ASHS 2025 Conference

Pollination is a prerequisite for optimizing both yield and fruit quality within commercial highbush blueberry (Vaccinium spp.) production systems. Although many insects can pollinate blueberry flowers, the honey bee (Apis mellifera) provides most of the pollination services within commercial settings due to the large number of foraging individuals within a single colony. Despite this, insufficient pollination frequently limits growers from achieving their full yield potential, and research-based recommendations to inform pollination strategies are lacking. The objective of this presentation is to summarize how the cross-disciplinary and multi-institutional Blueberry Pollination Project has addressed some of these barriers by investigating best practices to achieve optimal honey bee-mediated pollination and formulate decision-aid tools. Key findings that will be highlighted include the role of cross-pollination for optimizing yields in northern and southern highbush blueberry cultivars, the effects of hive placement on flower visitation and overall crop pollination, effects of changing stocking density and colony placement on farm income, and how landscape density and colony population size are more influential in determining flower visitation and pollination outcomes than traditional stocking density recommendations. Decision-aid tools that predict bloom phenology for the timely arrival and departure of honey bee colonies will also be introduced alongside other project resources available on our website (https://blueberrypollination.org/).

Blueberry (Vaccinium corymbosum interspecific hybrids) production in many regions of the world requires significant investments, including the use of soil amendments like pine bark. Prior research has identified V. arboreum as a potential rootstock which may reduce the need for costly soil inputs for growing southern highbush blueberries (SHB). Furthermore, use of V. arboreum as a blueberry rootstock may improve drought tolerance, increase plant longevity, confer tolerance to bacterial leaf scorch (Xylella fastidiosa), and make mechanical harvesting more feasible. However, V. arboreum propagation and grafting can be challenging. Thus, there is a critical need to develop nursery practices for the production of grafted blueberry liners. Preliminary observations suggest that interspecific hybrids of SHB × V. arboreum may have desirable rootstock characteristics like greater rooting success and wider scion compatibility than V. arboreum. This study aimed to identify optimal grafting practices by evaluating the effects of different grafting timings on subsequent plant development of SHB grafted onto SHB × V. arboreum hybrids and V. arboreum rootstocks. ‘Sentinel’ and ‘Albus’ SHB scion cultivars were grafted onto V. arboreum and hybrid rootstocks at four times in the year: February, March, September, and November. Scion takes and growth were evaluated. Grafting success and subsequent plant development were assessed using a bud development scale. Results showed that grafting in the spring improved scion development compared to fall grafting. Additionally, hybrid rootstocks exhibited greater compatibility with SHB scions than V. arboreum. The findings from this project will contribute to the optimization of nursery practices for producing grafted SHB nursery plants efficiently which is necessary for adoption of rootstock use in commercial blueberry production.

Blueberry fruit are rich in antioxidants and have become popular due to their numerous health benefits. In many fruits, a significant metabolic shift in carbon metabolism during fruit ripening leads to an increase in sugars, decrease in acids and accumulation of anthocyanins. The alterations in metabolic programs during fruit ripening in blueberry remain uncharacterized. Further, the role of ethylene in metabolic reprograming during blueberry ripening has not been studied. We quantified sugars, acids, anthocyanins and determined the expression of genes related to their metabolism. This study revealed that sucrose import into the fruit continues throughout ripening, with a corresponding increase in glucose and fructose. The transcript abundance of SUCROSE SYNTHASE and NEUTRAL INVERTASE was detected, suggesting sucrose catabolism in the cytosol. The high transcript abundance of VACUOLAR INVERTASE suggested that this gene plays a predominant role in sequestration of glucose and fructose in the vacuole. Malate and quinate were the major acids that displayed a decrease in concentration during ripening. The expression of MALATE DEHYDROGENASE and high transcript abundance of PHOSPHOENOLPYRUVATE CARBOXYKINASE suggested conversion of malate to phosphoenolpyruvate (PEP) during ripening. One of the potential fates of PEP, the generation of shikimate for anthocyanin production, was supported by the upregulation of multiple anthocyanin biosynthesis genes. Further, applications of ethephon and 1-aminocyclopropane-1-carboxylic acid, suggested that ethylene transiently stimulates sugar, acid and anthocyanin metabolism. This indicated ethylene is important for ripening initiation in blueberry. Overall, this study provided insights into metabolic programs, and the role of ethylene during blueberry ripening.

