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.

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.

Phosphorus (P) is an essential nutrient for snap bean growth, directly influencing root development, plant health, and overall yield. However, P bioavailability is often limited by soil fixation, particularly in highly acidic and alkaline environments. In the Hastings region, soil pH can drop to 4.7 during the growing season, leading to substantial P immobilization due to high concentrations of extractable aluminum (1,300–2,000 lbs/acre) and iron (250–600 lbs/acre). These metals readily react with P, forming insoluble complexes that restrict plant uptake. Chemically, one pound of aluminum can fix up to 2.6 pounds of phosphorus pentoxide, significantly reducing P availability for crop growth. Conversely, in the Homestead region, where soil pH reaches 8.4, P fixation occurs primarily through reactions with calcium, with one pound of calcium binding approximately 1.2 pounds of phosphorus pentoxide, further limiting P solubility. Conventional P fertilization typically relies on a single pre-plant application, which does not align with the plant’s continuous nutrient demands throughout the growing season. Moreover, prolonged soil-P interaction exacerbates fixation losses, further reducing bioavailable P. This study investigates the effectiveness of split P applications as a strategy to mitigate fixation and improve nutrient uptake efficiency. By minimizing phosphorus’s contact time with reactive metals, split applications—through multiple dry granular P applications or fertigation—help sustain adequate P concentrations in plant tissue. Preliminary results indicate that split applications significantly enhance P uptake and use efficiency, leading to higher snap bean yields compared to conventional single-dose treatments. These findings suggest that split P applications offer a more effective and sustainable approach to optimizing phosphorus management in snap bean and other vegetable production.

Biostimulants are gaining popularity as a tool for enhancing plant growth, mitigating abiotic stress, and improving crop yield and quality. Defined as substances or microorganisms that stimulate natural plant processes. Although skepticism about their efficacy initially limited their use, a growing body of research evidence demonstrates their positive effects on crop systems under both controlled environments and field conditions. However, the continuous development of new biostimulant formulations reinforces the need for further validation under commercial agricultural conditions. This study evaluates the effects of eight commercial biostimulant protocols, each with different composition and modes of action on tomato (Solanum lycopersicum) growth, fruit quality, and yield. The objectives are to: 1) quantify the effects on plant growth with parameters such as plant height, stem diameter and leaf chlorophyll content) 2) assess the impact on yield and fruit quality at harvest. The experiment followed a randomized complete block design with three replicates, each comprising eight treatments. Each plot contained 25 tomato plants, and data were collected from 10 selected plants per plot. Biostimulants were applied weekly or biweekly, via drench or foliar spray, according to the manufacturer’s instructions. Growth parameters were measured throughout the experiment, while yield and quality assessments were at harvest and during postharvest storage. According to the analysis of variance, plant height was significantly affected by protocol. Protocol 5 was statistically superior to the control in two of the three replicates followed by protocol 8 with one statistical significance in the three replicates compared to the control. There was not any statistical difference in diameter of treated plants compared to the control, however plants treated with protocol 8 had the greatest diameter in two of the three replicates. For the chlorophyll content, treatment 1 was the only one that showed a significant increase compared to the control. In terms of color, protocol 2 and 5 significantly increased fruit brightness while protocol 5 and 7 enhanced color saturation and protocol 1 altered hue compared to the control. The firmness of fruits at harvest was 2.08 to 2.85 kg without any significant differences within the protocol. In yield, protocol 5 was statistical significance in marketable weight, number 8 was statistical significance in count and weight in unmarketable category. According to the above, there is a significant benefit of specific biostimulants as treatments 5 and 8 in promoting tomato plant growth and improving certain fruit quality parameters. Key words: Biostimulants, protocol, plant growth.

Current vegetable production faces the challenge of productivity with growing demand for environmentally sustainable crop management practices. Biostimulants present a promising and sustainable strategy for mitigating the adverse effects of unpredictable weather patterns on vegetable crops, thereby enhancing resilience to heat stress, water deficits, and various biotic and abiotic stresses. While biostimulants have shown promising effects in various agricultural applications, there is limited literature on biostimulants and their role in regulating plant growth and development under conventional open field production systems. Additionally, there remains a research gap concerning the optimal application methods and rates of various biostimulants across different vegetable crops. Hence, this study analyzed the effectiveness of two different biostimulants seaweed extract and humic acid on mustard greens (Brassica juncea) performance using conventional farming methods in open field conditions. The biostimulants were applied through both soil and foliar application at two different rates to evaluate their effects on the growth, yield, and nutritional quality of mustard greens. Data was collected on various parameters, including the number of leaves per week, fresh and dry weight at harvest, nutrient content including chlorophylls, carotenoids, and mineral nutrient composition. Yield and nutrient compositions were improved by the application of seaweed at high concentration. In conclusion, seaweed application can be beneficial to improve mustard greens production in open field conditions.

