ASHS 2024 Conference

Sustainability Beliefs and Practices in the United States Floriculture Industry - Amanda Solliday
Hydroponic, Soilless, and Field Produced Cut Flower Bouquets in the Northeast US. - Jacob Schwab
Influence of UV-A Night Interruption Lighting on the Growth of Potted Basil Plants - Seth Benjamin
Evaluating Nighttime Application of Low Intensity LED Light Qualities to Suppress Downy Mildew Caused by Plasmopara obducens on Greenhouse Grown Impatiens - River Dean
Supplemental Day-Extension Lighting Influences Rooted Cutting Growth and Quality of Finished Annual Bedding Plants - Lauren Seltsam
Daily Light Integral Influences Adventitious Rooting of Achillea Cuttings - Garrett Owen

Today’s environmental and social concerns – including climate change and economic inequality – push sustainability to the forefront of many business strategies, from tech companies to grocery retailers to flower farmers. To better understand the scope and limitations of sustainable practices among flower growers, wholesalers, retail florists, and floral suppliers, the research team administered an industry-wide survey. Sections of the survey delve into aspects of floriculture businesses throughout the United States, including scale of operations, current sustainability measures, motivations driving sustainability activities, and barriers preventing sustainable practices. The results indicate strong personal motivations for sustainability measures within floriculture, yet respondents perceived a lack of financial or regulatory incentives to implement such practices. A subset of results for growers are compared to a 2008 survey to assess changes in sustainability practices within domestic flower production over time. Regional variances in perceived access to resources and implementation of sustainability practices will also be discussed. Our study aims to identify key areas where progress has been made or can be made in the industry, including educational efforts and incentives to address the perception of risk when implementing sustainability practices. A subset of results for growers are compared to a 2008 survey to assess changes in sustainability practices over time within domestic flower production. Our study aims to identify key areas where progress has been made or can be made in the industry, including educational efforts to address the perception of risk when implementing sustainability practices and communicating benefits to consumers.

Cut flower production in the Northeastern United States is restricted by a short growing season. This impacts profitability for many growers and reduces the number of flower options available to them. While there is a reduced selection available, it can still be difficult to select which flowers are profitable and high yielding during a short season. For these reasons, field and controlled environment production of a variety of flowers that could be used in bouquets sold at markets or available for events was investigated. An early- and late-season arrangement was designed utilizing six different plants which could be harvested, assembled, and sold as a bouquet. Two synchronized trials occurred in 2024 with one in the field and the other in the greenhouse. The field plants were germinated indoors and transplanted in a full sun location in USDA Hardiness Zone 5a. The greenhouse plants were grown in three systems which included drip irrigated plants in containers with 4:1 coconut coir: parboiled rice husks, drip irrigated containers filled with rockwool GrowCubes, or hydroponic nutrient film technique. Greenhouse and field plants in both trials were assessed for germination rate and timing; time to flower; flower number, stem length, and subjective quality; and vase life utilizing 3 different floral preservatives. Plants grown in the greenhouse were also compared for adaptability to each growing system. Seeds for the early season bouquet were germinated in April and transplanted into their respective systems in May. Seeds for the late season bouquet were germinated in June and transplanted in July. This information can be used by cut flower growers in the Northeast to potentially extend their season and develop a market for designed “grow-a-bouquet” planting strategies.

Basil (Ocimum basilicum) is one of the most popular culinary herbs sold in containers, but plants can quickly become tall, leggy, and unmarketable. Chemical plant growth regulators (PGRs) are not labelled for use on herbs, so there is a need for a nonchemical alternative. Ultraviolet radiation (UV) has been shown to be an effective alternative to PGRs on ornamentals, but there are no guidelines for effective use of UVA in potted basil production. Therefore, the objectives of this study were to determine the stage of development plants should be exposed to UVA radiation and the effective duration. Fifteen seeds of either sweet basil cultivars ‘Nufar’ or ‘Genovese’ were sown into 15-cm containers. The containers were placed in a glass-glazed greenhouse at 23 °C and under a 16-h photoperiod (LD) provided by LED supplemental lighting or under a 9-h photoperiod and 6-h night interruption lighting providing 385 nm of UVA radiation at an intensity of 20 µmol∙m–2∙s–1. Seeds were germinated for one week under either LD or UVA and then grown for 3 weeks under 10 treatments. The treatments included: LD entire time, LD 1 week-UV 2 weeks, LD 1.5 Weeks-UV 1.5 Weeks, LD 2 weeks-UV 1 week, LD 1 week-UV 1week-LD 1week, UV entire time, UV 1 week-LD 2 weeks, UV 1.5 weeks-LD 1.5 weeks, UV 2 weeks-LD 1 week, and UV 1 week-LD 1week- UV 1 week. Both cultivars responded differently to UVA radiation. Generally, plants grown under UVA from germination to harvest were the most compact. For example, ‘Genovese’ under UV entire time were 3.6 cm shorter than plants under LD entire. However, the chlorophyll content and dry mass of ‘Genovese’ were reduced by 33 and 53%, respectively, when exposed to UV entire compared to plants under LD entire. Additionally, if the treatment a plant ended under was LD, the chlorophyll content was generally higher than those ending under UV. Therefore, the most compact and green potted basil ‘Nufar’ and ‘Genovese’ were those grown under UV 2 weeks-LD 1 week.

Downy mildew (DM) of impatiens (Impatiens walleriana), caused by the oomycete, Plasmopara obducens, results in chlorosis, defoliation, and significant crop losses. Current management includes fungicides and genetic resistance. We applied photoperiodic light quality treatments to ‘Accent Premium White’ impatiens from seed sowing until flowering to limit DM and enhance plant quality. Seeds were sown in a greenhouse with a day and night greenhouse air temperature set point of 23 °C and a target daily light integral of 12 mol·m–2·d–1. A truncated 9-h short-day (SD) photoperiod was achieved by opening and closing opaque black cloth over individual greenhouse benches. Supplemental light-emitting diode (LED) fixtures provided 120 µmol·m–2·s–1 at plant height. Each bench was randomly assigned to one of nine discreet photoperiod treatments: 9-h SD (control) or 9-h SD extended by continuous 7-h LED fixtures emitting blue (405 nm), blue (445 nm), green (525 nm), red (660 nm), far-red (730 nm), white fixtures provided 100-nm waveband ratio (%) of 18:38:41:3 blue:green:red:far-red radiation, a screw-in LED flowering lamps provided 100-nm waveband ratio (%) of 7.6:15:72.4:5. Additionally, 6-h intermittent (1900 to 2200 HR and 0300 to 0600 HR) LED fixtures emitting ultraviolet-A (385 nm) were assigned to one bench. The total photon flux density was adjusted to 20 µmol·m–2·s–1 at plant height under black out curtains for each treatment. Impatiens were inoculated 70 days post sowing with a P. obducens sporangial suspension (2.6 to 3 x 105 sporangia·mL–1) until runoff on the abaxial side of the leaves. Afterwards, each plant was placed in a clear plastic bag containing 300 mL of Hoagland Solution (50%) and returned to its respective treatment. After 9-10 days post inoculation, the ratio of diseased leaves to the total leaf number was determined. In the initial experimental trial, control plants exposed to a 9-h SD treatment displayed an average disease incidence of 72.7%, while other treatment groups ranged from 30.6 to 98.3%. In the subsequent trial, control plants exposed to the same 9-hr SD treatment showed an average disease incidence of 42.6%, while other treatment groups ranged from 0 to 59.5%.

