Fluorescence of Cucumber Leaves Induced within the Photoexcitation Wavelength Range 380-540 nm and Its Dependence on Vegetation Time and Illumination Regime

摘要

A model of slow fluorescence induction excited in cucumber leaves by broad-band light (380-540 nm; 180 W/m~2) was considered. The ratio of fluorescence peaks in the red spectral region (F_(734)/F_(682)) was found to be close to two in both young and mature leaves. This value is supposed to be determined by the spillover-mediated increase in the contribution of long-wavelength fluorescence. The F_(734)/F_(682) value in plants grown under natural conditions correlated with chlorophyll and carotenoid concentrations. In plants grown under exposure to red and blue light, such correlation was not observed and the F_(734)/F_(682) ratio was maintained at a constant level. It is concluded that the F_(734)/F_(682) ratio depends on both the intensity and the spectral composition of actinic light used for growing plants.