ASHS 2024 Conference

Evaluating Nitrogen Application Rates on Open-field Fresh-market Tomato Production in North Mississippi: Preliminary Results - Ibukun Ayankojo
Effect of Bacterial Biostimulant Applied at Different N Rates in Potatoes - Lakesh Sharma
Evidence of Downregulation in Atmospheric Nitrogen-Fixation Associated with Native Hawaiian Sugarcane - Noa Lincoln
Nitrate Leaching Potential of UAN and Organic Soybean Extract Fertilizers Applied to Lettuce - Dave Goorahoo
Evaluating the N Status of Tomato Supplied with Soluble and Controlled-release Urea Formulations - Laura Jalpa
Understanding Nitrogen Uptake Potential of Two Wetland Plants Under Varied Water Temperatures and Nitrogen Concentrations - Saroj Burlakoti
Understanding the Boron-Yield Relationship in Pistachio Orchards - Mukesh Mehata

Nitrogen (N) is an essential crop nutrient and is a major production requirement for vegetable crops, critical for optimum yield and fruit quality. An adequate supply of N improves plant growth and health, reduces plant susceptibility to diseases, and minimizes the risk of groundwater and surface water pollution. There is limited information on the N requirements for commercial vegetable production systems in Mississippi (MS). This project aims to establish the critical N application rate for open-field fresh-market tomato production in northeast Mississippi. The study was conducted at North Mississippi Research and Extension Center, Verona MS. The evaluated treatments (0, 73, 109, 145, 218, and 290 kg/ha-N) were arranged in a randomized complete block design with three replicates per treatment. For each treatment, the total required amount of nitrogen application was applied at a split rate of 50% preplant (ammonium nitrate, 33-0-0 and fertigation (Calcium nitrate, 15.5-0-0). Fertigation was applied weekly starting at 6 weeks after transplanting. Both potassium and phosphorus were the same for all treatments and applied at 100% pre-plant using 0-46-0 and 0-0-60 formulations respectively. Yield data were collected at fruit maturity and analyzed for statistical differences among treatments. Preliminary results suggest significant differences (p < 0.05) among treatments for leaf tissue N concentration. The total marketable yield and extra-large fruit categories were highest (p < 0.05) at 290 kg/ha-N compared to other treatments. The results also clearly demonstrated that the observed yield increase at a higher N rate (290 kg/ha-N) was attributed to increase in total fruit number at maturity and bigger fruit size. The observed yield for the unmarketable fruit category was highest at N application rate of ≤ 73 kg/ha. Based on the preliminary results obtained, the optimum N application rate for open-field fresh-market tomato production in northeast MS could be up to 290 kg/ha. However, more studies are currently being conducted to validate these preliminary results.

Nitrogen is a crucial macronutrient for potato production, as it plays a vital role in promoting photosynthesis, chlorophyll synthesis, and overall plant growth, ultimately contributing to higher crop yield. However, the shallow root system of potato plants and the sandy soil conditions in this region make applied nitrogen unavailable to the crop, resulting in reduced nitrogen use efficiency (NUE). An alternative and eco-friendly solution is to integrate microbial consortium inoculation in nutrient management plans. This approach entails the introduction of a mixture of beneficial microorganisms known as plant growth promoting rhizobacteria (PGPR), into the soil to promote plant growth. These N2-fixing microbes can increase soil N availability which could meet N demand of potato crop, hence can help in reducing N fertilizer input rate. Therefore, a commercial microbial biostimulant was applied with five different N rates 0, 78, 157, 235, and 314 kg ha-1. We found that microbial biostimulant did not increase tuber yield but improved NUE. Increasing N rate increased tuber yield, biomass and NUE significantly.

The study of nitrogen fixation in sugarcane has a long history that has demonstrated high potential but with substantial variation in results. This 32-month study sought to assess the response of nitrogen fixation associated with sugarcane (Saccharum officinarum L. cvs. ‘Akoki, Honua’ula, and ‘Ula) to available soil nitrogen. Plants were grown in large pots of perlite along with a fixing and a non-fixing plant control and administered liquid fertigation with varying amounts of isotopically enriched nitrogen. Assessment of nitrogen fixation utilized nitrogen isotope tracing and acetylene reduction assay in the target and control plants. Isotope enrichment and acetylene reduction assay both indicated that nitrogen fixation peaked under low nitrogen application, and declined with higher application rates, with agreement between the two methods. These results suggest that sugarcane engages in a downregulation of nitrogen fixation under high nitrogen availability, potentially explaining the high variation in published experimental results. This suggests that nitrogen management and fertilization strategy can impact the atmospheric inputs of nitrogen in sugarcane cultivation, and the potential to improve nitrogen application efficiency in cropping systems utilizing sugarcane.

