Background and Aims: Potassium (K) fertilization is vital for grapevine growth and development, as well as for the quality and yield of grape berries. However, conducting experimental field studies to learn about the nutritional demand for K in table grapes can be challenging due to significant K storage in the soil. We examined the effects of various K application levels on two table grape cultivars: the early-bearing green "Early Sweet," and the late-bearing red "Crimson," for three consecutive seasons. Methods and Results: Grapevines were grown in 500-L lysimeters filled with perlite and subjected to three K-fertigation treatments (15, 40, and 72 mg L-1 K). The lowest K level resulted in improved K-use efficiency (> 80%) in both cultivars across the three seasons. However, this efficiency came at the cost of reduced vegetative growth, reflected by reduced leaf area index, and decreased pruning weight in "Early Sweet." Stomatal conductance also declined under low K supply toward the end of the summer, underscoring this mineral's (elemental nutrient's) role in stomatal regulation. Together, these resulted in reduced daily water consumption. Low K supply resulted in lower fruit juice pH in the 2022 and 2023 seasons in "Crimson." Conversely, elevated K levels in 2023 and 2024 suppressed sugar accumulation in developing berries of both cultivars. Conclusions: Varying K fertilizer levels significantly affected vegetative growth, physiological processes, and berry sugar content of early- and late-bearing table grape cultivars. Significance of the Study: Optimization of K levels is essential for promoting growth, nutrient uptake, yield, and fruit quality in table grapes.

Berry cracking is one of the major problems that face grapevine production because it commonly leads to sour rot. Cracking is believed to be partially related to the plant water status, though direct evidence for this assumption is lacking. We hypothesized that deficit irrigation would reduce the berry firmness, leading to lower cracking and sour rot incidence. The research was conducted over three seasons (2023-2025) on 'Scarlotta Seedless' vines using four irrigation regimes that tested the effect of the irrigation dosage and timing on sour rot incidence. We followed the plant water status, berry weight, firmness and sour rot incidence. The low water treatments had lower stem water potential (Ψstem), berry size, firmness, and lower incidence of sour rot in a season-dependent manner. Water deficit only at pre-veraison or post-veraison stages were less effective in mitigating the cracking incidence compared with sustained water deficit. Positive correlation was obtained between Ψstem and firmness, and the correlation was even stronger when the seasonal integral of Ψstem was used, highlighting the instantaneous water balance is less critical in shaping firmness compared with the effect of the irrigation on berry development. Healthy clusters incidence was negatively correlated to firmness with a value of 2.47 N corresponding to 80% of the clusters free of sour rot. Our findings highlight, for the first time, the link between irrigation, firmness and cracking. Deficit irrigation could be a sustainable mitigation strategy for cracking and sour rot.

Medjool dates are in high demand but the level of microbial load can exceed thresholds set by some countries. The objective was therefore to identify methods to reduce the microbial load of Medjool dates after harvest without compromising its quality. Medjool dates were obtained after harvest from the same orchard over 2 seasons or from a packing house after 6 month of storage. The dates were treated with ethanol vapor, coldplasma applicator of hydrogen peroxide and a commercial formulation of peracetic acid and stored at 0 degrees C for one month or -18 degrees C for 6 month. In all experiments, treatment with ethanol vapor for 20 hours reduced fungal load by at least 2 orders of magnitude but had lower efficacy with respect to bacterial load. The ethanol vapor treatment was also effective when carried out after 6 month of storage at -18 degrees C. Treatment with hydrogen peroxide reduced bacterial load but showed potential for skin damage. Similar levels of external and total microbial load were measured suggesting that external contamination was dominant in asymptomatic fruit. Sequencing of microbial DNA from the date tissue showed that Aspergillus was the predominant fungal genus while Bacillus was the dominant bacterial genus after shelf life. The treatment with ethanol vapor changed the volatile profile of the dates but did not have an apparent influence of their flavor. The ethanol vapor treatment can be a useful tool to reduce microbial load in relevant postharvest systems.

