ASHS 2025 Conference

With populations rising and cities expanding, it is necessary to consider new ways to supplement current energy and food systems. Urban agriculture has the potential to enhance food systems, energy production and stormwater management within urban areas. This can be achieved by implementing rooftop agrivoltaics (RAV), a combination of rooftops, agriculture, and photovoltaics. This study evaluates the growth and yield of leafy greens in RAV by examining how shade from photovoltaic arrays influences leafy green production. An RAV system was built at the CSU Spur Campus in Denver, Colorado, featuring a 45 cm deep substrate and three treatments: full sun, opaque silicon PV modules, and bifacial silicon PV modules. Leafy greens—arugula, kale, lettuce, spinach, and Swiss chard—were germinated and transplanted in randomized rows, with environmental conditions monitored continuously using HOBO sensors. Fresh weight, dry weight, stomatal conductance, and plant size at harvest were collected, and statistical analysis was conducted using two-way ANOVA to assess the effects of the treatments on each crop type. Leafy greens grown under the PV treatments had reduced stomatal conductance compared to the full sun treatment. The plant size at harvest was also higher in lettuce and spinach grown under the PV module treatments compared to the full sun. Fresh and dry weight of plants grown under the opaque and bifacial PV module treatments, however, were reduced compared to the full sun treatment. By understanding these interactions, the research aims to determine the feasibility of RAV systems for urban agriculture.

Extensive green roof mediums are shallow with low nutrient content and oftentimes susceptible to rapid drainage, which results in the use of concentrated synthetic fertilizers that can have a negative affect on runoff water quality. Therefore, a study was conducted on ‘Sweet Hungarian’ pepper (Capsicum annuum) over three growing seasons to compare organic and conventional synthetic fertilizers at manufacturer recommended rates for their impacts on fruit yield, leaf chlorophyll content (SPAD), and plant vigor on a green roof having an expanded clay medium. The fast release synthetic fertilizer utilized produced the highest yield per unit fertilizer cost while the controlled release synthetic fertilizer had the highest overall yield but at much higher cost compared to other treatments. Bloodmeal had the highest yield among organic treatments and was similar to the fast release synthetic. Although SPAD was correlated with yield differences among treatments, plant vigor rating better explained these variations in yield. Pre and post growing season medium analyses revealed several interesting trends over the three-years of the study regarding pH, soil organic matter and nutrient contents that will be reviewed in detail. Additionally, an analysis of yield tradeoffs with fertilizer product costs among several popular organic and synthetic fertilizers for a nutrient-demanding crop grown in an extensive green roof environment will also be discussed. Green roof agriculture is a promising solution to enhance sustainability, especially where growing space is limited, but nutrient management is an important part of this system that needs to be sufficiently considered.

Urban agriculture is important to provide sources of local food for urban residents. Extensive green roofs can be used to provide spaces for local agriculture in these urban environments, although extreme conditions in these environments can be challenging for edible crop production. Moisture in these environments are often the most limiting factor influencing growth and often create problems for urban agriculture activities. Therefore, two culinary herb experiments were conducted on the Southern Illinois University – Carbondale extensive green roof located on top of the agriculture building to evaluate the influences of various water management strategies on resulting plant growth and overwintering. Results indicated weekly irrigation was critical to increase both annual (basil) and perennial (sage and thyme) plant vigor compared to biweekly watering. Although the use of pine bark mulch improved basil growth, sage and thyme growth was not affected by its use. The addition of hydrogels in the medium for water retention did not influence resulting plant growth for either the annual or perennial herbs evaluated. Our results highlight the importance of consistent water supply for growth and overwintering success for both annual and perennial culinary herbs grown in an extensive green roof environment. Although many culinary herbs thrive in dry, well-drained conditions, mimicking their native Mediterranean climate, water management strategies are still important considerations for sustaining culinary herb production on extensive green roofs.

