ASHS 2025 Conference

Compared to other crops, potatoes have a low phosphorus (P) use efficiency (PUE). This characteristic, combined with low soil P availability, can impact the yield. The common method to verify the availability of a nutrient to the crops is through soil testing. In 2012, Florida transitioned from Mehlich-1 (M1) to Mehlich-3 (M3) for soil P recommendations; however, the updated M3 guidelines indicate that no additional P should be applied. Many other studies have confirmed that yield responses to P fertilizer continue to be observed. The objective of this study was to identify a P fertilization strategy involving multiple applications and using two different sources of P-fertilizer to increase potato yield and PUE. A field experiment with nine treatments and four replications was established in Hastings Agricultural Extension Center-HAEC/IFAS/UF in three areas with different soil P levels, 118, 179, and 219 mg/kg P (M3). These areas were cultivated with the potato cultivar Atlantic during the 2024 and 2025 growing seasons. A single rate of 120 lb/ac of P2O5 of granular phosphate was applied at 30 and 15 days before planting, at planting, and at 25 and 50 days after planting (DAP). The same P-rate was also split into 40 and 60 lb/ac of P2O5 applied at 0, 25, 50 DAP, and 0 and 25 DAP, respectively. In addition, a liquid P-source was applied using this same split application and times. At the harvest, tubers were graded according to USDA size standards, and specific gravity, total, and marketable yields were measured. To calculate PUE, the total yield was divided by the initial soil P content plus the applied P fertilizer. There were no significant differences in total yield as a function of the application timing within each area, as well as for specific gravity. The PUE significantly decreased with the increase in soil initial P level. In 2024, the area with the lowest initial soil P concentration had the highest yield, producing 332 cwt/ac, while the area with the highest initial P concentration produced 268 cwt/ac of potatoes, and the medium initial soil P area produced 324 cwt/ac. In 2025, the area with the highest initial soil P concentration produced 332 cwt/ac, while the lowest area produced 327 cwt/ac, and the medium initial soil P area had the lowest yield, producing 308 cwt/ac. The results of this study may support updating Florida’s recommendation guidelines to enhance P-fertilizer use efficiency and crop yield.

Macadamia integrifolia and M. tetraphylla, unlike M. ternifolia, are known for their edible nuts. All three species over-accumulate the trace metal nutrient manganese (Mn) in their shoots. This study seeks to examine tissue- and cellular-level distribution of Mn and other plant nutrients in the three Macadamia species. The distribution of Mn, calcium (Ca), iron (Fe) and potassium (K) were investigated in whole leaves and cross-sections of roots, petioles and lea ves using synchrotron-based X-ray Fluorescence Microscopy (µXRF) in M. integrifolia, M. tetraphylla and M. ternifolia. The results show Mn sequestration primarily in the leaf and midrib palisade mesophyll cells of all three species. Leaf interveinal regions, root cortical cells and phloem cells were also found to be Mn-loaded. The current study confirms earlier findings but further reveals that Mn is concentrated in the vacuoles of mesophyll cells owing to the exceptional resolution of the synchrotron µXRF data, and the fact that fresh hydrated samples were used. New insights gained here into Mn compartmentalisation in these highly Mn-tolerant Mac adamias expand knowledge about potentially toxic overaccumulation of an essential micronutrient, which ultimately stands to inform strategies around farming edible species in particular.