Floriculture makes up the largest sector of ornamental horticulture production, valued at $6.7 billion and dominated by the production of annual bedding-plants. Production is timed to meet spring market dates, starting during a time of year when ambient outdoor temperatures and daily light integrals are below optimal for high-quality plant production. As a result, heating and supplemental lighting can represent a significant operational and energy cost for producers. Yet, producers and investors of the industry have acknowledged an inability to evaluate their resource use due to a lack of industry-wide benchmarks and key performance indicators (KPIs). Past research has compiled energy and water data from controlled environment agriculture (CEA) and, for floriculture, investigated the potential of energy-efficient production strategies and used life cycle assessments (LCAs) to evaluate the environmental impact of the products produced. However, CEA focuses on food production and both the compiled CEA data and the LCAs are largely based off modeled data. Therefore, this research will validate models utilized in LCAs and carbon footprint studies with experimental data, giving producers additional benchmarks and KPIs to evaluate their operational resource-use efficiency. The objectives of this study were to (1) evaluate the use of supplemental day-extension lighting (SDEL) from two different fixtures [(light-emitting diodes (LEDs) and high-pressure sodium (HPS)] during unrooted cutting (URC) propagation of five annual bedding plants and (2) to quantify the greenhouse energy and water consumption. Unrooted cuttings were received from a commercial propagator and stuck in a 105- (calibrachoa, coleus, impatiens, and petunia) or 72- (geranium) propagation tray filled with a pre-moistened soilless propagation substrate and placed under oner of three SDEL treatments on root-zone heating set to 23℃. Each treatment consisted of a propagation tent for callusing and an adjacent rooting environment. Until adventitious root formation, cuttings were misted with clear water, and then were removed from the propagation tent where they were irrigated daily with 150 mg·L–1 nitrogen provided by 15-5-15 water-soluble fertilizer (JR Peters, Inc.; Allentown, PA). After 21 days, data were collected on rooted cuttings. As expected, the energy-use of HPS-lamps exceed that of the LEDs. However, cutting stem-length and stem and leaf dry mass were decreased under SDEL, resulting in liners that were more compact, uniform, and of higher quality than those propagated under ambient conditions. An opposite trend was observed for root dry mass. This indicates that SDEL is a critical tool when utilized for bedding-plant propagation.

Rooting of herbaceous perennial cuttings occurs year-round in greenhouses under photosynthetic daily light integrals (DLIs) ranging from ≈1–20 mol·m–2·d–1. The effects of DLI on rooting and cutting growth have not been quantified for many vegetatively propagated herbaceous perennials. As such, our objectives were to determine the effects of DLI on adventitious rooting and cutting quality of a popular herbaceous perennial, yarrow (Achillea sp.). Unrooted cuttings of yarrow (Achillea millefolium ‘Apricot Delight’) were received from a commercial cutting supplier and callused in a glass-glazed greenhouse for 5 d under ≈3.6 mol·m–2·d–1 at 24 °C root-zone and air temperatures. Upon callusing, cuttings were transferred to a rooting environment with 21 °C air temperature and 24 °C root-zone temperature set points. Cuttings were rooted under one of four different fixed-woven shadecloth providing ≈86%, 62%, or 26% shade or no shade (0%) thereby establishing mean DLIs ranging from 1.6 to 15.2 mol∙m‒2∙d‒1. Cutting growth and biomass accumulation evaluations were made 8, 11, and 14 d after transfer. In general, yarrow stem caliper, stem length, and leaf number were unaffected by increasing DLI; however, leaf, stem, root, and total biomass accumulation increased with increasing DLI though to different magnitudes. For example, as DLI increased from 1.6 to 15.2 mol∙m‒2∙d‒1, leaf, stem, root, and total biomass accumulation increased by 84%, 85%, 458%, and 93% at 8 days after transfer to 98%, 110%, 893%, and 128% at 14 days after transfer, respectively. When taken together, DLI should be properly managed to hasten and improve rooting and growth of yarrow cuttings during adventitious root development.

Quality Analysis of Bitter Acids in Hops (Humulus lupulus L.) from a Controlled Environment Versus Field Production System - Katie Stenmark
The Affect of High pH on Hydroponic Lettuce in a Controlled Environment - Alexander Speck
Drought Stress Responses of North American Native Bog Birch and Sweetgale in a Sensor-automated System - Jessica Hutchinson
Effects of Plant Growth Promoting Rhizobacteria on Yield of Amaranth viridis Linn. Grown in a Growth Chamber and Greenhouse - Zachary Williams
Shade-Avoidance Responses of Kale and Lettuce Elicited by Far-Red Light Can Persist Under High-Light Intensity - Jiyong Shin
Does Intermittent and Continuous Nutrient Flow Affect the Growth and Phytochemicals of Culinary Herbs in NFT Hydroponics - Abishkar Regmi
Adjusting Supplemental LED Light Intensities Based on Real-time Chlorophyll Fluorescence Measurements in a Greenhouse - Suyun Nam
Interactions of Far-Red Photons with Orange Photons or Red Photons: Photosynthetic Response, Morphology and Fruit Yield - Seonghwan Kang

Hop plants are produced for harvest of mature hop cones that are utilized in the medicinal, agricultural, cosmetic and craft beer industries. Hop plants are vigorously climbing perennials that require shorter than 15-hour days for flowering induction, and a trellis structure (3-6m annual height) for seasonal support. In the United States, the majority of hops are grown in field production systems in the Pacific Northwest where summer day lengths are long. The demand for hops has increased due to a boom in the craft beer industry which has led growers in southern states to seek alternative methods for producing hops outside of their traditional commercial growing region. Hop performance in greenhouse systems has not been evaluated in Oklahoma before, but controlled environments offer an alternative for hop producers in the south to limit pests, reduce contact with Downy Mildew (Pseudoperonospora humuli), and harvest multiple crops per year. Four cultivars of hops (‘Cascade’, ‘Comet’, ‘Newport’, ‘Tahoma’) were grown on a 3m trellis using a Dutch bucket hydroponic system with one rhizome per bucket spaced 0.5m apart without supplemental lighting in the USDA research greenhouses at Oklahoma State University. Four identical cultivars of hops were grown in a field system using a V-style trellis (5m height) at the Cimarron Valley Research Station in Perkins, OK. Mature hop cones were hand harvested at 80% moisture and dried at ambient temperature to 8-10% moisture. Hops were stored for up to six months frozen under nitrogen in vacuum sealed bags until analysis was performed. Hop bitter acids (α-acids and β-acids) were extracted using a 0.1% formic acid solvent, and hop quality was determined by HPLC. Bitter acids of greenhouse hops were determined to be highest in cultivars ‘Comet’ (α- 2.12%, β- 0.73%), ‘Cascade’ (α- 2.00%, β- 1.04%), and ‘Tahoma’ (α- 1.92%, β- 1.23%), where ‘Newport’ had a notably lower α and β-acid content (α- 0.71%, β- 0.81%). Bitter acid quality in field hops were comparable to hops produced in the greenhouse (‘Cascade’ α- 2.99%, β- 1.77%; ‘Newport’ α- 2.95%, β- 1.56%; ‘Tahoma’ α- 1.42%, β- 1.56%; ‘Comet’ α- 1.95%, β- 0.71%). With the information from this research, local greenhouse growers will be able to determine if hops are a viable option for their region.