Conventional breeding of woody fruit crops through hybridization is more time-consuming, labor-intensive, and costly than breeding annual plants, primarily due to their prolonged juvenile phase before flowering. Over the past two decades, significant efforts have been made to accelerate woody plant breeding, also known as as FasTrack breeding, by shortening juvenility using cutting-edge technologies. One key strategy involves genetic engineering of flowering pathway genes, particularly members of the phosphatidylethanolamine-binding protein (PEBP) family, such as FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1). Constitutive expression of FT or knockout/knockdown of TFL1 has proven effective in inducing early flowering. These approaches have successfully enabled FasTrack breeding in blueberry (Vaccinium cormbosum) and plum (Prunus domestica). In this presentation, I will share our success in blueberry FasTrack breeding and discuss recent progress in applying this strategy to grapevine (Vitis vinifera). More recently, we have developed FasTrack breeding blueberry (Vaccinium cormbosum) and made significant progress in applying this strategy to grapevine (Vitis vinifera) though FT overexpression and TFL1 gene editing.

Maypop (Passiflora incarnata) is a perennial vine native to North America, valued for its tropical fruit flavor, adaptability, and resilience to cold and drought. Unlike Passiflora edulis (Passion fruit), which thrives only in tropical and subtropical climates, Maypop has potential as a high-value fruit crop for temperate regions. In addition to its edible fruit, its leaves and flowers have medicinal applications, and its seed oil is rich in omega-3 and omega-6 fatty acids, making it valuable for cosmetic and therapeutic use. This study evaluated the performance of two Maypop cultivars, ‘PinkPop’ and ‘SnowPop,’ in a field trial at Kentucky State University’s Harold R. Benson Research Farm. A randomized complete block design was used to assess plant growth, fruit yield, fruit quality, and seed characteristics in 2024. Fruits from a wild relative were also analyzed for comparison. Preliminary results showed no significant difference in plant height (~86 cm) and stem diameter (~5.5 mm) between cultivars in June. ‘SnowPop’ produced more fruits and had higher yield than ‘PinkPop,’ though the difference was not statistically significant. However, ‘PinkPop’ produced significantly heavier fruits (30.8 g) compared to ‘SnowPop’ (26.09 g), while both had a similar average fruit diameter (~36 mm). The wild relative produced comparatively larger fruits (45.92 g, 55.67 mm diameter). Soluble solids content was comparable between ‘PinkPop’ (13.6° Brix) and ‘SnowPop’ (12.9° Brix), whereas the wild relative had significantly lower Brix (6.6°). Seed analysis indicated that ‘PinkPop’ had more and heavier seeds per fruit, contributing to a higher edible pulp content, while ‘SnowPop’ had fewer seeds, making it potentially more desirable for fresh consumption and processing. Overall, both cultivars demonstrated strong potential for commercial cultivation in Kentucky, and their traits, along with those of the wild relative, highlight opportunities for breeding programs to develop improved Maypop cultivars with enhanced fruit quality.

Blueberries (Vaccinium spp.) are small fruit crops native to North America but grown commercially in several countries worldwide. Blueberries are highly vulnerable to changing climatic conditions and prolonged heat waves. High temperatures pose a significant challenge for developing strategies for enhancing crop resilience and food security. As blueberry is a recently domesticated crop, the availability of genomic resources is minimal for accelerating climate-resilient blueberry breeding programs, especially for heat stress tolerance. Previously, we identified several single-nucleotide polymorphisms (SNPs) associated with heat-tolerant traits in blueberries. In this study, we developed 96 Kompetitive Allele-Specific PCR (KASP) marker assays and 10 Cleaved Amplified Polymorphic Sequences (CAPS) markers for heat tolerance-associated SNPs. KASP assays were screened on 384 plants comprising diploid and tetraploid intercross derivatives, cultivars, and wild germplasm. We found a high level of heterozygosity for these markers. A principal component analysis of the genotype data differentiated wild accessions and hybrids, whereas tetraploid derivatives and cultivars formed a single cluster. A diverse panel of 42 accessions was evaluated under controlled high-temperature conditions (40 °C for 4 days) in a separate study. Physiological responses to heat stress were quantified by measuring leaf malondialdehyde (MDA) content (an indicator of oxidative membrane damage) and chlorophyll fluorescence parameters to assess photosystem II efficiency. Cultivars varied in stress response: heat-tolerant genotypes accumulated significantly less MDA and sustained higher photochemical efficiency than sensitive ones. Five CAPS markers showed substantial allele-associated differences in MDA levels, effectively distinguishing tolerant vs. sensitive groups. Cluster analysis based on the CAPS genotypes further separated cultivars according to genetic background (highbush vs. rabbiteye), revealing the known heat-resilient cultivars (often with wild Vaccinium ancestry) grouped together. These findings highlight robust marker–trait associations between SNP-derived CAPS markers and heat-tolerance indicators. Upon further validation in diverse germplasm, the newly developed markers will facilitate breeding heat-tolerant blueberry cultivars.

