ASHS 2024 Conference

Maturity Stage at Harvest Modulates Fruit Softening and Quality of Jackfruit - Zor Singh
Growing Papaya in Mississippi - Guihong Bi

The maturity stage at harvest influences the postharvest quality and storage life of fruit. Harvesting jackfruit (Artocarpus heterophyllus Lam.) at the optimum maturity stage is more important due to the very large size of the fruit. Therefore, the present investigation was conducted to determine the impact of four different maturity stages on physicochemical parameters and fruit-softening enzymes in two jackfruit genotypes (Accession 242 and Accession 341). Fruit for the initial three stages were harvested at 10 days intervals commencing 90 days after flowering (DAF), while fruit for the final stage were harvested based on traditional maturity parameters (142 and 153 DAF) in Accession 341 and Accession 242 respectively. Results indicated an increase in fruit size, seed and bulb weight with the advancement of fruit maturity in both accessions. Moreover, there was a concurrent decline in spine density and an increase in spine flatness with the progression of fruit maturity. Whilst pulp percentage increased, there was a decrease in rag and core percentage at advanced maturity stages. However, peel and seed percentage were not influenced significantly by the advancement of fruit maturity. Additionally, there was a decrease in L* value with a concomitant increase in a*, b*, and C* values of the bulb with the advancement of fruit maturity. In both accessions, bulb firmness, and moisture content were highest in fruit harvested at 90 DAF. The decline in bulb firmness was associated with higher activities of polygalacturonase, pectin methyl esterase, cellulase, and pectate lyase. In both accessions, soluble solid content (SSC), DPPH radical scavenging activity, total flavonoids, and ascorbic acid content were higher in fruit harvested during the last stages of maturity while titratable acidity and total phenolics content were comparatively lower in advanced maturity stages. These findings highlight that the earlier stages (90 and 120 DAF) are suitable as meat alternatives due to better texture, while the most favourable stages for fresh consumption are 142 ± 4.7 and 153 ± 5.7 DAF in ‘Accession 341’ and ‘Accession 242’ due to better colour, higher pulp percentage, higher SSC and antioxidant activity, respectively.

Papaya (Carica papaya) is an herbaceous perennial plant native to the tropical Americas. It thrives in tropical and subtropical climates. While the United States is the world’s largest papaya importer, it also cultivates a modest number of papayas, primarily in Hawaii, California, Texas, and Florida. The subtropical climate in Mississippi offers favorable conditions for papaya cultivation. However, frosts in late fall or early spring could pose threats to both plants and fruits. Appropriate cultivar selection and management strategies are critical for successful papaya production in MS. Currently, limited information is available on growing papayas in MS. The objective of this study was to investigate the potential of growing papaya as an alternative crop for specialty crop growers in MS. Preliminary data suggest that papaya plants can grow well in Mississippi. Different cultivars exhibited variations in plant size and vigor. Plants produced papaya fruits with variations in fruit number, size, and shape, as well as timing to fruiting among different cultivars. However, the relatively shorter growing season in MS compared to tropical climates resulted in insufficient time for most fruits to ripen before the onset of frost in late fall. Further research will involve evaluating additional cultivars, adjusting production schedules, employing season extension techniques, and assessing economic feasibility.

Comparing The Effect Of Potyviruses On The Yield Of Different Generations Of Beauregard Sweetpotato Variety - Sathish Ponniah
“Midnite” and “Festival”: Combining Caribbean and African Hibiscus sabdariffa - Thomas Zimmerman
Metabolomic Survey of Puffy Skin Date Fruit - Yoko Hiraoka
Identifying the formation of aroma compounds in mango using a multi-omics approach - Yu Wang
Establishment of Avocado trees in the United States Virgin Islands - Samuel Joseph

Sweetpotatoes (Ipomoea batatas) have become increasingly popular over the last two decades. It is higher in beta-carotene than many other vegetables and a source of potassium, fiber, and vitamins A and C. Orange-fleshed varieties have a significant role in addressing vitamin A deficiencies, especially in pregnant women and children in developing countries. Sweetpotatoes are vegetatively propagated and susceptible to viruses that accumulate with each planting cycle (generation), leading to cultivar decline. This can affect the yield and quality of the sweetpotato roots. Over 30 viruses have been identified in sweetpotato. In U.S. commercial production fields, four potyviruses such as Sweetpotato feathery mottle virus (SPFMV), Sweetpotato virus G (SPVG), Sweetpotato virus 2 (SPV2), and Sweetpotato virus C (SPVC) are often commonly found. Potyviruses are aphid transmitted in a non-persistent manner. The potyvirus, Sweetpotato feathery mottle virus (SPFMV), is, by far, the most common sweetpotato virus. The objectives of the study are to compare the level of virus infection in five different generations (G1, G2, G3, G4, G6) with the yield performance in the Beauregard variety under field conditions. The different generation roots were collected from the previous experiments, and slips were multiplied under greenhouse conditions of the University of Arkansas at Pine Bluff (UAPB) farm. The slips were planted 12 inches apart with a 30-inch row spacing in four replications using a randomized block design during the summer of 2023. The roots were collected and cured to measure the various yield parameters like total marketable yield, U.S. No. 1, Jumbos Canners, and Culls. The random roots were selected to quantify the viral infections across the five generations using multiplex Reverse Transcription-Polymerase Chain Reaction (mRT-PCR). We observed significant differences in the U.S. No. 1 roots and Canners across the generations. In total marketable yield, 42.5% reduction was observed between the younger generation (G1, G2) and the older (G6) generation. Here, SPFMV was found to be dominant across the generations. Overall, a higher rate of virus infections was detected in the older generation (G6) than in younger generations (G1, G2).