In North Dakota, indoor-grown lettuce faces water pH levels higher than the ideal 5.5 to 6.5 range, with Fargo's water averaging a pH of 9.2 from 2018 to 2022. Addressing the gap in research on high pH's impact on lettuce, this study, running from 2023 to 2024, explored the effects of pH levels on the yield of lettuce grown in deep water culture (DWC) hydroponic systems. We tested three lettuce varieties (Casey, Gladius, and Tendita) under four pH conditions (6.3, 7.0, 8.3, and an unbuffered level), with each setup replicated four times. Th initial growth was in rock wool cubes under a clear dome for a month before transferring to DWC for another month. The results indicated significant differences in yield and size across pH levels and varieties. Gladius yielded the highest at pH 6.3 (86.0 g/plant), while Casey showed the lowest yield at pH 7.0 (9.6 g/plant). Gladius also achieved the largest diameter (25.1 cm) at pH 6.3, contrasting with Casey's smallest at 7.0 pH (10.2 cm). Notably, high pH (8.3) still produced reasonable yields and sizes, especially with the Gladius variety, highlighting the potential for selecting suitable varieties to mitigate adverse pH effects. This study underscores the importance of variety selection in hydroponic systems with non-ideal water pH, providing crucial insights for optimizing indoor lettuce production.

Climate change in the Northern United States is causing less consistent rain events that pressure horticulturists to mitigate the negative impacts of drought stress in ornamental plants. Selecting ornamental native plants that can adapt to predicted changes in climate is a way to preserve and strengthen landscape biodiversity and resilience. Bog birch (Betula pumila) and sweetgale (Myrica gale) are native, colony-forming shrubs indigenous to bogs across the Northern regions of North America with aesthetic features that merit their introduction as ornamental plants. The successful introduction of wetland plants into the nursery industry depends upon their tolerances to variation in water availability typical of managed landscapes. Our 8-week study assessed physiological responses to gradual declines in substrate volumetric water content (VWC) for both shrubs, as water stress intolerance may be a constraint in horticultural landscapes. To model a severe water deficit, we built an automated irrigation system using Arduino microcontrollers connected to soil moisture sensors and solenoid valves that allowed us to track and control VWC. Control plants were maintained at 40% throughout the 8-week period, while drought was simulated by decreasing VWC by 5% each week. Water potential, stomatal conductance, and rate of leaf photosynthesis declined in the plants experiencing drought, with symptoms of leaf dieback and yellowing. In contrast, plants held at 40% VWC maintained physiological functions and had minimal aesthetic decline. By week 8, droughted bog birch and sweetgale reduced their leaf dry masses by 20% and 28%, respectively, relative to control plants. Plants held at 5% VWC had lower stomatal conductance and photosynthetic rates compared to those held at 40%, with sweet gale showing a steeper decline compared to bog birch. During the experiment, stomatal conductance of drought-stressed bog birch and sweetgale decreased by 93% and 77% respectively, and increased for control plants. Similarly, bog birch and sweetgale experienced photosynthetic declines, with respective average decreases of 68% and 62%. At the end of the experiment bog birch maintained a higher leaf retention after severe drought. Most plants of both species retained some living leaf tissue under severe drought. Despite their natural habitats in waterlogged areas, bog birch and sweetgale have potential as drought tolerant, native ornamental shrubs for gardens and landscapes.

Amaranth viridis Linn. (amaranth), commonly referred to as Callaloo, is highly nutritious, drought tolerant, and require few inputs to grow. Amaranth is also known to have pharmacological properties. However, this crop is susceptible to pest damage, which hinders the crops growth, development, and marketable yield. Plant growth promoting rhizobacteria (PGPR) are naturally occurring soil microorganisms that live in the rhizosphere, aggressively colonize plant roots, and provide many benefits to plants. PGPR can promote plant growth, improve plant tolerance to biotic and abiotic stresses, increase nutrient and water uptake, and cause induced systematic resistance. This study was conducted to investigated the application of PGPR on yield and development of amaranth grown in a growth chamber and greenhouse. The study was conducted at the University of Maryland Eastern Shore Agricultural Experiment Station in a complete randomized design with four treatments (T1: Control, T2: Strand 209 (single strand), T3: Blend 5 (double strand), T4: Blend 8 (triple strand)), and six replications in the growth chamber study and nine replications in the greenhouse studies. One growth chamber study (duration for 5 weeks) and three greenhouse studies (summer 2022, fall 2022, and summer 2023) were conducted for ten weeks. Amaranth shoots grown in the greenhouse were harvested biweekly, and fresh weight and dry weight were measured. In both PGPR studies, height data and chlorophyll content were collected weekly, and fresh and dry weight of the whole plant (shoots and roots) were collected at the final harvest. Blend 5 was shown to significantly increase shoot growth when compared to the other treatments in the growth chamber study. In the 2022 summer greenhouse, Strand 209 and Blend 8 significantly increased root biomass, while Blend 5 significantly increased fresh weight of the whole plant. In the 2023 summer study, Strand 209 was significantly higher in average shoot dry weight and whole plant fresh weight when compared to the other treatments. The results of both studies showed that the application of PGPR increased amaranth growth and development. Future studies will evaluate the effects of the PGPR on systemic resistance of amaranth against the pigweed beetle.

Far-red (FR; 700–750 nm) light induces shade-avoidance responses such as stem and leaf elongation and an increase in specific leaf area (SLA). Previous studies have reported that a high photon flux density (PFD) can mitigate the effects of FR light. However, limited research has explored the impacts of individual waveband PFDs on the effects of high total PFD (TPFD) in regulating FR-light responses. To address this gap, we conducted an experiment hypothesizing that the effects of a high FR fraction [FR-PFD divided by the sum of red (R; 600–699 nm) and FR PFD] on shade-avoidance responses would persist when the TPFD increases were solely from increases in R and FR PFDs. We grew kale (Brassica oleracea var. sabellica) ‘Red Russian’ and lettuce (Lactuca sativa) ‘Rex’ and ‘Rouxai’ under 12 lighting treatments with a 24 h∙d−1 photoperiod, TPFDs of 85, 170, 255, or 340 µmol∙m−2∙s−1, and FR fractions of 0.00, 0.17, or 0.33. The blue (400-499 nm) PFD was constant in all treatments and the alterations in the TPFDs were solely due to R and FR PFDs. Based on preliminary results, high FR fractions increased the leaf length of kale to a similar degree at all TPFDs except for no increase at the TPFD of 85 µmol∙m−2∙s−1. High FR fractions increased the leaf length of lettuce ‘Rex’ and ‘Rouxai’ to a similar degree at all TPFDs. In contrast, the SLA of kale did not respond to the FR fraction at any of the TPFDs. The SLA of lettuce ‘Rex’ and ‘Rouxai’ was increased by high FR fractions to a similar degree at all TPFDs except for no increase at the TPFD of 85 µmol∙m−2∙s−1. Contrary to the paradigm, our results suggest that FR-fraction effects can persist under a high TPFD when R and FR PFDs are elevated. Moreover, the lack of response of kale leaf length and lettuce SLA to the FR fraction at the lowest TPFD implies that a low R and FR PFD attenuates the effect of the FR fraction in eliciting shade-avoidance responses.