In California, lettuce (Lactuca sativa) production generates over $1.8 billion in revenue. As a leafy green vegetable, Nitrogen (N) fertilizer applications can reach as much as 280 kg N/ha. The relative shallow root systems and frequent irrigation can enhance Nitrate (NO3) Leaching Potential (NLP) when the crop is grown on Sandy Loam soil. Because of economic, health, and environmental concerns, growers are exploring the option of using organically approved fertilizers such as water-soluble N derived from soy protein hydrolysate (GS) as an alternative to Urea Ammonium Nitrate (UAN). The objective of this study was to compare the NLP of equivalent rates of UAN and GS applied to a (1) soil-column study (Phase 1) and (2) greenhouse lettuce crop with 3 Irrigation regimes x 2 Fertilizers x 4 Rates as a factorial experiment replicated four times (Phase 2). In the Phase 1 study, approximately 2,150 ml of water containing a chloride (Cl) tracer and fertilizers at rates of 0, 56, 112, and 168 kg N/ ha were applied to a fixed volume of soil at a bulk density of 1.35 g/cm3. The chloride concentrations in the leachate from both fertilizer treatments were similar, and the water balance accounted for 95% of the solution applied. The concentration and amount of NO3 in the leachate collected from soil treated with GS were lower or at least equal to that obtained from the soils treated with UAN. In contrast, the amount of residual soil NO3 was significantly higher in the soil receiving the UAN, ranging from 2 to 4 times as the application rates increased from 56 to 168 kg N/ha, respectively, implying a relatively higher NLP for the UAN. In the case of the lettuce experiment (Phase 2), there were no significant differences in the chlorophyll content based on the choice of fertilizer or application rates. Lettuce yields, expressed on a dry matter basis, were not significantly (p=0.11) different for fertilizer type, with similar fertilizer rate response curves being obtained for both UAN and GS. Finally, the mean %N and %C in the lettuce leaves were 3.22% and 40%, respectively, regardless of whether the lettuce was grown with synthetic UAN or organically derived soybean hydrolysate (GS). These preliminary findings justify the need to investigate further the impact of higher irrigation rates and even saturated conditions on the NLP of vegetables subjected to the two fertilizers used in the current study.

Matching crop nitrogen (N) demand and supply is necessary to increase crop N use efficiency (NUE) and reduce environmental impact. Proximal optical sensors such as the Soil Plant Analysis Development (SPAD) meter have been found to be useful in monitoring the crop N status, providing insight into the effects of N fertilization practices in cropping systems. High N rate applications are common in conventional tomato production, where loss of N, more specifically NO 3 - , from the rootzone can decrease water quality. Thus, optimal N management of fertigated vegetable crops requires frequent and rapid assessment of the crop N status to quickly adjust application of N when required. A two-year field study was conducted in north Florida to evaluate the crop N status based on N fertilization practices associated with soluble urea and polymer coated controlled-release urea (CRU) for fall and spring tomato (‘HM 1823’) grown in sandy soils under a plastic-mulched bed system. In addition to a no N fertilizer treatment, three urea N sources [one soluble source and two polymer-coated CRU sources with different N release durations of 60 (CRU-60) and 75 (CRU-75) days] were applied at three N rates (140, 168, and 224 kg ha -1 ), where 224 kg ha -1 is the recommended N rate for tomato production in Florida. Soluble urea was split applied weekly over the 13-week growing season, whereas CRUs were applied at the full rate once at preplant. For all seasons, biweekly SPAD meter readings were taken and sampling periods coincided with the vegetative, flowering, fruit set, fruit growth, and harvest growth stages. Overall, minimal differences in tomato N status were observed among the tested N rates and N sources, indicating that all N fertilizer practices tested maintained similar N use. Thus, irrespective of the N source, this study found that tomato N demands could be met at a 38% reduction of the recommended N rate, potentially enhancing NUE in tomato production systems cultivated on sandy soils in north Florida.

Excessive use of commercial fertilizers in nursery production results in substantial fertilizer runoff, leading to surface and groundwater contamination. Therefore, to prevent contamination and comply with regulations, irrigation return flow (runoff water) is generally collected in a retention pond before it can be safely discarded or released. Nitrogen, applied as nitrate compounds is among the highest used fertilizer and is prone to leaching and runoff. Employing a phytoremediation strategy to remediate irrigation return flow (runoff water) has the potential to lower nitrate concentrations in water before release. In this study, we assessed the suitability of growing Helianthus maximiliani (maximilian sunflower) and Asclepias speciosa (showy milkweed) in a floating treatment wetland system (FTW) and evaluated the nitrate uptake capacity of these plants grown in three different nitrogen concentrations i.e., 10, 20, and 30 mg/L and two water temperatures of 75°F and 85°F. Increasing water temperature increased growth index for both species and increased dry weight for Asclepias speciosa. However, for Helianthus maximiliani, increasing temperature had a lesser effect on total dry weight. The accumulation of nitrate nitrogen in plant tissue was higher in Helianthus maximiliani at the nitrate nitrogen concentration of 20 mg/L under both temperature treatments. However, in Asclepias speciosa, the accumulation of nitrate nitrogen in plant tissue was higher at the high temperature treatment of 85⁰F and 20 mg/L nitrate nitrogen concentration. The nitrate nitrogen uptake from both plants in this study indicated suggests that Helianthus maximiliani ‘maximilian sunflower’ and Asclepias speciosa ‘showy milkweed’ can be grown as FTW and be used to remove nitrogen from a nursery retention pond.

Iron (Fe) and Zinc (Zn) are two micronutrients which are crucial for human health and proper functioning of the circulatory, endocrine, immune, nervous, and reproductive systems. Deficiencies in dietary Fe and Zn can result in numerous illnesses and disorders and are among the most prevalent micronutrient deficiencies worldwide. There is an urgent need for improving the dietary intake of these micronutrients and a promising, quick, and effective improvement strategy is agronomic biofortification. Microgreens are an ideal and versatile choice for meeting nutritional needs. They are nutrient-dense, have low phytic acid content, can be produced for a range of species, and have a relatively short growth cycle – making them a convenient biofortification target crop. Previous studies’ attempts towards the simultaneous biofortification of Fe and Zn have indicated their antagonistic interactions during uptake, where the increase of one mineral led to a decreased uptake of the other. However, limited information is available about the opportunity of enriching microgreens with both nutrients using fertigation. Therefore, in this study we aimed to assess the optimal combination of Fe and Zn fertilizer concentrations, provided via fertigation, to maximize their simultaneous accumulation in radish and sunflower microgreens without impairing yield and quality. Using a completely randomized block design setup, a factorial combination of FeSO4 (0, 20, and 40 mg/L of Fe) and ZnSO4 (0, 10, and 20 mg/L of Zn) was tested. Across both species, it was observed that fertigation using the treatment combination of 40 mg/L FeSO4 and 20 mg/L ZnSO4, (Fe40-Zn20), resulted in a substantial increase of both micronutrient levels. Compared to the untreated control, the Fe40-Zn20 treatment increased Fe and Zn accumulation by about 200% and 900%, respectively, in radish microgreens, and about 180% and 600% in sunflower microgreens. Additionally, this treatment resulted in minimal yield reduction. Fresh and dry biomass decreased by approximately 23% and 9%, respectively, in radish microgreens, and 38% and less than 1% in sunflower microgreens. Although increasing both Fe and Zn content proves to be a challenging endeavor, this study revealed evidence of an optimal combination of selected Fe and Zn sources and application rates that, via fertigation, was effective in their simultaneous enrichment in two microgreen species.