Hibiscus sabdariffa, regionally referred to as sorrel, is a popular annual fruiting crop in the Caribbean. During the winter holiday season, sorrel calyxes are used for making flavorful and refreshing deep crimson red juices and teas. Through years of breeding and selection among Caribbean and African lines, from Ghana and Nigeria, the University of the Virgin Islands developed and released two new cultivar “Midnite” and “Festival”. “Midnite” has 20% greater production over standard Caribbean cultivars. The dark crimson-black calyxes, of both new cultivars, are full of anthocyanins and bioflavonoids. “Festival” begins bearing a month earlier than photoperiodic cultivars and production can extend to early May. Being day-neutral, “Midnite” can be grown year-round but has heavier production during late summer to late Spring. “Midnite” is being widely used in the U.S. Virgin Islands and has potential to expand its use in other commercial industries.

Date palm, Phoenix dactylifera L., is one of the oldest fruit crops grown in the arid regions of the Arabian Peninsula, North Africa and the Middle East and plays a significant role in the economy, society, and environment in these areas. ‘Medjool’ is considered one of the most desirable date varieties worldwide. Skin separation, also known as “puffy skin”, is a widespread phenotypic phenomenon mostly seen in soft varieties such as‘Medjool’ and ‘Barhee’. Skin separation is a market defect that is a commercial disadvantage. In this study, we conducted a metabolomic study of 'Medjool’ fruits at the date genebank maintained in Thermal, California by the United States Department of Agriculture Agricultural Research Service. Date fruit were harvested at the tamar stage (the fruit development stage in which the puffy skin phenotype develops). The metabolomes found in mature date fruits exhibiting non-puffy and puffy phenotypes were characterized. In this study, targeted central carbon metabolism analysis was carried out to identify 126 total metabolites with 95 significant metabolites (p-value < 0.05) (75.4%). Principal Component Analysis (PCA) was carried out, revealing that specific metabolites were associated with the non-puffy skin phenotype, and other metabolites with the puffy skin phenotype.. These metabolomes included those associated with skin elasticity and integrity, supporting studies suggesting the involvement of mechanical properties of date fruit skin.

Mango (Mangifera indica L.) is a fruit renowned for its delectable flavor, making it a staple in tropical and subtropical regions and the second most significant fruit crop in horticulture. Despite its widespread popularity, the specific compounds responsible for its distinctive aroma remain elusive. Our study aimed to bridge this gap by employing untargeted metabolomics and proteomics approaches to investigate aroma compound biosynthesis in three mango cultivars: 'Ah Ping', 'Rosa', and 'Rosigold'. Through integrated metabolomics and proteomics analysis, we identified key pathways and enzymes involved in aroma compound biosynthesis. Fatty acid metabolism, amino acid metabolism, pentose and hexose metabolism, and terpenoid metabolism emerged as pivotal pathways influencing mango flavor diversity. In 'Ah Ping', upregulation of lipoxygenase, hydroperoxide lyase, and alcohol dehydrogenase led to the accumulation of C6 and C9 volatile compounds, contributing to its distinct aroma profile. Conversely, 'Rosa' exhibited varied contents of straight-chain volatile compounds facilitated by the upregulation of enzymes involved in fatty acid degradation. Amino acid metabolism played a crucial role, with glutamate, valine, and phenylalanine serving as precursors for the biosynthesis of butyl esters and aromatic compounds in all three cultivars. Differential expression of enzymes such as aminotransferase and decarboxylase further modulated aroma compound production. Additionally, variations in furan and pyran volatile compounds were linked to differentially expressed enzymes in pentose and hexose metabolism. Our findings provide a comprehensive metabolic and proteomic map elucidating the biosynthesis of specific aroma compounds across mango cultivars. By unraveling the molecular mechanisms underlying mango flavor, this study offers valuable insights for breeding programs aimed at enhancing mango varieties with superior flavor quality. Overall, our research sheds light on the interplay between metabolism and aroma compound biosynthesis in mango, paving the way for targeted breeding strategies and improved mango flavor profiles.