Biostimulants have the potential to enhance plant growth and improve resilience to environmental stresses such as drought. This study investigated the effects of biostimulant application on the growth and physiological responses of two lettuce cultivars, ‘Green Oakleaf’ and ‘Red Oakleaf’, grown in a greenhouse at Mississippi State University. Plants were grown in containers under three substrate field capacities (40%, 70%, and 100%) and treated with one of four biostimulant treatments: Tribus®, Huma Pro®16, Kelpak®, or an untreated control. Data collected included plant growth index (PGI), leaf SPAD readings, photosynthetic activity, fresh and dry weights, and leaf color. Water availability and cultivar significantly affected PGI, biomass accumulation, and SPAD readings. The 70% and 100% field capacities resulted in the highest fresh and dry weights, while ‘Red Oakleaf’ exhibited greater dry weight and SPAD values than ‘Green Oakleaf’. Biostimulant treatments had no significant effect on any of the measured parameters. These results indicate that water availability plays a critical role in greenhouse lettuce growth, while the biostimulants tested did not enhance plant performance under the conditions of this study.

With increasing focus and shift towards soil health, sustainable soil management practices stand as critical approach to enhance the crop productivity and quality while improving production system as a whole. One method to improve soil health is through addition of soil amendments such as compost, animal manure and crop residues. However, there is limited literature on emerging organic amendments like biochar, vermicompost and peatmoss and their role in crop production in field-based conditions. Specifically, biochar has high cation exchange capacity and improves soil homeostasis, while vermicompost has more readily available nutrients. Several researchers have found synergistic effects when biochar and vermicompost were used in combination with high nutrient retention and uptake, supported by high activity of soil microorganisms. Similarly, peat moss is rich in organic matter and has high water absorption capacity. Although its use in soilless substrates has been widely explored, peat moss as soil amendment in open fields has limited literature. Hence, the current study investigated the role of organic soil amendments on yield attributes and nutritional profile of a leafy green vegetable, collard greens. Furthermore, soil parameters like organic matter content, soil nutrients and soil bulk density were observed before and after the crop period. Two open field trials were conducted in spring and fall under at Students Farm, Oklahoma State University, following certified naturally grown production practices. The soil amendment treatments were arranged in randomized complete block design within four blocks. Collard greens’ phytochemicals such as chlorophylls, carotenoids, flavonoids, phenols, and sugars were analyzed after harvest. Results show that vermicompost facilitated better crop performance by improving soil physical and chemical properties. The findings of this study provides sustainable horticulture practices by providing more information on added amendments and their role in improving soil health and enhancing crop quality, offering actionable insights for soil health focused production systems.

Nitrogen (N) is the macronutrient required in the largest amount by strawberry plants (Fragaria ×ananassa Duch.) and is often the primary factor limiting their yield. Florida’s sandy soils are highly prone to leaching of mobile nutrients like nitrate. Optimizing N fertilization is essential not only for maximizing economic returns but also for reducing the risks of environmental pollution caused by nitrate leaching and runoff. This study aimed to determine the growth stage-specific optimum N rates for the winter strawberry production system in Florida. Three field experiments were conducted in west-central Florida, each following a factorial design with four cultivars [‘Florida Brilliance’ (Brilliance), Florida MedallionTM 'FL 16.30-128' (Medallion), Florida PearlTM ‘FL 16.78-109’ (Pearl 109), and Florida Pearl® ‘FL 18.52-66’ (Pearl 66)] and five N rates (0, 0.56, 1.12, 2.24, and 3.36 kg/ha/d). Different N rates were applied during Weeks 3–8 (early growth) in Expt. 1, Weeks 9–14 (mid-growth) in Expt. 2, and Weeks 15–20 (late growth) in Expt. 3, with a baseline rate of 1.12 kg/ha/d before or after the treatment period. All experiments concluded at the end of Week 20, with total N application rates ranging from 94 to 235 kg/ha. Model fitting analysis was conducted to explain the yield response for N rates. In Experiment 1, marketable yield was fitted to linear models (r2=0.82−0.98) as a response to N rate, with slopes of 0.45, 0.45, 0.36, and 0.35 for Brilliance, Medallion, Pearl109, and Pearl66, respectively. Increasing the N rate from 1.12 to 3.36 boosted total marketable yield by 128%, 132%, 129%, and 126% for Brilliance, Medallion, Pearl109, and Pearl66, respectively, by the season's end. In Experiment 2, marketable yield of Medallion and Pearl66 followed linear models (r2=0.9−0.96) with slopes of 0.44 and 0.26, respectively, while other cultivars showed no significant slope differences. Increasing the N rate from 1.12 to 3.36 enhanced marketable yield by 137% for Medallion and 111% for Pearl66. In Experiment 3, no significant pattern was observed between N rates and marketable yield during the treatment period, but increasing the N rate slightly increased marketable yield at season's end for Brilliance (101%), Pearl109 (113%), and Pearl66 (104%), while negatively impacting Medallion (91%). Across all experiments, unmarketable yield, small fruit number, and soluble sugar content were not significantly (p