Plant Nutrient Management Interest Group
The purpose of this meeting is to align the ASHS mission to develop nutrient management strategies for horticultural field and controlled environment-grown plants, (1) to maximize plant productivity, and (2) to reduce environmental footprints by restricting nutrient loss where it can impact greenhouse gas emissions and water quality.

Soil Amendments Alter Soil Chemical Properties and Toxic Elements Accumulation in Sweetpotato cvs. Bayou Belle and Beauregard - Mae Ann Bravo
Methods of Fertilization in Commercial Production of Saw Palmetto (Serenoa repens Small (Bartr.) form green and glauca) -Vania Pereira
Iron Biofortification in Radish and Pea Microgreens Using Alternative Iron Sources and Ascorbic Acid -Rishi Ravichandran
Combined Agronomic Biofortification of Iron and Zinc in Radish and Sunflower Microgreens - Rishi Ravichandran

Saw palmetto is an endemic palm of the Southeastern United States that has been widely used as an ornamental food source for birds and mammals, and the fruit is used as a medicinal supplement for prostate cancer. The production of this palm still relies on wild harvesting. We analyzed the effects of different fertilization methods on the plant growth and fruit production of two saw palmetto forms (green and silver) from 2022 to 2023. Fertilization methods consisted of 1. Control- no fertilizer application; 2. Injection by Arbor-Jet: Palm-Jet Mg 1-2-2 (N-P2O5-K2O) 2.5 ml per plant once a year (ArborJet, Woburn, MA); 3. Granular (Harrell’s, Lakeland, FL): 8-2-12 4 Mg (N-P2O5-K2O 4 Mg) with micronutrients 146 g/m2 of plant canopy; 4: Granular and drench fertilizer: 8-2-12 4 Mg with micronutrients 146 g/m2 with drench application – 20-10-20 Epsom salts Non-staining Micros (Harrell’s MAX, liquid foliar nutritional, Lakeland, FL). Treatments 3 and 4 were applied every three months for a year. Green saw palmetto only differed and performed better than silver form in the number of leaves and offshoot per plant. The granular and granular with drench fertilization provided the best plant growth rates, regarding plant height, width, visual quality, and green canopy cover, then control and injection treatments. Even though the drench had a higher supply of nutrients for the plants, the differences were not statistically significant from granular fertilization.

Field trials were conducted to investigate the feasibility of applying commonly used soil amendments to reduce the accumulation of arsenic (As), cadmium (Cd), and lead (Pb) in sweetpotato storage roots. The cultivars Bayou Belle and Beauregard were grown on an experimental site with natural levels of As, Cd, and Pb. The following soil amendments were used: agricultural lime (AGL) (1 t·ac−1), gypsum (GYP) (1 t·ac−1), biochar (BIO) (1 t·ac−1), and silicon provided as wollastonite (WOL) (2.5 t·ac−1). Compared to the unamended plots, WOL and GYP were associated with elevated soil pH and sulfur levels while reducing Mn and Fe availability. There were no differences in storage root yield grades for both cultivars. The soil amendments were associated with reducing As and Cd extractability by 12 to 31% and 2 to 5%, respectively. A notable finding was the increase in Cd and Pb accumulation in the cultivar Beauregard amended with WOL. We hypothesize that the elevated pH was associated with reducing available binding sites and surface complexes such as with Mn and Fe, leading to the increased bioavailability of Cd and Pb. These preliminary findings support the hypothesis that AGL is a viable soil amendment under mixed toxic element conditions, reducing Pb accumulation without increasing the uptake of other toxic elements. The data also support the need for a systems-based approach for the long-term management of toxic elements in sweetpotato, where soil amendment application is integrated with the use of cultivars associated with low accumulation of specific toxic elements.

Iron (Fe) is an essential and versatile micronutrient in plants and humans, and inadequate levels of dietary Fe can cause impaired development in children and poor physical and cognitive functioning in adults. Iron deficiency is the leading micronutrient deficiency worldwide, affecting around 1.6 billion people, with the most vulnerable demographic being pregnant women and infants. Contributing factors include diets that, particularly in developing regions, are predominantly comprised of cereal grains which are characterized by relatively low bioavailable Fe levels. Additionally, 30% of cultivated soils globally have low Fe availability. Defining effective ways to increase Fe content and availability in edible plants is therefore of utmost importance, and an agronomic approach to Fe biofortification could be a viable solution. Microgreens are an ideal candidate crop for tackling nutrient deficiencies. They are nutrient dense, have low antinutrient levels, can be grown in a relatively short amount of time, and can be consumed raw, making them a convenient target for agronomic Fe biofortification. Unfortunately, Fe uptake by plants is problematic, especially in alkaline and oxidizing conditions. Previous studies have suggested the potential of using ascorbic acid (AA) as an enhancer of Fe uptake. However, this approach has not been tested before in microgreens. Therefore, a study was conducted to 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 radish and pea microgreens’ Fe content. Treatments were arranged in a randomized factorial experimental design using three replications. We discovered that Ferric sulfate 0.1% AA was the most effective source in increasing Fe uptake, while Ferric citrate was the least efficient. Fertigating with 45 mg/L Ferric sulfate with 0.1% AA resulted in an approximately 110% increase in Fe accumulation in radish and pea microgreens, compared to the untreated control. However, using sodium hydroxide (NaOH) to adjust the nutrient solution pH, the same treatment was associated with an increased level of Na and resulted in a 3-30% reduction in fresh and dry biomass in both microgreen species. In conclusion, this study provides promising evidence that through fertigation, supplementation of AA with Fe fertilizers is effective in increasing Fe uptake in two microgreens species. However, careful consideration of Fe sources and concentrations needs to be made to not compromise yield and nutritional quality.