Avocado (Persea americana Mill.), also known as pear in the Caribbean, is a staple fruit in the United States Virgin Islands (USVI) and has one of the fastest expanding markets in Europe and North America. Multiple West Indian cultivars exist. The objective of this study was to evaluate the establishment of 13 avocado varieties in the USVI. Thirteen cultivars were sourced from Florida, these cultivars are ‘Brogdon’, ‘Catalina’, ‘Choquette’, ‘Day’, ‘Donnie’, ‘Lula’, ‘Marcus Pumpkin’, ‘Monroe’, ‘Oro Negro’, ‘Pollock’, ‘Russell’, ‘Thompson Red’, and ‘Uh La La’. These grafted cultivars were planted on July 7, 2022, at 5.5 m spacing with drip irrigation installed as a 1 m diameter around the trees. Data on vertical stem growth after planting and the number of lateral shoots was collected monthly. Walk-throughs are conducted biweekly to identify when each cultivar begins flowering. Similarities in vertical stem growth and flowering were observed after 2 years. ‘Day’, ‘Marcus Pumpkin’, ‘Monroe’, ‘Oro Negro’, ‘Russell’, and ‘Thompson Red’ all grew an average of 98 cm. ‘Brogdon’ grew 137 cm which was the most vertical growth of all the cultivars and ‘Catalina’ grew only 43 cm which was the least. By the second year ‘Brogdon’, ‘Catalina’, ‘Oro Negro’, ‘Pollock’, ‘Russell’, and ‘Thompson Red’ all began flowering from January through April with ‘Pollock’ flowering the earliest in January. Avocado cultivars ‘Day’, ‘Russell’, ‘Oro Negro’, ‘Thompson Red’, and ‘Marcus Pumpkin’ have shown similarities in vertical growth over 20 months with only ‘Oro Negro’, ‘Russell’, and ‘Thompson Red’, flowering during the same months.

Evaluating the Potential of Gaseous Ozone to Suppress Decay Incidence in Fresh Peaches During Cold Storage - Orestis Giannopoulos
Evaluation of different reflectance models to predict fruit firmness using compression values in sweet cherries cv ‘Skeena’ - Rene Mogollon
Effects of Harvest Regimes on Shelf-life and Quality of Rabbiteye Blueberries - Amit Godara
Facilitating Postharvest Elderberry Fruit Detachment with Ethylene - Steven Sargent
Integrated Analyses of Transcriptomics and Lipidomics Reveal Potential Mechanisms Related to Physiological Disorders of Cold-Stored Hardy Kiwifruit (Actinidia arguta) - Hyowon Park
β-Cyclodextrin Nano-encapsulated Carvacrol Inclusion Complexes Improve Postharvest Quality of Limes - Chang Shu
Nondestructive Detection of Chilling Injury Based on VIS/NIR Spectroscopy in Sweet Potato - Jonghwan Lee
Development and Characterization of Bio-based Nanoparticle Coatings from Sweetpotato Peels - David Picha

Sanitizing fruit and vegetables with gaseous ozone promotes food safety, marketability, and extended postharvest shelf-life. Ozone is a self-decomposing gas that disinfects and neutralizes microorganisms on packing equipment, water, and produce surfaces. The USDA permits ozone use in "organic" products. Ozone is produced on-site through a corona discharge mechanism using commercially gaseous ozone generators. This study studied gaseous ozone application on peaches, ranging from 0.5 - 5 ppm compared to control storage (CS). Gaseous ozone applications are known for postharvest spoilage vulnerability to assess microbial load reduction and defense against diseases like brown rot and gray mold. Investigated varieties (July Prince, Scarlet Prince, August Lady, and O’Henry), stored under controlled conditions of 35°F (1.7°C) at 90% relative humidity, revealed that 5 ppm ozone resulted in high decay (~40-42%). However, 0.5 ppm treatment maintained peach quality comparable to controls, with decay rates between 3.5 to 7%. Notably, peaches treated with 0.5 ppm also exhibited higher firmness than the other treatments and unaffected visual quality up to the 28th storage day. The findings suggest ozone’s potential to enhance postharvest practices, highlighting its efficiency, and could serve as an effective counteract treatment for decay incidence that will benefit the peach industry.

