ANALYSIS OF LASER-INDUCED FLUORESCENCE LINE-SHAPE OF INTACT LEAVES - APPLICATION TO UV STRESS DETECTION

In vivo laser-induced fluorescence spectra of intact leaves of healthy and UV-irradiated Salvia splendens plants excited at 337 nm by a nitrogen laser were recorded using an optical multichannel analyzer system. The spectra showed the typical fluorescence bands centered around 450, 530, 685 and 730 nm. Exposure to UV radiation changed the relative intensity values of these bands and their peak positions. The analysis of the acquired spectra in terms of a linear combination of Gaussian bands was carried out to determine accurately the peak positions and the relative intensity contribution of the various bands to the laser-induced fluorescence spectra on healthy and UV-treated plants of different age. The results indicate that a curve-fitting analysis of the measured fluorescence spectra is a useful and sensitive method to discriminate the various band contribution to the whole leaf fluorescence spectrum. The comparison among blue-green and red-far-red fluorescence of leaves was also confirmed as an effective indicator of UV stress in plants.