ASHS 2025 Conference

Powdery mildew, caused by the fungus Erysiphe pulchra, is one of the most serious diseases affecting the popular ornamental tree flowering dogwood (Cornus florida). Employing gene editing techniques such as CRISPR to introduce powdery mildew resistance by inactivating the Mildew Locus O (MLO) gene requires an efficient genetic transformation system. This novel research will fill a critical gap in our knowledge of flowering dogwood biotechnology. Previous research efforts have genetically transformed embryogenic dogwood cultures, now we are aiming to produce transgenic plantlets. Recent research focused on using the RITA® temporary immersion bioreactor system for testing germination of somatic embryos and conversion to plants. The primary test was the impact of the plant growth regulator (PGR) gibberellic acid (GA3). For this experiment, we analyzed the impact of different environmental light exposures on dogwood embryo stress levels by observing anthocyanin production. The starting material was unwashed callus transformed with the GUS reporter gene and subjected to one of three RITA® treatments to examine the influence of varying light levels. Treatments included full darkness, continuous low light, and a combination of both light conditions for different durations of time. Few somatic embryos germinated from the treatment with 60 days of full darkness, but the anthocyanin stress was absent. We observed the same result for constant low light exposure except for exponential growth of the transgenic callus. The treatment in which the somatic embryos were in full darkness for 30 days and switched to low light for another 30 days showed a higher germination rate, but there were increased signs of anthocyanin stress. Implementation of this research will assist in the optimization of the production of plantlets from dogwood cultures transformed with a CRISPR-Cas9 construct that can inactivate the MLO gene to obtain powdery mildew resistance.

Fresh fruits and vegetables are invaluable for human health, but their quality deteriorates before reaching consumers during distribution due to ongoing biochemical processes and compositional changes. The current lack of any objective indices for defining “freshness” of fruits or vegetables limits our capacity to control product quality and leads to food loss and waste. In this work, we undertook interdisciplinary research to address plant science challenges related to food security and human health. This work has leveraged machine learning technologies and multi-omics tools to understand post-harvest senescence and microbial spoilage of fresh produce for the purpose of developing a simple imaging “FreshID” device to evaluate fruit and vegetable quality. In essence, we are proposing a comprehensive research program to identify proteins and compounds as “freshness-indicators” and to aid development of an innovative and easy-to-use accessibility tool to accurately estimate the freshness and/or contamination of produce. The goal of the proposed research will be advances in both basic research and applied science. Such a tool would allow a new level of post-harvest logistics, supporting availability of high-quality, nutritious, fresh produce.

Plant natural promoters are always very long and contain many different promoter motifs, providing complex expression patterns, while synthetic promoters can be constructed to be very short in sequence and very strong in promoter strength. Bioinformatics-assisted de novo promoter motif discovery searches for statistically overrepresented motifs without the inclusion of biological information, leading to limited prediction efficiency. To overcome this limitation, we have developed a novel ensemble approach by mapping the motifs detected by a set of selected bioinformatics tools back to the promoter sequences and looking for overlapping motif regions among the detected motifs. Using this approach, we searched and identified novel constitutive promoter motifs from the soybean genome. Seven user-friendly bioinformatics tools, including BioProspector, CisGenome, HOMER, MEME, MotifSuite, RSAT Plants, and Weeder were employed for the de novo discovery of constitutive motifs among 11 published soybean constitutive promoters. A total of 62 promoter motifs were detected among the 11 soybean constitutive promoters by at least four of the seven bioinformatics tools. A tetramer (4×) of each promoter motif was cloned in front of the minimal 35S promoter driving GUS reporter gene expression, and used for tobacco leaf agroinfiltration and stable Arabidopsis transformation. Quantitative GUS activity assays following transient tobacco leaf agroinfiltration identified 26 of the 62 promoter motifs that drove GUS expression significantly higher than the basal level conferred by the minimal 35S promoter. Histochemical GUS analysis of stable transgenic Arabidopsis seedlings found that 16 of the 26 promoter motifs were 19 ~ 60 bp in length and exhibited constitutive expression with variable promoter strength, and 7 of the 26 promoter motifs showed strong constitutive expression which was comparable to (slightly weaker than) the 35S promoter. Thus, these novel constitutive motifs can be used to drive constitutive gene expression in dicot species.