The compression test is the standard procedure to measure fruit firmness in sweet cherries. Nevertheless, this measurement is not always well correlated with perceived texture by buyers and consumers; therefore, the cherry industry needs a better way to grade fruit firmness. Hyperspectral information was correlated to fruit firmness as an alternative to compression values. ‘Skeena’ cherries, grown under commercial conditions in central Washington, were harvested in 2023 and stored for 30 days at 0-1oC. Compression measurements (at 20oC; FirmTech 2, BioWorks Inc) were carried out at harvest and 15 and 30 days into storage. Immediately after these measurements, hyperspectral images from the fruit (n=1030) were taken using a Vi-NIR camera (Headwall Photonics). The comparison between low (< 303 mm/g), medium (303-374 mm/g), and high firmness (>374 mm/g) groups did not yield any spectral differences. Despite this, iPLS wavelength selection showed bands > 800 nm suitable to model these compression groups. On the other hand, Neural Network, Random Forest, and PLS models were not able to predict compression values (regression) or firmness groups (classification). Furthermore, the regression models tested did not have coefficients of determination higher than 0.42 with root mean squared errors of 40 mm/g for compression values with the training dataset. Classification models achieved total accuracies of around 65-70 % and had problems distinguishing between low-medium and medium-high compression values. All models showed poor performance when tested with an independent data set. These results are in contrast to previous reports, which used a lower fruit number, reinforcing the challenge of tailoring a non-destructive technique to predict firmness through compression values in sweet cherries, a highly variable phenotypic characteristic.

Blueberry producers in the United States are facing high input costs and labor shortages, which have led them to mechanize several areas of blueberry production, particularly harvesting. Even though the use of machine harvesters is advantageous to producers and new technologies have been developed in recent years, several parts of the process still require improvements. One of the issues caused by the adoption of mechanical harvesting is increased harvest intervals, due to the high capital expenses associated with the purchase of such machinery that in turn leads to limited availability of harvesters to perform the harvest in a timely fashion. This trend may compromise berry quality, particularly in the Southeastern United States. Firmness is a critical factor in determining consumer preference, shelf life, and market value of fresh blueberries. The postharvest quality of blueberries is influenced by various factors, including genotype, postharvest handling, and harvest conditions such as harvest intervals. This study aimed to investigate the impact of different harvest-regimes on fruit quality and storability of ‘Brightwell’ blueberries. The experiment was conducted at the Alma Blueberry Research Farm, with a randomized complete block design. Fruit were hand-harvested at different intervals: T1: every 2 days, T2: every 3 days, and T3: every 7 days. Each treatment was replicated four times, resulting in nine harvests across all treatments. Following the harvest, the berries were sorted for defects, packed in clamshells, and stored at 1°C (34°F) and 85% relative humidity. Fruit quality parameters: firmness, fruit size, color, total soluble solids (TSS), titratable acidity, and fruit rot evaluation were evaluated at four different intervals: 1, 7, 14, and 21 days after harvest. Preliminary results indicate that fruit from the second and third harvests, T1 and T2 exhibited higher firmness readings at harvest compared to T3. Throughout the storage period, the firmness of the fruit was consistently higher in T2 compared to other treatments. A bigger fruit size was obtained at the first harvest of all treatments which declined after 14 days of storage in all three treatments. At the second harvest, T2 had the highest TSS but after 21 days of storage, TSS declined and T1 had the highest TSS after 21 days of storage in all three harvests. Additionally, T3 had a higher fruit rot incidence, and wet, sunken berries in the second and third harvests. So, a harvest interval of less than 7 days is recommended to maintain the fruit quality.

Interest in producing elderberry (Sambucus nigra ssp. canadensis) fruit in North America has increased in recent years, including the subtropical climate of Florida. The fruit contain high amounts of antioxidants in both the juice and solid fractions and are processed into a wide variety of products. Fruit grow in clusters (cymes) of 500 or more fruit (1-2 mm diameter) each, and typically ripen at different rates, depending upon when the flowers were fertilized, the variety/selection and weather conditions. This non-uniform ripening from green to deep purple challenges growers, since unripe fruit must be removed. Delaying cyme harvest until all fruit ripen is not feasible since overripe fruit abscise before unripe fruit ripen. Fruit are typically destemmed from the cymes the day of harvest, either manually or with mechanized systems. Destemming can cause significant loss of salable product as the fruit are often crushed, releasing juice. In a series of tests, we investigated the potential to promote uniform ripening and detachment of elderberry fruit by postharvest exposure to gaseous ethylene, commercially used to initiate ripening in climacteric fruit crops. At a commercial farm in Chiefland, Florida, small segments (approximately 30 fruit each) were cut from cymes with 75% ripe fruit from three elderberry genotypes (DNS11, DNS23 and DNS36). The samples were returned to the UF Postharvest Laboratory that day, divided into two treatment groups ( /- 100 ppm ethylene) and sealed in glass jars (n=3; 3 segments/jar) at 22 °C/95% relative humidity. Jars were opened after 24, 48 and 72 hr to avoid CO2 accumulation; at each timepoint, one jar was removed and fruit examined; remaining jars were resealed and ethylene concentration was reestablished. Exposure to ethylene significantly increased ripe fruit detachment after 24 hr, however partially ripe fruit ripened after 48 hr, irrespective of treatment. Fruit juice content was 46%, pH=5.0. Ethylene did not affect the following parameters, although there were differences in germplasm: soluble solids content (7-14%), total titratable acidity (0.44-0.70%), and total anthocyanin content (8-20 mg · g-1). Attached or detached fruit lost 6-10% weight after 24 hr, whereas stems lost about 50% weight; after 48 hr, shrivel symptoms appeared and weight loss roughly doubled for these same groups. Consideration must be given as to exposure to ethylene for 24 hr for easy fruit removal versus holding for 48 hr for ripening with accompanied higher weight loss and shriveling.