Micronutrients like boron, similar to essential macronutrients (nitrogen, phosphorus, and potassium), play a crucial role in plant growth and productivity, even though they are required in smaller quantities. In California’s pistachio production, boron deficiency was initially identified as a concern. However, more recently, the issue has shifted to excess boron in soils and water, potentially affecting the plants as boron toxicity. The current study is investigating the relationship between soil and leaf boron levels, leaf surface area damage and yield in pistachio drip irrigated orchard. Soil, leaf and yield data were collected from a second year running salinity management trial on an eight-year-old pistachio orchard (established in 2015) on the west side of the San Joaquin Valley. Our preliminary findings indicate that while soil boron levels significantly reduced pistachio yield, no significant correlation was found between leaf boron level or percentage of leaf damage (indicative of boron toxicity) and yield. This indicates that the decrease in yield with increasing soil boron is not caused by a reduction in active photosynthetic area. Based on these findings, focusing on monitoring and maintaining optimal soil boron levels might be the most effective strategy for minimizing potential yield losses associated with boron issues in pistachio orchards.

Aerated Compost Tea Impacts on Soil Parameters and Yield of Tomato, Carrot, and Beet - Charlie Rohwer
The Effect of High Concentrated Liquid Fertilizer at Hydroponic Culture to the Contents of Amino Acids and Mineral in Watermelon Fruits - Sentaro Tomiyama
Changes Of Fruit Profile And Content Of Carotenoids At Different Nutrient Conditions In Hydroponically Grown Watermelon - Xiangyu Cui
Phosphorus Fertilizer Application Strategies to Improve Phosphorus Availability and Utilization in Potatoes. - Samuel Essah
Nitrate Leaching in Processing Tomato Production Subjected to Deficit Irrigation and On-Demand Nitrogen Fertilization - Dave Goorahoo
Greenhouse Nitrogen application rate optimization for optimal bamboo (Dendrocalamus asper) growth and productivity in Florida - Cyrus Januarie
Determining Adequate Nutrient Application Rates for Water Spinach (Ipomoea aquatica) Production in Deep Water Culture - Shelbie Bohensky
The incorporation of black soldier fly larvae to fish feed increased fish and plant growth - Most Tahera Naznin

The intentions of aerated compost tea are to provide nutrients to plants or beneficial microbes to the soil or phyllosphere. Compost tea may also contain organic compounds which alter plant physiology (growth or induced defenses). Compost tea is mainly encountered in organic systems, but there is evidence for improved outcomes when using both organic and conventional nutrient sources. The objective of this study is to understand more about the impacts of aerated compost tea (ACT) on soil microbial activity and nitrogen status and plant responses. ACT was applied weekly or bi-weekly as a drench or as a spray to field-grown tomatoes, carrots, and beets fertilized organically or conventionally at two locations in Minnesota. Results presented here focus on produce yield from year 1 of the 3-year study. We found no difference in any of the yield parameters measured due to compost tea application. We generally observed higher yields in organically-fertilized produce in both locations. One location, with a longer history of organic production, had higher soil microbial activity in the organically-fertilized treatment but the difference in yield between conventional and organic tomatoes was similar at both locations.

We have previously reported the sugar distribution and accumulation in watermelon fruit grown hydroponically (Tomiyama et al. 2023 . Hort Science). In this research, the contents of amino acids and mineral in watermelon fruits grown hydroponically at high concentrated nutrient solution were investigated. Three different hydroponic culture conditions were set by Electric Conductivity: EC 5.0, 3.0, and 1.2 dS-m-¹. Initially watermelon seedlings (Citrullus lanatus (Thunb.) Matsum. Et Nakai ‛Hitorijime-BonBon) were grown at EC 1.2 dS-m-¹ (Control) conditions on deep flow technique in a glasshouse. Treatment was initiated two weeks after pollination. Forty days after pollination, watermelon fruits were harvested and measured its size. Then, mineral and amino acids content were analyzed by HPLC. We measured NH⁴⁺, K⁺, Mg⁺, and Ca²⁺ as cations and PO⁴- and NO³- as anions. Twenty amino acids were measured also. As result, the fruit size and weight decreased under high nutrient conditions. At mineral analysis, the cations NH⁴⁺, Mg⁺, and Ca²⁺ content in the flesh did not increase at the high concentrated treatment, but K⁺ increased in the pericarp at higher treatment. Similarly, the anions PO⁴- and NO³- content increased as K⁺. In control, amino acids was accumulated in the center of flesh, whereas in the higher concentration amino acids was concentrated in the pericarp. When we focused on citrulline and proline, they were accumulated more in pericarp than flesh. In conclusion, mineral (K⁺, PO₄³-, NO₃-)and some amino acids such as citrulline, and proline, which accumulate in the pericarp, accumulated under high concentrated liquid fertilizer at hydroponic culture.