Iron (Fe) is an essential micronutrient involved in numerous metabolic processes and is vital for proper growth and development in plants and humans. However, in humans, dietary Fe deficiency is one of the leading micronutrient deficiencies affecting approximately 10 million people in the U.S., and over 1 billion people worldwide. Fe deficiency can lead to many health complications, including Fe deficiency anemia. Pregnant women and young children are particularly at risk for developing Fe deficiency and severe consequences can result in maternal and neonatal deaths during pregnancy. Improving dietary Fe intake is critical and utilizing agronomic approaches to enhance Fe levels in plants could be a viable, sustainable solution. Microgreens are a noteworthy nutritional source and are a convenient candidate crop for agronomic Fe biofortification as they can be grown quickly, have low anti-nutrient levels, require fewer inputs for cultivation, and can be consumed raw. Conventional Fe fertilizers like ferrous sulfate (FeSO4) have been widely used in agriculture and research for Fe biofortification, however in oxidizing and alkaline conditions, plant Fe uptake is reduced, even with sufficient levels present in the environment. Various studies have reported the use of Fe chelate and Fe nanofertilizers as an alternative, more efficient option for improving Fe availability, than conventional Fe fertilizers. However, there is limited information comparing multiple Fe fertilizer sources and their effectiveness in Fe biofortification in microgreens. Herein, we investigate, in a soilless system, the effect of different Fe sources (Ferrous sulfate, Ferric sulfate, Fe-EDTA, Fe-EDDHA, Fe-NP) applied via fertigation at different concentrations (0, 15, 30, 45 mg/L of Fe) on the Fe content in radish and pea microgreens. We found that Fe-EDTA was the most effective fertilizer source and increased Fe content by 2-3-fold in pea microgreens and 3-5-fold in radish microgreens, compared to the untreated control. Additionally, Fe-EDTA treatments increased Zn concentration by 5-20% in pea microgreens. In radish microgreens, however, we found that the same treatments showed slight phytotoxicity symptoms and reduced fresh and dry biomass. Further evaluation of Fe sources and concentrations is needed to avoid compromising yield and nutritional quality. However, these results suggest that using alternative Fe fertilizers through fertigation can improve Fe concentration in pea and radish microgreens more effectively than standard sources. Fe-enriched microgreens may be used as functional foods to combat Fe malnutrition at both individual household and larger community scales.

Zinc (Zn) is essential for human cell growth and development, metabolism, cognitive function, reproduction, and the immune system. Biofortification aimed at enhancing the bioavailability and its interaction with nitrogen metabolism in spinach (Spinacia oleracea L.) remains poorly understood. Spinach, known for its high nutritional value and rapid growth cycle, is emerging as a promising candidate for biofortification. As leafy green, spinach has significant nitrogen requirements, underscoring the need for further research into how varying nitrogen levels affect Zn uptake and accumulation in edible leaves. This study investigated the effects of different zinc application rates (2.3 µM, 9.2 µM, 18.4 µM, and 27.6 µM) on yield, mineral content, phytochemical profiles, and gene expression under low (50 ppm) and high (100 ppm) nitrogen conditions. The results showed that increasing the amount of Zn significantly boosted its concentration in the leaves across both nitrogen regimes. Applying 18.4 µM of zinc led to a twofold increase in both fresh and dry biomass at high nitrogen and significantly greater Zn content in the leaves under both nitrogen conditions. The initial findings from enzyme activities and RNA-Seq profiling could improve our understanding of Zn uptake and other bivalent cations in the context of rising nitrogen availability. Comprehending these interactions is crucial for optimizing nutrient management and enhancing the nutritional value of spinach.

In the arid and semi-arid regions of the southwestern United States, particularly Arizona, lettuce production is challenged by high input costs, water scarcity, and nutrient leaching due to coarse-textured soils. These constraints underscore the need for sustainable solutions that maintain productivity while reducing fertilizer dependency. Biostimulants—products that stimulate natural plant processes—are emerging as promising tools to improve nutrient use efficiency and stress tolerance in vegetable crops grown under desert conditions. This study evaluated the efficacy of three commercial biostimulants—silica-based, plant and animal peptide-based, and insect larvae and frass-based—on head lettuce (Lactuca sativa cv. ‘Iceberg’) grown under two fertilizer regimes: 100% and 50% of the recommended inorganic fertilizer rates. The field experiment followed a partial split-plot design with three replications at the Maricopa Agricultural Center, University of Arizona. Biostimulants were applied during the rosette and head formation growth stages. Morphological and physiological traits (plant diameter, height, leaf thickness, SPAD chlorophyll index, stomatal conductance, and mesophyll quantum absorption) were measured at multiple growth stages. Two-way ANOVA revealed significant effects of both fertilizer rate and biostimulant treatment, with 50% fertilizer often matching or outperforming 100%, particularly in SPAD. The peptide-based biostimulant showed the most consistent enhancement in plant diameter after the second application. These findings demonstrate that targeted use of biostimulants may allow fertilizer reductions without yield penalties, offering a viable strategy for resource-efficient lettuce production in arid environments.