Hardy kiwifruit (Actinidia arguta) is highly sensitive to low temperatures, which can cause chilling injury (CI) as a physiological disorder. Peel surface pitting with black/dark brown spots was developed as CI symptoms in cold-stored hardy kiwifruit. In this study, we performed transcriptomic and lipidomic analyses to elucidate the potential mechanism of CI symptoms in cold-stored hardy kiwifruit. The peel tissues of hardy kiwifruit were collected after harvest (HV) and after cold storage; pitted peel tissues from CI-damaged fruit (PT) and healthy peel tissues from CI-unaffected fruit (HT) were also collected. Transcriptomic analysis identified 10,612 differential expressed genes (DEGs) between HV and HT tissues, and 3,206 DEGs were detected between HT and PT tissues. Among the 3,206 DEGs, 1,322 transcripts were up-regulated in HT tissues, while 1,874 transcripts were up-regulated in PT tissues. The KEGG pathway enriched by up-regulated DEGs in HT indicated protein modification, L-valine degradation, and polyol metabolism, while up-regulated DEGs in PT enriched alkaloid biosynthesis, protein modification, and lipid metabolism. In lipidomics analysis, a total of 101 lipids clustered into 14 subgroups were detected in peel tissues of cold-stored hardy kiwifruit. Based on the results of VIP scores (> 1.5), the levels of triacylglycerol (TAG) 54:8, TAG 54:9, phosphatidylcholine (PC) 36:4, PC 34:2, PC 36:5, PC 34:3, and TAG 54:7 were higher in PT tissues, but the levels of phosphatidylethanolamine (PE) 36:2, phosphatidylserine (PS) 38:3, PS 36:0, PC 36:1, PE 34:1, and PE 36:1, were higher in HT tissues, compared with the other tissues. Therefore, the results indicated that the CI symptoms in cold-stored hardy kiwifruit would be derived from integrated transcriptomic and lipidomic results.

The ripening and senescence of fresh fruit and vegetables are inevitable during storage, transportation, and sale, which will reduce their marketability and cause substantial economic losses. The infection of pathogenic microorganisms can also lead to food safety problems. Plant essential oils are considered a promising strategy to preserve fresh produce. However, their application is limited by several aspects, including high volatility, low solubility, off flavor, etc. Encapsulation technology has emerged as a promising solution to alleviate these limitations. Nanoencapsulation is a delivery system for bioactive compounds that is usually employed to support the stability of the agents, maximize their retention, and control the release of the compounds at the target locations. A nanoemulsion composed of carvacrol and β-cyclodextrin was prepared by an ultrasound-mediated method, and the encapsulation process was conducted using a Buchi® Nano Spray Dryer B-90. The inclusion complex powder was collected and filled to air-permeable sachets. The sachets were then fixed inside commercial clamshells containing limes to simulate shelf-life. Fruit quality and total microbial population were analyzed. The results showed that the dimensions of spray-dried powders were primarily at nanoscale. The encapsulation process did not affect the antimicrobial and antioxidant activities of carvacrol. The nanocapsules prolonged the release of carvacrol. It effectively delayed the rapid color deterioration of limes without causing phytotoxicity, and maintained lime quality with higher firmness and lower weight loss. Free carvacrol and carvacrol/β-cyclodextrin treatments significantly reduced the growth of P. digitatum and total bacteria on fruit peel and inside of the wounds. However, the GC-MS results showed carvacrol residue detected from free carvacrol-treated fruit, but not from the carvacrol/β-cyclodextrin-treated fruit. The results indicate that nano-encapsulated carvacrol/β-cyclodextrin inclusion complexes can be applied as an effective strategy to preserve postharvest produce. Keywords: Nanoencapsulation, nano spray drying, essential oil, postharvest quality, lime