In sweetpotato (Ipomoea batatas L.), the sink strength of developing adventitious roots limits storage root formation. Sucrose synthase (SuSy) has been identified as a marker for sink strength in developing storage roots. In model systems, declining nitrogen (N) availability has been associated with increased carbohydrate allocation to root systems. To test the hypothesis that N limitation triggers increased SuSy activity that leads to storage root formation, we subjected sweetpotato cv. ‘Beauregard’ to progressively declining N treatments in a split-root system. SuSy expression and root system architecture were evaluated over 15 days, and storage root formation was assessed at 50 days. Declining N availability enhanced SuSy activity in the root base tissue across all time points and was associated with increased lateral root count at 15 days. Previous work has shown that the anatomical cue of the onset of storage root formation, the appearance of anomalous cambia, is initially limited to the root base tissue. The omission of N was associated with decreased root base SuSy activity and an overall reduction in root architectural attributes. These data support the hypothesis that declining N could be a critical switch for storage root formation in sweetpotato. Our findings have profound implications for increasing N fertilizer efficiency and enhancing our understanding of the intrinsic and environmental variables that mediate storage root formation and productivity in this globally important crop.

Investigating novel sensing solutions is important for improving the existing phenotyping pipeline. Polarization is strongly correlated with the geometric properties of an object, such as surface roughness and its orientation relative to the sensor or light source. It has the potential to detect leaf wilting and quantify leaf angles in turfgrass, which are both crucial in precision turfgrass irrigation and crop coefficient determination. This study explores the integration of polarization imaging into RGB imaging pipelines for evaluating turfgrass responses to drought. A controlled dry-down was conducted on two zoysiagrass cultivars and two bermudagrass cultivars grown in pots. Polarization images, RGB images, and visual wilting ratings were collected daily during the four-day dry-down period. Leaf angles, both azimuth and zenith, were derived from top- and side-view RGB images, respectively. We analyzed polarization metrics, including the degree of linear polarization (DoLP) and the angle of polarization (AoP), to assess their relationship with drought stress indicators, such as wilting scores, low Excess Green Index (EGI) values, and changes in leaf angles. EGI and the standard deviation of AoP strongly correlated with wilting scores. Furthermore, DoLP values correlated with leaf zenith angle when the incident light angle was known.

Ornamental plants are essential components of both rural and urban landscapes, with the horticultural industry generating $2.01 billion in bedding and garden plant sales in 2019. However, increasing drought stress, affecting 99.3% of Utah in 2023, highlights the need for water-efficient landscaping. Water-wise landscaping offers a promising solution by conserving water while maintaining visual appeal, making it increasingly popular in arid and semi-arid regions. This study was to investigate the effects of deficit irrigation frequency on the morphological and physiological of 13 landscape plant taxa: Caryopteris ×clandonensis ‘Blauer Splatz’ (Sapphire SurfTM bluebeard), Cercis canadensis (eastern redbud), Cercis occidentalis (western redbud), Cotoneaster ×suesicusn ‘OSUCOT2’ (Emerald BeautyTM cotoneaster), Hesperaloe parviflora ‘Straight Up Red’ (‘Straight Up Red’ Texas red yucca), Miscanthus sinensis ‘NCMS2B’ (bandwidth maiden grass), Penstemon barbatus ‘Novapenblu’ (Rock CandyTM blue penstemon), Penstemon pinifolius (pineleaf beardtongue), Penstemon strictus (rocky mountain beardtongue), Physocarpus opulifolius ‘Diabolo’ (‘Diabolo’ ninebark), Physocarpus opulifolius ‘Little Devil’ (Little DevilTM ninebark), Rosa ×hybrida ‘Meifranjin’ (Blushing Drift® rose), and Vitex agnus-castus ×rotundifolia ‘Helen Froehlich’ (Summertime BluesTM vitex). The experiment was conducted at the Utah Agricultural Experiment Station’s Greenville Research Farm in North Logan, UT, from 1 Jun to 31 Oct 2024. Eight plants per species were randomly assigned to one of three irrigation frequencies based on reference evapotranspiration (ETo): high (80% ETo), moderate (50% ETo), and low (20% ETo). Overall plant appearance was evaluated biweekly using a visual rating scale from 0 (dead) to 5 (excellent). Plant growth, stomatal conductance, and canopy temperature were recorded monthly. Net photosynthetic rate, transpiration rate, and vapor pressure deficit were measured in August and September. Results indicate species-specific responses to deficit irrigation. Some species, such as P. barbatus and P. strictus, exhibited improved visual quality, lower canopy temperatures, and higher photosynthetic rates under more frequent irrigation. In contrast, other species were not affected by reduced irrigation frequency.

