmol ms. The inability of C. flavum to acclimate to higher temperature resulted in the depression of photosynthetic rate at the lower altitude (Kunming). The results suggest that C. flavum adapts poorly to the warmer temperatures at low altitudes. It can be cultivated at a lower attitude, but proper agronomical methodology will need to be developed for better growth.