γ-Aminobutyric acid (GABA) plays important roles in plant development, including the maintenance of fruit quality when applied as postharvest treatment. However, little information is available about the effects of preharvest GABA treatments. Thus, GABA (10, 50 and 100 mM) was applied as foliar spray at key points of fruit development in three sweet cherry cultivars and over two years. The results show that quality parameters, such as total soluble solid content, titratable acidity and firmness were higher in the fruit from GABA-treated trees than in the controls, either at harvest or during four weeks of cold storage. In addition, the total phenolic and total and individual anthocyanin concentrations were also enhanced by GABA treatments and the fruit color was improved. The activities of the antioxidant enzymes catalase, ascorbate peroxidase and peroxidase were also enhanced by the GABA treatments. The most effective concentration was 50 mM, which led to extending the storage period of sweet cherries with high quality traits to up to four weeks, while for the controls this was two weeks. Thus, GABA treatment had a clear effect on delaying the postharvest ripening and senescence processes in sweet cherries, with an additional effect on enhancing the content of bioactive compounds, such as phenolics and anthocyanins, with antioxidant properties and health benefits.

Spain is a great producer of organic lemon; however, it is necessary to reduce the losses caused by post-harvest diseases. Melatonin (MEL) is a naturally occurring compound with physiological functions in fruit growth and ripening and is able to modulate postharvest ripening and senescence, most of it being concentrated in climacteric fruit. Thus, the aim of this study was to apply MEL to organic lemon fruit with stems and leaves (LEAF) and to organic lemon without those components (LEAFLESS) after harvesting and storage during 21 days at 2 °C to understand the effects of this treatment on the fruit quality. For this purpose, two experiments were carried out. First, MEL was applied at 0.01 mM, 0.1 mM and 1.0 mM by immersion for 15 min on lemon fruits, and the quality parameters and bioactive compounds of the fruit were analysed. Subsequently, a second experiment was carried out where the best concentration (1 mM) was selected and another time (15 and 30 min) was added, with the same quality parameters being analysed. As a result, we observed that all MEL treatments showed positive effects on weight loss reduction, softening (higher fruit firmness), total acidity and lower colour changes. Total phenols increased in MEL-treated lemons, both in peel and juice. For the three concentrations tested, the best efficiency was obtained with MEL at 1.0 mM, while LEAF lemons were the most effective. In conclusion, lemons containing stems and leaves (LEAF) improved preservability by using MEL at 1.0 mM with better organoleptic quality and enhanced phenolic compounds.

GABA (γ-Aminobutyric acid) is an amino acid with diverse effects on plant development, including delayed senescence in horticultural commodities. The main goal of this research was to investigate the impact of GABA applications to pomegranate trees on the ‘Mollar de Elche’ quality traits and antioxidant compounds during storage for 60 days at 10 °C. In the 2019 experiment, pomegranate trees received foliar sprays of GABA at 10-, 50- or 100-mM concentrations at three stages of fruit development. Pomegranates harvested from GABA-treated trees exhibited enhanced fruit firmness, titratable acidity, the red color of skin and aril, and higher levels of total phenolics and total and specific anthocyanins compared to those obtained from the control group. These quality traits were maintained at higher levels during 60 days of preservation at 10 °C, and the most important effects were observed for 100 mM dose. In a 2020 experiment, GABA was sprayed at a 100 mM dose, and results were confirmed, showing a retard of the ripening process in pomegranates from GABA-treated trees concerning controls for two months of storage and an extension of their shelf life (with optimal quality traits appreciated by consumers) from 30 to 60 days. Moreover, the increase in anthocyanin content due to GABA treatments resulted in redder fruits, which would appeal more to consumers and have improved health benefits.

γ-aminobutyric acid (GABA) is a naturally occurring plant compound that acts as a signalling agent during stress conditions, mainly due to unstable events, although sometimes the endogenous content does not reach sufficient levels. Thus, the main aim of this study was to apply GABA preharvest treatments in lemon and to study its effects on quality attributes at harvest and during postharvest storage. GABA was applied as foliar spray at 10, 50, and 100 mM, and quality traits during 28 days of storage at two temperatures (at 2 and 10 °C) were determined. Results show that all GABA treatments had a positive effect on reducing the weight losses and fruit softening. In addition, crop yield in terms of kg tree⁻¹ and fruit number tree⁻¹ was improved for the first and second harvest as well as the total phenolics content and total antioxidant activity (TAA). In conclusion, GABA at 50 mM concentration was the most effective preharvest treatment, enhancing shelf life being enhanced for 14 and 7 days at 2 and 10 °C, respectively, with respect to control lemons.

γ-Aminobutyric acid (GABA) occurs naturally at a low concentration in fruits, but can be increased following several stress events, playing a physiological effect. Lemon trees were preharvest treated with GABA at three concentrations (10, 50, and 100 mM) during two consecutive seasons (2019–2020 and 2020–2021). Fruit growth (diameter) and crop yield (kg tree⁻¹ and number of fruits tree⁻¹) and quality traits were evaluated at harvest. Results showed that treatments were effective at increasing lemon size (a 5% higher) and yield, especially for GABA at 100 mM, for the two assayed seasons. Thus, yield was increased between 13 and 18% with respect to the control trees for the two harvest dates. With respect to the quality traits, GABA treatments did not impact any negative effects on the quality attributes, since the total soluble solids (7–8° Brix), total acidity (5–6 g 100 g⁻¹), and fruit firmness (13–14 N mm⁻¹) were similar to the control fruits. Therefore, GABA applied as preharvest treatment could be considered as a potent tool to enhance the yield of lemon fruits.

Pitahaya or dragon fruit is an exotic fruit native to Mesoamerica and is cultivated in several regions of the world. In recent years, pitahaya has become increasingly in demand, firstly, for its good nutritional and organoleptic qualities and, secondly, for its richness in antioxidants and bioactive compounds. Spain has opted for new tropical crops, and among them, pitahaya is one of the most planted in recent years. Most of the investigations on pitahaya were conducted with red cultivars, while the research on yellow pitahaya (Selenicereus megalanthus Haw.) is very scarce. In this review, the current knowledge about types of pitahayas, the fruit growth and ripening, the quality attributes, the postharvest storage, the use of by-products, and the health attributes were covered.