Researches on carotenoid content in hydroponically grown watermelon fruits are rarely conducted. In hydroponic system, nutrient condition can be easily monitored and precisely controlled by regulating the concentration of culture solution. To study the changes of fruit profile and content of carotenoids at different nutrient conditions, we cultured watermelon in hydroponic system and changed the electric conductivity (EC) of solution which can represent the condition of nutrient. Forty seedlings were provided by Hagihara Farm company and replanted in the hydroponic system where the electric conductivity of solution equaled 1.2 dS·m-1. Three branches were remained for one plant and each pistil after 20 nodes were pollinated by hands. The nutrient condition was divided 14 days after pollination into 3 groups which were Control (EC = 1.2 dS·m-1), the regime of solution EC = 3.0 dS·m-1 (group 2) and the regime of solution EC = 5.0 dS·m-1 (group 3). Samples were taken every 10 days interval, and the fruit size, weight as well as Brix of flesh were measured on the sampling day. Carotenoid contents were determined by high performance liquid chromatography. Results showed that compared to the control group, fruit size and weight were promoted in group 2 but restrained in group 3. However, group 3 had the highest Brix among three groups. In terms of β-carotene, the higher the concentration of solution was the earlier its promotive and restraining effects showed out. Lycopene was also promoted in the early stage (10-30 days) in group 2 and group 3 but the total amount on 40 days decreased and dropped to near or below the control group.

Phosphorus (P) is a poorly soluble plant nutrient. Therefore, P uptake by the potato crop is primarily through root interception and short distance diffusion. This limits the percentage of soil supplying P to potato roots. Placement of P fertilizer is a management variable that can influence P uptake and P use efficiency, thereby improving tuber yield and quality. Recent studies conducted at Colorado State University’s San Luis Valley Research Center, USA, has shown that blending orthophosphate fertilizers with 10-34-0 reduces required P fertilizer cost and improves P use efficiency, as well as increase potato tuber yield and quality, compared to using 10-34-0 as sole source of P fertilizer. Information on placement method of blended P fertilizers for maximum use efficiency and tuber performance has not been documented. Studies were conducted at Colorado State University’s San Luis Valley Research Center, USA, with the objective of evaluating the effect of blended liquid P fertilizer placement method on Russet potato performance in the field. Three orthophosphate fertilizers each blended with 10-34-0 were evaluated under three placement methods (banding, in-furrow, and banding in-furrow application). Banding of blended liquid P fertilizers increased medium size (4-10 oz) tuber yield by 22%, compared to in-furrow application. In-furrow application of blended liquid P fertilizers increased production of premium size (> 6 oz and > 10 oz) tuber yield by 8 and 49%, respectively, compared to banding application. Results from this study suggest that appropriate liquid P fertilizer placement method can enhance sustainable potato production.

The information presented in this poster represents the first-year findings of an ongoing two-year study to assess the efficacy of two nitrogen (N) fertilization and irrigation approaches on tomato yield and quality, and the Nitrate (NO3) Leaching Index (NLI) defined as the ratio of the amount of NO3 in 60-120 cm of soil to the amount in 0-120 cm. Water and N use efficiency (WUE and NUE) were determined for processing tomatoes (Solanum lycopersicum) grown on a Handford Sandy Loam soil, with a pH of 6.7, in the San Joaquin Valley (SJV), California, USA. The experiment was a split-plot design with three replications of irrigation rates (I) as the main factor based on evapotranspiration (ET) scheduling amounts of 74% and 100% of crop evapotranspiration (ETc) and two fertilizer (F) application methods as the subplot factor. The Growers Practice (GP) was seven equal applications of CAN-17 for a total of 201 kg N/ha (180 lbs N/ac) over the growing season, whereas the Soil Nitrate Quick Test (SNQT) approach was to apply 17kg N/ha (15lbs N/ac) whenever the NO3 test strip value was less than 20 ppm. A total of 36 beds with a width of 130 cm x length of 2,700 cm were planted so that each subplot comprised three beds, with the two outer beds used as buffer rows. There were no significant differences in the total yield of all tomatoes (reds, breakers, and green) harvested as a function of either the irrigation (p= 0.79) or fertilizer rates (p=0.12). However, for the fully matured marketable red tomatoes, fertilizer practice had a significant effect (p=0.02), with the GP yielding approximately 30% more tomatoes than the plots subjected to SNQT. There was no interaction effect of F x I on the yield of these red tomatoes. With respect to sugar content, I (p

Bamboo, a giant tropical and temperate region grass, is used for food, timber, furniture, building and construction material, and paper making, among others. With the US being the world's number one importer of bamboo shoots, many growers are venturing into bamboo production with little or no knowledge of the best management practices. There is no reliable literature conducted in Florida about the crop. Therefore, this study was conducted to develop site-specific nitrogen (N) requirements for young bamboo plants in a controlled environment. This study was done in a greenhouse at UF/IFAS Citrus REC in Lake Alfred. One-year-old bamboo plants were transplanted into 37.85 L pots and treated with varying rates of N (0,112,224, and 336 kg N ha-1). Growth, photosynthetic rate, and tissue composition were measured biweekly for five months. Initial and final soil analyses were done. The results demonstrated that higher rates of N (up to a certain amount, i.e. 224 kg N ha-1) increased growth rate, number of culms, and dry matter accumulation. Analysis of Variance (ANOVA) test and regression analysis were conducted for the response variables in R software. Chlorophyll content and culm diameter were comparable. It was concluded that 200 kg/ha N was optimal for young bamboo plants since it demonstrated the peak growth rate, number of culms, and dry matter compared to the rest of the treatments. Key words: Dendrocalamus asper, nitrogen fertilization, best management practices