Sweet potato (Ipomoea batatas L.) is one of the seven major food crops grown worldwide. The optimal storage temperature for sweet potatoes is 12-15℃, and chilling injury occur when it falls below 10℃. The initial symptom of chilling injury in sweet potatoes is difficult to discern in visual judgment and requires checking through a cut-off sections. Therefore, this study intended to develop a non-destructive chilling injury prediction model using VIS/NIR spectroscopy sensors. USB4000 Fiber Optical Spectrometer was used for collecting spectrum data in the wavelength of the visible to near-infrared region (400 nm to 1100 nm), and the average value was used by measuring six areas divided into upper, middle, and lower parts to reduce errors. Firmness, total soluble solids, internal chromaticity, chilling index, and Malondialdehyde (MDA) were measured as reference data, and Partial Least Squares Regression(PLSR) method was used for prediction. To increase the accuracy of the model, the near-infrared spectrum data were preprocessed using the Savitzky–Golay 1st and 2nd derivatives (S–G), standard normal variate (SNV), and multiplicative scattering correction (MSC) methods. Excellent performance models for each preprocessing methods were selected, and as a result of verification through the prediction model, the 'Hogammi' variety showed excellent performance in the preprocessing of Savitzky-Golay 2st derivative in TSS and Malondialdehyde (MDA), and CI index showed the best performance in the processing of SNV. As indicators of chilling injury such as the CI index involve subjective opinions of experimenters, the findings of this study could be used as a fundamental step to develop more objective and accurate chilling injury prediction models by including various internal indicators.

Bio-based nanoparticle coatings were developed using nanomaterials extracted from sweetpotato peels and combined with other biopolymers to reduce postharvest deterioration of sweetpotato roots and other fresh produce items. The sustainable coating materials applied as thin films to the surface of washed sweetpotato roots reduced postharvest deterioration, weight loss, and respiration rate, while maintaining root market quality. Chemical and physical characterization was made of the cellulose nanomaterials (CNMs), pectin, and phenolic compounds from ‘Beauregard’ sweet potato peel tissue. The peel contained 40.2% cellulose, 19.1 % lignin, 10.8% hemicellulose and 29.8% pectin. The extracted CNMs from the peel tissue showed a high degree of crystallinity, particularly for cellulose nanocrystals. The CNMs and pectin fractions formed stable water dispersions with strong shear thinning behavior suitable for coating application. The thin films formed by the CNMs and pectin fractions exhibited an entangled fiber network structure with significantly reduced water and gas permeability. Our results demonstrated the feasibility of using sweetpotato peel tissue as an integral component in a bio-based nanoparticle film coating.

Optimizing Nitrogen Fertilization for Evergreen Blueberry (Vaccinium corymbosum interspecific hybrids) in Florida - Gerardo Nunez
The Effects of Nutrient Management on Yield in Cut-and-Come-Again Kale Production.- Leigh Whittinghill
Optimization of Tissue Culture Medium for Enhanced Proliferation of Little-Leaf Mockorange (Philadelphus microphyllus A. - Razieh Khajehyar
Nano NPK and Salicylic Acid Chemigation in Processing Tomato Production: Impact on Efficiency and Sustainability - Thomas Harker
Nano NPK and Salicylic Acid Chemigation on Tomato Phytochemicals and Fruit Quality - Thomas Harker
Alternative Fertilizer Methods For Palm Trees - Mica Mcmillan

There are multiple ways to grow highbush blueberries (Vaccinium corymbosum interspecific hybrids). In Florida, an evergreen growing system was developed to overcome unpredictable chill hour accumulation. In this system, blueberry bushes retain their leaves throughout the year when fertilized appropriately. Deciduous blueberry farms typically skip fertilization during the fall and winter months. On the other hand, evergreen blueberry farms require winter fertilization to ensure healthy foliage. Therefore, fertilizer recommendations for deciduous blueberry are not applicable to evergreen blueberry. This research aims to optimize nitrogen fertilization for evergreen southern highbush blueberry plants in Florida. ‘Arcadia’ and ‘Sentinel’ southern highbush blueberry plants were grown in a high tunnel in Citra, FL. Plants were fertigated according to commercial practices, except for nitrogen (N). Nitrogen was applied manually as ammonium sulfate at 5 different annual rates (in Kg/ha): 5.6, 83.4, 138.9, 222.3, and 444.6. Plant size, leaf area index, leaf N concentration, fruit yield, and fruit quality were measured during the 2023 and 2024 seasons. Nitrogen fertilization rates affected plant growth during the spring and summer, but not during the fall and winter. Higher N fertilization rates led to higher leaf area index, a proxy for leaf retention. Plants in the lowest N fertilization treatment were not evergreen, as they dropped nearly all their leaves in the winter. Leaf N concentrations of plants in treatments 83.4 Kg/ha or higher were above the reference levels for N deficiency. Linear plateau regressions were used to identify optimum fertilization rates. During the 2023 season, ‘Arcadia’ exhibited a yield plateau, but ‘Sentinel’ did not, suggesting that N fertilization has cultivar-specific effects. All fruit harvested exhibited commercial quality in terms of soluble solids. However, fruit in the lowest fertilization rate was softer and more acidic than fruit in all other treatments. These results suggest that multi-year studies with multiple varieties are necessary to identify N fertilization rates that maximize agricultural productivity while minimizing fertilizer inputs.

