The effects of glycine betaine application on frost tolerance in three table grape cultivars

Abstract

Cryoprotectants like glycine betaine (GB), have colligative properties that both delay the intracellular ice crystals formation and reduce the potential for osmotic damage during the freezing and thawing processes. Here the study, in which three different grape cultivars of Vitis vinifera L. were used, the effects of GB application three days before sampling on frost tolerance were tried to be determined. Samples were taken at three different stages of dormancy (transition to acclimation, hardening and deacclimation) and low temperature exotherm for 50% (LTE50) degrees were determined by testing the winter buds with differential thermal analysis (DTA). In addition, two different biochemical analyses, which were stated in previous studies to be important in frost tolerance, were performed to determine the physiological effects of GB. The effect of GB treatment varied according to cultivars, years and dormancy stages but the greatest effect was an increase of 3.07°C frost tolerance in the third dormancy stage, during 2020 for the ‘Michele Palieri’ cultivar. The LTE50 data showed that the GB application enhanced frost tolerance during two stages during the dormant season (1st stage 1.72°C and 3rd stage 1°C) in 2021 for the same cultivar. Also, the GB application provided 1.75°C greater frost tolerance in the spring of 2020 for the ‘Red Globe’ cultivar. Our results showed that there was no relationship between GB treatment and biochemical content (proline and MDA).