Fresh local produce is often limiting in densely populated cities, resulting in unhealthy food option for urban residents. Roof tops are underutilized spaces that can be used to help supplement production of fresh edibles for urban consumers. Peppers are used in a variety of cuisines and desired by many consumers in urban areas. Therefore, three pepper (Capisum annuum) varieties (San Joaquin, Red Impact, and Pot-a-Peno) having different growth habits and fruit types were compared with the application of a pine bark mulch or no mulch for resulting growth and yields in the extensive green roof environment located atop the Southern Illinois University-Carbondale Agriculture Building. Growth characters were collected during early-, mid-, and late-season, while fruit were harvested at 4-week intervals six times through the growing season. Pepper variety and mulch use did not generally influence (P > 0.05) leaf chlorophyll content or plant vigor at any timing. Marketable fruit yields differed (P < 0.05) among varieties, with ‘San Joaquin’ having higher fruit numbers than ‘Red Impact’ and weights greater than ‘Red Impact’, and ‘Pot-a-Peno’. Pepper plant vigor, leaf chlorophyll content and yield results indicate that this crop can be effectively grown in an extensive green roof environment with proper variety selection although mulch use was not beneficial. These results will be further discussed regarding the use of pepper as an edible crop in extensive greenroof environments.

Urban farmers across Indiana are facing the effects of rising fertilizer, chemical, and energy prices. In this climate, soil health has emerged as a top priority. In a 2023 statewide survey of Indiana urban farmers, 91.6% expressed interest in learning more about improving soil health (n=81), underscoring a strong desire for practical, sustainable strategies that reduce costs and boost productivity. Cover crops and compost application represent two fundamental approaches to improving soil health and fertility. Implementing cover crops and incorporating compost are essential practices for regenerating and maintaining healthy soil ecosystems. Farmers seeking to enhance soil vitality often rely on two primary methods: planting cover crops and applying compost. Soil health can be significantly improved through the integration of cover cropping systems and regular compost applications. hairy vetch, sunn hemp, rye, and mustard, are gaining traction as an alternative or complement to compost. These crops can trap nitrogen, build organic matter, and improve water retention, which are relevant benefits in compacted, nutrient-depleted, and low-organic-matter soils common in urban spaces. However, barriers like limited space, short-term leases, and concerns about short-term yield reduction can make adoption difficult for small-scale growers. When managed properly, composting transforms organic waste like food scraps, straw, and manure into a slow-release soil amendment that boosts organic matter, microbial life, and nutrient retention. However, not all compost is created equal. Overapplication, especially of manure-based compost, can lead to nutrient imbalances, phosphorus buildup, nitrate leaching, and elevated pH, which may reduce yields. Urban farmers are encouraged to test compost for nutrient content and monitor soil health regularly to guide application timing and rates. The Soil to Market project, an ongoing Purdue-led study launched in 2021, is evaluating cover crop and compost combinations at multiple Indiana locations. At the Meigs Purdue Agriculture Center in Lafayette, IN, cover crops alone, particularly sorghum and sunn hemp, did not significantly increase total available phosphorus (P). In contrast, compost treatments, especially high volume (2 yd³), manure-based applications, resulted in statistically significant increases in soil P, with mean values ranging from 280 to 365 mg/kg. These treatments highlight potential effectiveness in improving P availability in nutrient-depleted, urban soils. However, high phosphorus levels in compost treatments highlight the need for careful, adaptive management in sensitive environments, such as near waterways due to the increased risk of P runoff or leaching. Management of application timing, placement, and rates is crucial to maximize benefits while minimizing environmental impacts on urban farms.

Open to all attendees.

