Utilization and Dissipation of Absorbed Light Energy in the Epiphytic Crassulacean Acid Metabolism BromeliadTillandsia ionantha

Abstract

Past studies of the ability of epiphytic Crassulacean acid metabolism bromeliads to acclimate to different light levels yield conflicting findings; some indicate that these plants are similar to shade plants whereas others stress their similarity to sun plants. This study investigates the ability of individuals of Tillandsia ionantha to acclimate to low or high irradiance. Plants were exposed to 100 and 800 μmol m−2 s−1 photosynthetic photon flux density under controlled conditions for 4 wk. Individuals exposed to the lower light level exhibited higher chlorophyll concentrations and higher photosynthetic rates at low light relative to plants exposed to high light. Low‐light plants also exhibited a greater efficiency in the photochemical utilization of absorbed light energy and a lower ability to dissipate excess energy nonphotochemically, relative to the plants exposed to the higher light level. Photosynthetic rates at high light were similar in both sets of plants, reflecting the higher efficiency of ene...