Cut-and-come-again, or repeat harvesting, is a practice in which a single planting of greens is harvested on multiple occasions. This is a common practice among small-scale, urban, and home producers in which the outermost leaves are removed, leaving the growing center of the plant intact enabling multiple harvests without compromising plant health. As this practice is not common among large-scale and commercial producers, there are currently no research-based fertilizer recommendations for cut-and-come-again greens. General guidance simply suggests continued, nitrogen-heavy fertilizer applications to ensure repeated harvests. This type of guidance is not easy to follow for beginners or for growers looking to improve their cut-and-come-again yields. An experiment was designed to examine eight different fertilizer application strategies to determine which provided better growth and nutritional quality in later kale harvests while limiting nutrient leaching. Fertilizer applications for the cut-and-come-again treatments (CC) ranged from an initial fertilizer application matching local nutrient recommendations, to repeated applications either the initial complete application or a nitrogen side dressing at every third, every other, or at each harvest. A single harvest control (ODB) was also harvested at the baby stage at each CC harvest. At each harvest, total and marketable yield were measured and crop quality for marketability was assessed per the USDA guidelines for kale and greens. There were more issues with slow growth, slow regrowth, and missing harvests for pots in the fall than the spring, and more issues in 2023 than in 2022. Some issues were directly related to significant caterpillar damage in the fall of 2023 which also affected the marketability of the leaves harvested. The expected dose response to fertilizer treatment was not observed in any growing season of the two years of the study completed so far. While some differences in yield between treatments were observed, these were predominantly between the ODB control and CC treatments, but not among CC treatments. The expected drop in yield with successive harvests was also not consistently observed in CC treatments. The CC treatment receiving only the initial fertilizer application exhibited a drop in yield with successive harvests in only two of the four growing seasons. Further examination of the fate of nutrients in the leaf material, soil and leachate from the experiment should explain these unexpected results and provide more clarity on an optimal fertilizer treatment.

Native plants play a crucial role in landscape ecosystems due to their adaptability, yet propagating certain species through traditional methods can pose challenges. Tissue culture emerges as a promising alternative for efficient propagation, demanding an optimized culture medium for desirable proliferation. Efficient proliferation of newly introduced plant species in tissue culture often necessitates meticulous experimentation with varying salt compositions to optimize mineral concentrations and growth regulator levels within the culture medium. This study aimed to employ Response Surface Methods (RSM) to assess the effects of different mineral combinations, including nitrogen (N), calcium (Ca), potassium (K), and phosphorus (P), along with a cytokinin (zeatin), on the shoot proliferation and growth of little-leaf mockorange in tissue culture. Forty-six treatment combinations were designed, with zeatin concentrations of 0.82, 1.095, or 1.37 µM, and varying levels of N (22.5, 30, or 37.5 mM), Ca (1.125, 1.5, or 1.88 mM), P (0.31, 0.625, or 0.94 mM), and K (5, 10, or 15 mM). These treatments were evaluated for their impact on axillary shoot formation, shoot length, and shoot dry weight. Response surface analyses revealed optimal concentrations of N (32.5 to 35 mM), Ca (1.5 mM), and P (0.625 mM), while the influence of potassium on responses was found to be nonsignificant in the regression models, hence, K concentrations were limited to linear trends in the analysis. Notably, medium supplemented with 1.1 µM zeatin demonstrated a significant positive impact on shoot proliferation. The RSM model demonstrated the feasibility of determining optimal concentrations of zeatin, N, Ca, and P in a single experiment, facilitating the in vitro growth of little-leaf mockorange shoots. This study underscores the efficacy of RSM in tissue culture experiments, offering a time- and cost-effective alternative to conducting multiple separate experiments and providing valuable insights into medium optimization. Such findings contribute to the advancement of tissue culture techniques, particularly in propagating native plant species critical for landscape sustainability.

Chemical fertilizers are key to enhancing tomato productivity, yet their excessive or imbalanced use can lead to higher costs, energy inefficiency, and negative environmental impacts. Recent advancements in nano fertilization seek to optimize nutrient use, minimize losses, and improve farm economics and environmental sustainability. Additionally, salicylic acid (SA) as a chemical inducer has shown potential to boost crop yields by enhancing stress tolerance in plants. Our research evaluated the effects of various rates of nano NPK fertilization combined with SA chemigation on the efficiency and sustainability of processing tomatoes (Solanum Lycopersicum L., cv. BHN 685) production in a drip-irrigated plasticulture system. Conducted over the 2022 and 2023 growing seasons, this two-factorial experiment tested nano NPK rates (0, 40, 80, 120 kg/ha) and SA levels (0 vs. 0.3%), using conventional NPK fertilizers as the control. The results showed that tomato yields were significantly influenced by SA chemigation, nano NPK fertilization, and the growing year, without interactive effects between and among these factors. SA chemigation with 120 kg NPK/ha increased yields by 9% compared to the control. Yields were similar between the 120 kg/ha SA chemigation and 120 kg/ha nano NPK treatments but were significantly higher (by 21%) under the 120 kg nano NPK with SA chemigation, suggesting effective synergy between SA and nano fertilization. SA chemigation and NPK fertilization reduced cull fruit yields, with nano NPK showing the most substantial reduction. Production costs were slightly higher for the combination of SA chemigation and nano NPK ($7,114/ha), but profitability was significantly increased, peaking at $2,487/ha in this treatment. Energy use efficiency also increased from 42.3% in the control (120 kg NPK/ha) to 51.1% with the combined treatment (120 kg nano NPK/ha with SA chemigation), and specific energy use per unit of tomato was decreased from 1.9 MJ/kg to 1.6 MJ/kg. Greenhouse gas emissions per ton of tomato were reduced from 46.3 kg CO2 equivalent/ha in the control to 42.7 kg/ha with combined nano NPK and SA chemigation. In conclusion, nano NPK fertilization coupled with SA chemigation proves to be an effective strategy for enhancing the efficiency and sustainability of processing tomato production, improving yield, profitability, and environmental outcomes.

