Characterization of the laser‐induced blue, green and red fluorescence signatures of leaves of wheat and soybean grown under different irradiance

Abstract

The blue, green and red fluorescence emission of green wheat (Triticum aestivum L. var. Rector) and soybean leaves (Glycine max L. var. Maple Arrow) as induced by UV light (nitrogen laser: 337 nm) was determined in a phytochamber and in plants grown in the field. The fluorescence emission spectra show a blue maximum near 450 nm, a green shoulder near 530 nm and the two red chlorophyll fluorescence maxima near 690 and 735 nm. The ratio of blue to red fluorescence, F450/F690, exhibited a clear correlation to the irradiance applied during the growth of the plants. In contrast, the chlorophyll fluorescence ratio, F690/F735, and the ratio of blue to green fluorescence, F450/F530, seem not to be or are only slightly influenced by the irradiance applied during plant growth. The blue fluorescence F450 only slightly decreased, whereas the red chlorophyll fluorescence decreased with increasing irradiance applied during growth of the plants. This, in turn, resulted in greatly increased values of the ratio, F450/F690, from 0.5 - 1.5 to 6.4 - 8.0. The decrease in the chlorophyll fluorescence with increasing irradiance seems to be caused by the accumulation of UV light absorbing substances in the epidermal layer which considerably reduces the UV laser light which passes through the epidermis and excites the chlorophyll fluorescence of the chloroplasts in the subepidermal mesophyll cells.

The use of chlorophyll fluorescence excitation spectra for the non‐destructive in situ assessment of UV‐absorbing compounds in leaves

“…2001). This confirmed earlier observations in the domain of fluorescence remote sensing (Stober & Lichtenthaler 1993;Schweiger, Lang & Lichtenthaler 1996;Lichtenthaler & Schweiger 1998) that increased irradiance during plant growth decreases UVexcited ChlF, presumably due to an increase in UV-absorbing compounds in the epidermis.…”

Studies on the Localization and Spectral Characteristics of the Fluorescence Emission of Differently Pigmented Wheat Leaves

“…Growth ofseedlings Materials and Methods al., 1990;Lichtenthaler and Stober, 1990;Lang et al, 1991;Stober and Lichtenthaler, 1992, 1993a, 1993b. The plants' blue-green fluorescence seems to originate mainly from plant phenolics and phenylpropanes (Hartley, 1973;Fry, 1979Fry, , 1982Schnabl et al, 1986;Goulas et al, 1990;Lang et al, 1991;Chappelle et al, 1991) such as coumarins (aesculetin), various hydroxycinnamic acids and quercetin, which appear to be located in the vacuoles and cell walls of leaf cells.…”

Laser-induced Fluorescence Spectroscopy (LIFS) for Discrimination of Genetically Close Sweet Orange Accessions (Citrus sinensis L. Osbeck)

“…The fluorescence spectroscopy on the leaves of plants has emerged as a specific and important tool for remote sensing to access accurately the physiological state of plants and allow early diagnosis of biotic and abiotic stresses in vegetation. 23,24 Their applications in agriculture, biology, and botanics has been published in a numerous of reviews in the last 20 years. 18,[23][24][25][26][27][28][29] Laser-induced fluorescence spectroscopy has an optical configuration which allows non-invasive interaction with the sample.…”