Muscadine grape seeds are a rich source of polyphenols with known health benefits, yet the specific compounds responsible for their anticancer effects remain poorly understood. This study investigates the cytotoxic potential of muscadine seed metabolites against African American triple-negative breast cancer using an integrated OMICS approach combining genomics, metabolomics, cytotoxicity assays, HPLC, gene expression profiling, molecular modeling, and statistical analysis. Among 1,781 metabolites identified by LC/MS-MS, we identified three compounds that exhibited the strongest anticancer activity by targeting Eph receptor signaling, cell proliferation, and inducing apoptosis. These findings highlight the therapeutic potential of muscadine seed phytochemicals and support their development as functional food components or leads for targeted cancer therapies.

Plasma activated water (PAW) is produced when plasma generated by high-voltage discharge is delivered to an atmospheric gas and interacts with water to create a new solution containing reactive species. The resulting water contains nitrate nitrogen (ca. 20-176 ppm N), small amounts of nitrite and ammonium, as well as reactive oxygen species. The benefits of PAW use for agricultural crops can include improved germination, increased seedling vigor and health, resistance to pests and disease, an alternative nitrogen source, and an overall improved plant health and yield. However, further research is needed to understand the characteristics of PAW, PAW shelf-life stability, crop specific PAW application and timing, and its overall effects in plant production. Our overall objective is to determine if PAW can enhance plant quality/yield in organic greenhouse tomato production. Studies were conducted to evaluate tomato germination and seedling growth in response to PAW application. A study was conducted to evaluate if germination of tomato seeds and subsequent growth in seedling trays with container media is affected when soaked prior to seeding with plasma water or tap water for three, six, or 12 hours. The study was replicated four times over time, with each replicate lasting for 15 days. Data was collected on daily germination, weekly heights and widths, and fresh mass, dry mass, and leaf area at harvest. Most seed treatments for 6 or 12 hours, regardless of water treatment, enhanced germination on day 5 and day 6 compared to control. However, by final harvest at day 15 there were no significant differences between treatments and control. Our second phase of research evaluated PAW application during organic tomato seedling production stage. Seedlings were treated with a drench of 4 mL per cell of different PAW sources generated for 5, 10, 30, or 60 minutes for a total of three applications every three days. On day 7, 30-minute PAW had significantly greater germination counts compared to the control. At final harvest on day 22 60-minute PAW had significantly greater fresh mass, dry mass, and leaf area compared to the control. In conclusion, a pre-seed soaking treatment for 12 hours is recommended for earlier germination and a drench application of PAW generated at a duration of 60 minutes is recommended for greater seedling growth. Further research includes PAW application timing and frequency and its carry-over effects in tomato crops grown to fruiting.

Light of different wavelengths influences the crop yield and quality by modulating metabolic pathways, resulting in variations in phytochemical abundances. Therefore, optimized light conditions could enhance the plant-protecting and health-promoting attributes of tomato fruit. However, the effects of supplemental blue (B) and ultraviolet-B (UV-B) light on amino acids (AAs) and phenolics, particularly hydroxycinnamic acids (HCAs), as well as fruit firmness and yield characteristics in tomatoes, are not well understood. Therefore, the current study examined the effects of supplemental light on yield, firmness, and levels of amino acids (AAs) and hydroxycinnamic acids (HCAs) in red-ripe, greenhouse-grown tomato fruits. This study was conducted with two tomato varieties (Plum Regal and TAM Hot-Ty) exposed to supplemental blue light (238 µmol m-2 s-1 at 40 cm from the plants for 8 hours), UV-B light (5 µmol m-2 s-1 at 46 cm from the plants for 4 hours), a combination of blue and UV-B light (B UV-B), and a control group with no supplemental lighting. Our findings revealed that blue light alone significantly enhanced yield and firmness in both varieties. Similarly, UV-B light alone resulted in increased yield and higher HCA levels. The combined B UV-B treatment produced firmer fruits with high HCAs without compromising yield. Important amino acids like γ-amino butyric acid (GABA) and glutamine were also significantly enhanced by B UV-B. Therefore, supplemental blue and UV-B light could be used to improve nutritional value by increasing the abundance of bioactive compounds in tomato fruits grown under controlled environmental conditions. This work was partially supported by USDA-NIFA-2024-51181-43464, USDA-NIFA-AFRI 2023-67013-39616 through the Vegetable and Fruit Improvement Center and Institute for Advancing Health Through Agriculture of the Texas A

