| Summary: | Maximal and partial quantum yields of photosystem II (Fv/Fm and Fv–/Fp) in Phaseolus vulgaris leaves were determined in response to the turning on saturating and low (undersaturating) actinic light, accordingly. Measuring lights (ML) of blue, green, and red colors were applied simultaneously using a novel method of the polychromatic fast Fourier transforming pulse amplitude modulation (FFT PAM) chlorophyll fluorometry. Colors of ML were cross-combined with the colors of low and saturating actinic light. Fv/Fm values measured with the green ML were found to be close to that of red light, whereas application of blue ML leads to lower Fv/Fm. In addition, 5-nm resolved excitation spectra were measured to evaluate the dependence between red/far red fluorescence ratios (peak height based – F685/F730, and deconvolved peak square based – F685sq/F730sq) and wavelength of the excitation light. It demonstrates that chlorophyll fluorescence ratio red/far red may be dependent on the spectral absorbance of chlorophyll. The data obtained confirm the results of the previous studies which explain high photosynthetic activity of the green light in terms of redistribution of absorbed quanta throughout thickness of the leaf, thus suggesting possible advisability of green light application in greenhouse lighting, especially for the plants having thick leaves.
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