Bacterial spot, caused by Xanthomonas arbicola pv. pruni, is considered an economically important disease of peach and other stone fruit. In peaches, bacterial spot can affect leaves, twigs, and fruit. The disease can cause slight to nearly complete defoliation of infected trees. When significant defoliation occurs early in the season, fruit size can be reduced. In more severe cases, fruit may become infected. Small water-soaked spots can develop on the fruit at any time during fruit development. Early infection is the most concerning because unsightly cratering or pitting on the fruit can occur. Copper based fungicides are the main product used to manage bacterial spot in peaches and are associated with the potential for elevated phytotoxicity. This damage to the leaves resembles the actual disease and can cause defoliation in severe cases. Bacteriophage technology employs viruses that specifically infect bacteria offering a targeted approach to managing bacterial spot without the risk of phytotoxicity. The efficacy of these products have not been widely tested in the southeastern United States. The objective of this study was to determine the optimal timing during the growing season for applying a bacteriophage product in Central Alabama to achieve control of bacterial spot that is comparable to or better than a traditional copper-based spray program. A study was conducted at the Chilton Research and Extension Center in Clanton, AL. Treatments were applied to single tree replications and each treatment was replicated four times. The study followed a randomized complete block design. The control treatment (standard protocol) consisted of a copper-based product applied at each phenological stage. Bacteriophage treatments consisted of applications of the bacteriophage at select phenological stages in place of the copper-based product. Treatments were applied weekly. The entire canopy of each treatment tree was rated for incidence of bacterial spot every two weeks. At harvest, fruit were separated by degree of bacterial spot infection, counted, and weighed. Applications of bacteriophage during specific phenological stages—such as from pink to open bloom, delayed dormant to early bud swell, and from petal fall to early shuck split—were associated with the lowest incidence of foliar bacterial spot. Across all bacteriophage treatments, most fruit exhibited only mild symptoms and remained marketable. These findings suggest that targeted application timing may improve bacteriophage efficacy, though additional studies are needed to validate and optimize these strategies.

Sweet cider serves as both a fresh juice product and a precursor for hard cider production and is an important facet of agrotourism within the apple industry in the U.S. In this study, juice characteristics and physiological traits of apple cultivars developed by the Midwest Apple Improvement Association (MAIA) and apple cultivars bred at Iowa State University (ISU) by Spencer Ambrose Beach were compared to an industry-standard cultivar for sweet cider quality from 2022 to 2024. Given the historical and economic significance of apple production in Iowa during the early 1900s and its subsequent decline due to multiple factors, including a devastating winter storm that killed thousands of apple trees, this research examines the potential for regionally bred cultivars to compete with established industry standards. Juice quality parameters were analyzed, including pH, Brix, titratable acidity (TA), sorbitol content, nutritional composition, and oxidation rates. Flowering and harvest dates were assessed to determine the impact of climatic risks like spring and fall freezes, which are typical weather occurrences and concerns for apple growers in the Midwest during bloom and harvest periods, respectively, on production timing and feasibility. Preliminary findings indicate that Secor (ISU) demonstrated comparable juice quality metrics to the industry standard GoldRush and ranked highest in sensory preference evaluations. Sweet Zinger (MAIA) also received high consumer preference scores, suggesting promise as a regionally bred apple that is marketable both as a fresh-eating or cider apple. One cultivar, the Original Delicious (Iowa), scored the lowest consistently in consumer preference. While having relatively high Brix, it lacked acidity, with a pH of 4.0. GoldRush, a preferred cultivar, had a pH value of 3.2, suggesting the need for blending with more acidic cultivars to optimize cider quality. These findings provide insight into the quality and economic viability of regionally bred cultivars and their potential role in strengthening the cider industry in the U.S. Midwest.

Traditional cider apples are typically classified by their sugar, acid, and phenolic composition and concentration, which all impact the sensory profile and fermentation characteristics of the final beverage. Despite the practical importance of these traits, the genetic basis underlying cider apple fruit quality remains poorly understood and few functional genetic markers have been successfully adapted for cider apple breeding. Using a genome-wide association study (GWAS) on 253 cider apple accessions from the USDA-Plant Genetic Resources Unit Malus collection held in Geneva, NY, we found 19 significant marker-trait associations for titratable acidity, pH, total polyphenols, and non-structural carbohydrates. Notably, we identified a distinct marker on chromosome 15 strongly associated with total polyphenols, a key determinant of bitterness and astringency. A major association on chromosome 16, near the Ma1 locus, explained a substantial proportion of the phenotypic variance for titratable acidity and pH, confirming the importance of this region. Significant marker-trait associations were detected for sugar concentration on chromosomes 1, 6, 8, and 10. Further analysis confirmed identification of favorable alleles for titratable acidity, total polyphenols, glucose and sucrose concentration. These results provide a foundation for identifying apple cultivars with desirable phenotypic traits for cider production from germplasm collections and for making marker assisted selections within breeding programs.