Hydroponic cultivation has emerged as an innovative method for efficient and sustainable production of different crops because of year-round production and precise nutrient delivery. Light plays a major role when plants are grown in a controlled environment. Supplemental light is necessary for the physiological function of crops when grown in a hydroponics system. In nutrient film technique (NFT) hydroponic production, crops are usually produced with continuously flowing nutrient solutions. However, intermittent flow, where nutrient solutions are paused for periods of time instead of continuous cycling, has been proposed as a more efficient hydroponic system. Intermittent flow of nutrients increases the efficiency of hydroponic systems as it reduces the cost of running pumps continuously. Culinary herbs can be grown easily in NFT hydroponic systems. These herbs are a high-value crop and are a rich source of vitamins, nutrients, fibers, and phytochemicals that are known to fluctuate in concentration in different production systems. Yet it is not known if intermittent irrigation will impact phytochemicals in culinary herbs with or without supplemental lights in NFT production. This experiment investigated the effect of intermittent and continuous flow of nutrients in two culinary herbs, cilantro (Coriandrum sativum) and parsley (Petroselinum crispum) with or without supplemental lights. To regulate nutrient solution flow, the pump was turned on continuously in the continuous flow treatment, whereas it was turned on and off periodically for 30-minute intervals in the intermittent flow system. The herbs were grown for a month and different plant growth parameters like plant height, plant fresh weight, dry weight, root length (RL), total phenolic content (TPC), total flavonoid content (TFC) and proline were measured. Interestingly, nutrient delivery only affected plant height and plant fresh weight in cilantro. Plant height was greater in intermittent flow whereas plant fresh weight was greater in continuous flow. However, nutrient flow did not show any differences in other studied growth parameters in both herbs. Supplemental light significantly increased the root length, plant fresh weight, and dry weight of both herbs. TFC of cilantro was affected by the interaction of supplemental light and nutrient flow system with greater flavonoids in a continuous flow without supplemental light. In parsley, supplemental light increased the proline content. These findings suggest that cilantro and parsley can be grown easily in intermittent flow by reducing the associated cost of production. However, supplemental lighting is necessary to increase the yield of herbs.

Precise and efficient control of supplemental lighting is vital to minimize electrical energy costs in controlled environment agriculture. Even though various environmental factors such as temperature, vapor pressure deficit, CO2 concentrations, and water status influence photosynthetic capacity, current supplemental light control strategies are controlled only based on ambient sunlight conditions. Meanwhile, chlorophyll fluorescence is widely used as an indicator of environmental stress and photosynthetic capacity on account of its easy and non-invasive measurement. A chlorophyll fluorescence-based biofeedback system has been proposed as an innovative approach for precise control of supplemental LED light intensities. The biofeedback system can dynamically optimize LED light intensities based on real-time measurements of chlorophyll fluorescence while allowing plants to decide the amount of supplemental light they need. The biofeedback system has been previously validated in a growth chamber, but its application in an actual greenhouse condition remains unexplored. The objective of this research was to implement the biofeedback system in a greenhouse environment for real-time control of supplemental light intensities based on photosynthetic activity. Additionally, the productivity and energy efficiency of the biofeedback strategy were evaluated and compared to conventional light control strategies. Two fluorometers (MINI-PAM; Heinz Walz, Effeltrich, Germany) were used to monitor the electron transport rate (ETR) and quantum yield of photosystem II (ΦPSII) every 10 minutes, and the Biofeedback system adjusted supplemental LED light intensities until the predefined target ETR and ΦPSII were achieved. Three popular greenhouse crops [lettuce (Lactuca sativa), sweet basil (Ocimum basilicum), and spinach (Spinacia oleracea L.)] were grown under five supplemental light conditions. Specific targets of 1) electron transport rate (ETR), 2) quantum yield of photosystem II (ΦPSII), 3) photosynthetic photon flux density (PPFD), 4) daily light integral (DLI), and 5) no control (ambient sunlight) were used to control supplemental light intensities. In contrast to conventional lighting control methods, the biofeedback system tailored supplemental light intensities according to not only sunlight levels but also temperature and humidity. The result underlines the effectiveness and energy efficiency of the biofeedback system that could integrate variable environmental factors in the greenhouse and apply them to adjust supplemental light intensities precisely.

Plant response from the interaction between far-red and orange photons were rarely known, compared to that of far-red and red photons. Recent previous studies have found application of supplemental orange photons increases the openness of tomato plant architecture, resulting in improved dry weight than supplemental blue, green and red photons. However, limited information is available on the effects of orange photons on plant growth, morphology, and photosynthetic efficiency. Thus, our objective was to quantify the effects of orange photons on growth and photosynthetic responses during long term crop cultivation, compared to red photons. Dwarf tomatoes ‘Red Robin’ were grown in a walk-in chamber with controlled environmental conditions for 96 days after sowing (day temp. 24.3 ± 0.4℃ / night temp. 19.8 ± 0.5℃ and RH 60.5 ± 3.5%). Four light spectral treatments were applied as follows: 1) B25G25O200 (orange), 2) B25G25R200 (red), 3) B25G25O165FR35 (O FR), and 4) B25G25R165FR35 (R FR) (subscripts denote photon flux densities in µmol m² s-1). All spectral treatments had the same total light intensity of 250 µmol m² s-1 with a 18-h photoperiod. Leaf photosynthetic rate was measured before the fruit stage under sole-source orange or red light, as well as under combination lights (RGB or OGB), in a random order. Plant height and main stem length significantly increased under the two spectral treatments with far-red photons (i.e., O FR or R FR), compared to treatments without far-red photons (i.e., orange and red treatments). In comparison between orange and red treatments (without far-red), total dry weight of orange treatment was significantly higher than in red. However, the trend was opposite in the treatments with far-red photons (O FR treatment was lower than R FR treatment). In comparison between with and without far-red photons, total leaf area and fruit dry weight under far-red photons were significantly higher than those in the treatments without far-red photons, whereas stem weight was lower. Brix° under with far-red photons was higher than the treatment without far-red, and that of orange treatment was higher than in the red. Photosynthesis rate under sole-source orange photons was higher than under red photons, but no significant difference was observed among under combination lights. Overall, our results indicated that application of orange photons instead of red photons led to improved biomass and fruit yields in dwarf tomato, resulting in enhanced openness in the canopy structure; however, the trends were reversed with the application of far-red photons.

Non-invasive Assessment of Haskap Growth (Lonicera caerulea) Utilizing X-ray Computed Tomography and Image Processing - Arturo Duarte Sierra
Vase Life Prediction for Cut Roses Using Deep Learning and Hyperspectral Imagining Techniques - Yongtae Kim
Extending the Postharvest Storage of Caladium Tubers to Unlock Late-Season Pot Plant Production Potential in Florida - Gasselle Cordova
Analysis of Oxidative Decreases in Hop (Humulus lupulus L.) Bitter Acids Produced Postharvest - Katie Stenmark
Transcriptome Analysis Revealed that Metabolites and Hormone Signaling Pathway Differently Respond to Non-chilling and Chilling Temperatures in Cucumber (Cucumis sativus L.) Fruit During Storage - Yujin Sim
Fresh Weight of Indoor-Grown Lettuce under Different Postharvest Storage Practices -Caroline Blanchard
Modified Hydrocooling and Optimized Postharvest Handling Practices Can Improve the Shelf Life of Water Spinach During Summer in Humid Subtropical Regions - Wei Shiang Liao
Discovery of Biomarkers for Postharvest Pecan Color Stability Using Metabolomics and Machine Learning Algorithms - Min Jeong Kang
Evaluating the Effects of Controlled Atmosphere Storage on Two Georgia-grown Pecan Cultivars - Ramsey Corn

The latest advances in technology have made it easier to accurately assess the quality of fresh produce, reducing the amount of physical handling required. Computed tomography (CT) is a non-intrusive method that can effectively monitor and categorize fresh produce at different stages of development and maturity. Implementing novel CT scanning techniques can provide innovative means for classifying fresh produce in the early stages of development. The present work provides information for the calculation of the volume and the porosity of the haskap during its ontology. Samples of haskap were taken at four stages of growth prior to harvest and at the time of harvest. Image data were acquired using X-ray microcomputed tomography (SkyScan 1272, Bruker, Billerica, MA, USA) at a resolution of 19.69 μm per pixel, operating at 60 kV and 166 μA, using a 0.25 mm aluminum filter. The resultant data was exported to the BMP file format. BMP files were then processed using Avizo 3.0 (Thermo Fisher Scientific, Waltham, Massachusetts, USA). Automated thresholding using factorization in criteria was applied to the 8-bit images. Subsequently, the images were labeled and an axis connectivity of 26 neighborhoods was established. Finally, a measurement was derived using the volume fraction tool. The results showed that the porosity at stage 3 was 26.56%. It then decreased to 7.52% in the 4th stage and reached a peak of 13.45% during the harvesting stage. These results may have implications for commercial cultivation strategies and optimization of pre- and post-harvest practices and add to the existing understanding of Haskap growth and development.

