Chlorophyll fluorescence emission spectra in photosynthetic organisms (invited chapter)

LAGORIO, M. G.

Chlorophyll: Structure, Production and Medicinal Uses

Nova Science Publishers

Lugar: New York; Año: 2011; p. 115 - 150

The description, analysis and applications of chlorophyll fluorescence emission spectrum in biological organisms are reviewed. At room temperature, in photosynthetic tissues, chlorophyll fluorescence presents a peak in the red (about 680 nm) due to emission from chlorophyll-a linked to photosystem II and in the far-red (about 735 nm) due to contribution of both photosystems (I and II). Chlorophyll fluorescence analysis is a powerful tool for plant physiologists but its interpretation is usually complicated by the presence of light re-absorption processes inside the photosynthetic tissue. A great deal of important conclusions on photochemistry of plants is usually inferred from leaves fluorescence ratios at different emission wavelengths (typically the fluorescence ratio red/far-red). Nevertheless, most of them are deduced from observed spectra distorted by light re-absorption processes and the resultant conclusions are not reliable. A review of the empirical and theoretical approaches to evaluate the chlorophyll emission spectra inside the photosynthetic organism, free from light re-absorption processes, published to date in literature, is detailed and discussed in this chapter. Not only the steady-state spectrum from plant leaves but also from algae and chlorophyll-containing fruits are discussed. Applications in plant physiology and in monitoring plant stress are presented.