Kale (Brassica oleracea L. var. acephala) is a highly nutritious cruciferous vegetable valued for its abundant phytochemicals, particularly carotenoids such as β-carotene, lutein, and zeaxanthin. These compounds play crucial roles in human health by acting as antioxidants and precursors to vitamin A, aiding in the prevention of non-communicable diseases such as cancer, cardiovascular disorders, and age-related macular degeneration. Despite the health benefits of carotenoids, their concentration in kale can be significantly influenced by environmental and agronomic factors, particularly nutrient availability. Magnesium (Mg), an essential macronutrient and a core component of the chlorophyll molecule, plays a pivotal role in photosynthesis, enzyme activation, and nutrient translocation. While its role in general plant metabolism is well established, the impact of magnesium fertilization on carotenoid accumulation in kale remains underexplored. This study investigates the effect of different magnesium fertilization rates (12.3 mg/L, 24.6 mg/L, 36.9 mg/L, and 49.2 mg/L) on the accumulation of carotenoids and elemental nutrients in three kale cultivars—Darkibor, Mamba, and Red Russian—under hydroponic conditions. A split-plot experimental design will be implemented in a greenhouse using an NFT (Nutrient Film Technique) system. The research will evaluate chlorophyll (‘a’ and ‘b’) contents in the leaves, fresh and dry biomass, crop height, crown diameters, elemental nutrient concentrations using the ICP mass spectroscopy method, and carotenoid levels through HPLC analysis. The results will be statistically analyzed using ANOVA in RStudio. This study seeks to identify optimal magnesium application rates that enhance the nutritional quality of kale, providing insights into sustainable fertilization strategies for maximizing the health benefits of this functional crop.

Watercress (Nasturtium officinale L.) is a leafy green vegetable, that is a member of the Brassicaceae family. It provides a rich and bioavailable source of vitamin C, significantly higher than many fruits and vegetables, including oranges. Vitamin C is associated with numerous health benefits, such as antioxidant protection, immune system support, enhanced collagen production, improved iron absorption, improved eye health and lowered risks of chronic diseases such as cardiovascular disease and cancer. Thus, consuming adequate amounts of vitamin C daily is important for human health. A 100g of watercress provides 62mg (103% Recommended Dietary Allowance) of vitamin C. In humans, vitamin C takes part in various physiological processes; however, due to the functional loss of the gene coding for L-gulonolactone oxidase, humans cannot synthesize vitamin C and must rely primarily on plant-based foods for their needs. For this reason, increasing the vitamin C content of crops is essential for supporting human health. Some studies have shown potential effects of fertilization, particularly magnesium fertilization on vitamin C content. Therefore, this study aims to contribute to optimization of nutrient management in hydroponics to enhance nutritional value. The research was conducted using a split-plot design. Four magnesium fertilization rates (100 mg/l, 150 mg/l, 200 mg/l and 250 mg/l) were applied to watercress in Nutrient Film Technique (NFT) hydroponic system under controlled environment, ensuring desirable nutrient application, temperature, light, pH and electrical conductivity. Spectrophotometric methods were used to quantify Vitamin C. The preliminary findings indicate an increase in Vitamin C content with an increase in magnesium application rates, with the highest rate maximizing its accumulation. These results contribute to understanding the effects of magnesium fertilization on vitamin C synthesis in watercress and will help guide farmers and producers in optimizing vitamin C content during production to support human dietary needs and health. Keywords: Watercress, Vitamin C, Magnesium Fertilization, Hydroponics, Nutrient Optimization