Horticulturists and landscape managers are often highly skilled professionals with an extensive understanding of plant biology and growth requirements. However, despite this knowledge, the post-construction soil conditions in which new landscapes are often installed can undermine the success of plantings. In the best-case scenario, horticulturists with passion and perseverance provide attentive management to the plants to help establish the landscape, but this process can often require a deep dive into soil science, an area that many horticulturists may not be equipped to handle fully. The issue of urban soil is gaining increased attention from soil scientists, but a greater integration of horticulture and urban soil science is essential. Similarly to how soil science and crop science are often interwoven, a more holistic approach is needed to bridge the gap between plant knowledge and urban soil conditions. This would better equip horticulturists and landscape professionals to manage the complexities of urban environments. A notable example of this challenge can be found in downtown Oklahoma City, where three large public gardens have been developed within a one-mile span. Each garden presents its own set of unique challenges, including varying soil types, management timelines, and irrigation sources. Myriad Gardens, established in 1970’s has soil that has been disturbed and modified since the early 1900’s. With a complete garden renovation in 2012, Myriad has an average soil pH range of 6.7-7.7. Upper Scissortail previously, an industrial neighborhood was established in 2019 and constructed utilizing seven different soil formulas. With 1000 newly planted trees, poor quality well irrigation water, and a soil pH over 8.0, plant establishing has been challenging for the staff. Finally, Lower Scissortail built in 2022 was also developed with five soil formulas and like Myriad is on city water that has shown to be a better source of water. This case study highlights the complexity of managing urban landscapes and underscores the importance of addressing soil issues at the onset. For horticulturists, it is no longer enough to possess plant knowledge alone. They must also understand the intricate soil dynamics that can make or break the success of a landscape.

Flower production in the Northeastern United States is experiencing a revival as consumer demand for locally grown flowers rises alongside increased interest in sustainable agriculture. However, growers in the region face persistent challenges, including a short and unpredictable growing season, limited land availability, high input and labor costs, and market saturation during peak months. This study draws from field interviews, survey data, and stakeholder engagement with flower growers, floriculture educators, and agricultural service providers across New England. It examines key production and marketing strategies that successful flower farms have adopted, including diversified cropping, succession planting, season extension, direct-to-consumer sales, and floristry integration. Additionally, this work highlights systemic needs in research, infrastructure, and technical assistance tailored to the ornamental crop sector. Findings emphasize the potential for expanded investment in floriculture education, cooperative distribution models, and grower networks to strengthen the viability of flower farming in the region. By elevating grower perspectives and showcasing practical innovations, this presentation contributes to the broader discussion on supporting ornamental crop producers through targeted outreach and research.

The Japanese maple scale (JMS) (Lopholeucaspis japonica) is an armored scale insect that causes significant losses in the ornamental industry through direct injury, plant rejection, unmarketable stock, increased pest control costs, and restricted interstate plant movement. Ornamental growers typically identify JMS by visually inspecting trunks, branches, and twigs for waxy covers or by using sticky tape traps to monitor crawler activity. However, its microscopic size and camouflaged appearance make early detection challenging. This study aims to develop an artificial intelligence (AI)-guided, on-the-go pest scouting system to address the current challenges in early management of JMS in ornamental crop production. To develop the scouting system, a Sony ILX-LR1 professional camera with a 61.0 megapixel full-frame sensor and interchangeable E-mount lenses designed for detailed industrial applications is used to capture high-resolution images. A small amount of data has been collected so far, with plans to gather a larger image dataset during the summer months. In the initial analysis, captured images were sliced into smaller patches to make the microscopic JMS detectable. These sliced images were used to train a transformer-based AI model for detecting JMS. The trained model, tested on the small dataset, showed it could detect JMS with an Intersection over Union (IoU) of over 0.8. While the model shows potential for detecting microscopic JMS, comprehensive training and testing with a larger dataset are needed to validate its performance. Upon completion, the developed scouting technology will serve as an effective tool for early detection and management of JMS in nursery environments, reducing plant injury and rejection while improving profits for ornamental growers.

