Ecophysiological studies of Dendrobium crumenatum Sw.

Abstract

The photosynthetic physiology of the epiphytic CAM orchid, Dendrobium crumenatum Sw., was compared with that of the terrestrial C3 orchid, Arundina graminifolia(D. Don.) Hochr.; and its flowering physiology was compared with that of the free-flowering hybrid, D. Manadona. D. crumenatum showed a down-regulation of photosynthetic capacity in the evening. Different patterns of carbohydrate accumulation and antioxidant responses were exhibited by D. crumenatum and A. graminifolia to varying daily PPFD levels during the study. The transition from vegetative to reproductive development in both D. crumenatum and D. Manadona seemed to be positively related to the levels of total soluble sugars and cytokinins in the shoot apices and leaves. After flushing with water for 2 h in a cold environment, the photosynthetic capacity remained unchanged in D. crumenatum. After cold treatment, NPQ, soluble sugar and fructan concentrations increased. The presence of some floral induction genes was also determined in D. crumenatum.