Consumers want year-round supply of high quality fresh produce. However, the low sunlight has limited greenhouse vegetable during the winter months in high-latitude region. In order to boost yields and meet market demand, supplemental lighting is required. However, utilizing electric lighting, even high-efficient LED fixtures results in high electricity costs. Photoperiod extension (up to 24h) is a promising strategy which can be implemented in many countries as the utility companies incentivize the use of low cost, off-peak electricity use during the night. In this way, extending the photoperiod from the conventional 16h up to 24h can result in reduced electricity cost when the daily light integral (DLI) remains the same. In this study, we look at the impact of two different 24h lighting strategies in two cherry tomato cultivars and their impact on photoperiod injury compared to a 16h control. One 24h treatment involved a change from white light during the day to blue light at night at a reduced photosynthetic photon flux density (PPFD; i.e., dynamic) while the other kept a static spectrum and PPFD for 24h. In addition, each treatment also had a low blue (10%) and high blue (30%) variation. The experiment took place in a glass greenhouse at the Harrow Research and Development Centre in Harrow, Ontario, Canada. It was determined that the 24h dynamic lighting strategy has similar maximum quantum yield of photosystem II (Fv/Fm) values as the 16h controls while the 24h static treatments values were drastically reduced. What’s more, the Fv/Fm value from the 24h static treatment with high blue content was lowest among all treatments indicating that elevated levels of blue light may be detrimental during a 24h photoperiod. In addition, the overall yield from the 24h dynamic treatments were similar to the 16h controls while the 24h static treatments were statistically lower. Taken together, these results indicated that a 24h dynamic light treatment is essential to mitigate photoperiodic injury in cherry tomato. This data suggests that the use of such a lighting strategy could also reduce electricity costs for greenhouse cherry tomato producers.

The thermotolerance responses of tomato plants have been assessed using various physicochemical parameters. However, even within the same genotype, thermotolerance strategies can vary among plant organs. This study aimed to investigate heat stress responses in tomato genotypes across vegetative and reproductive stages, focusing on a comprehensive analysis of thermotolerance mechanisms. Ten tomato varieties, including seven commercial cultivars and three Texas A

Small-scale greenhouse growers commonly use perlite as substrate in the Dutch bucket hydroponic production of vine crops such as tomatoes. However, perlite is prone to an excessive nutrient solution leaching primarily due to its free-draining and low water holding capacity properties. Alternative organic substrate to perlite is needed for a sustainable hydroponic production of these fruiting vegetables in the Dutch bucket system. This study thus evaluated the growth and yield performance of two tomato cultivars (BHN 589 and Geronimo) in five substrates (clay pebbles, loose rockwool, perlite, coco coir, and Lensli) in a randomized complete block design with three replications inside a polyethylene film greenhouse from February to July 2024. Results showed no significant effects of the interaction of substrates and cultivars on all the measured growth and yield traits. Averaged over the two cultivars, the substrates tested significantly influenced the total yield ranging from 338 to 464 Mg/ha and marketable yield ranging from 328 to 445 Mg/ha. More specifically, Lensli increased marketable yields by 15, 31, and 36% than those of coco coir, perlite, and clay pebbles, respectively. These increases are primarily due to a significant increase in the number of marketable fruit per plant (19%) and average marketable fruit weight (10%). Lensli also increased leaf area index by 44 and 60% than those of perlite and clay pebbles, respectively. Based on these results, Lensli, a blend of fine Baltic and superfine black peat, is proving to be a promising organic alternative substrate for tomato production in the Dutch bucket hydroponic system.