Japan is a major export market for the Korean cut rose flower industry. The longevity of cut roses significantly influences consumer purchasing decisions, prompting Japan to establish a quality guarantee system to ensure cut flower longevity. However, existing longevity guarantee methods rely heavily on subjective evaluations, overlooking critical factors such as senescence characteristics and disease infections. Hyperspectral imaging (HSI) technique is used for quality control of many fruits and can be performed at video rates, and could thus provide accurate data on aspects of cut flower quality. The You Only Look Once version 8 (YOLOv8) and Random Forest models for object detection and classification enable consistent quality assessment and swift longevity prediction. In this study, we developed a non-contact and rapid detection technique for the potential longevity of cut roses using deep learning techniques based on HSI data. Cut ‘Unforgettable’, ‘Egg Tart’, and ‘Catalina’ rose flowers were held in wet conditions during the exportation to Japan. HSI data within the visible near-infrared range 450-900 nm wavelengths were obtained for analysis of the disease infection and quality of cut roses. Image data of diseased cut roses were collected and corresponding data processing was carried out to build diseased cut roses and quality detection dataset. We developed the longevity prediction model based on scoring a grading standard on the flower quality and this model was then used to predict the longevity and evaluate quality changes of cut roses after exporting to Japan. The results showed that the longevity of exported cut roses was 8 d (‘Egg Tart’), 5.9 d (‘Catalina’), and 4.9 d (‘Unforgettable’). The longevity of cut roses was primarily terminated by gray mold disease (‘Unforgettable’ and ‘Catalina’), petal wilting and discoloration (‘Egg Tart’ and ‘Catalina’), and petal abscission (‘Catalina’). The predictive accuracy of the three rose flowers longevity prediction model was three rose flowers ‘Egg Tart’ (r2=0.80), ‘Unforgettable’ (r2=0.78), and ‘Catalina’ (r2=0.65). These results demonstrate that the combination of HSI and deep learning is a reliable method for evaluating the longevity of exported cut roses.

Florida is home to the largest caladium production in the world, supplying essentially all the global caladium tuber demand. These plants are famous for their vibrant leaf colors and patterns and are asexually propagated through tubers. Following plant development, tubers are harvested and stored for a few months before being forced from March to September for potted plant production and direct landscape planting. During extended postharvest storage, caladium tubers face the risk of severe weight loss, tissue decay, and Fusarium tuber rot. The current practice of storage under ambient conditions with high temperatures and high relative humidity exacerbates weight loss and tuber rot. The challenges of long-term tuber storage make it difficult to produce pot caladium plants for winter holidays, including Thanksgiving, Christmas, and New Year. These challenges also affect the commercialization of tubers in the Southern Hemisphere during the summer. Opening these marketing opportunities can allow growers to extend and increase their production. Additionally, the identification of caladium tubers suitable for late-season production will give Florida growers a competitive advantage. To identify caladium varieties with long-term tuber storage potential and late-season production, 12 varieties were evaluated to target Thanksgiving and Valentine’s Day. No.1-sized tubers were potted in 5-inch containers and grown in a greenhouse. For each variety, 10 tubers were monitored for sprouting and leaf expansion and later evaluated for plant quality using a rating scale from 1 to 5. Eight cultivars were identified as suitable to grow for Thanksgiving, whereas 3 were identified for Valentine’s Day based on long-term storage potential and plant performance. Identification of cultivars will allow growers to expand their commercialization window not only for major holidays but also to supply tuber demand to the Southern Hemisphere.

Nearing maturity, female hop plants develop inflorescences called hop cones. Inside of a mature hop cone is the lupulin gland where glandular trichomes are present. Within the lupulin gland, the glandular trichomes secrete alpha acids (α), and beta acids (β). Hop bitter acids are extremely sensitive to photolysis and oxidation reactions causing the degradation of α-acids and β-acids which negatively affect their use in beer, and the beer brewing industry accounts for 98% of world use of hops (Fandino et al., 2015). Determining hop storage index (HSI) is a way to measure the amount of α and β-acids lost during postharvest handling. HSI is a ratio determined by measuring the spectrophotometric UV absorption of hop extract at 275nm for oxidative compounds, and 325nm for bitter acids. Bitter acids and any oxidative decreases were determined in eight cultivars of hops (‘Cascade’, ‘Chinook’, ‘Comet’, ‘Mount Rainier’, ‘Newport’, ‘Tahoma’, ‘Willamette’, ‘Zeus’) produced at the Cimarron Valley Research Station in Perkins, Oklahoma. Mature hop cones were hand harvested at 80% moisture and dried at ambient temperature to 8-10% moisture using a centrifugal fan. Hops were stored no longer than six months frozen under nitrogen in vacuum sealed bags until analysis. Hop bitter acids were extracted using toluene and UV absorbance was measured at 355, 325, and 275nm using a spectrophotometer. Based on the HSI, hops were assigned a quality score of good (0.4). Seven of the eight cultivars of hops were of good quality (‘Cascade’, 0.20; ‘Chinook’, 0.19; ‘Comet’, 0.17; ‘Mount Rainier’, 0.12; ‘Newport’, 0.23; ‘Tahoma’, 0.18; ‘Willamette’, 0.22). ‘Zeus’ hops were of questionable quality (0.31) but contained a slightly higher moisture content at storage (11%) than the other cultivars (7-10%), which could have negatively affected hop storage quality. Understanding sources of oxidative stresses to hop bitter acids during postharvest handling is valuable information for determining and maintaining hop quality.

Cucumber (Cucumis sativus L.) fruit is sensitive to chilling temperatures during storage, and the physiological mechanism of chilling injury (CI) is not well known. Understanding the chilling response in cucumber fruit is necessary to delay CI and extend the storage duration during postharvest. In this study, our goal was to identify CI symptoms and investigate key factors influencing on the chilling response in cucumber fruit (C. sativus var. ‘Hangang’). To assess the severity of CI symptoms, cucumber fruits were stored at low temperatures of both 13 °C (non-chilling response) and 2 °C (chilling response) for 9 d and exposed to 20 °C. As a result, various CI symptoms of discoloration, shirankage, water-soaking and necrosis area appeared on a cucumber fruit peel stored at 2 °C, resulting in loss of its marketability from 6 d. To clear the cellular mechanism of CI symptoms, transcriptome analysis was conducted in cucumber fruit stored for 1 d (early response) and 6 d (late response). The results suggested that phytohormone synthesis and signalling played major roles in chilling responses. To reveal the main phytohormone involved in the chilling response, eight phytohormones were quantified in cucumber fruit peel using LC-MS/MS. Among them, ABA was not sufficiently accumulated at 2 °C compared to 13 °C during the early response, and SA levels gradually increased by persisting chilling stress. Through these results, major phytohormone synthesis and signalling genes were selected by RT-qPCR. For further understanding of CI, targeted metabolite analysis was conducted, and amino acids such as isoleucine, serine, valine, threonine, and sucrose were identified as significant metabolites for acclimating to chilling temperatures. These findings help to elucidate the hormonal mechanisms involved in chilling response as well as the complex interplay of various molecular components involved in chilling response of cucumber fruit during storage.