Zoysiagrass is a popular choice for Florida lawns but requires supplemental fertilization and irrigation. Nitrogen-fixing bacteria, such as Azospirillum Brasilense (Azb), may improve nutrient uptake and rooting, potentially reducing fertilizer and irrigation needs. The experiment is taking place from Summer 2024 to Fall 2026 at the University of Florida, evaluates the effects of Azb on Zoysiagrass under varying nitrogen (N) and irrigation rates. The experiment uses ‘CitraZoy’ Zoysiagrass treated with three Azb products (Tazo-B, AzoPro Turf, Azo Root) and a non-inoculated control. Treatments are applied monthly at three N levels (100%, 50%, 0%) and two irrigation levels (100% and 75% recommended irrigation), using a randomized complete block design with four replicates per treatment. Weekly data collection includes normalized difference vegetation index (NDVI), visual quality, soil moisture, and digital image analysis. Statistical analysis is performed using ANOVA, with mean comparisons determined by Fisher’s Protected Least Significant Difference (LSD) at p ≤ 0.05. Results indicate that Azb products mitigate the impact of reduced irrigation on soil moisture. Combining Tazo-B or Azo Root with 50% N achieves an optimal balance of turf quality and sustainability. Additionally, Tazo-B with 100% N and 75% irrigation yields green cover comparable to fully irrigated treatments. These first-year findings suggest Azb enhances Zoysiagrass performance while reducing nitrogen and irrigation requirements. A second year of research will confirm these results, supporting the potential of Azb to improve turfgrass sustainability.

As climate variability increases and urban water demand rises, the turfgrass industry faces challenges in maintaining high-quality landscapes with limited irrigation. Water restrictions and escalating costs necessitate sustainable solutions to improve water efficiency without compromising turf performance. Research from the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) has shown that compost incorporation can enhance soil structure, increase plant-available water, and potentially reduce irrigation needs for warm-season turfgrasses in Florida. While initial studies demonstrated benefits for new landscape installations, limited research exists on established lawns. Our study aims to evaluate the influence of compost and fertilizer applications under varying irrigation conditions on turfgrass quality. This study, conducted in 2023 and 2024 at the UF/IFAS Plant Science Research and Education Unit in Citra, Florida, examines the combined effects of compost and fertilizer applications under different irrigation regimes. The experimental design had six distinct management practices: a control with neither compost nor fertilizer; compost topdressing once per growing season; combined compost topdressing and fertilizer application once per season; compost topdressing twice per season; both compost and fertilizer applied twice per season; and fertilizer alone applied twice per season. Irrigation was applied at 50%, 75%, and 100% of UF/IFAS recommendations. Compost was applied at 0.5 yd³/1000 ft², and fertilizer at 1.0 lb N/1000 ft². Results from statistical analysis consistently demonstrated that compost topdressing combined with fertilizer twice per season (CTD

Preemergence herbicides play a critical role in weed management but can pose challenges for ornamental plant safety during establishment. Black-eyed Susan (Rudbeckia hirta) cv “Denver Daisy” is a popular ornamental cultivar valued for its vibrant blooms and adaptability. An experiment was conducted in 2024 at the Southwest Research and Extension Center in Hope, AR to evaluate transplanted Black-eyed Susan tolerance to topically applied S-metolachlor. S-metolachlor was applied as a broadcast application at 0, 2.8, 5.6, and 11.2 kg ai ha-1 two weeks after Black-eyed Susan plants were transplanted into raised beds. Visual injury, plant heights, and plant widths were collected at 2- and 4-weeks after application. There was no visual injury at any rating, however, some damage from deer feeding on plants was observed so only plant widths are reported. Plant widths ranged from 9 to 10.5 cm at 2-weeks after treatment and 15.7 to 17.3 cm at 4-weeks after treatment, with no differences between treatment at either data collection timing. Data from this study suggests that topically applied S-metolachlor may be a viable residual weed control option for ornamental Black-eyed Susan.