The Foraged Fruit Project began in 2021 and involves researchers from Cornell and Rutgers Universities, with support from the New York Cider Association and funding from the David M. Einhorn Center for Community Engagement. The aim of this project was to better understand the practice of foraging in New York through a transdisciplinary lens, which includes ethnographic interviews, genetic identification of apple trees, and fruit quality assessments of the foraged apples. Over 30 commercial cider producers were interviewed for this study and we analyzed fruit samples from nearly 50 different trees. Seventy-eight percent of the submitted samples were unique apple genotypes, meaning there was no match among the thousands of samples in the MyFruitTree reference panel managed by Washington State University. According to the Long Ashton Research Station’s cider apple classification, 45% of the apple samples were bittersharp, 14% were bittersweet, 35% were sharp, and 6% were sweet. Based on these data, New York cider producers are largely foraging for high tannin and high acid apples which are difficult to procure from commercial apple producers in the region. Common themes revealed through the ethnographic interviews related to climate change resiliency, reparation for indigenous groups, intellectual property control, discovering unique genetics, and access to public and private lands. By studying these factors, we sought to better support the practice of foraging, unlock unique apple genetics that can benefit growers in a rapidly changing climate, and increase the profitability and uniqueness of New York cider.

Modern apple production has moved from traditional open orchard formats to that of high-density trellised plantings. As industry has shifted, the number of trees in commercial apple orchards typically reaches 1,500 per acre, making the management of these orchard blocks on a per-tree basis impractical. The use of unmanned aerial vehicles (UAVs) in the form of portable drones offers a method for collecting image data for thousands of trees in a matter of minutes. Combining these UAVs with multispectral cameras, which collect visual data on spectra that the human eye cannot perceive, allows for the calculation of vegetation indices (VIs) such as the normalized difference vegetation index (NDVI) for individual trees. Many VIs correlate with important orchard management considerations such as tree vigor, nutrient status, and disease severity. Multiple challenges hinder the incorporation of VIs into orchard management: parsing data on a per-tree basis is challenging in high-density systems, there is no comprehensive understanding of how VIs vary across a growing season and between cultivars, and at what magnitude deviation from expected norms is indicative of a weak tree is uncertain. This experiment aimed to classify this variation in VIs by examining a large cohort of cultivars at multiple timepoints and sites. A DJI Mavic 3M equipped with a 4-channel (green, red, red edge, and near infrared) multispectral camera was used to perform flights at both commercial and research orchards in upstate New York. Orthomosaics of each site were created using Agisoft Metashape and analyzed in QGIS and R (using the FIELDimageR package). Results showed statistically significant differences in VI values between cultivars and timepoints. These differences increased in intensity later in the growing season- in September, differences in cultivar explained 40% of the observed variance in NDVI at one orchard site, compared to only 19% in July.

Understanding the dynamics of oxidative stress during the growth of strawberry fruits is essential for optimizing fruit yield, quality, and shelf life. By strategically targeting reactive oxygen species (ROS) generation and the antioxidant defense mechanisms across various developmental stages, researchers and producers can refine cultivation practices, resulting in healthier and more flavorful strawberries. Strawberry fruits were categorized into six distinct developmental and ripening stages: small-size green fruits (S1, indicating the early stage of development), medium-size green fruits (S2, characterized by continued growth and elongation), full-size green fruits (S3, where the fruit attains its final size), white fruits (S4), turning-stage pink fruits (S5), and fully matured red fruits (S6). To evaluate the influence of oxidative stress and antioxidant defenses throughout the growth phases, several parameters were analyzed. These included hydrogen peroxide (H2O2), malondialdehyde (MDA), superoxide dismutase (SOD), lipoxygenase (LOX), catalase (CAT), guaiacol peroxidase (GPOD), ascorbate peroxidase (APOD), glutathione reductase (GR), and glutathione-S-transferase (GST). The levels of H2O2 and MDA exhibited variation across the different developmental stages. SOD and POD activities demonstrated an initial increase followed by a decline, while CAT and APOD levels showed a decrease in the later stages of fruit development. Additionally, LOX activity was elevated in the early developmental stages and declined as maturation progressed. The intricate role of oxidative stress in strawberry fruit growth highlights its significance for improving cultivation methods and post-harvest management. This understanding not only contributes to delivering superior-quality strawberries to consumers but also promotes sustainable agricultural practices.