Real-time nutrient management is crucial in controlled environment agriculture (CEA) for enhancing crop production, reducing fertilizer costs, and mitigating environmental impacts. Inadequate fertilization can reduce crop productivity and nutrient runoff. Sap-based sufficiency ranges could maintain balanced fertilization. The main objective of this study is to establish sap-based sufficiency ranges for lettuce (Lactuca sativa), tomatoes (Lycopersicon esculentum), and cucumbers (Cucumis sativus) across developmental stages and fertilizer levels in CEA. Lettuce was grown using a Randomized Complete Block Design (RCBD) with three cultivars (‘Casey,’ ‘Cherokee,’ ‘Chicarita’) and three fertilizer levels (low 50%, medium 100%, and high 200%) in a vertical farm and greenhouse. A split-plot in RCBD was used for tomatoes (‘Grandice,’ ‘Macxize,’ ‘Prodice’) and cucumbers (‘Georgia,’ ‘Verdon,’ ‘Camaro’) under the same fertilizer levels. Rockwool substrate was used for lettuce, and coco-coir for tomatoes and cucumbers. We monitored and maintained the environmental parameters: daily light integral (DLI) ranged from 17–23 mol/m²/day for tomatoes and cucumbers and 12–18 mol/m²/day for lettuce. Tomatoes received supplemental light from 1 AM to 10 AM. Temperature and relative humidity (RH) were maintained at 18–22°C and 70–80% RH for lettuce, and 22–25°C and 60–70% RH for tomatoes and cucumbers. We monitored pH and EC weekly. Sap samples were collected at half and final stages for lettuce and four stages for tomatoes and cucumbers. Chlorophyll and anthocyanin content, yield, number of fruit, soluble solids content (SSC), and titratable acidity (TA) were recorded, while fresh/dry weight, leaf area, SSC, and TA were measured for lettuce. The tissue crushing method was used to establish sap-based sufficiency ranges for nitrogen (NO₃⁻-N), phosphorus (PO₄³⁻-P), potassium (K⁺), calcium (Ca²⁺), magnesium (Mg²⁺), and sulfur (SO₄²⁻-S). Our results provide general sufficiency recommendations (in mg/L): For greenhouse lettuce, the sufficiency ranges were NO₃⁻-N (546–1027), PO₄³⁻-P (520–616), K⁺ (6250–7052), Ca²⁺ (690–899), Mg²⁺ (280–371), and SO₄²⁻-S (93–101). For lettuce in vertical farm, NO₃⁻-N (1122–1139), PO₄³⁻-P (524–629), K⁺ (5455–5672), Ca²⁺ (426–595), Mg²⁺ (173–205), and SO₄²⁻-S (102–129). For tomatoes, NO₃⁻-N (547–805), PO₄³⁻-P (730–927), K⁺ (5360–7151), Ca²⁺ (3139–3716), Mg²⁺ (1133–1427), and SO₄²⁻-S (2796–3127). For cucumbers, NO₃⁻-N (888–1081), PO₄³⁻-P (25–38), K⁺ (4291–5478), Ca²⁺ (2147–2493), Mg²⁺ (1458–1813), and SO₄²⁻-S (1615–1946). In conclusion, sap-based sufficiency ranges were established which enable real-time nutrient monitoring and support more efficient fertigation in CEA.

The Pour-through method is a recommended best management practice (BMP) for nurseries in Florida for managing nutrient levels in container-grown crops. An investigation into fertility management in container nurseries was conducted by comparing traditional methods of monitoring EC with more recently developed sensor-based technologies. A field experiment was conducted to establish a relationship between sensor-based EC measurements and the pour-through method under two different irrigation methods (sprinkler and drip irrigation) and fertilizer rates (low and high) under open field and high tunnel environments. A sensor system was designed for field deployment, and wireless communication was established to monitor sensor data remotely. Results showed that a correlation could be established under sprinkler irrigation, but no correlation could be established under drip irrigation. Salt stratification was shown to vary significantly with irrigation type, with results suggesting that sensor installation in the center of the container is an optimal choice for monitoring EC of the root zone under multiple irrigation methods. Finally, variation in the data was modeled to determine the minimum number of sensors needed to maintain the same precision as the pour-through method. It was estimated that four sensors per 1000 pots are necessary. However, more sensors may be required to maintain this precision at higher EC levels.