'Orri' mandarin is the main citrus variety grown and exported from Israel. In the current study, we assessed the potential of utilizing large-scale preharvest and commercial packinghouse data to predict the postharvest storage performances of different sets of 'Orri' mandarins. For that purpose, we examined during 3 years (2022-2024), the postharvest performances of between 79 and 93 sets of 'Orri' mandarins per year after 2, 4 and 8 weeks storage at 5 degrees C and one-week at shelf life at 22 degrees C. The observed preharvest data consisted climatic features (amounts of rain and warm days) and horticultural features (harvest time, tree age, yield, and soil type), and the observed packinghouse data consisted ripening features (total soluble solids, acidity and juice contents) and packing line quality evaluation features (occurrences of various defects and packaging rates). Consolidating the observed preharvest and packinghouse data with the postharvest storage data using machine learning algorithms, allowed the prediction of decay percentages by an R2 of 0.60 and RMSE of 10.56 %, and of fruit quality acceptance score by an R2 of 0.74 and RMSE of 0.57 on a quality scale from 1 (very bad) to 5 (excellent). The development of fruit quality prediction models based on preharvest and packinghouse data can assist in the future implementation of intelligent logistic management system that will allow to direct specific fruit sets to different market destinations based on their predicted shelf life's, thus assuring that only high-quality produce will arrive at the recipient markets.

Evaluation of phosphorus (P) level is vital for vineyard management; however, our current understanding of how P supply affects table grapes, particularly growth, productivity, and quality parameters, is limited. We investigated the influence of various P-application levels on two table grape cultivars: the early-bearing white 'Early Sweet' and the late-bearing red 'Crimson'. During two consecutive seasons, grapevines were grown in 500-L lysimeters with perlite as the growth medium and subjected to three P-fertigation treatments (1, 5 and 15 mg L-1 P). High P-utilization efficiency (>90 %) was achieved for 1 and 5 mg L-1 P. Levels of P application were reflected in the P levels of diagnostic leaves, with blade analysis providing more consistent results than petiole analysis. Increased P supply reduced sugar accumulation in developing fruit. Primary cluster number was reduced with increased P supply for 'Crimson' vines in 2022. Low P caused a reduction in SPAD in leaves toward the end of the summer, indicating the importance of P for chlorophyll stability. In addition, low levels of P led to reduced vegetative growth, as reflected in evapotranspiration and leaf area index in 'Early Sweet' and in the dry pruning weight of both cultivars. Precise P management in 'Early Sweet' and 'Crimson' may increase growth, yield, and fruit quality, and will enable better P-utilization efficiency, thereby reducing costs and environmental contamination.

Although the optimal storage conditions for grapes are well-established, deviations can occur in commercial settings. Our goal was to study the extent to which these deviations will affect grape properties, and if this can be effectively modeled. In the first year, we focused on how constant temperature shifts affect grape properties; in the second, on how temperature interruptions in the first period of storage influence fruit quality. The main features quantified were weight loss, rachis browning, decay, firmness, bleaching, and cracking. With respect to a 2% threshold of decay, 0 ºC enabled storage for 9 weeks, 3 ºC for 6 weeks, and 6 ºC for 3 weeks, all plus 3 d of shelf life, suggesting that storage temperature can be modified according to storage duration. Notably, temperature interruptions in the initial storage period demonstrated that the temperature of the interruption has a more significant impact on fruit quality than the duration of the interruption, particularly for weight loss and decay. Feature-importance analysis identified storage time as the primary factor influencing postharvest quality, but it highlighted the role of additional features as well. Dynamic models such as XGBoost consistently outperformed linear regression models in predicting both acceptance and rachis browning scores, but the latter had better R2 values. Results suggest that deviations from optimal storage conditions should be considered in future quality predictions and logistics management of grapes.