Many low-lying coastal areas worldwide, including Florida, experience soil salinization due to tropical rainstorms, storm surges that cause superficial flooding with saline water, and groundwater salinization from saltwater intrusion. Additionally, excessive fertilizer applications can increase soil salinization, which can reduce the productivity of soil and affect crop growth. This study evaluated the response to salinity stress of two peach rootstocks: 1) Flordaguard, the current recommended rootstock in Florida, and 2) MP-29, a peach-plum hybrid rootstock with the potential to be recommended in the state. A total of 60 plants were distributed in five blocks and exposed to three salinity levels (0, 75, and 150 µM NaCl) for 24 days in a greenhouse. Photosynthetic rate (A), stomatal conductance (gs), and efficiency of photosystem II (ΦPSII) were recorded every other day. Stem water potential (Ψs) and foliar nutrient concentrations were assessed at the end of the experiment. A decline in A level was observed in all plants over time, with a higher reduction under salinity treatments. Starting 16 days after treatment, gs was significantly lower in plantlets exposed to 150 µM NaCl compared to controls. Interestingly, ΦPSII was more stable in Flordaguard plants during the experiment. Moreover, ΦPSII response suggested higher sensitivity to salinity in MP-29 plants. Similarly, Ψs in salinity stressed plants was at least 33% lower compared to the control group. On the other hand, Ψs in ‘MP-29’ was 11% lower compared to ‘Flordaguard’, indicating higher water stress in the hybrid rootstock. Foliar nutrient concentrations were influenced by treatment (N), cultivar (Ca, B, Mn, Zn), or their interaction (Mg, S), while P, K, Fe, and Cu remained unchanged. These results suggest that MP-29 rootstock is more sensitive to salinity stress than Flordaguard, which may have implications for rootstock selection in saline-prone soils.

Table olives in California have historically been hand-harvested. Hand labor crews are increasingly difficult to attract to small acreage orchards and are often prohibitively expensive when available. Mechanical harvesting equipment is available; however, harvest efficiencies typically range from 55-65%, leaving 35-45% of the crop on the tree. While much less expensive than hand-harvesting, the harvest efficiency is not adequate and leaves growers to decide whether to glean the remaining crop or forfeit the income from that portion of the crop. This low efficiency is partially due to the inherent architecture and physiology of olive trees. Additionally, the force required to remove an olive fruit from the tree is relatively high because table olives are harvested before their physiological maturity. In 2024 we conducted a study to evaluate the effects of altering tree architecture by skirting trees in May, removing lower limbs up to 4 feet from the ground to avoid any contact with the harvest machinery. This led to a 15.5% increase in harvest efficiency over trees where lower limbs were left, without affecting total yield. In addition, we examined the effect of a foliar application of 1-aminocyclopropane-1-carboxylic acid (ACC, commercially available as Accede®), an ethylene precursor, at 100 gallons per acre of 1500ppm solution a week before harvest. ACC applications reduced the amount of force required to remove fruit from the tree by 26% and increased harvest efficiency by up to 10.7%. The combination of both removing the skirts of the trees and applying ACC improved harvest efficiency by 23%. These strategies provide clear pathways to improving the economic sustainability of the table olive industry in California.

