Exploring the Role of Biostimulants in Sweet Cherry (Prunus avium L.) Fruit Quality Traits

Sweet cherries are among consumers' preferred fresh fruits, known for their attractive organoleptic properties and high nutritional value. Agronomical practices, which are now shifting to more environmentally sustainable options, can influence several key quality traits of sweet cherries. In this context, reducing conventional agrochemicals and increasing the application of preharvest biostimulants has emerged as an innovative strategy. This approach can not only enhance cherry production and quality but also ensure the economic and environmental sustainability of the cherry supply chain. Hence, this work is aimed at studying the effect of the application of two concentrations of glycine betaine (GB) and Ecklonia maxima-based (EM) biostimulants, and their combination, in two cultivars of sweet cherry: the early-maturing 'Early Bigi' and the late-maturing 'Lapins', both grafted onto SL-64 rootstock. Evaluated parameters included fruit weight and dimensions, color, firmness, total soluble solids (TSS), titratable acidity (TA), phenolic and anthocyanin contents, and sensory profile. Key findings highlight that, with a few exceptions, biostimulant treatments had a positive impact on the studied parameters, although the responses varied between cultivars. For instance, fruit size increased by 13.41% in 'Early Bigi' and 47.20% in 'Lapins'. Additionally, reduced color values, coupled with higher TSS/TA ratios, indicate advanced fruit maturation, which could allow for an earlier harvest. The total phenolic content rose by 56.88% in 'Early Bigi' and 30.24% in 'Lapins', while anthocyanin levels surged by 88.28% and 36.10%, respectively. Fruit firmness also improved following biostimulant application. Sensory analysis further revealed enhancements in key descriptors such as "overall aspect", "firmness", and "cherry flavor", underscoring the beneficial effects of these treatments. These combined results indicate that the preharvest application of glycine betaine or Ecklonia maxima-based (EM) biostimulants significantly improves key quality traits of sweet cherries. This approach offers benefits not only from a commercial perspective but also for the sweet cherry supply chain sustainability by reducing the application of chemical-based products and replacing them with ecofriendly substances while enhancing the quality of the fruit.