Sporulation modifies the photosynthetic activity of sporotrophophyll leaves of Platycerium bifurcatum

Platycerium bifurcatum is an epiphytic fern, occurring mainly in the forests of Australia and New Guinea. The location and spatial structure of its sporangia makes this fern a unique research model for physiological experiments. Our research aimed to determine changes in photosynthesis in the sporophilic and trophophilic parts of P. bifurcatum leaves during spore tying and maturation. For this purpose, the JIP-test and gas-exchange measurements of leaves were performed. In the study, we showed that changes typical of plant responses to stress factors also happened at critical periods in plant ontogenesis (e.g., in the generative phase) not related to environmental stress. Measurements of chlorophyll a fluorescence kinetics, the intensities of net/gross photosynthetic rate, and the respiration of sporotrophophilic leaves indicated that the intensities of these processes were related to the location of spores and to the stage of sporulation. The results are the first to describe the photosynthesis process and dark respiration of leaves during sporulation in ferns.