Table grapes suffer significant losses due to issues such as fungal infections, cracking, and berry shattering, which affect them both in the vineyard during ripening and throughout postharvest storage. Current control methods, such as sulfur dioxide (SO₂) treatments, are increasingly constrained by potential fruit damage and regulatory limitations, prompting a search for sustainable alternatives. This comprehensive review synthesizes the current scientific understanding and recent studies regarding calcium dynamics and proposes sorbitol as an innovative preharvest solution to enhance table grape quality through improved calcium (Ca) transport. Ca is a vital macronutrient for cell wall integrity and fruit resistance; however, its inherent low mobility in the phloem restricts its effective delivery to developing fruits, particularly after the veraison stage. This review thoroughly discusses the mechanistic hypotheses by which sorbitol, a naturally occurring sugar-alcohol, acts as a “vector” by forming stable, soluble complexes with Ca, thereby facilitating its crucial translocation to fruit tissues. Preharvest foliar applications of these calcium-sorbitol complexes have demonstrated numerous benefits, improving fruit firmness, reducing the incidence of cracking and shattering, mitigating fungal decay, and boosting antioxidant activity. These effects collectively enhance overall fruit quality and extend storability. Finally, we outline future directions for investigation, aiming to further clarify the molecular mechanisms involved and explore the potential of sorbitol to form complexes with other poorly mobile nutrients and plant elicitors, opening new avenues for sustainable crop management.

Table grapes suffer significant losses from issues such as fungal infections, cracking, and berry shattering, which affect them both in the vineyard during ripening and throughout postharvest storage. Current control methods, such as sulfur dioxide (SO2) treatments, are increasingly constrained by potential fruit damage and regulatory limitations, prompting a search for sustainable alternatives. This review proposes sorbitol as an innovative preharvest solution to enhance table grape quality through improved calcium (Ca2+) transport. Ca is a vital macronutrient for cell wall integrity and fruit resistance; however its inherent low mobility in the phloem restricts its effective delivery to developing fruits, particularly after veraison. Sorbitol, a naturally occurring sugar-alcohol, acts as a "vector" by forming stable, soluble complexes with Ca, thereby facilitating its crucial translocation to fruit tissues. Preharvest foliar applications of these calcium-sorbitol complexes have demonstrated numerous benefits-, improving fruit firmness, reducing the incidence of cracking and shattering, mitigating fungal decay, and boosting antioxidant activity. These effects collectively enhance overall fruit quality and extend storability. Future investigations will aim to further clarify the molecular mechanisms involved and explore sorbitol’s potential to complex with other poorly mobile nutrients and plant elicitors, opening new avenues for sustainable crop management.

Postharvest losses in onion (Allium cepa L.) bulbs constitute a major economic challenge globally, primarily driven by fungal pathogens and premature sprouting during long-term storage. Addressing these issues with effective preharvest strategies is critical for market stability and supply chain integrity. This study evaluated the effects of two preharvest fungicide strategies, i.e., T1 (dimethomorph + pyraclostrobin) and T2 (metalaxyl + mancozeb + copper oxychloride), on the crop yield, postharvest quality, and sprouting behavior of dried onion bulbs. Both treatments significantly reduced the incidence of foliar disease in the field and improved the crop yield of commercial bulbs compared to the control in two consecutive seasons. T1 achieved the highest yield (~76 and 88 t ha⁻¹ in ‘Mata Hari’ and ’Recas’ onions). During storage at 20 °C for 84 days, in the ‘Mata Hari’ cultivar, the T1 bulbs exhibited the lowest weight loss and respiration rate, the lowest sprouting incidence (1%), and superior firmness retention and higher total soluble solids. In contrast, control bulbs exhibited accelerated weight loss and tissue degradation, with up to 95% sprouting. Pyruvic acid content, an indicator of pungency, was highest in T1 bulbs and increased significantly in sprouted controls, likely due to internal enzymatic activation and tissue senescence. The fungicides indirectly delayed dormancy release by delaying sprouting and internal stem axis formation. Overall, T1 was the most effective strategy for preserving onion quality during storage without using synthetic sprout inhibitors. These findings support the integration of specific fungicide programs into preharvest management to improve onion storability, reduce postharvest losses, and maintain commercial value in intermediate-dormancy dried onion cultivars, such as ‘Mata Hari’.

‘Mollar de Elche’ pomegranate is highly valued for its sweet flavor but faces significant commercial hurdles due to pale coloration and sensitivity to postharvest disorders. This study investigates the impact of preharvest foliar applications of L-α-amino acids, applied alone (AA) or combined with 2.5% sorbitol (Sor–AA), on secondary metabolism and physiological resilience, defined here as the fruit’s capacity to maintain metabolic homeostasis and stabilize antioxidant pigments during cold storage (7 °C). Our results show that both treatments triggered a substantial shift in secondary metabolism, doubling anthocyanin concentrations at harvest and effectively overcoming the cultivar’s color deficit. While the AA treatment maximized fruit quantity per tree, the Sor–AA combination achieved the highest total yield (83.58 ± 6.82 kg) and individual fruit weight (469.00 ± 16.00 g) through a ‘metabolic bypass’ that optimizes energy use. Crucially, the physiological resilience of the fruit was uniquely bolstered by the Sor–AA treatment, which was the only strategy to stabilize anthocyanin levels (~108 mg L⁻¹) and maximize free ellagic acid in the husk (371.72 mg kg⁻¹) throughout 42 days of storage. Multivariate PCA (explaining 79.79% of variance) confirmed that the synergy of amino acids and sorbitol triggers systemic metabolic reprogramming. Consequently, this targeted agronomic approach could provide significant economic benefits by increasing the proportion of export-grade fruit and extending the commercial window for the pomegranate sector.

The ‘Mollar de Elche’ pomegranate cultivar is highly valued for its organoleptic properties, yet it often suffers from inadequate fruit pigmentation, reducing its commercial competitiveness. This study, carried out in a mature commercial orchard located in Spain (Alicante), evaluated the impact of preharvest applications of sorbitol at different concentrations (0, 0.1, 0.5, and 1% in 2023, and 2.5 and 5% in 2024) and three application periods: S1 (nine applications from fruit set), S2 (six applications from seed hardening), and S3 (three applications at the onset of colour change) over two consecutive growing seasons (2023 and 2024). Treatments were applied via foliar spraying from the time of fruit set until the onset of external colour change. The results showed that sorbitol acted as an effective metabolic ‘vector’, significantly increasing fruit weight and total yield, particularly at concentrations of 1 and 5%. Furthermore, sorbitol treatments enhanced fruit firmness by stabilizing cell wall structures and significantly improved exocarp red pigmentation by reducing the hue angle. While the highest doses (1, 2.5, and 5%) enhanced biomass accumulation, they also triggered a potential negative feedback loop in sugar sensing that could interfere with secondary metabolism at excessive thresholds. These findings suggest that preharvest sorbitol applications, particularly at concentrations between 1 and 5% starting from early application period (S1), serve as an effective strategy for improving yield and external pigmentation in ‘Mollar de Elche’ pomegranate fruit.