Involvement of Chlorophyll a Fluorescence Analyses for Identification of Sensitiveness of the Photosynthetic Apparatus to High Temperature in Selected Wheat Genotypes

Abstract

The aim of our work was to evaluate the sensitivity of testing procedure and different parameters derived from the basic parameters of chlorophyll a fluorescence as well as from fluorescence kinetics analysis for their application in screening of wheat genotypes. In several testing cycles during vegetation period we examined a set of 31 wheat (Triticum aestivum L.) genotypes and local landraces of different provenances cultivated in the field trials of the RICP Piestany, Slovak Republic. In all tests we used procedure of heating of detached leaf segments closed in glass tubes for 1 hour immersed in the thermostated water bath (40 °C) in the dark. Before and after the heat treatment, the chlorophyll a fluorescence in a fast phase was used. To compare the leaf samples we used the maximum quantum yield of PSII photochemistry FV/FM and, relative variable fluorescence at 0.3 ms (WK). The results showed considerable differences in heat sensitivity among wheat genotypes, and offered a potential to identify more tolerant or susceptible genotypes. The termostability increased and genotypic differences decreased across the vegetation period. Parameter derived from the fluorescence kinetics (Wk) was generally more sensitive and hence more useful than the basic chlorophyll fluorescence parameter (FV/FM).KeywordsHeat stressChlorophyll a fluorescencePhotosynthetic thermostabilityWheat