Table grape production requires adequate nitrogen (N) supply to sustain vine performance and obtain high yields. However, excess agricultural N fertilization is a major source of groundwater contamination and air pollution. Therefore, there is a strong need for empirically based precision N fertilization schemes in vineyards, for optimizing grape yield and quality while minimizing their environmental impact. Our aim was to unequivocally quantify table grape N requirements, elucidate the drivers of daily N uptake, and quantify the relationship between fertigation N levels and vine growth, fruit yield, composition, and quality. For this, forty 'Early Sweet' (early-maturing, white) and 'Crimson seedless' (late-maturing, red) vines were grown in 500L drainage-lysimeters for 2 fruiting seasons, while subjected to five continuous N fertigation treatments ranging from 10 to 200 ppm. Irrigation and drainage volume and macronutrient concentrations were measured bi-weekly. Vegetative growth, leaf mineral composition, and fruit ripening were monitored, and the fruit harvested and analyzed for quality-related parameters. Vine temporal N uptake across seasons and treatments was largely driven by N availability and water uptake, independently of fruit phenology. N levels affected the composition of other macro and micro-nutrients in diagnostic tissues. A dose-dependent effect of N on plant growth, fruit ripening, yield, and fruit size and composition highlighted doses that improve both yield and quality, and nitrogen use efficiency. Our findings lay the basis for data-driven precision N nutrition in vineyards for optimizing yield, fruit quality, and the environmental sustainability of commercial vineyards.

The optimal temperature for postharvest storage of 'Rustenburg' navel oranges is 5 ºC, and any deviations from this temperature may harm fruit quality. The goals of the current study were to examine the effects of different temperature interruptions on the quality of stored 'Rustenburg' navel oranges, and to develop a dynamic fruit-quality prediction model that takes into account any deviations from the optimal storage temperature. The temperature interruptions included exposures to a temperature of 22 ºC for different lengths of time (1, 3 or 7 d) at different time points during the cold-storage period (after 4, 8 or 12 w). The experiment included 126 cartons of 30 fruit each, which were stored under different temperature-interruption regimes. Quality evaluations were conducted every 4 w during a prolonged storage period of up to 24 w. Storage time appeared to be the most important feature affecting fruit quality, followed by the length and the timing of the temperature interruptions. Statistical analysis revealed that storage time significantly affected most of the examined quality parameters; whereas the duration and timing of the temperature interruptions significantly affected fruit weight loss, firmness, internal dryness, shriveling, flavor and quality-acceptance scores. Overall, the longer the temperature interruptions and the later during storage they were applied, the more harmful they were for fruit quality. The collected data was further used to develop dynamic quality-prediction models. It was found that an extreme gradient boosting (XGBoost) model allowed the prediction of fruit acceptance score on a scale of 1–5 with a root mean square error (RMSE) of 0.233 and R2 of 0.876. The XGBoost model also effectively predicted fruit quality at various fictive data points within and outside the tested data set, including different durations and timings of temperature interruptions during the cold-storage period. Dynamic quality-prediction models that consider storage interruptions will assist in assuring produce quality and reducing food losses.

Fast-melting peaches have a shelf life of only 3-4 d due to their rapid softening, and this poses a problem in marketing and consumer acceptability. A postharvest 22 h treatment at 20 degrees C of low oxygen (<1%) or 2 mu l L-1 1-methylcyclopropene (1-MCP) was applied to delay softening. 1-MCP was ineffective, but the anaerobic stress delayed softening as expressed by texture measurements, ethylene levels, and chlorophyll index values. Taste panels showed a preference for untreated fruit of the same firmness as treated fruit, probably due to off-flavors volatiles evaporation. Nevertheless, consumer acceptance of treated fruit was high after 3 d at 20 C and 4 d of cold storage, while control fruit was too soft to be sampled. Volatile compounds were analyzed on control and low oxygen-treated fruit following treatment and 48 h later. Forty-eight compounds were identified, and thirty-nine significantly differed among all four conditions. Eleven volatile compounds associated with anaerobic conditions increased in the low oxygen treatment after 72 h. However, the low oxygen treatment did not affect most ripening-related peach fruit volatiles, primarily lactones. It is hypothesized that these compounds dimin-ished the perception of off-flavors associated with the anaerobic volatiles. This simple low oxygen treatment demonstrates promising results in delaying softening and extending the market life of fast-ripening peaches.