Two-thirds of food waste occurs once the product has reached the consumer. In an effort to extend the shelf-life of produce, a common practice of hydroponic lettuce growers, particularly those who use controlled environment production systems such as greenhouses or indoor growing facilities, is to harvest the lettuce without removing the root tissue. However, the postharvest quality of this “living lettuce” has not been a focus of academic research, and its effect on the shelf-life of the produce is unknown. In this study, lettuce harvested from an indoor production facility that utilizes a vertical hydroponic setup was subjected to four postharvest treatments. Treatments included harvesting the complete lettuce plant or removing the roots after harvesting and storing the harvested produce either inside or outside of a plastic clamshell. Lettuce was stored for 28 days at 4 °C and 85% relative humidity. Fresh weight of the lettuce heads was assessed for 18 days post-harvest. As days in storage increased, the fresh weight of lettuce decreased by 0.37 grams per day. The rate of lettuce fresh weight decrease was the same across postharvest treatments, but the lettuce with roots intact stored inside a plastic clamshell had a higher fresh weight across all measured time points. A better understanding of the relationship between fresh lettuce weight and storage time under different postharvest conditions can help to increase the shelf life of the stored produce and reduce food waste.

In an effort to improve the shelf life of water spinach (Ipomoea aquatica Forsk.) and amaranth (Amaranthus tricolor L.) during summer in humid subtropical regions like northern Taiwan, the study investigated the effectiveness of modified hydrocooling and optimized postharvest handling practices. Most farmers in Taiwan often compromised postharvest vegetable quality due to uneven cooling. The first trial implemented a modified hydrocooling system using a 10-minute 5°C shower with a multi-hole perforated pipe and smaller baskets for precooling to substitute the conventional method. The results showed that the modified hydrocooling improved cooling uniformity and reduced vegetable loss rates. Meanwhile, for some farmers needed to meet the specialized market requirement which extend vegetable shelf life, the second trial conducted optimized postharvest handling practices including storage vegetables at 11°C, consistently clean 10°C water for washing/hydrocooling, and wrapping vegetables in plastic film. These practices revealed significantly decreased the water spinach quality loss for longer duration but less effective for amaranth. Even with the addition of hypochlorous acid in washing/hydrocooling water, the shelf life of amaranth was difficult to extend due to severe pre-harvest leaf disease. In conclusion, the study showed that modified hydrocooling offers benefits for most conventional farmers by reducing vegetable loss rates. On the other hands, for farmers needed to meet the specialized market requirement, optimized postharvest handling practices significantly improves the quality of water spinach in longer shelf life. Also, the research emphasized the importance of disease management in amaranth cultivation for postharvest quality.

Nut kernel color is a crucial quality indicator affecting consumers' first impression of the product. In the postharvest stage, nut kernels (e.g., pecans) gradually darken with increasing blue/red colors, which have a negative impact on consumers' preference. While growing evidence suggests that plant phenolics and their derivatives are linked to pecan kernel color, the compounds (biomarkers) responsible for kernel color stability during storage remain elusive. We hypothesized that: (1) the phenotype of pecan color exhibits notable variation among different cultivars during storage; and (2) this variation is attributed to changes in metabolites and their combination effects in the stage of phenolic biosynthetic pathways related to color formation. Here, pathway-based metabolomics with machine learning (ML) algorithms were employed to identify key metabolites of postharvest pecan color stability. Nine pecan cultivars with different color stabilities were selected, and the color of each cultivar was measured over a 6-month storage period (0, 1, 2, 3, and 6 months). Metabolites in phenylpropanoid, flavonoid, and anthocyanin biosynthetic pathways were analyzed in the outer layer of the kernel (testa) using liquid chromatography–mass spectrometry. Different ML models were compared to find relevant biomarkers of pecan color phenotypes. Lasso regression and support vector machine (linear kernel) in conjunction with recursive feature elimination were chosen as the most effective models to select biomarkers that predict the kernel color of pecans. Results revealed twenty marker compounds (flavonoid precursors, flavonoids, anthocyanidins, and anthocyanins) within phenylpropanoid, flavonoid, and anthocyanin biosynthetic pathways, and their roles in pecan color phenotypes during storage. Our findings provide a foundation for future research in the area and will help select genes/proteins for the breeding of pecans with stable and desirable kernel color. The collected information on biomarkers and their effects will also help set up strategies for the quality control of pecans after harvest.

Pecans are an important commodity in Georgia with 180,000 planted acres in 2022. The crop undergoes quality deterioration through lipid oxidation, off-flavor development, and kernel browning in storage. Many new varieties have been introduced to the State with little known about their storage viability. Knowing the varieties performance after harvest can help growers plan for an uncertain market by reducing storage costs. The standard industry technique for storage is low temperature (0°C) cold rooms, which can quickly become expensive over long periods of time due to rising electricity costs. The addition of controlled atmosphere (CA) may possibly aid in reducing oxidation rate and kernel browning during storage. The controlled atmosphere would reduce the amount of oxygen (O2) substituted by carbon dioxide (CO2). Previous studies reported shelf-life increases after oxygen levels were reduced to 2-3% using nitrogen (N2), however carbon dioxide is less commonly seen. Half pecan kernels were hand shelled and sorted before being stored under varied conditions for up to five months. Three treatments were applied to two GA pecan varieties (‘Desirable’ and ‘Sumner’). Conditions included elevated storage temperature at 10 °C, low temperature storage (5 °C) plus CA (10% CO2 4% O2), high temperature storage plus CA, and a control of cold storage at (0 °C). Quality assessments were conducted every month for change of weight, firmness, and color values. Firmness values were conducted using MecMesin texture analyzer to penetrate the half kernel until the breakpoint was achieved. A significant difference was seen in ‘Desirable’ when comparing the days of storage against the atmospheric conditions in the chroma values with the CA treatments exhibiting higher chroma. The Sumner variety saw significant differences in the chroma after two months of storage and varied differences in lightness values throughout storage. A significant difference was seen between the two varieties in firmness values with Sumner exhibiting higher firmness.

Genome-wide Association Study and Genome Prediction of Bolting Trait in Spinach - Hanan Mohammedsaeed Alkabkabi
Towards the Improvement of Lettuce for Heat Tolerance Adapted to Controlled Environment Agriculture - German Sandoya Miranda
Root Phenotyping in Chile Pepper: Key Steps and Challenges with the RhizoVision Explorer - Ehtisham Khokhar
Genome-wide Association Study and Genome Prediction of Tallness Trait in Spinach - Ibtisam Alatawi
Capitalizing on the Global Capsicum Core Collection to Advance Pepper Breeding - Derek Barchenger
Private-public Partnership for Sustainable Cucurbit Breeding and Production in Asia - Narinder Dhillon
Characterization of A Novel Locus for Fruit Flavor Aroma in Tomato - Qian Feng

Spinach (Spinacia oleracea L.) stands as a globally significant vegetable celebrated for its rich array of nutritional and health-promoting compounds. Bolting, a crucial trait in spinach cultivation across diverse seasons and regions, is heavily influenced by photoperiod sensitivity. The premature induction of bolting in spinach due to extended daylight exposure can render the plant unsuitable for market. This study aimed to conduct a comprehensive genome-wide association study (GWAS) to pinpoint single nucleotide polymorphism (SNP) markers associated with late bolting in spinach and to perform genomic prediction for this trait. GWAS was executed on a panel of 295 USDA spinach germplasm accessions, utilizing 16,563 SNPs derived from whole-genome resequencing. Various statistical models, including GLM, MLM, FarmCPU, and BLINK, were deployed in the analysis using the GAPIT 3 tool. A significant quantitative trait locus (QTL) region on chromosome 6 was identified, with three SNP markers — SOVchr6_13545609, SOVchr6_13545882, and SOVchr6_13545887 — located between 13,545,609 bp and 13,545,887 bp, demonstrating robust associations with late bolting. Additionally, the gene SOV6g004620, encoding a TTF-type domain-containing protein and situated at 13,566,721 bp to 13,567,164 bp on chromosome 6, emerged as a potential candidate for regulating bolting. Genomic prediction exhibited a high prediction ability (GA) with an r value of 0.85. The identified SNP markers and GA metrics present valuable tools for breeders to selectively cultivate late-bolting spinach plants and lines through marker-assisted selection (MAS) and genomic selection (GS), thereby facilitating enhanced spinach breeding endeavors.

