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The purpose of this study was to explore influence of abiotic factors, such as high temperature, water deficiency and high solar radiation on the photomembrane of grapevine leaves. Grapevine leaves were collected from variety Rkatsiteli (Vitis vinifera) and placed at a temperature of +45 °C and +55 °C for 5 min, respectively. The relative volume of water in leaves was gradually reduced to 50%, and then leaves were irradiated with 6,000 μmol/m·s of white light. Changes provoked by stressful abiotic factors were determined using rapid and delayed chlorophyll fluorescence methods. It was shown that value of variable component of chlorophyll fluorescence (Fv), intensity of electron transport between the photosystems (ETR), intensity of expended electrons in carboxylation (ETRn) and oxygenation (ETRp) and index of non-photochemical quenching (NPQ), allow studying molecular mechanisms of the impact of abiotic factors and the resulting damage degree. Based on delayed and rapid fluorescence data, it was demonstrated that temperature of +45 °C adversely affects oxygen production system and CO2 assimilation mechanisms, while at +55 °C, the ETR decreases. Reduction of relative water volume in leaves up to 50%-55% leads to sharp reduction in ETR and inhibition of photosynthesis. In case of irradiation of leaves with high-intensity light of 6,000 μmol/m·s, NPQ of light falling on a leaf increases, thus protecting photosynthesis apparatus from damage.

Use of Chlorophyll Fluorescence Methods for the Study of Physiological Condition and Resistance against Abiotic Factors of Grapevine