Abiotic Stress Diagnosis via Laser Induced Chlorophyll Fluorescence Analysis in Plants for Biofuel

Abstract

In the past few decades there has been a widespread scientific and technological interest in laser-induced remote techniques to monitor the status of terrestrial vegetation (Svanberg, 1995). The most employed nowadays are those which exploit the fluorescence emission from the plant leaves generated in the photosynthesis process. The fluorescence of terrestrial vegetation consists almost exclusively of the fluorescence of leaves, which account for the largest surface of plants above ground. A small part of the absorbed light energy in the photosynthesis process is lost during the migration from the pigment antenna to the reaction centers and are dissipated by a number of non-photochemical processes, including heat, and re-emission of a small but easily detectable amount (2-5% in vivo) of the absorbed radiation. This re-emission occurs at longer wavelengths in the red and far-red spectral regions and is termed as Chlorophyll Fluorescence (ChlF) (Shreiber, 1983; Backer & Bradbury, 1981). Chlorophyll fluorescence represents an intrinsic signal emitted by plants that can be employed to monitor their physiological state including changes of the photosynthetic apparatus, developmental processes of leaves, state of health, stress events, stress tolerance, and also to detect diseases or nutrient deficiency of plants. In particular, the application of laser induced chlorophyll fluorescence spectroscopy has drawn much attention recently owing to the non-invasive and nondestructive nature of the technique (Svanberg, 1995; Lang & Lichtenthaler, 1991; Chappelle et al., 1984). The technique can be applied for chlorophyll level monitoring in basic photosynthesis research, agriculture, horticulture, and forestry. Abiotic stress (water deficit, salinity, heat, heavy metals soil contamination, intense light, etc) affects significantly crop growth and yield in agricultural areas all over the world. Thus, it is imperative to study their effect upon the crops and discriminate among abiotic stresses using new noninvasive and nondestructive remote sensing precision diagnostic techniques. These procedures allow one to employ intervention measures that will prevent damage to the crop and will not provoke economical losses. Our aim here, is to exploit laserinduced fluorescence signatures from plants to evaluate the effect of abiotic stresses (water