Effects of 1-MCP on tomato fruit ripening have been well studied, but much less attention has been given to its effects on vine quality. In a series of experiments, 0.5 or 1 µL L-1 1-MCP was applied to tomato clusters when the least mature fruit on the vine was mature green (MG), breaker (BR) or light red (LR). The clusters were stored at 12oC for 18 days. Overall fruit quality remained high in the MG, BR and LR fruit clusters for 18, 9, and 6 days, respectively. Quality of the 1-MCP-treated BR stage fruit did not decline until after 12 days, while little effect of 1-MCP was found for the LR fruit. Cluster weight was not affected by 1-MCP treatment. However, visual appearance of the vine tissues was greatly affected by 1-MCP. Loss of vine quality was lowest in the MG vines without 1-MCP treatment. However, the highest quality ratings were found in 1-MCP treated vines, regardless of fruit maturity. Retention of vine quality by 1-MCP was closely associated with reduced water loss from the vine tissues. These results confirm that 1-MCP can delay ripening of tomato fruit, but also highlight that the benefits of 1-MCP may be through better visual appearance of the cluster vines.

Fresh produce quality is a critical determinant of consumer preference and market value, with high-quality tomatoes often fetching premium prices. Traditional quality assessment methods, though effective, are typically labor-intensive, destructive, and impractical for real-time monitoring. In this study, we explore the potential of low-cost ($0.99 per unit) metal oxide semiconductor (MOS) gas sensors—MQ series (MQ2, MQ5, MQ6, MQ7, MQ9, and MQ135)—as a rapid, non-destructive, and cost-efficient tool for distinguishing high-quality tomatoes based on their cultivation in nitrogen-rich or nitrogen-deficient soils. Organic tomatoes, harvested from plants exposed to relatively high (High-N) and relatively low (Low-N) levels of bioavailable nitrogen (N) were enclosed in airtight containers equipped with MQ sensors to capture their volatile organic compound (VOC) emissions over 48 hours. Three replicates were used for each N level. Complementary laboratory-based quality assessments measured fresh weight, soluble sugar content, titratable acidity, pH, firmness, color space (Lab*), antioxidant capacity (DPPH assay), and total phenolic content. Gas chromatography-mass spectrometry (GC-MS) was utilized for VOC profiling. The resulting sensor and analytical data were preprocessed and normalized, followed by training 193 machine learning models with principal component analysis (PCA) at a 95% variance threshold in MATLAB. Significant differences were observed between High-N and Low-N treatments across several quality parameters. High-N tomatoes exhibited a 25.32% increase in average fruit fresh weight (p = 0.002), whereas Low-N tomatoes had 18.80% higher firmness (p = 0.020). Low-N tomatoes showed a 27.09% increase in antioxidant capacity (p = 0.0001), a possible indication of an adaptive response to N deficiency. Whereas VOC analysis revealed higher concentrations of octanoic acid, nonanoic acid, and 2-methyl-1-propanol in High-N tomatoes, with increases of 142.67%, 191.46%, and 37.72%, respectively, compared to Low-N tomatoes (p = 0.007, p = 0.020, p = 0.040). Sensor performance analysis demonstrated that MQ9 and MQ5 sensors were the most effective in differentiating between the two nitrogen treatments, with ensemble learning, neural networks, and support vector machines achieving 100% classification accuracy, followed by MQ135 and MQ2. Feature reduction criterion identified a minimal yet highly discriminative subset—including MQ9 sensor responses, octanoic acid, 4-heptanone, nonanoic acid, 1-penten-3-ol, 2-methyl-1-propanol, limonene, 3-methylbutanoic acid, 2-heptanone, fresh weight, and DPPH values—yielding classification accuracies of 97.06% during training and 89.29% in testing with a tri-layer neural network model. These findings underscore the potential of low-cost MOS gas sensors, particularly MQ9, as a viable, non-destructive alternative for real-time quality assessment of tomatoes.

