Comparative study of the thermoluminescence glow curves recorded from varieties of <i>Vitis vinifera, V. labrusca</i> and <i>V. champini</i>

Abstract

Thermoluminescence (TL) glow curves were recorded from leaves of eight Vitis varieties grown in South-West India, viz. Thompson Seedless, Sonaka, Anab-E-Shahi, Kishmish Charni, Tas-A-Ganesh, Black Monuka, Bangalore Purple and American Dogridge belonging to the Vitis vinifera, V. labrusca and V. champini species. The TL peaks were analysed, using a computer-assisted model based on the general order kinetics theory, to determine thermodynamical parameters such as activation energy, entropy, frequency factor and free energy. It was observed that all six V. vinifera samples showed an entirely different TL pattern consisting of only one prominent and highly narrow peak at around -5 degrees C (peak II). The prominence of this peak attributed to S₂/S₃ Q_a^- recombination suggests a modification at the plastoquinone electron acceptor sites. On the other hand, the remaining two varieties Bangalore Purple and American Dogridge showed broader TL spectra consisting of a higher number of peaks. This basic difference is attributed to the difference in species of the selected varieties. Moreover, the TL recorded from Bangalore Purple resembled the standard TL spectra of spinach. The study undertaken in this paper may be relevant in grape breeding programs.