The effects of actinic light (AL) intensity on the age dependence of nonphotochemical fluorescence quenching (qN) and effective quantum yield in PSII (ΦPSII) were studied in continuously illuminated wheat leaves of the upper tier. Regular changes were revealed in both age dependence of qN at elevated AL intensities and light curves of qN. These changes are related to alterations in strategies of redistribution and use of absorbed light energy by the photosynthetic apparatus at different stages of wheat leaf development. Unlike ΦPSII, qN as a parameter was more sensitive to the differences in the leaf age at a certain range of light intensities. At the same time, the stability of qN at moderate light intensities may serve as an indication of leaf maturity., T. V. Nesterenko, V. N. Shikhov, A. A. Tikhomirov., and Obsahuje seznam literatury
Effect of UV-B (1.9 W m-2) alone or in combination with supplemental "white light". WL (20 W m-2) exposure was studied on the energy transfer process of intact phycobilisomes isolated from Spirulina platensis. Exposure of UV-B or supplemental irradiation induced a decrease in room temperature fluorescence intensity and caused a shift towards shorter wavelengths. The low temperature fluorescence measurements showed that UV-B impairs energy transfer from phycocyanin to allophycocyanin B and the extent of damage may be reduced by the exposure to supplemental WL. and S. Rajagopal, Prasanna Mohanty, S. D. S. Murthy.