Water Spinach (Ipomoea aquatica) is a novel crop within the U.S. that is widely grown throughout southeast Asia. Although considered a noxious weed by USDA, interest from ethnic communities has led to the restricted permittance of cultivation within Georgia, USA. In order to determine nutrient requirements for hydroponic production of water spinach, a study was conducted using a deep-water culture in a greenhouse located in Watkinsville, Georgia, USA in the summer of 2023. Two selections of water spinach were grown in plastic containers filled either a ¼ or ½ strength Hoagland’s solution arranged in a randomized complete block design with four replications of each selection by nutrient solution combination. Initially, 15 plants of each selection were placed into the tubs. Beginning at 21 days after transplanting, two plants were removed from each tub for determination of biomass and nutrient concentrations. Additional plants were removed at 10-day intervals until a final harvest at 61 days after planting. The trial was then repeated. Results indicated that biomass (root and shoot) and nutrient removal within foliar tissues were significantly greater in the ½ strength solution compared to the ¼ strength solution. Total nutrient accumulation for most macronutrients exhibited a quadratic response, increasing until 51 days after planting and then plateauing. Plants grown in the ½ strength and ¼ strength Hoagland’s solution accumulated similar concentrations of foliar macronutrients though due to differences in biomass accumulation, total nutrient removal was significantly different between the two nutrient solutions. At harvest (day 61), ½ strength plants had an average potassium (K) concentration of 5.24% (dry weight), while those grown in the ¼-strength Hoagland’s solution averaged 4.48% K on a dry weight basis. However, due to significant differences in biomass production, K nutrient removal rates were more than twice as much in the plants grown in the ½ strength Hoagland’s solution compared to those grown in the ¼ strength solution. Our results suggest that although water spinach may grow in river systems in its native environments, that growth benefits from additional levels of fertilizer nutrients when cultivated in greenhouse systems and that a ½ strength Hoagland’s solution should be an appropriate baseline to develop recommendations for hydroponic nutrient solutions for greenhouse production of water spinach.

The economic success of the aquaponics industry and fish farming is mostly dependent on the use of inexpensive, nutritionally adequate meals. Approximately sixty percent of the economic balance is accounted for by fish feeding. The substitution of insect meal for fish meal appears to offer a promising approach to reducing cost and the environmental impact. The black soldier fly larvae (Hermetia illucens) possess 40–45% proteins and a favorable essential amino acid profile. The objective of this experiment was to investigate the effects of commercial and black soldier fly larvae (BSFL)-based diet on Nile tilapia growth, plant growth, and antioxidant accumulation in crops. The results showed that tilapia fish can grow at a higher rate on BSFL-based meals than on commercial diets. On the other hand, a study revealed that BSFL BSFL-based fish feed waste water significantly stimulated plant growth and antioxidant accumulation in aquaponic systems. This study opens up new possibilities for using BSFL as a substitute for fish meal, which could help to reduce the environmental effect of aquaponic production systems while also contributing to a circular economy.

Optimizing Nitrogen Fertilization for Evergreen Blueberry (Vaccinium corymbosum interspecific hybrids) in Florida - Gerardo Nunez
The Effects of Nutrient Management on Yield in Cut-and-Come-Again Kale Production.- Leigh Whittinghill
Growth Responses of Hydroponic Vegetable Transplants to Nutrient Solution Concentrations Made with Food Waste Liquid Ana - Emily WebbFoliar Boron Nutrition in Grafted Watermelon: Impact on Fruit Development, Yield, and Quality - Bhupinder JatanaOptimization of Tissue Culture Medium for Enhanced Proliferation of Little-Leaf Mockorange (Philadelphus microphyllus A. - Razieh KhajehyarNano NPK and Salicylic Acid Chemigation in Processing Tomato Production: Impact on Efficiency and Sustainability - Thomas HarkerNano NPK and Salicylic Acid Chemigation on Tomato Phytochemicals and Fruit Quality - Thomas HarkerAlternative Fertilizer Methods For Palm Trees - Mica Mcmillan

There are multiple ways to grow highbush blueberries (Vaccinium corymbosum interspecific hybrids). In Florida, an evergreen growing system was developed to overcome unpredictable chill hour accumulation. In this system, blueberry bushes retain their leaves throughout the year when fertilized appropriately. Deciduous blueberry farms typically skip fertilization during the fall and winter months. On the other hand, evergreen blueberry farms require winter fertilization to ensure healthy foliage. Therefore, fertilizer recommendations for deciduous blueberry are not applicable to evergreen blueberry. This research aims to optimize nitrogen fertilization for evergreen southern highbush blueberry plants in Florida. ‘Arcadia’ and ‘Sentinel’ southern highbush blueberry plants were grown in a high tunnel in Citra, FL. Plants were fertigated according to commercial practices, except for nitrogen (N). Nitrogen was applied manually as ammonium sulfate at 5 different annual rates (in Kg/ha): 5.6, 83.4, 138.9, 222.3, and 444.6. Plant size, leaf area index, leaf N concentration, fruit yield, and fruit quality were measured during the 2023 and 2024 seasons. Nitrogen fertilization rates affected plant growth during the spring and summer, but not during the fall and winter. Higher N fertilization rates led to higher leaf area index, a proxy for leaf retention. Plants in the lowest N fertilization treatment were not evergreen, as they dropped nearly all their leaves in the winter. Leaf N concentrations of plants in treatments 83.4 Kg/ha or higher were above the reference levels for N deficiency. Linear plateau regressions were used to identify optimum fertilization rates. During the 2023 season, ‘Arcadia’ exhibited a yield plateau, but ‘Sentinel’ did not, suggesting that N fertilization has cultivar-specific effects. All fruit harvested exhibited commercial quality in terms of soluble solids. However, fruit in the lowest fertilization rate was softer and more acidic than fruit in all other treatments. These results suggest that multi-year studies with multiple varieties are necessary to identify N fertilization rates that maximize agricultural productivity while minimizing fertilizer inputs.