Two nitrogen (N) sources – synthetic urea ammonium sulfate (UAS, 33-0-0) and organic bloodmeal (BM, 13-0-0) were evaluated for growing tea transplants in southeastern Louisiana. In Expt. 1, UAS and BM were applied at three rates (150, 250, and 350 lbs. N/A/year) to a 1-year-old tea field. Expt. 2 evaluated five treatments by substituting UAS with BM at 0%, 25%, 50%, 75%, and 100%, all at 350 lbs. N/A/year, applied to a 2-year-old tea field. N applications were divided into seven applications and applied every 40 days from April to October in 2023 and 2024 for a total of 11 applications. Despite periodic pruning to encourage branching for the building of a plucking table, plant growth metrics, such as leaf greenness and size index were similar across treatments in both experiments. However, tissue nitrogen concentration (N%) was consistently higher in BM-treated plants compared to UAS-treated plants at all application rates in Experiment 1. The highest tissue N% was also observed in the 100% BM treatment in Experiment 2. One year after treatment initiation, plants fertilized with UAS exhibited faster recovery after pruning compared to those treated with BM, though this difference diminished over time. In both experiments, plots treated with blood meal or more than 75% blood meal replacement resulted in less acidification compared with those treated with UAS. Further research on leaf quality (e.g., health-promoting compounds) and a more comprehensive evaluation of soil microbial activity are required to refine recommendations for nitrogen application rates and sources for tea production.

Planting a cover crop in orchard middles can have many benefits for the health of the trees. In California, improved water infiltration, especially during the winter rainy season, is a common motivation for cover cropping, and the benefit to soil health through increased biological activity resulting from biomass incorporation is also gaining renewed attention. Cover crops can also play a part in nutrient management by “mining” and holding existing nutrients, especially nitrogen, at the end of the season and, when legumes are included, by direct sequestration of nitrogen from the atmosphere through the symbiosis of their roots with nitrogen-fixing bacteria. Different cover crop types can contribute in different ways to these outcomes, but benefits depend on successful establishment and a significant amount of biomass being produced. We evaluated three common cover crop types over three years in a walnut orchard in northwestern San Joaquin valley with a heavy clay-loam soil. Treatments included a pure stand of winter triticale, a ‘pollinator’ mustard mix (multiple Brassica spp. plus Raphanus sativus [Daikon]), and a multi-species mix including grain rye and triticale, mustards (Sinapis alba and Raphanus sativus), and legumes (Vicia faba, Vicia sativa, Lathyrus oleraceus). Treatments were planted with a seed drill in two adjacent orchard middles at two parts of the orchard in early Nov. 2022, 2023, and 2024 and depended on rain for germination and growth. In 2023 and 2024, unplanted controls were maintained in rows adjacent to the trial rows. Sampling plots were defined at five representative points in the planted rows. Just before cover crop termination early in the April following each planting, above ground vegetation was sampled using a one-meter quadrat. While triticale and the mustard blend produced above ground dry biomass at 0.13 to 0.28 and 0.04 to 0.27 kg/sq. m, respectively, the multi-species mix consistently produced three to five times that amount, ranging from 0.53 to 0.68 kg/sq. m. Analysis of soil sampled one week before cover crop termination in 2025 did not show significant differences in organic matter, N, P, and K content, but samples of chopped cover crop taken at termination showed plant N content twice as high in the multi-mix treatment than in the others. This trial has highlighted the resilience of planting a diverse plant mix in comparison to more homogeneous cover crop types, and the advantage of including legumes when N may be a limiting factor to cover crop biomass growth.

