Apples (Malus domestica Borkh) are prone to preharvest fruit drop, which is more pronounced in ‘Honeycrisp’. Hexanal is known to improve fruit retention in several economically important crops. The effects of hexanal on the fruit retention of ‘Honeycrisp’ apples were assessed using physiological, biochemical, and transcriptomic approaches. Fruit retention and fruit firmness were significantly improved by hexanal, while sugars and fresh weight did not show a significant change in response to hexanal treatment. At commercial maturity, abscisic acid and melatonin levels were significantly lower in the treated fruit abscission zone (FAZ) compared to control. At this stage, a total of 726 differentially expressed genes (DEGs) were identified between treated and control FAZ. Functional classification of the DEGs showed that hexanal downregulated ethylene biosynthesis genes, such as S-adenosylmethionine synthase (SAM2) and 1-aminocyclopropane-1-carboxylic acid oxidases (ACO3, ACO4, and ACO4-like), while it upregulated the receptor genes ETR2 and ERS1. Genes related to ABA biosynthesis (FDPS and CLE25) were also downregulated. On the contrary, key genes involved in gibberellic acid biosynthesis (GA20OX-like and KO) were upregulated. Further, hexanal downregulated the expression of genes related to cell wall degrading enzymes, such as polygalacturonase (PG1), glucanases (endo-β-1,4-glucanase), and expansins (EXPA1-like, EXPA6, EXPA8, EXPA10-like, EXPA16-like). Our findings reveal that hexanal reduced the sensitivity of FAZ cells to ethylene and ABA. Simultaneously, hexanal maintained the cell wall integrity of FAZ cells by regulating genes involved in cell wall modifications. Thus, delayed fruit abscission by hexanal is most likely achieved by minimizing ABA through an ethylene-dependent mechanism.

Avocado is known to be a climacteric fruit that must be harvested during the suitable physiological maturity stage to achieve the best edible characteristics and reach the required export standards. It is very hard to visually determine the optimum maturity phases in the different avocado varieties for harvesting, especially because of the limited changes in the external fruit morphology during the maturity phase and because the harvest season is extended throughout several months. Therefore, some laboratory analyses are very crucial to determine the best timing to harvest the fruit. The aim of this study was to evaluate the postharvest maturity indices over 3 harvest stages, mainly dry matter (DM), oil content (OC), fruit firmness, titratable acidity (TA), total soluble solid (TSS/Brix), and fruit weight in commercial avocado varieties in regard to different altitudes and agricultural practices. The varieties in this study were as follows: Hass, Lambhass, Ettinger, Fuerte, Pinkerton, Reed, and Horshim growing at different altitudes that ranged from 50 to 400 m in 7 different regions in Lebanon. Statistical comparison of maturity indices under different locations by variety and harvest stage was performed using one-way ANOVA as well as by principal component analysis (PCA). The results showed a high linear correlation between DM and OC over the different harvest stages. During the late harvest stage, the weight showed a negative correlation between fruit firmness and TSS. The minimum oil content % and dry matter % were recorded for Reed variety (8.2 DM and 9.7 OC%) and the highest oil content % and dry matter % were recorded for Fuerte variety (28.5 DM and 21.6 OC%). The data obtained during this study are used to achieve the best edible characteristics and export standards of commercial avocado varieties growing along the Lebanese coast.

Salinity is one of the most destructive environmental challenges for citriculture worldwide, and all climate change scenarios are predicting an increased impact of salinity on citrus orchards. Citrus cultivars are grown as grafts on various rootstocks to provide specific adaptation to abiotic stress and tolerance to major diseases such as citrus tristeza virus. To understand rootstock–scion interactions with regard to salinity, transcriptome profiling of mRNA expression was analyzed for 12 candidate genes in leaves, shoots, and roots of five Hernandina clementine scions grafted on Rangpur lime (LR), Volkamer lemon (CV), Carrizo citrange (CC), sour orange (Big), and Cleopatra mandarin (MC) rootstocks in response to moderate and severe salinity. qRT-PCR analysis revealed differential gene expression that varied by rootstock, salinity level, and tissue. The majority of induced genes were those involved in ion transporter proteins (mainly NHX1 and HKT1 genes), Cl⁻ homeostasis (CCC1 gene), biosynthesis and accumulation of compatible osmolytes, proline (P5CS gene) and glycine betaine (CMO gene), accumulation of proteins (LEA2 gene), and ROS scavenging antioxidant activity (mainly APX). We show that these expression patterns could explain the relative tolerance of the used rootstocks and report new insights on the main salt tolerance mechanisms activated by these rootstocks.

