Improving Fruit Coloration, Quality Attributes, and Phenolics Content in 'Rainier' and 'Bing' Cherries by Gibberellic Acid Combined with Homobrassinolide

The purpose of this work was to evaluate the potential of gibberellic acid (GA(3)) combined with homobrassinolide (HBR) treatment to improve fruit anthocyanin content, to maintain high-quality properties, to reduce susceptibility to physiological disorders, and to retard the development of bioactive compounds in yellow-fleshed 'Rainier' and red-fleshed 'Bing' sweet cherries. Application of 1, 5, and 10 mg L-1 HBR once at straw color did not affect anthocyanin accumulation in 'Rainier', but 5 or 10 mg L-1 HBR application elevated anthocyanin content in 'Bing'. No significant differences were observed in fruit size, soluble solids content (SSC), titratable acidity, or surface pitting between the control and HBR treatments in either cultivar after 4 weeks of storage at 0 degrees C; however, low rates of stem browning and decay were noted in HBR treatments. A single application of GA(3) resulted in firmer fruit. Spraying HBR and GA(3) to cherries effectively recovered anthocyanin synthesis and increased the levels of phenolics and SSC. Moreover, in combination, these compounds reduced stem browning and pitting development. In conclusion, pre-harvest application of 10 mg L-1 GA(3) combined with 5 mg L-1 HBR had a potential to retain the normal skin color development and phenolics synthesis, to increase SSC accumulation, and to reduce fruit susceptibility to disorders in mid-season sweet cherry.