Laser monitoring of stress conditions of plants

Abstract

Based on our own research and analysis of existing methods for monitoring vegetation cover, the advantages of laser remote sensing have been proven. Preliminary experiments were carried out on such simplified models as extracts of pigments that play a major role in the photographic processes of interest to us. These models were chlorophyll fractions “a” and “b” extracted from plant leaves. These measurements made it possible to state that by selective excitation of fluorescence in preparations from acetone solutions of chlorophyll, it is possible to identify certain effects caused by differences in the groups and configurations of pigments inherent in their native state in the photosynthetic apparatus. Measurements carried out on plants subject to mineral stress showed that cotton grown under conditions without the addition of basic nutrients such as potassium, nitrogen and phosphorus to the substrate shows a lower fluorescence yield compared to control plants grown under normal mineral nutrition. At the same time, the dynamics of changes in the spectral characteristics of plants subject to water stress showed the opposite pattern. On the sixth day after stopping watering, when signs of wilting began to appear, the fluorescence output increased by 30% compared to control plants. As a result, these two competing processes make it difficult to unambiguously diagnose the real state from the integrated fluorescence output. However, the spectral shape turned out to be more informative than the integral fluorescence output. Therefore, to most accurately identify the state of the plant, an analysis of the spectral structure of the fluorescent response was chosen