Timely detection of aqueous analytes is essential for informed decision-making in agriculture, particularly in controlled environments such as greenhouses, vertical farms, and space-based cultivation systems. Traditional aqueous sensing technologies typically depend on single-point measurements, capturing data at fixed times and locations. This constraint limits their ability to detect analytes that may emerge elsewhere in the system or at different intervals. In response, we present an innovative, low-cost sensor platform featuring a 3D-printed housing integrated with a mass-manufactured, nanotextured diffraction surface. This housing includes a lighting element and a camera sensor to enable continuous image-based analysis of water quality. Designed for seamless integration into hydroponic lines, the sensor units are both affordable and easily reproducible, allowing for deployment at multiple points within a system to provide real-time monitoring. Our results demonstrate the sensor’s capability to detect and quantify a range of aqueous analytes—including visible and UV-absorbing compounds, dust particles, and various microalgae species. Our sensor performs similarly to a commercial UV-Vis instrument, often used to measure contaminants present in water. Specifically, calibration curves derived from increased concentrations of a simulated contaminant had a calculated R2 value of 0.998 from the UV-Vis instrument and 0.996 from our device. Performance is further enhanced through machine learning algorithms that improve detection and classification. This scalable and cost-effective sensing system offers a practical solution for real-time water quality assessment across controlled environment agriculture, greenhouse systems, and extraterrestrial farming applications—particularly in contexts where labor is limited and rapid response is critical.

Vitamin C is a vital antioxidant that plays a crucial role in plant photosynthesis, enzymatic reactions, and stress resistance, while also being a key micronutrient for human health. Evaluating the potential of enhancing vitamin C content in food crops like lettuce (Lactuca sativa L.) can contribute to better health outcomes and disease prevention. This study investigates the effect of ascorbic acid foliar application on biomass, phytochemicals, and mineral nutrient content in lettuce using a Nutrient Film Technique (NFT) hydroponic system. Lettuce was treated with different concentrations of ascorbic acid (0, 500, 750, and 1000 ppm) via foliar application. Chlorophyll and biomass were recorded, while vitamin C content was analyzed using high-performance liquid chromatography (HPLC). Other micronutrients were also analyzed and assessed based on treatments. Results from this study will contribute to understanding how micronutrient deficiency in humans can be addressed and potentially maximized through agronomic biofortification.

Food waste liquid anaerobic digestate (FWLAD) has strong potential as an organic fertilizer due to its nutrient-rich composition. However, organic nutrient solutions often have lower dissolved oxygen (DO) levels than inorganic ones, which may limit oxygen availability in the root zone, restricting nutrient uptake and plant growth. This study examines whether increasing perlite content in a soilless substrate and aerating the nutrient solution can enhance root-zone oxygen availability and improve lettuce (Lactuca sativa 'Muir') growth when cultivated with FWLAD. Lettuce seeds were sown in a 128-cell plug tray filled with a peat-based growing mix blended with perlite at 100%:0%, 70%:30%, and 40%:60% (v:v). Increasing perlite content from 0% to 60% increased substrate porosity from 47% to 56%, while air space remained between 30% and 33%. One week after sowing, seedlings were sub-irrigated with four nutrient solutions prepared from either crude or nitrified FWLAD at an electrical conductivity (EC) of 2 dS·m-1, each under aerated and non-aerated conditions. Control nutrient solutions were prepared using inorganic fertilizer at 2 dS/m EC. Lettuce seedlings were grown indoors for three weeks at the air temperature of 24°C with a photosynthetic photon flux density of 210 µmol·m-2·s-1 under an 18-hour photoperiod. Regardless of nutrient solution type, increasing perlite from 0% to 60% had little to no effects or decreased leaf number (by 7-13%), leaf area (by 13-26%), and shoot fresh mass (by 10-42%). DO levels remained below 1.5 ppm in non-aerated crude or nitrified FWLAD solutions, while aerated solutions and inorganic fertilizer treatments maintained DO above 6 ppm. Aerating the nutrient solution with crude FWLAD decreased total leaf number (by 4-17%), total leaf area (by 28-45%), and shoot fresh mass (by 37-44%) across all substrate conditions, whereas aeration with nitrified FWLAD increased these parameters by 22-35%, 174-343%, and 138-325%, respectively. At each substrate condition, lettuce seedlings grown with inorganic fertilizer had the highest leaf number, leaf area, and shoot fresh mass. These results suggest that increasing perlite content did not enhance lettuce growth under FWLAD. Aeration improved growth with nitrified FWLAD but reduced it with crude FWLAD. Across all conditions, inorganic fertilizer resulted in the highest growth, suggesting that factors beyond oxygen availability may limit the effectiveness of FWLAD as a nutrient source.