The leafy greens have generated significant worldwide interest due to their nutritional quality. Cress is among the leafy greens that are known for their nutrient-dense, phytonutrient content. Upland cress (Barbarea verna) is among the Cress varieties with tender greens known for their vibrant flavor and impressive nutritional profile. It possesses high metabolic activity, which enables it to synthesize a rich variety of phytonutrients. Magnesium, as a macronutrient, is known for influencing the biosynthesis of plant metabolites, including the glucosinolates biosynthesis pathway. The high accumulation of glucosinolate in upland cress could not only increase its nutritional quality but also market demand. The study assessed by supplementing magnesium fertilization rate on upland cress grown under a Nutrient Film Technique (NFT) system to identify the magnesium concentration that led to maximum accumulation of glucosinolate and biomass in upland cress. The split plot design was used, where four treatments of magnesium fertilization rates (100 mg/l, 150 mg/l, 200 mg/l, and 250 mg/l) were used. All treatments were under a controlled environment, ensuring nutrient application, temperature, light, pH, and electrical conductivity are in a good range required for Upland cress. After two weeks of germination, the Upland cress reached its maturity stage, and samples for leaf biomass were collected, and High-performance liquid Chromatography (HPLC) was employed for glucosinolate analysis. Preliminary findings showed that the magnesium fertilization rate of 150 mg/l and 200 mg/l stimulated high accumulation of leaf biomass and glucosinolate in upland cress, and the research is still ongoing. Keywords: Upland cress, Magnesium fertilization, leaf biomass, nutritional quality, Hydroponics.

A forum for discussion of potential collaborations with regards to plant growth and culture – i.e. propagation, root growth, water management, weed control, PGRs, plant nutrition, etc.

Current literature on blackberries indicates that inadequate nitrogen (N) fertilizer application negatively impacts plant growth and profitability for blackberry growers. Overapplication of fertilizer can decrease fruit marketability and increase labor costs, while insufficient fertilization stunts plant growth and decreases yield. The current N fertilizer rate recommendation for southeastern blackberry (67–101 kg N/ha) was developed outside the Southeast. The objectives of this study were to verify the current blackberry N fertilizer rate recommendation for the Southeast by investigating the effect of N fertilizer rate on ‘Ouachita’ blackberry yield and plant growth. Tissue culture plug plants of ‘Ouachita’ were planted in 2021, and fertilized with ammonium-nitrate from 2022 to 2024 at six different rates (0, 34, 67, 101, 134, 168 kg N/ha) at the University of Arkansas Fruit Research Station in Clarksville, AR. Fertilizer was applied via drip irrigation over fifteen weeks starting at primocane emergence. The experiment was laid out in a randomized complete block design with five plants in each replicate (n=4). Each year marketable and non-marketable blackberry yield was recorded. Subsamples from plots were also collected to assess fruit firmness at the day of harvest and fruit quality after seven days (decay, leakage, and red drupelet reversion). In the spring (2023-2025) plants were pruned to a grower standard and pruning weights (kg) were collected. In this study, marketable yield ranged from 2.64–2.82 kg/plant per year. No significant differences in yield were observed across fertilizer rate or fertilizer rate by year interaction. Total yield and percent non-marketable fruit were not observed to be significantly different across N treatment. Percent fruit decay after seven days was highest at the 168 kg N/ha rate, which was significantly higher than the 0, 34, and 67 kg N/ha rates. Firmness at day of harvest, percent leakage and red drupelet reversion after seven days were not impacted by N rate. Higher rates of N fertilizer resulted in higher pruning weights (p