A comparative study of two grapevine rootstocks with contrasting drought stress responses revealed that the drought-resilient RUG harbors an efficient antioxidant defense system, characterized by increased activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT), along with elevated proline (Pro) levels compared to the drought-sensitive MGT. This robust scavenging machinery enables RUG to maintain redox balance, effectively mitigating oxidative stress and preserving cellular integrity during drought. Anatomical evaluations showed severe xylem disruptions in MGT, including extensive tylosis, leading to leaf necrosis and impaired water transport. Conversely, RUG maintained a structurally intact and functional xylem, crucial for sustaining hydraulic conductivity and water supply during drought. The pronounced rise in Pro underscores its critical role in drought resilience, working synergistically with other cellular components to facilitate osmotic adjustment while detoxifying reactive oxygen species (ROS) and minimizing oxidative damage. Transcriptome profiling suggested that RUG displays sequential gene expression during drought driven by distinct molecular processes for photosynthesis, osmotic adjustment, and structural remodeling, a dynamic notably absent in MGT. These findings emphasize the complex interplay of osmotic and oxidative homeostasis in RUG, illustrating the adaptive mechanisms that contribute to its drought resilience, potentially guiding future rootstock selection and breeding strategies.

Sweet cherries (Prunus avium L.) are among the most important stone fruits in Lebanon. They are harvested between May and July; however, the introduction of new early varieties in low and medium altitudes (500–1000 m) and late varieties in higher altitudes (1800–2200 m) along with postharvest technologies can extend harvesting season. In this study, physicochemical characteristics along with total phenolic content, total anthocyanin content, and antioxidant activity of the most commercial cherry cultivars were evaluated at different altitudes to determine optimum harvesting time. Findings indicated that some varieties, such as “Teliani” and “Irani”, are more significantly impacted by altitude than the other varieties in terms of maturity indices. Duration of fruit development was prolonged with altitude, and in most instances, higher fresh weights and sizes were observed; however, fruit firmness decreased. While total phenolic content (expressed as gallic acid equivalent) did not significantly vary between varieties, the antioxidant activity (FRAP and DPPH assays) showed the lowest value in “Banni” and the total anthocyanin content showed the highest levels in “Irani” and ”Feraouni” and the lowest in “Mkahal” and “Banni”. Furthermore, total phenolic content and reduction of ferric complex (FRAP) were interestingly influenced by geographical locations, in contrast to total anthocyanin content and radical scavenging activity (DPPH) which were unaffected.

Table grapes are harvested based on well-known maturity indices that must be monitored after fruit veraison. The aim of this study was to assess these indices across multiple locations and environmental conditions, encompassing different table grape cultivars such as Black Pearl, Crimson Seedless, Superior Seedless, and Red Globe. For this reason, grape sampling was conducted across six distinct locations characterized by varying altitudes above sea level (m asl) and environmental conditions over the ripening season. The main maturity indices, including pH, sugar content, titratable acidity, berry firmness, and other parameters were monitored over the growing season. Moreover, the quantification of total polyphenols, total anthocyanins, and antioxidant activity was determined using spectrophotometric assays at harvesting. The study has examined the effect of the vineyard’s location on grape quality and its interaction with the cultivar and environment. Crimson Seedless maintained a relatively high level of acidity with altitude near harvesting. Black Pearl exhibited a notable decline in both sugar content and berry firmness as elevation increased, whereas Red Globe demonstrated contrasting outcomes. The optimal maturity of Superior Seedless was observed at an elevation of 1000 m asl. Black Pearl and Crimson Seedless exhibited better adaptability to intermediate elevations (650 and 950 m asl), while Red Globe and Superior Seedless showed better adaptability to higher elevations (1000–1150 m asl). Among the studied cultivars, Black Pearl exhibited significantly higher levels of total polyphenols and anthocyanins, while close values were noticed between red and green cultivars.