Salicylic and oxalic acid treatments provide targeted postharvest benefits for citrus fruit

Preharvest and postharvest applications of salicylic acid (SA) and oxalic acid (OA) can provide targeted benefits during long-term cold storage of citrus fruit, although their effectiveness depends on the cultivar. This is the conclusion of a study evaluating both compounds on 'Lane Late' navel oranges and 'Summerina' mandarins stored for 10 weeks at 1 °C, followed by one week at 20 °C to simulate commercial shelf-life conditions.

Researchers assessed a wide range of quality parameters to determine whether these treatments could improve fruit preservation during postharvest storage.

Limited effects on overall fruit quality

The study measured weight loss, firmness, total soluble solids, titratable acidity, colour, respiration, ethylene production, vitamin C content, chilling injury and several biochemical markers.

Overall, salicylic acid and oxalic acid treatments produced limited and inconsistent effects across most quality attributes. No significant improvements were detected for chilling injury, colour retention, respiration rate or vitamin C preservation.

Reduced stem-end rot in mandarins

One of the most significant findings was a reduction in calyx stem-end rot in mandarins treated with postharvest salicylic acid.

This treatment lowered disease incidence by approximately 30%, suggesting potential value for improving the commercial storage performance of specific mandarin cultivars.

Enhanced membrane stability

Researchers also observed reduced electrolyte leakage, an indicator of improved cell membrane integrity.

In oranges, membrane stability improved following preharvest salicylic acid application, whereas postharvest oxalic acid produced the best results in mandarins, indicating cultivar-dependent physiological responses.

Cultivar-specific optimisation remains essential

The combined application of salicylic and oxalic acids did not generate consistent synergistic effects, and treatment responses differed between oranges and mandarins.

The authors conclude that these compounds offer targeted postharvest advantages but require cultivar-specific optimisation to maximise their effectiveness under long-term cold storage conditions.

Source

Kavanagh, M., Golding, J. B., Pham, H. N. T., Bowyer, M. C., Palou, L., Bullot, M., & Pristijono, P. (2026). Effects of Preharvest and Postharvest Salicylic Acid and Oxalic Acid Treatment on the Long Cold Storage Quality of ‘Lane Late’ Navel Oranges and ‘Summerina’ Mandarins. Horticulturae, 12(7), 872. https://doi.org/10.3390/horticulturae12070872

Image from Asaja Andalucia