Lettuce (Lactuca sativa L.) is one of the top ten most consumed vegetables in the United States. In Controlled Environment Agriculture (CEA), lettuce is one of the most cultivated vegetables. The crop yield is severely affected by heatwaves during production. As a result of severe warmer temperatures, lettuce develops physiological disorders such as bolting and tipburn and consequently less marketability and yield. In order to reduce cooling costs and extend the growing season of lettuce crops, breeding heat-tolerant germplasm is imperative. In this research our aim was to confirm heat tolerance in lettuce identified in fields when grown in hydroponics. Initial screenings were conducted at the North Florida Research and Education Center- Suwannee Valley. One hundred and four lettuce accessions from four morphological types (Boston, Latin, leaf, and romaine) were planted in a Nutrient Film Technique (NFT) hydroponic system in a passively vented greenhouse in two experiments. Germplasm included commercial cultivars, plant introductions, legacy cultivars, and breeding lines from the University of Florida /Institute for Food and Agricultural Sciences (UF/IFAS) Lettuce Breeding Program. Data was collected on head weight and related characteristics including marketability, head height, density and width, and core length. Presence of disorders such as bolting, chlorosis and tipburn were also registered as indicators on the negative effects of warmer temperatures. Germplasm with tolerance to warmer temperatures were identified within each of the lettuce types used on this research. This germplasm had an acceptable head weight with less plants that bolted and insignificant presence of tipburn. Several of the germplasm considered heat tolerant are commercial cultivars currently used by the industry in CEA. Similarly, breeding lines from the UF/IFAS Lettuce Breeding Program showed better tolerance than commercial germplasm and are candidates for breeding and genetics studies to decipher mechanisms of heat tolerance in lettuce for this specific environment. Mapping and breeding populations will soon be developed to first study the genetics of tolerance to warmer temperatures and to select germplasm in this specific environment. While tolerant germplasm will aid to decrease cost production for CEA, additional management strategies should be optimized to decrease even further cost of production for growers.

Genetic studies of root architecture provide valuable insight into the overall yield potential of chile pepper (Capsicum annuum L.) under various biotic and abiotic conditions. Phytophthora root rot , caused by soil born pathogen Phytophthora capsici, is one of the most destructive diseases of chile pepper that incur huge losses under severe infection. Rotting of the roots and crown are the primary symptoms with lesions on stem, wilting, and necrosis leading to the plant death. RhizoVision Explorer is a high throughput phenotyping tool that facilitates precise and in-depth phenotyping of root architecture. In this study, four chile pepper cultivars were planted in three replications under greenhouse conditions. A virulent isolate ‘6347’ was used to inoculate the cultivars. At maturity, shoots were removed, and roots were thoroughly washed to prepare them for scanning. A flatbed scanner was used where a transparent plastic flat allowing roots to be submerged in the water was set up to proceed with scanning and analysis using the RhizoVision Explorer. Analysis of variance (ANOVA) demonstrated significant differences between the treated and control groups coupled with strong positive correlation (r > 0.90; P < 0.001) for maximum number of roots (MNR), number of root tips (NRT), total root length (TRL), depth (DPT), maximum width (MAXW), and width-to-depth ratio (WDR). Preliminary results provided insights into root architecture under P. capsici infection and the optimization of key procedures such as root washing and scanning. Overall, the efficiency of root phenotyping using the RhizoVision Explorer under pathogen infection could be improved by modifying specific steps related to the washing and processing of chile pepper samples. Keywords: High throughput phenotyping, Phytophthora blight, root architecture

Spinach (Spinacia oleracea L.) is a highly nutritious leafy green known for its abundance of health-promoting components. Plant height (tallness), particularly relevant for efficient machine harvesting, is a critical trait of interest in spinach cultivation. This study aimed to conduct a genome-wide association study (GWAS) to identify single nucleotide polymorphism (SNP) markers associated with tallness in spinach and to perform genomic prediction for this trait. GWAS was conducted on a panel of 307 USDA spinach germplasm accessions, utilizing 15,058 SNPs derived from whole-genome resequencing. Various statistical models, including GLM, MLM, FarmCPU, and BLINK, were employed in the analysis using the GAPIT 3 tool. Significant quantitative trait loci (QTL) were identified on chromosome 2, along with two QTL on chromosome 6. Specifically, the SNP marker SOVchr4_38323167 at 38,323,167 bp on chromosome 4, and two SNPs, SSOVchr6_8139833 and SOVchr6_91175684 at 8,139,833 bp and 91,175,684 bp respectively on chromosome 6, exhibited robust associations with tallness. Genomic prediction demonstrated high accuracy, with a prediction ability (GA) represented by an r value of 0.71 in the panel. The identified SNP markers and genomic prediction metrics provide valuable tools for breeders to select spinach plants and lines with desired tallness traits through marker-assisted selection (MAS) and genomic selection (GS), thereby enhancing spinach breeding efforts.

Unlike other crops, access to genetic and genomic tools enabling more efficient breeding is limited in pepper. The majority of the research in pepper is based on analyzing traits in biparental populations, and in addition, limited access to pathogen strains or races reduces the wide-scale applicability of the developed molecular markers across populations and breeding programs. In contrast to research in bi-parental populations, genome-wide association studies utilizes the broad range of genetic diversity present in natural populations, including historical recombination events, which allows for the identification of more alleles potentially associated with the trait. A well-designed core collection captures the diversity that is present in an entire germplasm collection, which is crucial for preserving unique alleles and traits and facilitates more efficient phenotyping and GWAS. A core collection of 423 accessions was assembled representing the genetic diversity present in the G2P-SOL global collection of 10,038 wild and cultivated Capsicum accessions from 10 major genebanks .The G2P-SOL Capsicum core collection has been phenotyped for resistance to anthracnose, bacterial wilt, phytophthora blight, and Chili leaf curl virus, as well as for heat stress component traits in several locations in Asia. Genome wide association studies have revealed multiple significant loci associated with the individual traits. These loci are being utilized in the breeding program to more efficiently develop and release cultivars.