Nitrogen (N) is often the primary limiting factor in strawberry (Fragaria ×ananassa Duch.) production. Optimizing N fertilization is crucial for maximizing economic returns while minimizing environmental pollution risks. This study aimed to determine cultivar- and growth stage-specific optimum N rates for winter strawberry production in a subtropical sandy soil. Three field experiments (Expt. 1, 2, and 3) were conducted in west-central Florida, with four cultivars [‘Florida Brilliance’ (Brilliance), Florida MedallionTM (Medallion), Florida PearlTM (Pearl 109), and Florida Pearl® (Pearl 66)] and five N rates (0, 0.56, 1.12, 2.24, and 3.36 kg·ha–1·d–1). Different N rates were applied during Weeks 3–8 (early growth) in Expt. 1, Weeks 9–14 (mid-growth) in Expt. 2, and Weeks 15–20 (late growth) in Expt. 3, with a baseline rate of 1.12 kg·ha–1·d–1 outside the treatment period. All experiments concluded at the end of Week 20, with total N application rates ranging from 94 to 235 kg·ha–1. Model fitting revealed cultivar- and growth stage-specific yield responses to N rates. In Expt. 1, the best-fit models were linear for Brilliance, Medallion, and Pearl 109, with maximum yield increases of 102%, 109%, and 71%, respectively. For Pearl 66, the best-fit model was quadratic, with a maximum yield increase of 126% at 3.34 kg·ha–1·d–1. In Expt. 2, Medallion maintained a linear response with a maximum yield increase of 90%, whereas Brilliance followed a quadratic model, with a maximum yield increase of 70% at 2.27 kg·ha–1·d–1. Pearl 109 and Pearl 66 followed exponential plateau models, reaching 90% of their respective maximum yields with 89% and 73% increases at 1.64 and 2.09 kg·ha–1·d–1, respectively. In Expt. 3, no cultivar exhibited a significant model fit. Agronomic N use efficiency (ANUE, kg yield increase per kg N applied) showed contrasting results. In Expt. 1, only Pearl 109 exhibited a significant model fit, with a linear reduction of up to 30%. In Expt. 2, Medallion showed no significant model fit, whereas the other three cultivars reduced ANUE linearly by 27% to 38%. In Expt. 3, all cultivars followed exponential decay models, with maximum reductions of 57% to 63%. These results suggest that Medallion is the most responsive to N fertilization, while Pearl 109 is the least. Moreover, N fertilization efficiency could be improved by increasing its distribution during the early and mid-season growth stages and limiting late-season inputs.

Increasing salt stress and water scarcity necessitate research on plant salinity tolerance. This study investigated the effects of biochar crossandra (Crossandra infundibuliformis) under saline conditions. Three biochar rates (0%, 15%, 25%) were incorporated into commercial substrates, with salinity treatments of control, medium, and high at 0.2 dS∙m-1, 2 dS∙m-1, and 4 dS∙m⁻¹ respectively. Growth parameters (growth index, chlorophyll content, number of flowers), biomass, and physiological responses (photosynthesis, transpiration, stomatal conductance rate) were evaluated over time. The results showed crossandra tolerated salinity up to 4 dS∙m⁻¹ with minimal effects on flower production, biomass, and physiological responses, though growth index and SPAD values declined. At 2 dS∙m⁻¹, 15% biochar improved growth index, SPAD, number of flowers, biomass, and physiological rates comparable to controls. These results suggest biochar can mitigate salinity effects for crossandra plants.