Iron (Fe) deficiency is one of the leading micronutrient deficiencies in the world, impacting almost two billion people globally. Contributing factors include non-diverse diets (cereal grain-centered diets, processed and junk foods) that are characterized by relatively low bioavailable Fe levels. Additionally, 30% of cultivated soils around the world report low Fe availability. Inadequate levels of dietary Fe can cause numerous physiological disorders and impaired cognitive functioning, with pregnant women and infants being particularly vulnerable. To help alleviate the harm of Fe malnutrition, a straightforward and sustainable solution to increase dietary Fe availability is through agronomic biofortification of crops. Unfortunately, Fe uptake by plants is problematic, especially in alkaline and oxidizing conditions. However, various studies have reported the role of ascorbic acid (AA) as an enhancer of Fe absorption. A suitable candidate crop for Fe biofortification are microgreens, as they are nutritional powerhouses that have low phytic acid levels, short growth cycles, and are typically consumed raw. Testing the use of AA for Fe biofortification in microgreens has received limited attention in literature. Therefore, in this study we investigate in a soilless system the effect of different Fe sources with and without organic acids (Ferric sulfate, Ferric sulfate 0.1% Ascorbic acid, Ferric citrate), applied via fertigation at different concentrations (0, 15, 30, 45 mg/L of Fe), on Fe content of sunflower microgreens. Treatments were arranged in a completely randomized factorial design using three replications. We discovered that Ferric sulfate 0.1% AA provided at 45 mg/L was the most effective source and rate in increasing Fe content, resulting in approximately 300% increase compared to the untreated control. Fertigating with Ferric sulfate 0.1% AA also showed a significant increase in total antioxidants and total phenol concentrations, but a decrease in chlorophyll and carotenoid levels. When using sodium hydroxide (NaOH) to adjust the nutrient solution pH, the same treatment was associated with relatively high Na content and resulted in an average reduction in fresh and dry biomass of 50% and 30%, respectively. Further assessment of Fe sources, concentrations, and bases for pH adjustment should be considered to not compromise yield and nutritional quality. However, these results indicate that through fertigation, the supplementation of AA with Fe fertilizers can significantly promote the enrichment of Fe as well as certain phytochemicals in sunflower microgreens. This strategy can produce Fe-biofortified functional foods that can potentially improve health outcomes of Fe-deficient individuals.

Circadian rhythm, a vital adaptive mechanism in green organisms, synchronizes plants' physiological processes with daily and seasonal environmental changes. Circadian clock oscillator genes significantly regulate transcriptional and post-transcriptional changes, emphasizing their role in mediating plant responses to environmental stresses. Understanding these regulatory mechanisms is essential for optimizing plant growth, enhancing productivity, and improving resilience to ecological changes, contributing to sustainable agriculture and food security. Nitrogen is an essential plant nutrient; both depleted and excessive nitrogen fertilization can negatively impact plant growth, development, and yield. Overapplication of nitrogen fertilizers can disrupt soil properties, limiting nutrient availability and altering soil composition (including soil acidification, salinization, and disruption of beneficial microbial communities). Additionally, excessive nitrogen usage contributes to harmful gas emissions from the soil into the atmosphere, which can affect human health, climate, and overall ecosystems. Effective nitrogen management is crucial for promoting healthy plant growth and minimizing environmental damage, making a balanced approach essential for sustainable agriculture. This study evaluated the daily regulation of transcriptional changes in nitrogen metabolism under nitrogen depletion (Low N: 50 ppm) and spinach leaf repletion (High N: 200 ppm) conditions. The RNA-Seq analysis reveals that high nitrogen (HN) conditions induce more significant transcriptomic changes than low nitrogen (LN), particularly in nitrogen assimilation, transport, and amino acid metabolism genes. Expression patterns of these genes vary across time points, with distinct regulation during light and dark cycles. Validation through qPCR and RNA-Seq confirms that nitrogen assimilation peaks at the end of the dark cycle. In contrast, nitrogen transport (NRT1) and amino acid synthesis are more pronounced during the light cycle under HN conditions. The circadian clock gene Late Elongated Hypocotyl (LHY) regulates the timing of nitrogen assimilation. LHY expression increases at the end of the dark cycle, correlating with higher expressions of nitrogen assimilation genes, including Nitrate Reductase (NIA) and Nitrite Reductase (NiR). These results underscore the significance of circadian rhythms, mainly through LHY, in optimizing nitrogen acquisition and utilization.