The landscape maintenance industry is under growing legislative scrutiny for its environmental and noise impacts. Among professional tools, the leaf blower is most frequently targeted due to its high decibel output and widespread use. In response, advancements in battery technology have introduced commercial-grade battery-powered alternatives. Despite this progress, many landscape professionals remain concerned about the work capacity and efficiency of battery-powered blowers compared to traditional gas-powered models. This study evaluated commercial gas and battery leaf blowers through controlled laboratory tests measuring runtime, task efficiency, output force, and sound levels. Results showed that some battery-powered models operated longer on a single charge than gas-powered blowers on a single tank of fuel. However, gas-powered blowers were 24% to 200% more effective in completing standardized tasks when operated by experienced users. This advantage stemmed from their ability to maintain high, consistent output throughout operation. In contrast, most battery-powered blowers sustained peak performance only briefly before throttling output to conserve energy, reducing their effective work capacity. Additionally, several battery models failed to meet manufacturer claims regarding output force. While battery blowers offered quieter operation—producing 20% to 26% lower decibel pressures than gas units—the performance tradeoffs remain a concern for high-demand applications. These results highlight the disparity between power sources in leaf blowers, one of the most frequently used tools in landscape maintenance, and emphasize the current limitations and tradeoffs involved in transitioning to battery-powered equipment under regulatory pressure.

Providing protection from winter elements and seasonal temperature shifts are important considerations for nursery growers and landscape contractors. Frost protection fabrics can provide additional insulation to sensitive plants by maintaining temperatures at more moderate thresholds; however, with a wide range of weights and materials on the market, it is necessary to understand the extent to which various frost fabrics can serve this purpose. Five frost cloth materials were evaluated over a three-month period (January through March 2025) at the LSU AgCenter Hammond Research Station, with individual landscape bed replicates covered with one of four different weights of a non-woven frost fabric, one woven frost fabric, or left uncovered. Landscape bed replicates were comprised of typical landscape bed media (i.e. aged pine bark and sand) with a steel edging frame and support hoops. Each replicate was provided with a temperature sensor below the bed surface and a temperature and light sensor at the bed surface. Sensors recorded temperature and light conditions every 30 minutes, providing insights towards ambient environmental conditions beneath the frost fabrics (or in open air) as well as within the landscape bed media. Uncovered plots received the most amount of light and were subject to the highest degree of variability in temperature; however, the frost protection fabrics provided varying degrees of light transmission and temperature moderation. The woven frost protection fabric allowed the greatest amount of light transmission for all frost protection fabrics investigated, where it also yielded higher surface and subsurface temperatures relative to non-woven materials and uncovered replicates. Non-woven frost fabrics of varying weights generally provided similar levels of insulation to each other; however, it was observed that heavier frost fabrics were capable of minimizing temperature fluctuations. All investigated frost fabrics were effective in raising the minimum surface and subsurface temperatures relative to the uncovered replicates. As the study (and spring season) progressed, peak temperatures under frost cloths were at times elevated above uncovered plots. The results indicate that frost cloths of various materials and weights provide different levels of insulation, and that careful attention to environmental conditions is necessary for deciding when to place and remove frost cloths in the field.

