Photosynthesis and chlorophyll fluorescence of Calathea 'Medallion' exposed to different light intensity

Calathea is one of the most popular and important in the field of ornamental foliage plants. The purpose of this experiment was to clarify effects of light intensity on photosynthesis and photo inhibition in leaves of Calathea 'Medallion'. Plants exposed to different light intensities including natural light intensity of 560 µmol PPF m^-2 s^-1, 50% shade (230 µmol PPF m^-2 s^-1), and 80% shade (6 µmol PPF m^-2 s^-1) for 8 weeks. The results revealed that CO₂ assimilation rate, stomatal conductance and transpiration rate of plants exposed to ambient light intensity and 50% shade significantly decreased. Additionally, F_v/F_m indicating PSII efficiency also declined. Regarding to plants exposed to 80% shade, gas exchange and PSII efficiency could be maintained to the highest value continuously. Therefore, Calathea 'Medallion' is a shade-loving plant which could not be cultivated under high irradiances.