The optimal conditions and duration of storage of fresh produce has been the subject of ongoing effort for many decades. In practice, variable fruit quality at harvest and deviation from the optimal temperature can cause substantial losses. It is therefore of interest to use computational tools to account for the reduction of quality considering both the initial quality and the time-temperature variables. Supervised machine learning models require large data sets. To that end, 2204 clusters of grapes were scored for quality features at harvest, packed in standard commercial format, and examined every 3 weeks during 3 months of cold storage. Grapes could be effectively stored free of decay for 3 weeks at 6 degrees C, 6 weeks at 3 degrees C, and 9 weeks at 0 degrees C. The level of decay at harvest in 9 vineyards was associated with the level of decay after 9 weeks of storage suggesting that this is an important predictor of storage quality. The data presented in this research will assist in taking into account the effects of deviations from optimal storage temperature and the potential outcomes of storage of grapes from vineyards suffering from high sour rot incidence.

Phenolics are ubiquitous compounds that represent the most abundant and diverse class of plant metabolites. From an analytical point of view, phenolics can be divided into soluble phenolics such as phenolic acids, phenylpropanoids, flavonoids and quinones, and nonsoluble compounds such as proanthocyanidins, lignins, and cell wall-bound hydroxycinnamic acids. Extraction of phenolics from the sample material is the first step toward their analysis. Biochemical methods for determination of total phenolics content were widely used in the past but modern chromatographic and mass spectrometric methods for identification and quantification of individual compounds are available in recent years. In this chapter, we describe methods for phenolic compounds extraction used in our laboratories from berries of Vitis vinifera and analytical methods including HPLC coupled to DAD detector and Q-TOF LC/MS for their analysis.

Cytokinin and gibberellin are plant growth regulators (PGRs) used to increase berry size in seedless table grapes but their effects on wine grape phenolics and volatiles was not studied. In the current study, gibberellic acid (GA3) and synthetic cytokinin forchlorfenuron (CPPU) and their combination were applied to fruitlets of Sangiovese and berries were sampled 79 days following application. All the treatment significantly increase berry diameter and berry weight and CPPU containing treatment increased skin thickness. All treatments reduced sugar accumulation and color development but did not have an effect on acid levels. HPLC analysis showed that total flavan-3-ols level was increased by CPPU, GA containing treatments reduced the levels of flavonols and anthocyanins were significantly reduced in all the treatment (≈50%). Phloroglucinol analysis showed that proanthocyanidins level were significantly increased whereas the mean degree of polymerization was reduced from 40 to ≈21 by all the treatments. GC–MS analysis of berries showed a decrease in fatty acid derived volatile compounds by all treatments with potential impact on flavor. Analysis of wine phenolics in subsequent harvest was in general agreement with the previous results. In summary, this study provides new information on how PGRs can change berry composition and subsequently wine attributes.

We conducted a large-scale, high-throughput phenotyping analysis of the effects of various preharvest and postharvest features on the quality of ‘Valencia’ oranges in order to develop shelf-life prediction models. Altogether, we evaluated 10,800 oranges (~3.6 tons) harvested from three orchards at different periods and conducted 151,200 measurements of 14 quality parameters. The storage time was the most important feature affecting fruit quality, followed by the yield, storage temperature, humidity, and harvest time. The storage time and temperature features significantly affected (p < 0.001) all or most of the tested quality parameters, whereas the harvest time, yield, and humidity conditions significantly affected several particular quality parameters, and the selection of rootstocks had no significant effect at all. Five regression models were evaluated for their ability to predict fruit quality based on preharvest and postharvest features. Non-linear Support Vector Regression (SVR) combined with a data-balancing approach was found to be the most effective approach. It allowed the prediction of fruit-acceptance scores among the full data set, with a root mean square error (RMSE) of 0.195 and an R2 of 0.884. The obtained data and models should assist in determining the potential storage times of different batches of fruit.

