Evaluation of water stress tolerance of old autochthonous grapevine cultivars using chlorophyll fluorescence parameters

This study monitored the evolution of the main climatic indicators, the characteristics and phenological trends of 8 old autochthonous grape varieties for white and red wines and two other varieties of table grapes, as well as chlorophyll fluorescence, as a method of determining the tolerance of varieties to water stress. The evaluation of climatic parameters consisted of studying climatic data for the period 1979-2023, and the phenological advance was calculated with the data of the last 3 years to explain the phenology-temperature relationship. The chlorophyll fluorescence of the 10 autochthonous grape varieties for white and red wines and grapes for the table cultivated in the germplasm collection was evaluated to determine the water stress tolerance. "Frumoasă de Ghioroc" demonstrated the lowest variation in terms of harvest date, as well as the shortest harvest interval, respectively 28 days. While "Galbenă măruntă" was at the opposite pole, with variation and a harvest interval of 37 days. The most pronounced linear trends in phenophase at the onset of flowering were observed in the varieties "Bacator" and "Coarnă neagră aromată" where the phenological advance was over 7 days/year, and the smallest advance, with approximately 3 days/year, was recorded in the varieties "Moroștină" and "Coarnă roșie". The values obtained regarding indicators responsible for establishing the Fv/Fm ratio highlighted a high tolerance to water stress 7 out of 10 old native varieties analyzed, with values ranging between 0.76 Mol/m2/s ("Galbenă măruntă" and "Frumoasă de Ghioroc") and 0.80 Mol/m2/s ("Tâța caprei neagră").