Variations of Chlorophyll, Proline, and Abscisic Acid (ABA) Contents in Grapevines (Vitis Vinifera L.) Under Water Deficit Conditions

The aim of the research was to determine the impact of regulated deficit irrigations (RDIs) on the accumulation of chlorophyll, proline, and abscisic acid (ABA) in grapevines. Cuttings of Vitis vinifera L. cv ‘Adakarası,’ ‘Papazkarası,’ ‘Karasakız,’ ‘Karalahana,’ ‘Yapıncak,’ ‘Vasilaki,’ ‘Cabernet Sauvignon,’ and ‘Sauvignon Blanc’ were treated to different RDIs that were applied by reducing the maximum irrigation amount by 0%, 25%, 50%, and 75% according to reference evapotranspiration (ETo) under semi-controlled conditions over 2 years. ‘Karalahana’ and ‘Sauvignon Blanc’ cultivars reached the highest chlorophyl la (Chla) in the mean of 2 years. The highest total chlorophyll (Chltot) was determined in ‘Karalahana’ cultivar. The lowest Chltot was determined in ‘Adakarası’ cultivar. The proline with lower RDIs increased in 2019. In 2020, a relationship was discovered whereby, contrary to the previous year, RD4 indicated the least content of proline. The highest ABA among RDIs was determined in the RD4, but was not statistically significant. Leaf ABA was higher in 2019 in the mean of all cultivars and all RDIs. The impact of RDIs on ABA varied according to the cultivar and year. ‘Adakarası’ cultivar, like ‘Cabernet Sauvignon’ cultivar, may adjust its metabolic process to a decrease in water supply. ‘Karasakız’ cultivar also appears to be promising in terms of drought resilience.