Carotenoids are natural pigments that give fruits and vegetables their yellow, orange, and red colors, and their consumption is associated with numerous health benefits. Most carotenoids occur in isomeric forms (primarily cis and trans); this poses challenges for efficient separation and identification during chromatographic analysis. Tomato (Solanum lycopersicum), an economically important crop, has high nutritional and health benefits, attributed mainly to carotenoids. Lycopene, a major carotenoid in tomatoes, predominantly exists in the trans isoform; however, the trans isoform is less bioavailable than the cis isoform. To accurately measure these isoforms in tomatoes and thus provide information for breeding tomatoes with more cis lycopene, we aimed to develop an Ultra-High Performance Liquid Chromatography (UHPLC) method based on mobile phase (MP) modifiers to measure a wide range of carotenoids (cis and trans) across different tomato varieties (heirloom and cherry) with different colors (green, yellow, orange, purple, and red). The chromatographic parameters, such as temperature (15-30 °C), flow rate (0.3-1.5 ml/min), column lengths (50, 150, and 250 mm), and gradients, and MP modifiers (water, acetonitrile, tetrahydrofuran, triethylamine, ammonium acetate, and ethyl acetate) were optimized. Among the tested parameters, methanol and tert-butyl methyl ether as MP, including ethyl acetate (10%) as a modifier, and C30 column (150 x 4.6 mm) at 20 °C gave the best resolution, allowing the separation of up to 20 peaks indicating individual compounds and isoforms in 35 min. The optimized UHPLC method was also validated for complete profiling, recovery, precision, limit of detection, and quantification. The complexity of the profile based on the number of peaks followed the following order: Orange Heirloom (15) > Orange Cherry (15), Red Cherry (15) > Red Heirloom (13) > Green Heirloom (13) > Purple Cherry (13) > Yellow Cherry (2). Among all the tested tomatoes, trans-lycopene, 5-cis-lycopene, and β-carotene were the predominant carotenoids, followed by 9- and 13-cis-lycopene, and for the first time, mutatoxanthin was detected in Orange Heirloom tomatoes. This method provided efficient peak separation resolution, although not all of them were identified as potential carotenoids; however, their identification could be confirmed by mass spectrometry analysis in future studies. The efficiency, separation, and quantification in this method make it robust for carotenoid analysis in any tomato variety regardless of color. USDA-NIFA-2024-51181-43464 supported this work through the Vegetable and Fruit Improvement Center and partially funded by the Texas A

Tomato metabolism changes in response to environmental conditions such as heat, drought, and soil salinity. This response causes changes in amino acid levels, which are directly related to enzyme activity, photosynthesis, and stress responses. For example, measuring the increase of proline during drought is a biomarker for stress conditions. Qualitative and quantitative analysis of amino acid levels requires precise chromatographic conditions in controlled settings. To accomplish consistent amino acid separation, individual chemical groups require adjustments to chromatographic parameters such as mobile phase composition, pH levels, column type and size, temperature, absorbance/emission wavelength, and gradient combination. This study developed a precise ultra-high performance liquid chromatography (UPLC) approach with a fluorescence detector (FLD) to quantify various amino acids, including γ-aminobutyric acid (GABA), using optimized concentrations of a weak acid (formic acid) and weak base (triethylamine) as modifiers in water and acetonitrile mobile phases, respectively. Buffers are commonly employed in amino acid chromatography; however, excessive usage can result in precipitation and salt accumulation, blocking the pumps. They may also cause pH shifts under high pressure and temperature conditions. Optimized chromatographic conditions improve amino acid separation and quantification. A mobile phase of 0.2% formic acid in water (A) and triethylamine in acetonitrile (B) produced the best results, with maximal separation at 55°C. The gradient began at 90% A and gradually decreased until minute 20, when it returned to the beginning conditions. The injection volume remained steady at 5 µL, with FLD detection peaking at 360 nm. Distinct peaks formed at a 1.0 mL/min flow rate while the pressure was maintained at 1300 psi. Calibration R² results were between 0.97 and 1.0, indicating technique correctness. Separation of real samples found 18 chemicals with retention time changes ranging from 0.01 to 0.05 min. Tomato fruit samples were procured from two developmental stages and amino acid levels were measured. This will provide a benchmark for distinguishing the tomato varieties based on their stress-resilient behavior. This work was partially supported by USDA-NIFA-2024-51181-43464, USDA-NIFA-AFRI 2023-67013-39616 through the Vegetable and Fruit Improvement Center and Institute for Advancing Health Through Agriculture of the Texas A

