The commercial quality of sweet cherries depends on a complex balance between visual appearance, organoleptic properties, and the ability to maintain high quality standards during postharvest storage.
Flesh firmness, skin color, sugar content, and the stability of bioactive compounds are key factors determining market competitiveness, but they are strongly influenced by both environmental conditions and orchard management practices.
In this context, a recent study conducted in the Piedmont region of northern Italy evaluated the effectiveness of prohexadione-calcium (Pro-Ca), a plant growth regulator known for inhibiting gibberellin biosynthesis, in improving the quality of the sweet cherry cultivar 'Sweet Saretta' grafted onto the 'Gisela 5' rootstock and grown under two contrasting environmental conditions: a hillside orchard and a lowland orchard.
The objective was to determine whether preharvest Pro-Ca applications could enhance the quality characteristics of the fruit and extend its shelf life. Pro-Ca was applied as two foliar sprays during fruit set and the early stages of fruit development.
Cherries were evaluated at harvest and after 14 days of storage at 2 °C. Morphological traits, fruit firmness, sugar and organic acid composition, skin color, and nutraceutical compounds, including anthocyanins, total phenolics, and antioxidant capacity, were assessed.
The effects of the treatment were found to be highly dependent on the growing environment. In the hillside orchard, Pro-Ca produced the most evident benefits, resulting in firmer fruit at harvest and excellent maintenance of flesh texture throughout the storage period.
In contrast, the apparent increase in firmness observed in untreated fruit during storage was mainly attributed to dehydration rather than to the actual preservation of tissue integrity.
In the lowland orchard, Pro-Ca-treated cherries maintained or even increased their sugar content during storage, whereas untreated fruit showed a progressive decline, probably due to higher respiratory activity promoted by the warmer growing conditions.
Under hillside conditions, the pattern was different, with an overall increase in sugar concentration during storage and less pronounced differences between treated and untreated fruit. Regarding organic acids, Pro-Ca promoted greater retention of tartaric acid and improved the stability of the sugar-to-acid ratio.
Furthermore, the treatment contributed to stabilizing the metabolic relationships between sugars and organic acids, reducing the differences normally induced by contrasting environmental conditions.
Pro-Ca-treated cherries also retained higher concentrations of anthocyanins, polyphenols, and antioxidant capacity during storage, particularly in fruit produced under hillside conditions, where these parameters remained nearly unchanged until the end of the shelf life.
In the lowland orchard, the treatment likewise reduced the loss of the main bioactive compounds, confirming the role of Pro-Ca in preserving not only the nutritional value but also the commercial quality of the fruit.
The effects on fruit size were more limited and variable: in the lowland orchard, Pro-Ca slightly reduced the proportion of the largest fruit while maintaining commercially acceptable sizes and achieving higher yields, whereas in the hillside orchard, differences in fruit size between treatments were negligible.
Overall, prohexadione-calcium (Pro-Ca) proved to be a promising tool for improving the postharvest quality of sweet cherries, with particularly pronounced benefits under hillside growing conditions, where it enhanced fruit firmness, preserved nutraceutical compounds, and promoted greater metabolic stability during storage.
These findings suggest that the effectiveness of this plant growth regulator should be evaluated according to specific environmental conditions, allowing growers to adopt targeted management strategies that increase the commercial value of sweet cherry production while reducing postharvest losses throughout the supply chain.
Source: Varaldo, A., Dacomo, A., Donno, D., & Giacalone, G. (2026). Combined effects of prohexadione‐calcium and growing environment on sweet cherry fruit quality and postharvest performance. Journal of the Science of Food and Agriculture, 106(8), 4901-4912. https://doi.org/10.1002/jsfa.70574
Image source: Stefano Lugli
Andrea Giovannini
PhD in Agricultural, Environmental and Food Science and Technology - Arboriculture and Fruitculture, University of Bologna, IT
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