The global cucurbit breeding program of the World Vegetable Center (WorldVeg) focuses on tropical pumpkin (Cucurbita moschata) and four gourds: bitter gourd (Momordica charantia), ridge gourd (Luffa acutangula), sponge gourd (Luffa aegyptica = cylindrica) and bottle gourd (Lagenaria siceraria). This breeding program uses the diversity of hitherto unexploited landrace collections to develop high yielding and disease resistant lines and F1 hybrids with a range of fruit types suitable for various market segments. The program supports breeding research of partners from national agricultural research and extension systems organizations and the private seed industry to develop better cucurbit cultivars for the benefit of stakeholders along the vegetable value chain. To facilitate these partnerships, the WorldVeg cucurbit team displays improved cucurbit lines and F1 hybrids during the cucurbits open field days at the WorldVeg East and Southeast Asia Research and Training Station, located on the campus of the Kasetsart University in Kamphaeng Saen, Thailand. This annual event attracts breeders, pathologists, product development managers, marketing and sales managers, R

Tomato flavor has become an important trait for targeted crop improvement. Because of the historical emphasis on yield and other agronomically important traits, many modern tomato varieties have lost their rich flavor, leading to consumer dissatisfaction. While volatile compounds play an important role in defining the distinct tomato flavor, little is known about their biochemical pathways, making it difficult to build a desirable volatile profile. Identifying the genes involved in volatile production can help us better understand the biochemistry as well as accelerate the breeding process. This study focuses on two consumer-desired volatiles, 1-nitro-2-phenylethane and phenylacetaldehyde, and has mapped a novel QTL on chromosome 8 by combining results from linkage mapping and GWAS (genome-wide association study). A cluster of Amino Acid Decarboxylases (AADCs) were identified as the candidate genes underlying this QTL and a total of four SV haplotypes of the AADC cluster were found in the Varitome collection. Among these haplotypes, Type III was lost during domestication and is a likely beneficial allele to increase the concentrations of phenylacetaldehyde and 1-nitro-2-phenylethane in tomato fruits. Preliminary data of transgenic plants created by CRISPR/Cas9 suggested a positive involvement of this AADC locus in volatile production. Enzymatic analysis of the AADC proteins and incorporation of the beneficial allele into modern tomato varieties is in progress. The outcome of this study will provide breeders valuable tools to facilitate the selection process for better tomato flavor. Characterization of volatile pathways will also give us insights on plant secondary metabolite biosynthesis and the evolution history during adaption and domestication. This research is funded by NSF IOS 2151032.

Composted Pecan Shells: A Potential Growing Media Amendment For Container Grown Pecan Seedlings In Georgia - Srijana Thapa Magar
Oil and Dormex® improve bloom and yield in pistachios by driving metabolite changes - GURREET BRAR
Water requirements of Peacan Orchards in the Southeast US - Kriti Poudel

Pecan (Carya illinoinensis) production in Georgia holds significant economic importance nationally. It is an energy-intensive practice with a very low output-to-input ratio. Pecan byproducts, notably pecan shells and husks, account for up to 49% of the nut but are underutilized. A greenhouse experiment was conducted at the USDA facility in Byron, Georgia in 2023 to study the feasibility of composted pecan shells as a growing media amendment for container-grown pecan seedlings. The composted pecan shell was collected from a local pecan grower’s three-year-old composted pile, while fresh goat manure was sourced from the Fort Valley State University’s farm. Various ratios (25, 50, 75, and 100%) of composted pecan shells, along with biochar, goat manure, and chicken manure, were compared to a commercial soil mix (control). All the growing amendments underwent steam sterilization at 98°F for a couple of hours to eliminate any potential contaminants such as weeds, bacteria, fungi, and parasites. Each treatment combination was placed in individual floats to sow the one-year-old stratified ‘Elliott’ seeds. Once the seedlings developed two juvenile leaves, they were transferred to 3-gallon pots to evaluate further soil and plant physiological parameters. The treatments were arranged in a randomized complete block design with four blocks, each containing one treatment combination. Various soil and plant parameters were evaluated monthly, including soil electrical conductivity and temperature, plant size, photosynthesis, stem water potential, and chlorophyll content, to assess the impact of soil amendments on soil and pecan seedling growth. Results determined that composted pecan shell outperformed others in terms of germination (~80%), while none of the seeds germinated in any chicken manure treatment combination. Remarkably, the growth performance of pecan seedlings under different pecan shell ratios was comparable to those grown in commercial soil mix, biochar, and goat manure, indicating good plant health. The stem water potential values overall ranged above -6 Bar, suggesting no signs of plant water stress throughout the study. However, the 100% goat manure treatment consistently showed seedlings with significantly lower chlorophyll content and photosynthetic activity, leading to the smallest plant size compared to the control and biochar treatments. These findings highlight the potential of composted pecan shells as a sustainable soil amendment for container-grown pecan seedlings, offering a novel approach to repurpose pecan byproducts to enhance soil quality, promote sustainable agriculture practices, and serve as an additional income source to pecan growers, thus contributing to the economic viability of pecan production in Georgia.

Lack of dormant chilling is a major problem in producing pistachio trees in locations with warm periods during the winter time. In the past years, some locations in California have received insufficient winter chilling which has led to late bloom and crop reduction. Horticultural oil has been used as a rest-breaking agent to promote bud break and improve production. However, there is limited information regarding the merit of chill portion spray timing and the physiological mechanism behind bloom advancement by oil application. In the present study, three locations in California, North (Colusa County), Central (Madera County) and South-Western Fresno County (Cantua Creek) were selected for oil spray applications while Hydrogen cyanamide (Dormex®) was sprayed at Cantua Creek site. Tree of cv. Kerman (female) and Peters (male) on UCB-1 rootstock were sprayed with horticultural oil (IAP 440) @ 6% v/v or Dormex @4% at various chill portion (CP) accumulation milestones. Bloom period from bud swell to full bloom, tree yield, yield components, non-structural carbohydrates and macro and micro nutrients in buds and bark of pistachio shoots were analyzed. NMR-based metabolomics analysis was conducted to investigate the changes in metabolic profiles induced by exogenous oil or Dormex® application. Results showed that oil spraying in two southern locations advanced bud break but not in the northern site showing each location respond to oil spray differently. In Cantua site, Dormex® and oil spray at CP55 could significantly increase the yield while in Madera, oil spray at CP59 showed the highest yield. Results also showed that oil spray at different CPs and Dormex® could change the trend of soluble sugars and starch in bark and bud of pistachio trees. In Cantua, Dormex® significantly increased nitrogen (N), phosphorous (P), sulfur (S), boron (B), copper (Cu) and zinc (Zn) mobilization towards bud swell. Moreover, oil spray increased N, P, S in all CPs at all locations. A multivariate analysis conducted to compare the metabolite changes in control samples of bark and bud with these two rest-breaking agents led to the identification of nine metabolites that show a significant change in at least one of the comparisons (Creatine, Aspartate, Sucrose, Asparagine, Succinate, Fumarate, Leucine, Adenosine, and Uridine). It seems that oil and Dormex® applications can significantly increase the yield of pistachio trees by advancing bud break, improving bloom synchrony and also, by changes in carbohydrate, nutrients and metabolite changes in bark and bud of pistachio tree.

The state of Georgia is one of the states leading in pecan production in the U.S. However, the seminal papers on water management using state-of-art techniques like eddy-covariance system and micro lysimeters are far and few. Much of the information available on water-use efficiency arises from earlier studies done in the Southwest. However, crop varieties, Georgia soils, and rainfall, when coupled with a long, hot and humid climate of the Southeast, lead to contrasting water management practices from that of the Southwest. The present paper addresses the water needs of pecans in trees six to ten-year old throughout different physiological stages of the orchard in Georgia using the current irrigation schedule. Several record-breaking temperatures and the shifting rainfall patterns have had an important impact on pecan production. This precipitation variability further exacerbates the needs to tailor water-use efficiency to these new normal conditions. Along with the in situ meteorological data and soil moisture information, an eddy-covariance system is installed in Hawkinsville, Georgia. This poster shows how southeastern pecan orchards have different water requirements for optimum yield. This paper focuses on the differences between the current schedule, irrigation application at the farm and water-use data from the present study. Such results obtained likely for the first time will help to devise water management practices, optimize irrigation scheduling leading to increased water conservation and yield.
Keywords: water-use efficiency, production, climate change