Agriculture accounts for up to 80% of the total U.S consumptive water use. Increasing water scarcity and severity of droughts have accelerated the need for alternate water sources, including the use of reclaimed wastewater for irrigation and other agricultural operations. However, concerns over wastewater-borne pathogens and emerging contaminants necessitate effective treatment methods. In our short-term study, we evaluated a novel integrated electrodialysis-forward osmosis (iEDFO) method for wastewater treatment and its impact on southern highbush blueberry (Vaccinium corymbosum L.) grown in soilless media. Plants were fertigated with untreated municipal or dairy digestate, recovered nutrient water from the digestates treated by iEDFO, or a modified Hoagland solution (control). Leaf area and shoot biomass were similar across all treatments, indicating no adverse effects of the treated and untreated digestates on growth. While salinity levels exceeded threshold for blueberry (> 2 dS·m-1), periodic freshwater flushing mitigated osmotic stress in the plants. Nutrient analysis indicated high potassium levels amongst all treatments, suggesting the need for adjustments to optimize nutrient balance in each solution. Mass spectrometry confirmed significant removal of pharmaceuticals and pesticides (>90%), demonstrating effectiveness of iEDFO in treating reclaimed water for potential pathogens and reducing potential human health risks. A longer-term study is currently underway to assess the viability of the iEDFO system and its enduring impact on crop performance and potential contaminants in the fruit. In this case, 2-year-old ‘Star’ blueberry plants were transplanted to 25-L containers filled with soilless media and irrigated three times a week with untreated municipal digestate, recovered nutrient water from the digestates treated by iEDFO, or a modified Hoagland solution. Initial findings showed that while the control had the overall highest plant growth, treatments did not differ in cane or stem mass or visible root growth. Leaf macro- and micronutrients were also similar amongst the treatments, except for boron, which was highest with municipal wastewater. This summer, we will evaluate the effects of these treatments on production and quality of the fruit.

Phosphorus (P) is an essential nutrient for the growth and development of southern highbush blueberry plants (SHB, Vaccinium corymbosum interspecific hybrids). SHB plants exhibit both morphological and physiological responses to P deficiency. Previous studies have shown that P-deficient SHB plants shift their biomass allocation strategy—favoring root growth while limiting canopy development. Although this response may be detrimental in fruiting fields, it could be advantageous in nursery settings, where young plants must rapidly establish roots in new soils or substrates. Here, we report the results of an experiment evaluating the response of two SHB cultivars, ‘Farthing’ and ‘Sentinel’, to five different P fertilization rates during the nursery stage. Rooted cuttings were transplanted into 1.0-L pots filled with a substrate consisting of 70% coconut coir and 30% horticultural-grade perlite. Plants received weekly applications of 0, 15, 30, 45, or 60 mg P, while all other nutrients were supplied through a P-free commercial fertilizer. The plants were grown in a temperature-controlled greenhouse for 12 weeks. Subsets from all treatments (n = 6) were destructively harvested at weeks 0, 4, 8, and 12 to assess plant growth and nutrient content. P fertilization treatments had profound effects above and belowground. Leaf P concentrations exceeded the deficiency threshold only in plants receiving more than 15 mg P per week. Root biomass responses to P treatments differed between cultivars: low P rates increased root biomass in ‘Farthing’ SHB but decreased it in ‘Sentinel’ SHB. P deficiency symptoms appeared in ‘Farthing’ SHB leaves after 12 weeks, while symptoms appeared in week 8 in ‘Sentinel’ SHB leaves. These findings suggest that a brief period of suboptimal P fertilization could be used to promote rooting in ‘Farthing’ SHB during nursery production. However, this strategy may not be effective for ‘Sentinel’. Future research should explore P deficiency responses across a broader range of SHB cultivars to develop generalizable nursery practices that encourage rapid root development while minimizing P leaching.