The grapevine is an economically important plant, with a historical connection to the development of human culture. Currently, over 6000 accessions are known as individual grapevine varieties, some of which are important to national heritage, valuable for current viticultural practices, and as genetic resources to maintain plasticity under changing climatic conditions, environmental sustainability, and market demands. Recently, the diversity of cultivated grapevines has declined significantly, due to the increased focus of global wine industries on a few major cultivars. Moreover, due to biotic and abiotic stresses, the wild V. vinifera germplasm’s genetic diversity has declined, with some varieties on the verge of extinction. Vitis germplasm conservation can be achieved via either in situ (e.g., protected areas) or Ex situ (e.g., field collections, seed banks, and tissue culture collections) methods. This study aims to highlight the importance of Vitis field bank collections. We demonstrate the research done in the Israeli indigenous Vitis vinifera collection. The multi-layer analysis of the varieties enabled the identification of drought stress-resistant varieties, and suggested a mechanism for this resistance through noting the dramatic phenological differences in foliage development between resistant and sensitive varieties. In addition, we show a general characterization of the varieties via major grape characteristics, including bunch and berry shape, as well as their possible utilization based on their aromatic and phenolic profiles.

At harvest, table grape clusters may seem intact but can suffer from unacceptable levels of decay by Botrytis cinerea after storage. Sour rot is a disease complex that initiates from cracked or injured berries in which yeast and acetic acid bacteria develop, and the disease is propagated by Drosophila flies. Initial results from storage of grapes with and without microcracks showed that the latter had a low level of postharvest decay. Evaluation of the incidence of sour rot in nine Vitis vinifera cv. Scarlotta vineyards showed a range of 2–41% after veraison and 27–83% on day of harvest. Clusters from those vineyards that were free of sour rot symptoms were stored for 9 weeks with SO2 sheets followed by 3 d of shelf life. Decay levels after storage ranged from 3% to 15%, with the highest incidence of decay encountered in grapes from vineyards with the highest level of sour rot at harvest. The correlation coefficient between the sour rot index and Botrytis decay after storage was 0.32 and 0.25 for the evaluations at veraison and harvest, respectively, with significant P values. Further strengthening of these results was obtained by sampling of two vineyards with low and high incidence of sour rot that displayed a 10-fold reduction in Botrytis decay after storage. These results suggest that sour rot in the vineyard can be an important indicator for decay development during storage.

We conducted a large-scale, high-throughput phenotyping analysis of the effects of various pre-harvest and postharvest features on the quality of ‘Rustenburg’ navel oranges, in order to develop shelf-life prediction models to enable the use of the First Expired, First Out logistics strategy. The examined pre-harvest features included harvest time and yield, and the examined postharvest features included storage temperature, relative humidity during storage and duration of storage. All together, we evaluated 12,000 oranges (~4 tons) from six different orchards and conducted 170,576 measurements of 14 quality parameters. Storage time was found to be the most important feature affecting fruit quality, followed by storage temperature, harvest time, yield and humidity. The examined features significantly affected (p < 0.001) fruit weight loss, firmness, decay, color, peel damage, chilling injury, internal dryness, acidity, vitamin C and ethanol levels, and flavor and acceptance scores. Four regression models were evaluated for their ability to predict fruit quality based on pre-harvest and postharvest features. Extreme gradient boosting (XGBoost) combined with a duplication approach was found to be the most effective approach. It allowed for the prediction of fruit-acceptance scores among the full data set, with a root mean square error (RMSE) of 0.217 and an R2 of 0.891.

