In this chapter, chlorophyll fluorescence in plant leaves of three genotypes of cotton cultivated in Uzbekistan and characterized at different degrees of drought tolerance is studied. The light and CO2 responses of the chlorophyll fluorescence and the photosynthesis and possible mechanisms of adaptation of plants to moderate long-term drought are described. The chlorophyll fluorescence and various morpho-physiological indicators of well-watered and moderately drought-stressed cotton plants have been measured simultaneously over a long period of plant ontogenesis to establish direct correlations between them to estimate the magnitude of drought effect using fluorescence parameters. It is shown that determination of such correlations and their calibration by photoacoustic signals generated in plant leaves at application of low-frequency-modulated light may be used for monitoring of the drought tolerance of crops in the field.
Part of the book: Applied Photosynthesis