Cut-and-come-again, or repeat harvesting, is a practice in which a single planting of greens is harvested on multiple occasions. This is a common practice among small-scale, urban, and home producers in which the outermost leaves are removed, leaving the growing center of the plant intact enabling multiple harvests without compromising plant health. As this practice is not common among large-scale and commercial producers, there are currently no research-based fertilizer recommendations for cut-and-come-again greens. General guidance simply suggests continued, nitrogen-heavy fertilizer applications to ensure repeated harvests. This type of guidance is not easy to follow and could lead to overapplications and nutrient leaching. An experiment was designed to examine eight different fertilizer application strategies to determine which provided better growth and nutritional quality in later collard harvests while limiting nutrient leaching. Fertilizer applications for the cut-and-come-again treatments (CC) ranged from an initial fertilizer application matching local nutrient recommendations, to repeated applications either the initial complete application or a nitrogen side dressing at every third, every other, or at each harvest. A single harvest control grown to maturity (ODM) was also monitored for nutrient leaching. Leachate from collards was collected weekly and the volume measured. Leachate was then tested for pH, conductivity, color, and turbidity using bench top instruments. A portion of the leachate was also filtered and tested for nitrate-nitrogen, ammonia-nitrogen, and phosphate using microplate spectroscopy. Another filtered portion was acidified and tested for mineral nutrient content using ICP-OES. Nutrient management treatment had no effect on leachate volume, which was affected by sample collection time, season, and year, likely due to weather variation and plant growth factors. Nutrient management treatment did have an effect on water quality metrics; however, no metric displayed a dose response. Differences between nutrient management treatments were seen during the spring of 2024 more often than any other growing season. Most metrics were higher in the spring than in the fall, which could be due to poor growth and fewer harvests in the fall, and therefore lower nutrient additions. While the two fall growing seasons were very similar to each other, there were some differences between the spring of 2023 and the spring of 2024, although which had higher nutrient content depending on the nutrient measured. Leachate pH, color, and increased with the number of days after planting in most cases. Leachate conductivity, turbidity, potassium, magnesium, total phosphorus, and sodium decreased with number of days after planting.

Nutrient biofortification in leafy vegetables is a promising strategy to enhance dietary health benefits, improve crop nutritional quality, and promote sustainable agricultural practices. Advanced plant cultivation techniques, such as hydroponic production and targeted micronutrient fertilization, provide a controlled environment for optimizing nutrient uptake and secondary metabolite synthesis. Selenium (Se), an essential micronutrient, has been shown to influence plant metabolism, particularly the synthesis of bioactive compounds such as carotenoids and glucosinolates. However, its role in modulating these phytochemicals in hydroponically grown Nasturtium officinale (watercress) and Barbarea verna (upland cress) remains underexplored. This ongoing study investigates the effects of selenium fertilization at varying concentrations (0, 1.0, 2.0, and 4.0 mg Se·L⁻¹) on carotenoid and glucosinolate accumulation in two cress varieties cultivated under controlled hydroponic conditions. The hydroponic system provides a consistent environment for plant growth, allowing precise manipulation of nutrient levels, pH, temperature, and light intensity. Selenium treatments follow a randomized complete block design to ensure replication and statistical rigor. Growth parameters, biomass accumulation, and biochemical analyses of carotenoid and glucosinolate levels are being monitored to determine the interactions between selenium uptake and secondary metabolite biosynthesis. Carotenoid content in plant tissues will be quantified using high-performance liquid chromatography (HPLC), while glucosinolate concentrations will be determined through chromatographic and spectrophotometric methods, ensuring precise assessment of bioactive compound accumulation. Preliminary observations suggest that selenium supplementation may modulate plant physiological responses, potentially enhancing carotenoid and glucosinolate synthesis. Differences in metabolite accumulation between the two cress varieties indicate potential genotype-specific responses to selenium fertilization. Understanding these interactions will contribute to optimizing hydroponic production systems, improving the nutritional and functional quality of leafy greens, and informing sustainable agricultural practices. Findings from this study could advance nutrient-fortification strategies, enhance functional food development, and address micronutrient deficiencies, thereby supporting both horticultural innovation and public health. Keywords: Selenium fertilization, Beta-carotene, Hydroponic, Watercress varieties, Agricultural sustainability, Crop yields, Environmental impact, Spectrophotometric analysis,