Cytokinin and gibberellic acid (GA) are growth regulators used to increase berry size in seedless grapes and it is of interest to understand their effects on the phenylpropanoid pathway and on ripening processes. GA 3 and synthetic cytokinin forchlorfenuron (N-(2-chloro-4-pyridyl)-N′-phenylurea, CPPU) and their combination were applied to 6 mm diameter fruitlets of ‘Sable Seedless’, and berries were sampled 51 and 70 days (d) following application. All treatments increased berry size and delayed sugar accumulation and acid degradation with a stronger effect of CPPU. CPPU, but not GA, reduced berry color and the levels of anthocyanins. While CPPU reduced the levels of anthocyanins by more than 50%, the combined treatment of GA+CPPU reduced the levels by about 25% at 51 d. CPPU treatment had minor effects on flavonols content but increased the levels of monomeric flavan-3-ols by more than two-fold. Phloroglucinol analysis using HPLC showed that proanthocyanidin content was significantly increased by CPPU, whereas mean degree of polymerization was reduced from 26 to 19. Volatile analysis by GC-MS showed changes in composition with CPPU or GA treatment with potential impact on flavor. RNA-seq analysis showed that GA had a minor overall effect on the transcriptome whereas CPPU had pronounced effects on gene expression at both 51 and 70 d. Comparing the control and CPPU at similar Brix of ca. 19.7°, a reduced expression of stilbene synthases (STSs) including their regulators MYB14 and MYB15 , and other phenylpropanoid-related genes was observed in CPPU-treated grapes. Overall, our study shows that CPPU had a major influence on the phenylpropanoid pathway and affected multiple ripening-related processes.

Dark-grown (etiolated) branches of many recalcitrant plant species root better than their green counterparts. Here it was hypothesized that changes in cell-wall properties and hormones occurring during etiolation contribute to rooting efficiency. Measurements of chlorophyll, carbohydrate and auxin contents, as well as tissue compression, histological analysis and gene-expression profiles were determined in etiolated and de-etiolated branches of the avocado rootstock VC801. Differences in chlorophyll content and tissue rigidity, and changes in xyloglucan and pectin in cambium and parenchyma cells were found. Interestingly, lignin and sugar contents were similar, suggesting that de-etiolated branches resemble the etiolated ones in this respect. Surprisingly, the branches that underwent short de-etiolation rooted better than the etiolated ones, and only a slight difference in IAA content between the two was observed. Gene-expression profiles revealed an increase in ethylene-responsive transcripts in the etiolated branches, which correlated with enrichment in xyloglucan hydrolases. In contrast, transcripts encoding pectin methylesterase and pectolyases were enriched in the de-etiolated branches. Taken together, it seems that the short de-etiolation period led to fine tuning of the conditions favoring adventitious root formation in terms of auxin–ethylene balance and cell-wall properties.

Consumers expect ready-to-eat grapes to have excellent quality and flavor. In practice, most table grape cultivars have a neutral flavor relying mainly on the combination of sugar and acidity due to limited levels of volatiles that impart the unique aromas. This study investigated the possibility of improving grape flavor by incubating the berries in monoterpene-enriched modified atmosphere. The berries were sanitized by dipping in ethanol and packaged in trays sealed with plastic films of different perforation levels. The optimal conditions selected for further study were one micro-perforation per package containing 250 g berries and storage at 5 degrees C for 2 weeks. To test the possibility of improving grape flavor during storage, berries of the cultivars Flame Seedless, Adominique, 4111 and Crimson Seedless were stored in the presence of the monoterpenes linalool or geraniol. After two weeks of storage in the presence of linalool, it accumulated in the berries to levels of 551, 704 and 3273 mu g kg(-1) in Adominique, 4111 and Crimson Seedless, respectively. Application of linalool or geraniol resulted in appearance of many other monoterpenes, probably by the action of endogenous enzymes. Organoleptic preference assays indicated that berries of Adominique and 4111 stored in the presence of linalool were favored over the control berries. Overall, the results demonstrate the feasibility of using monoterpenes to enhance berry flavor during storage.