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 for beginners or for growers looking to improve their cut-and-come-again yields. An experiment was designed to examine eight different fertilizer application strategies to determine which provided better growth and nutritional quality in later kale 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 (ODB) was also harvested at the baby stage at each CC harvest. At each harvest, total and marketable yield were measured and crop quality for marketability was assessed per the USDA guidelines for kale and greens. There were more issues with slow growth, slow regrowth, and missing harvests for pots in the fall than the spring, and more issues in 2023 than in 2022. Some issues were directly related to significant caterpillar damage in the fall of 2023 which also affected the marketability of the leaves harvested. The expected dose response to fertilizer treatment was not observed in any growing season of the two years of the study completed so far. While some differences in yield between treatments were observed, these were predominantly between the ODB control and CC treatments, but not among CC treatments. The expected drop in yield with successive harvests was also not consistently observed in CC treatments. The CC treatment receiving only the initial fertilizer application exhibited a drop in yield with successive harvests in only two of the four growing seasons. Further examination of the fate of nutrients in the leaf material, soil and leachate from the experiment should explain these unexpected results and provide more clarity on an optimal fertilizer treatment.

Food waste liquid anaerobic digestates (FWLAD) have received much public attention for its potential as an organic fertilizer source as they are rich in mineral elements. However, FWLAD can contain high salinity and high NH4 concentration, and thus, the optimum application rates need to be determined to deliver required plant nutrients without excessive salt and NH4 level. The objective of this study was to evaluate the effects of nutrient solution concentration made from FWLAD on the growth of leafy vegetable seedlings. The seeds of lettuce (Lactuca sativa) ‘Rex’, ‘Muir’, and ‘Roxy’, Swiss chard (Beta vulgaris subsp. vulgaris) ‘Rhubarb’, bok choy (Brassica rapa subsp. chinensis) ‘Mei Qing Choi’, and kale (Brassica oleracea var. sabellica) ‘White Russian’ were sown in rockwool plug and grown at 22 °C under sole-source LED lighting with an 18-h photoperiod at a photosynthetic photon flux density of 200 µmol∙m-2∙s-1. After germination, the seedlings were sub-irrigated with nutrient solution made with either crude or processed FWLAD at electrical conductivities (ECs) of 1, 2, 3, or 4 dS·m–1. Four weeks after treatment, when using crude FWLAD, shoot fresh mass of three lettuce cultivars decreased by 76-92% as EC increased from 1 to 4 dS·m–1. In contrast, with processed FWLAD, lettuce ‘Adriana’ and ‘Roxy’ showed 68-1080% greater shoot fresh mass at an EC of 2 dS·m–1 compared to an ECs of 1, 3, or 4 dS·m–1. Shoot fresh mass of lettuce ‘Muir’ at an EC of 2 dS·m–1 was similar with that at an EC of 1 dS·m–1 but 380-516% greater than those at ECs of 3 or 4 dS·m–1. In lettuce, the EC of FWLAD had similar effects on leaf area as it did on shoot fresh mass, but it had minimal effects on leaf number, relative chlorophyll concentration, and shoot dry mass. In kale, Swiss chard, and bok choy, the EC of FWLAD had little effects on plant growth attributes. Our results suggest that leafy vegetable seedlings vary in their responses to nutrient solution concentrations derived from FWLAD, with lettuce exhibiting greater sensitivity than Swiss chard, bok choy, and kale. In lettuce, lower concentrations of FWLAD (at an EC ≤2 dS·m–1) increased shoot fresh mass.

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 the key micro-nutrient 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 with the objective to evaluate the impact of foliar boron applications on pollen viability, pollination, fruit set, and periodic fruit yield as compared to regular watermelon nursery. The experiment was comprised of four treatments including a regular watermelon nursery control, in randomized complete block design. The soils had medium to low boron content of 0.1 pounds/acre. The soils were medium in potassium (133 pounds/acre), zinc (5.2 pounds/acre) and manganese (13 pounds/acre). Within first 25 days of transplanting, we did not observe any difference in the watermelon aboveground growth and biomass accumulation, in different treatments. Further, we will evaluate the impact of foliar boron application on pollen viability, pollination, watermelon fruit set, fruit yield and quality in SB grafted nursery.

Native plants play a crucial role in landscape ecosystems due to their adaptability, yet propagating certain species through traditional methods can pose challenges. Tissue culture emerges as a promising alternative for efficient propagation, demanding an optimized culture medium for desirable proliferation. Efficient proliferation of newly introduced plant species in tissue culture often necessitates meticulous experimentation with varying salt compositions to optimize mineral concentrations and growth regulator levels within the culture medium. This study aimed to employ Response Surface Methods (RSM) to assess the effects of different mineral combinations, including nitrogen (N), calcium (Ca), potassium (K), and phosphorus (P), along with a cytokinin (zeatin), on the shoot proliferation and growth of little-leaf mockorange in tissue culture. Forty-six treatment combinations were designed, with zeatin concentrations of 0.82, 1.095, or 1.37 µM, and varying levels of N (22.5, 30, or 37.5 mM), Ca (1.125, 1.5, or 1.88 mM), P (0.31, 0.625, or 0.94 mM), and K (5, 10, or 15 mM). These treatments were evaluated for their impact on axillary shoot formation, shoot length, and shoot dry weight. Response surface analyses revealed optimal concentrations of N (32.5 to 35 mM), Ca (1.5 mM), and P (0.625 mM), while the influence of potassium on responses was found to be nonsignificant in the regression models, hence, K concentrations were limited to linear trends in the analysis. Notably, medium supplemented with 1.1 µM zeatin demonstrated a significant positive impact on shoot proliferation. The RSM model demonstrated the feasibility of determining optimal concentrations of zeatin, N, Ca, and P in a single experiment, facilitating the in vitro growth of little-leaf mockorange shoots. This study underscores the efficacy of RSM in tissue culture experiments, offering a time- and cost-effective alternative to conducting multiple separate experiments and providing valuable insights into medium optimization. Such findings contribute to the advancement of tissue culture techniques, particularly in propagating native plant species critical for landscape sustainability.