Cranberry, a fruit crop native to North America, has found a thriving production hub in Southern Chile. While the USA and Canada lead global production, Chile stands out in the Southern Hemisphere, achieving remarkable yields and demonstrating significant potential for future growth. Crucial to this success is effective nutrient management, as cranberries are cultivated in sandy soils with limited clay content. This research investigates the critical nutritional requirements of cranberry plants in Southern Chilean agroecosystems, correlating soil and plant tissue analyses across different phenological stages. We aim to establish optimal nutrient levels for maximizing yield and quality. Our study, conducted in collaboration with Cran Chile from 2018 to 2020, monitored 'Pilgrim' cranberry plants across three parcels under four different fertilization strategies. We tracked the foliar variation of ten essential nutrients, comparing plants grown in soils with varying fertility levels and aligning these data with growing degree days (GDD) to model nutrient dynamics. Key findings reveal distinct patterns in nutrient concentration over time: Nitrogen, phosphorus, and potassium levels decreased, while magnesium, sulfur, iron, and zinc followed a third-degree polynomial curve. Calcium, boron, and manganese concentrations increased throughout the season. These nutrient dynamics provide a broader window for tissue sampling and are essential for establishing critical nutrient concentration benchmarks for cranberry plants. Furthermore, this study examines the phenology of cranberry in Southern Chile, comparing it to established models from the USA and Canada. We utilized GDD-based functions to model phenological stages, revealing a notable difference: cranberry development in Chile occurs earlier than in the Northern Hemisphere. This advancement is likely attributed to the milder winters in Chile, which result in less pronounced dormancy compared to the colder climates of the USA and Canada. In conclusion, this research provides valuable insights into the nutritional needs and phenological behavior of cranberry plants in Southern Chile. By understanding these dynamics, we can optimize cultivation practices, ensuring sustainable and high-yield cranberry production in the region.

The goal of this project is to determine what electromagnetic radiation wavelengths correlate with the changes in the nitrogen status of three cranberry cultivars. For this project, isolated propagation containers or “mini-bogs” were evenly split between three cultivars: Early Black, Stevens, and Mullica Queen. Each “mini-bog” was planted with 98 cranberry plugs. Each cultivar was subsequently split into four even groups with each group assigned one of four fertilizer regimes: 10% optimal, 50% optimal, 100% optimal, and 150% optimal. Over that growing season, physiochemical and spectrographic data was collated from 48 sets of cranberry plants grown separately in “mini-bogs”. Canopy and contact level spectrographic data was collected using the ASD FieldSpec 4 field spectrometer and leaf clip attachment. Clippings from each “mini-bog” were collected after spectrographic data collection and sent for wet digestion total nitrogen laboratory analysis. Using the Automated Radiative Transfer Models Operator (ARTMO) package within MATLABs and ARTMO’s Machine Learning Regression Algorithms (MLRAs) toolbox and Spectral Indices (SI) toolboxes, we were able to examine 298 datasets collected during the 2024 growing season. MLRA results show strong correlation between the changes in the nitrogen concentration and the spectrographic readings. The MLRA produced correlation results for 30 machine learning regression algorithms, including gaussian processes, kernel ridge process, random forest processes, linear regressions, and neural network processes. Early Black had a correlation up to 98.41%, Stevens up to 91.43% correlation, and Mullica Queens had up to 99.98% correlation. Applying the strongest correlation of the MLA functions to the band analysis tool within MLRA, we identified the top 20 bands out of 2151 bands that strongly correlate with the changes in the nitrogen concentration. This study showed that over 20 electromagnetic radiation wavelengths correlated strongly with the changes in the nitrogen status of our cultivars. Combining these wavelengths with reference wavelength in a spectral index is the next step to finding a combination that can accurately and precisely derive the nitrogen status of cranberry vegetation.

Current fertilization recommendations for mature peach orchards rely on spring soil sampling and postharvest leaf analysis. Soil sampling assesses nutrient status at the soil level, while standard leaf analysis is mainly useful for the next crop cycle, limiting major in-season adjustments. The objective of this study was to understand how macro and micro elements change over time using leaf sap nutrient analyses. This study was conducted in a nine-year-old peach orchard using a split-plot randomized complete block design with three replicates, where irrigation systems, drip vs micro-sprinkler, served as whole-plots and foliar treatments as split plots. Foliar treatments included water (control), nanocellulose crystals (CNC 3%), Calcium (Ca 6%), Potassium Silicate (K2SiO3), CNC plus Ca, and CNC plus K2SiO3. Trees did not receive any soil-based fertilization and water was managed based on the Peach Smart Irrigation App recommendations (https://smartirrigationapps.org/peach-app/). Foliar applications were carried out three or four days prior to leaf sampling. Leaf samples, including petioles, were collected between 8 am and 11 am at 40, 72, 86, and 100 days after full bloom (DAFB) for sap analysis. Leaf sap analysis showed that N, primarily as NH₄, and Mg, were within sufficiency ranges. P and K were excessive; and Ca, S, and all micronutrients were deficient. Elevated P likely limited Zn and Fe uptake. B deficiency may have impaired sugar, N, and P loading and transport to sink tissues. Mo (

