Spectral variations of laser induced fluorescence from peanut leaves and characteristics of transverse distribution of fluorescence in leaves excited at 325 nm and 375 nm.

摘要

This study clarified UV-B stress, ozone stress and water stress using laser-induced fluorescence (LIF) spectra (325 nm and 375 nm) of the leaves of the peanut (Arachis hypogaea L.). The LIF spectral variation characteristics differed between the two wavelengths. At 375 nm, the fluorescence peak ratio of 685 nm to 530 nm (F685/F530) decreased in response to increased UV-B stress, corroborating the findings of our previous study using an Ar+ laser (351-364 nm). On the other hand, excitation at 325 nm resulted in a decrease in the F685/F530 under irradiation at 27 kJm-1 of UV-B, with a gradual increase observed under UV-B irradiation greater than 54 kJm-2. This increase in the F685/F530 at 325 nm was not observed under ozone and water stress. The transverse distribution of fluorescence in leaves was examined to clarify increments in the F685/F530 under irradiation at 325 nm. The findings suggested that excess UV-B irradiation damaged UV-B-absorbing pigments in the upper epidermis, and also that irradiation at 325 nm was capable of exciting chlorophyll in the palisade tissues. These results show that the use of LIF spectra with different excitation wavelengths in the UV region is effective for accurate diagnoses of stress in plant leaves.