this study aimed to assess how irrigation water and seed magnetization affected the initial growth of okra, bell pepper, cucumber, lettuce, and eggplant seedlings. Five treatments and four replications were used for each species in the randomized block design (RBD) experiment. T1 was irrigation with tap water; T2 was neodymium magnetization of seeds plus irrigation with tap water; T3 was commercial magnetization of seeds plus irrigation with tap water; T4 was lack of seed magnetization plus irrigation with neodymium magnetized water; and T5 was lack of seed magnetization and irrigation with commercial magnetized water. We assessed the following: emergence speed index (ESI), average emergence time (AET), emergence percentage (E%), shoot dry matter (SDM), root dry matter (RDM), number of leaves (NL), root length (RL), stem diameter (SD), and plant height (PH). Normality and variance analysis were performed on the data, and the Tukey test was used to compare the means at a 5% probability level. The study's findings demonstrate the advantages of magnetically treated water for seedlings. Using water that has been magnetized by a neodymium magnetizer produced superior results for lettuce seedlings. The highest RL, NL, RDM, and ESI values were obtained for bell peppers when they were irrigated with water that had been magnetized by a neodymium magnetizer. The time it took for cucumber, eggplant, and okra seedlings to form was shortened by either magnetizing the seeds or watering them with tap water. Overall, the results of seed magnetism have been more noteworthy than those of irrigation water magnetization.

Agriculture continues to account for over 70% of global freshwater withdrawals, despite extensive research into water conservation methods in food production. A significant portion of this water usage is attributed to irrigation. In vegetable crops, the traditional raised bed system with plastic mulch can reduce irrigation application by minimizing evaporative losses. However, this system does not prevent water and nutrient losses to deep percolation or lateral movement outside the bed area. Therefore, this study evaluates an alternative raised bed system (H2grow), and compares its impact on water use, yield, and fruit quality in bell pepper production against the conventional raised bed system. Six treatments were tested, which included three nitrogen (N) application rates in both raised bed systems (bed type). A split-plot design was used, with bed type as the primary factor and nitrogen rates as the secondary factor. All treatments were replicated four times. Soil moisture sensors were used to trigger irrigation when soil moisture levels fall below 90% field capacity. Soil moisture, nutrient levels, and tissue nutrient content were monitored throughout the growing season. Yield and fruit quality (fruit wall thickness), were assessed at harvest. Preliminary results show that cumulative water use under the H2grow was 33% lower than the conventional raised bed, regardless of nitrogen application rates. This corresponds to a water savings of 1460 m³/ha. Although there were no significant differences in yield or wall thickness between bed types; the H2grow system showed promising potential over conventional beds with a p-value of 0.08 for yield and 0.06 for wall thickness. Nitrogen application rates had no significant effect on yield or fruit wall thickness, though fruit biomass was lowest under the low-N treatment. These findings demonstrate that the H2grow system significantly conserves water in bell pepper production and has the potential to reduce the water footprint in commercial vegetable production. As water conservation becomes an increasing concern in agriculture, this innovative technology offers a critical solution to address the growing challenge of freshwater use in food production.

Strawberry production in Florida traditionally relies on impact sprinklers for bare-root transplant establishment and freeze protection, leading to significant water consumption and potential nutrient leaching and runoff. This study assessed micro-sprinkler systems as alternatives to enhance water use efficiency while maintaining crop performance. The objectives were to (1) evaluate micro-sprinklers in research and commercial settings and (2) assess sprinkler distribution uniformity under different wind conditions. Field trials at the Plant Science Research and Education Unit in Citra, FL compared four micro-sprinklers to an impact sprinkler (control), measuring water use, plant vigor, and yield. The tested systems utilized Mini Revolver, SuperNet Jet, Mini-Wobbler, and Xcel Wobbler micro-sprinklers. The irrigation systems were arranged in a randomized complete block design with four replications. Additionally, lower quarter distribution uniformity (DUlq) tests with catch cans were conducted to evaluate sprinkler efficiency for freeze protection across varying wind conditions in Citra. The best-performing micro-sprinkler system was evaluated on a commercial strawberry farm in Plant City, FL in comparison with the grower’s Rotator sprinkler system. In Citra, all micro-sprinkler systems used less water than the impact sprinkler for bareroot transplant establishment and freeze protection. Water use was lowest with the Mini-Revolver, which decreased water use by 66% during establishment and 64% during freeze protection without adversely affecting plant survival or yields. Similar reductions were observed at the commercial farm, with water savings reaching 58% during establishment and 63% during freeze events. Significant variation in DUlq in response to wind conditions was observed among the sprinkler systems. Wind speeds >7 mph decreased DUlq, with the Mini-Revolver resulting in the lowest DUlq. However, at wind speeds 7 mph, which would decrease freeze protection effectiveness.

