Benefits of oxalic acid in table grapes

Oxalic acid (AO) is a metabolic product of plants with many physiological functions, the most important being the increase in the defence responses of various enzymes and secondary metabolites. For this reason, in 2017 three doses of AO were applied in the field: 0.5, 1 and 5 mM, on the 'Magenta' grape variety. The effect of the treatment on the evolution of the physiological and quality parameters of the berries, as well as on the content of bioactive compounds and antioxidant systems was evaluated during 45 days of storage at 2 °C. The treatment showed a significant reduction in weight loss and respiration rate of the treated berries, as well as an improved condition of the stems and a delay in the loss of firmness. In addition, an increase in both the red colour and the content of bioactive compounds and antioxidant systems of the treated berries was observed at harvest and during storage, with the AO 5 mM dose showing the best results. In conclusion, AO can be a good strategy to increase the quality of table grapes at harvest and to maintain their quality during storage.