Tomato stands out as a premier high-value specialty crop globally. However, the inefficiency of conventional fertilizers in nutrient utilization necessitates excessive fertilization to maintain tomato yields, which adversely impacts fruit quality. Nanotechnology, aimed at precise nutrient management to enhance efficiency and economic viability in farming, is gaining attention in agriculture. Similarly, salicylic acid (SA) has emerged as a potential chemical inducer to enhance plant metabolic activities, stress tolerance, and crop yield in the face of climate change. Our two-year field study aimed to assess the impact of varying rates of nano NPK fertilization and SA chemigation on the phytochemical properties, nutritional quality, and fruit attributes of processing tomatoes (Solanum Lycopersicum L., cv. BHN685), relative to conventional fertilization. Employing a two-factorial drip-irrigated plasticulture setup in a completely randomized design, we tested four levels of nano NPK (0, 40, 80, and 120 kg/ha) and two levels of SA (0 vs. 0.3%), each replicated four times. Results showed that tomato fruits subjected to SA chemigation with nano-NPK fertilization exhibited a significant increase in concentration of phytochemicals. Notably, vitamin-A, vitamin-C, lycopene, β-carotene, polyphenol, flavonoid, anthocyanin, and antioxidant capacity displayed substantial increases ranging from 2.5% to 51.2% compared to the control. Particularly noteworthy were the remarkable enhancements in flavonoid and anthocyanin concentrations, registering at 50% and 51.2%, respectively. Conversely, application of nano NPK alone led to discernible increases solely in flavonoid and anthocyanin concentrations, accompanied by decreases in other phytochemicals. Further analysis underscored the synergistic benefits of SA and nano-NPK, resulting in superior color, taste, and phytochemical richness of tomato fruits. K-means cluster analysis corroborated the efficacy of the SA with nano NPK (120 kg/ha) treatment in eliciting optimal fruit characteristics. Moreover, quality assessment revealed the superiority of the SA nano-NPK (120 kg/ha) treatment, with a quality index of 0.61 compared to the control's 0.47, indicative of its superior attributes. Additionally, the nutritional quality index demonstrated a gradual increase in nutrient enrichment across treatments, with the SA and nano NPK (120 kg/ha) combination yielding the highest score. In conclusion, our study highlights the pivotal role of SA in conjunction with nano NPK (120 kg/ha) in enhancing tomato phytochemical content and overall fruit quality. These findings bear significant implications for optimizing horticultural practices and promoting sustainable food production endeavors.

Lack of water holding and cation exchange capacity severely limit fertilizer application methods for new palm tree transplants in sandy soils in S. Florida. Typically, palm trees are fertilized using an 8-2-12 4 granular fertilizer but with little rooting to enhance fertilizer capture and no soil solution to improve nutrient uptake, establishment may be slow. Alternative fertilizers, including palm tree injection, were evaluated to determine the best method to improve palm tree establishment under these conditions. A research trial was conducted using Christmas Palms (Adonidia merrillii) that were established on sandy soils with less than 2% organic matter. After planting, palms were not fertilized for six months. Palm trees were treated with the following fertilizers: 1) 8-2-12 4 (PS), 2) 0-0-22 4(KM) 3) PHOSPHO-jet PALM-jet injection (PJ) 4) PHOSPHO-jet PALM-jet apical meristem drench (AM) and 6) “Gator Grip” (GG) fertilizer pouch directed at the apical meristem. Visual quality and drone imagery were used to assess palm health. Volumetric water content (VWC) was determined at three different depths and root growth was captured using a mini-rhizotron. Six months after the initial treatment application, treatment differences were not visually apparent and VWC was below 10% for the majority of measurements captured at all depths. Rooting data at this stage was minimal. Palm trees may grow very slowly and under these environmental conditions, it may take the palm over a year to replace an entire crown. Therefore, yearly updates will be presented for this three-year trial to best determine which treatment provides the best solution to establish transplanted palms in the landscape and maintain palm health.