Deficit irrigation is an agricultural practice that can enhance crop water productivity (CWP) when yields are not affected, and be a technique to support crop production under persistent droughts and reduced agricultural water availability. Over two seasons, we evaluated grafted and ungrafted cantaloupe melon (Cucumis melo L.) under three consistent irrigation regimes: 100% of field capacity (FC; full irrigation), and 70% and 50% irrigation volumes of the full irrigation, resulting in moderate and severe deficit irrigation treatments, respectively. Although the deficit irrigation treatments accentuated drought stress through the season, plants in the moderate deficit irrigation (70% FC) maintained their plant water status and slightly lowered stomatal conductance (gs) and photosynthetic rate (Pn) when compared to full irrigation. Under severe deficit irrigation (50%), plants had lower water potential than the full irrigation, and a reduction of 65% in gs and 47% in Pn, when compared to the full irrigation. The yields of the 100% and 70% irrigation treatments were similar in one year and lower for the 70% FC in the second year. The severe deficit irrigation had on average a 40% lower yield than the full irrigation. Overall, the moderate deficit irrigation had a 25% reduction in applied water, and either a similar or a higher CWP, depending on year, when compared to the full irrigation. Melon grafting did not improve yield under deficit irrigation conditions; however, it increased yield under full irrigation and low environmental stress (i.e., year). This study shows that melons can acclimate to lower water availability and sustain yields under a constant, moderate deficit irrigation, which can be an alternative for growers that face long-season droughts and lower irrigation water allocation.

Sustainable management of irrigation water is critical for soilless greenhouse production systems, particularly in ornamental plant cultivation, where agrochemical (pesticides, nutrients, and growth regulators) use is intensive. Recycled irrigation water carries agrochemicals from production surfaces, containers, substrates, and system components. Even at low concentrations, these compounds can be phytotoxic to sensitive crops or pose environmental risks if discharged. While recirculating irrigation systems improve water efficiency, they require the use of treatment technologies to remediate agrochemicals. Woodchip bioreactors, commonly used for nitrate removal, have also shown promise in remediating phosphates and pesticides. They provide a carbon source and growth matrix for diverse microbial communities. Typical anaerobic conditions facilitate denitrification, and the biofilm further increases the reactive surface area where pesticides can interact with degrading enzymes to enhance pesticide remediation. Integrating aerobic bioreactors as a secondary stage can promote dissolved organic carbon release and enhance degradation of certain pesticides. Hydraulic retention time (HRT) is a key design factor, influencing nutrient retention and pesticide removal by controlling contact time with bioreactor microbiomes. Shorter HRTs support nutrient recycling for irrigation reuse, while longer HRTs enhance nutrient and pesticide degradation through extended microbial processing. We evaluated the performance of a sequential two-stage non-aerated (stage 1) - aerated (stage 2) bioreactor configuration in reducing effluent pesticide concentration and load under varying hydraulic retention times (HRTs). Two two-stage systems, each consisting of two bioreactors, were installed at a Michigan wholesale greenhouse, treating recirculating operational water from an 11,500 m² production area. These systems operated for 160 days at HRTs of 30 (30HRT) and 60 minutes (60HRT) per stage, corresponding to bioreactor volumes of 1,135 L and 2,271 L per stage, respectively. Preliminary results indicate that both 30HRT and 60HRT systems treated an average daily volume of 36,225±2,395 L. Average recycled Total Nitrogen load was 91% and 2.6 kg d-1 for 30HRT, and 78% and 2.3 kg d-1 for 60HRTs, respectively. Phosphate and pesticide content is currently being analyzed, with early observations showing phosphate load shifts from non-aerated to aerated conditions. These results will be presented at the conference.

