Diurnal changes in chlorophylla fluorescence and carotenoid composition inOpuntia ficus-indica, a CAM plant, and in three C3 species in Portugal during summer.

摘要: Diurnal changes in chlorophylla fluorescence were determined four species, differing life form, Portugal during the summer of 1989. These includedOpuntia ficus-indica, a CAM plant, andHelianthus annuus, Ficus carica andArbutus unedo, three C3 species. Steady state yield,FS, and maximum yield,FM′, at different times day. Using model Genty et al. (1989), photon use efficiency photosystem II electron transport,φe, was calculated from (FM′−FS)/FM′. relative rate non-cyclic transport through II,Je, derived by multiplyingφe incident flux density (PFD). WhenJe, for each species various points time throughout day, plotted against corresponding values PFD, light response curves obtained showed thatJe linearly dependent on PFD low approached saturation high light. The highest ofJe observed inHelianthus followed byOpuntia unedo. proportion xanthophyll zeaxanthin to total carotenoids, around noon, inversely related rates ofJe.