Grafting is an effective management strategy in watermelon crop against soil borne pathogens. Carolina strongback (SB) rootstock used for grafting, is resistant to both fusarium wilt and root knot nematodes which are devastating soil borne pests of watermelon. However, recent trials have shown that SB grafted plant bear fruits 7-10 days later than regulate plants leading to farmers losing early market which is more profitable. Further, tissue boron content in SB grafted plants were reported to be lower than regular watermelon nursery plants. Boron is a key micro-nutrient that involves in cell wall and cell membrane, pollination, pollen germination, cell division, translocation of carbohydrates and fruit development. We hypothesize that foliar application of boron will cure the boron deficiency in grafted plants and leads to early fruit set similar to regular watermelon nursery. To test this hypothesis, a field experiment was conducted at Edisto Research and Education Centre, SC. Two foliar boron applications at 30 and 50 days after transplanting significantly improved the pollen viability of SB grafted SP6 pollinizer at 60 days than control and non-grafted plants. Similar to pollen viability two foliar boron applications recorded the highest total fruit yield and tissue boron content than all other treatments. Highest gross, and net returns were observed with two foliar boron application treatments and lowest net returns were observed in one foliar boron application treatment. We will be repeating the experiment in 2025 to collect second year of data.

Arizona ranks as the second-largest lettuce producer in the United States, with leafy greens contributing approximately $2 billion annually to the state’s economy. As interest in sustainable production systems grows, organic lettuce production is becoming increasingly important due to its potential to reduce synthetic input use, enhance soil quality, and support agroecosystem services. However, managing the high nitrogen demand of lettuce, particularly during its rapid vegetative and heading stages, presents a major challenge in organic systems, especially under arid conditions. Despite these benefits, limited research in local conditions has made it difficult for farmers to effectively incorporate biostimulant into organic cropping systems. The research objectives were to: (1) assess the combined impacts of biostimulant and organic fertilizeron lettuce growth development and yield production: (2) evaluate the efficiency of biostimulant in improving soil health quality (soil water retention, mitigate salt stress): and (3) evaluate the adoption of best management practices, such as site-specific, sensor-based monitoring of soil nitrate levels, to enhance nutrient use efficiency while minimizing environmental risks. This research is conducted at Yuma Agricultural Center, Yuma, Arizona, a region characterized by an arid climate with less than 3 inches of annual precipitation. The field was planted with the iceberg lettuce variety SVLD0023 on October 29th, 2024, under the subsurface drip irrigation method with two irrigation scheduling strategies (sensor-based irrigation (SI) and traditional irrigation (TI) based on growers' standard decision basis that is common in the Yuma area. Two fertilizer treatments were imposed: (1) organic fertilizer, and (2) a combination of biostimulant and organic fertilizer. The experimental site consists of clay loam soil, with a field capacity of 31.9% volumetric water content, a permanent wilting point of 15.5%, and a particle size distribution of 21% sand, 48% silt, and 31% clay. The topsoil contains 1.5% organic matter. Two types of organic fertilizers were applied: 2,000 lbs/acre of chicken pellets (4-4-2) and 1,800 lbs/acre of a high-nitrogen organic fertilizer (9-6-1). Preliminary results revealed the highest plant height of 20.3 cm under the organic fertilizer treatment with TI. Similar findings were observed for yield. The data strongly support the conclusion that the greatest yield and highest plant height were found under the organic fertilizer treatment with TI.