Irrigation return water (IRW) from the nursery and greenhouse industries contains agrochemicals (pesticides, nutrients, and growth regulators) that pose significant phytotoxic and environmental risks within the operation and to the surrounding ecosystem. Agrochemicals can contribute to plant injury, eutrophication, groundwater contamination, and ecological toxicity. Woodchip bioreactors offer a cost-effective, sustainable solution for contaminant mitigation by supporting diverse microbial communities. Under anaerobic conditions, woodchip bioreactors facilitate nitrate reduction, while biofilms enhance pesticide degradation via enzymatic activity. Hydraulic retention time (HRT) regulates the duration of contaminant-microbiome interactions, balancing nutrient recycling in IRW at shorter HRTs and enhanced pesticide degradation at longer HRTs. However, newly established bioreactors typically experience a lag phase before reaching optimal contaminant removal efficiency due to the time required for microbial communities to develop. In this study, we investigated the potential of seeding new bioreactors with biofilms from established systems to accelerate this transition. Thirty-six woodchip bioreactors were evaluated under three HRTs (4, 14, and 24 hours) and three seeding levels (0%, 5%, and 10%) over 170 days. Simulated IRW containing nitrate, phosphate, and eight pesticides (acephate, atrazine, bifenthrin, chlorpyrifos, cyazofamid, oxyfluorfen, sulfoxaflor, and thiophanate-methyl) was used to assess performance. Preliminary results indicate that the 10% seeding at 4HRT yields the highest total nitrogen removal (6.2 g/day), compared to the 5% seeding at 4HRT (3.1 g/day) and the unseeded treatment at 4HRT (2.8 g/day). This suggests that a higher microbial load, combined with a shorter retention time, may be the most effective approach for removing Total Nitrogen.

In-situ resource utilization at the lunar surface has been proposed for food production during human exploration missions. However, lunar regolith’s sandy texture holds less plant-available water than most of Earth's fine-textured agricultural soils. Reduced gravity at the lunar surface limits drainage from containerized media, likely causing root-zone hypoxic stress without appropriate irrigation management. Sensor-based irrigation systems may mitigate these challenges by maintaining an optimal medium volumetric water content. Evaluating the palatability of crops is also crucial, though sensory evaluation is uncommonly included in crop production studies. Hence, this research aimed to quantify the effects of sensor- and time-based irrigation strategies on the development and growth of Lactuca sativa (lettuce) grown using two continuous harvesting techniques in a containerized Turface MVP medium, a coarse calcined clay aggregates. Lettuce seeds were sown in 48 containers filled with the Turface MVP (particle sizes 0.8-3.4 mm) premixed with 15N-3.9P-10K controlled release fertilizer. Additionally, 24 containerized media were left unseeded to serve as controls. The containerized media were randomly assigned to sensor- and time-based irrigation under “pick-and-eat” and “cut-and-sow” harvesting techniques. Sensor-based irrigation maintained volumetric water content at 0.40 m3·m-3 through frequent sensor scanning and automated irrigation when sensor readings fell below the setpoints, while the media at time-based irrigation management were irrigated to saturation once per day. Under the “pick-and-eat” method, sensor-based irrigation increased the leaf fresh and dry weights, and photosynthesis rate by 81%, 39%, 61%, respectively, compared with plants under time-based irrigation at the end of experiment. The “cut-and-sow” method resulted in lower leaf fresh and dry weights than the “pick-and-eat” under both irrigation treatments. However, sensor-based irrigation led to increases in the medium’s electrical conductivity, causing plants under salinity stress because the phosphorus, potassium, and magnesium concentrations in the leaf tissue increased compared with those under time-based irrigation. Sensor-based irrigation improved overall acceptability of samples under “pick-and-eat” in sensory testing, with 50% of respondents disliking the time-based samples. However, the "cut-and-sow" samples under time-based irrigation exhibited higher overall acceptability, though 75% or more testers liked both samples. Sensor-based irrigation improved the yield of lettuce under "pick-and-eat" method but caused salinity stress. Conversely, the "cut-and-sow" method led to lower yield, but improved plant palatability under time-based irrigation. Nevertheless, with higher yield, increased mineral content, and improved consumer acceptability, the “pick-and-eat” method under sensor-based irrigation demonstrates potential for sustaining continuous crop production.