Large-canopy training systems commonly used in Washington pear orchards create sunlight exposure disparities among fruits. Pear ripening is influenced by sunlight exposure and variability contributes to non-uniform ripening postharvest outcomes. To enhance uniformity in fruit batches based on sunlight exposure, d ‘Anjou pears were sorted according to a newly adapted Chlorophyll-carotenoid index (Cri) based on Hyperspectral images. In September 2024, d’Anjou pears were harvested in three commercial orchards located across distinct growing regions in Washington and Oregon. Reflectance spectral information for each fruit was extracted from Hyperspectral images, and wavebands related to Chlorophyll and carotenoids (430, 662, 454, 549 nm) were subsequently used to calculate Cri values for each fruit. This index value allowed for sorting of fruit into batches under three sunlight categories: Low, Medium, and High. Fruit was kept in controlled atmosphere storage (3.0 % O2, 0.8 % CO2, 0 oC) and quality (Chlorophyll degradation (IAD), firmness (lb)), was studied after 4 months of storage plus 7 days at room temperature (20 oC). Fruit maturity indexes, at harvest, showed no differences between fruit categories. Chlorophyll degradation (IAD) on fruit surface showed that in two of the three orchards, low-exposure fruits exhibited lower values in comparison to high-exposure ones (P ≤ 0.01). Firmness values were significantly lower in high-exposure categories after cold storage and room temperature periods, landing at around 12 lbs and 3 lbs, respectively (P ≤ 0.01). No major differences in physiological disorders incidence between sunlight categories were observed. Further investigation needs to be conducted to determine how these categories behave in longer cold-chain storage scenarios.

In Washington state, pears are typically cultivated on trees with large canopies, which results in different levels of sun exposure and, therefore, fruit maturity variability at harvest and postharvest. Hyperspectral reflectance imaging has been previously used to detect sun stress and predict sunscald risk through a chlorophyll-carotenoid index (Cri; 430, 662, 454, 549 nm) on apples. The objective of this work was to adapt a non-destructive sorting index to standardize groups of fruit with predictive postharvest outcomes throughout the cold chain and treatments. d ‘Anjou pears were harvested from different canopy positions (internal, external, and random) in three commercial blocks during 2023. Hyperspectral images (640 x 840 px; 400–1100 nm) were captured from the exposed and unexposed sides of the fruit at harvest. The reflectance information was then extracted and pre-processed with Savizky-Golay and Standard Normal Variate filters. With this information, the Cri was calculated for every fruit. Cri values ranged from 0.9 to 3.6 for fruit from external canopy positions and 1.1 to 3.8 for those from internal ones. The analysis of variance showed significant differences in Cri values across fruit sides and tree positions (p < 0.01). These findings support the viability of using the chlorophyll-carotenoid index to sort pears with different sun stress levels at harvest. Further research is needed to evaluate the consistency in response of the different fruit groups when submitted to different cold chain scenarios and postharvest treatments.

Citramalate synthase is proposed to be the first committed step in the formation of branched chain esters in apples based on detailed biochemical, pharmacological, isotopic, and molecular data. However, the function of the full citramalate pathway, from the formation of citramalate to the formation of the branched chain esters containing 2-methylbutyl and 2-methylbutanoate moieties has not been tested using a gain of function model. In this work, we report on the transient transformation of ripening banana fruit with functional and non-functional alleles of MdCMS (MdCMS_1 and MdCMS_2, respectively) and report on the compounds induced by the addition of this gene. Banana do not produce appreciable levels of citramalate and make little to no 2-methylbutyl and 2-methylbutanoate containing esters. Following the transformation event, citramalate accumulated in banana transformed with MdCMS_1, but not MdCMS-2. Similarly, banana with the functional form of MdCMS produced modest levels of 2-methylbutyl acetate and 2-methylbutyl butanoate esters. Fruit transformed with MdCMS_1 also accumulated isoleucine as a by-product of the enhanced pathway throughput. Finally, there was a marked enhancement of propyl esters, likely a function of an increase in alpha-ketobutyrate, which is an intermediate in the citramalate pathway between citramalic acid and 2-methylbutyl and 2-methylebutnoate esters. The data provide the last necessary evidence for the conclusively documenting function of citramalate synthase as a functional pathway in apple useful for the production of aroma active branched-chain esters.