Chemical fertilizers are key to enhancing tomato productivity, yet their excessive or imbalanced use can lead to higher costs, energy inefficiency, and negative environmental impacts. Recent advancements in nano fertilization seek to optimize nutrient use, minimize losses, and improve farm economics and environmental sustainability. Additionally, salicylic acid (SA) as a chemical inducer has shown potential to boost crop yields by enhancing stress tolerance in plants. Our research evaluated the effects of various rates of nano NPK fertilization combined with SA chemigation on the efficiency and sustainability of processing tomatoes (Solanum Lycopersicum L., cv. BHN 685) production in a drip-irrigated plasticulture system. Conducted over the 2022 and 2023 growing seasons, this two-factorial experiment tested nano NPK rates (0, 40, 80, 120 kg/ha) and SA levels (0 vs. 0.3%), using conventional NPK fertilizers as the control. The results showed that tomato yields were significantly influenced by SA chemigation, nano NPK fertilization, and the growing year, without interactive effects between and among these factors. SA chemigation with 120 kg NPK/ha increased yields by 9% compared to the control. Yields were similar between the 120 kg/ha SA chemigation and 120 kg/ha nano NPK treatments but were significantly higher (by 21%) under the 120 kg nano NPK with SA chemigation, suggesting effective synergy between SA and nano fertilization. SA chemigation and NPK fertilization reduced cull fruit yields, with nano NPK showing the most substantial reduction. Production costs were slightly higher for the combination of SA chemigation and nano NPK ($7,114/ha), but profitability was significantly increased, peaking at $2,487/ha in this treatment. Energy use efficiency also increased from 42.3% in the control (120 kg NPK/ha) to 51.1% with the combined treatment (120 kg nano NPK/ha with SA chemigation), and specific energy use per unit of tomato was decreased from 1.9 MJ/kg to 1.6 MJ/kg. Greenhouse gas emissions per ton of tomato were reduced from 46.3 kg CO2 equivalent/ha in the control to 42.7 kg/ha with combined nano NPK and SA chemigation. In conclusion, nano NPK fertilization coupled with SA chemigation proves to be an effective strategy for enhancing the efficiency and sustainability of processing tomato production, improving yield, profitability, and environmental outcomes.

Tomato stands out as a premier high-value specialty crop globally. However, the inefficiency of conventional fertilizers in nutrient utilization necessitates excessive fertilization to maintain tomato yields, which adversely impacts fruit quality. Nanotechnology, aimed at precise nutrient management to enhance efficiency and economic viability in farming, is gaining attention in agriculture. Similarly, salicylic acid (SA) has emerged as a potential chemical inducer to enhance plant metabolic activities, stress tolerance, and crop yield in the face of climate change. Our two-year field study aimed to assess the impact of varying rates of nano NPK fertilization and SA chemigation on the phytochemical properties, nutritional quality, and fruit attributes of processing tomatoes (Solanum Lycopersicum L., cv. BHN685), relative to conventional fertilization. Employing a two-factorial drip-irrigated plasticulture setup in a completely randomized design, we tested four levels of nano NPK (0, 40, 80, and 120 kg/ha) and two levels of SA (0 vs. 0.3%), each replicated four times. Results showed that tomato fruits subjected to SA chemigation with nano-NPK fertilization exhibited a significant increase in concentration of phytochemicals. Notably, vitamin-A, vitamin-C, lycopene, β-carotene, polyphenol, flavonoid, anthocyanin, and antioxidant capacity displayed substantial increases ranging from 2.5% to 51.2% compared to the control. Particularly noteworthy were the remarkable enhancements in flavonoid and anthocyanin concentrations, registering at 50% and 51.2%, respectively. Conversely, application of nano NPK alone led to discernible increases solely in flavonoid and anthocyanin concentrations, accompanied by decreases in other phytochemicals. Further analysis underscored the synergistic benefits of SA and nano-NPK, resulting in superior color, taste, and phytochemical richness of tomato fruits. K-means cluster analysis corroborated the efficacy of the SA with nano NPK (120 kg/ha) treatment in eliciting optimal fruit characteristics. Moreover, quality assessment revealed the superiority of the SA nano-NPK (120 kg/ha) treatment, with a quality index of 0.61 compared to the control's 0.47, indicative of its superior attributes. Additionally, the nutritional quality index demonstrated a gradual increase in nutrient enrichment across treatments, with the SA and nano NPK (120 kg/ha) combination yielding the highest score. In conclusion, our study highlights the pivotal role of SA in conjunction with nano NPK (120 kg/ha) in enhancing tomato phytochemical content and overall fruit quality. These findings bear significant implications for optimizing horticultural practices and promoting sustainable food production endeavors.

Lack of water holding and cation exchange capacity severely limit fertilizer application methods for new palm tree transplants in sandy soils in S. Florida. Typically, palm trees are fertilized using an 8-2-12 4 granular fertilizer but with little rooting to enhance fertilizer capture and no soil solution to improve nutrient uptake, establishment may be slow. Alternative fertilizers, including palm tree injection, were evaluated to determine the best method to improve palm tree establishment under these conditions. A research trial was conducted using Christmas Palms (Adonidia merrillii) that were established on sandy soils with less than 2% organic matter. After planting, palms were not fertilized for six months. Palm trees were treated with the following fertilizers: 1) 8-2-12 4 (PS), 2) 0-0-22 4(KM) 3) PHOSPHO-jet PALM-jet injection (PJ) 4) PHOSPHO-jet PALM-jet apical meristem drench (AM) and 6) “Gator Grip” (GG) fertilizer pouch directed at the apical meristem. Visual quality and drone imagery were used to assess palm health. Volumetric water content (VWC) was determined at three different depths and root growth was captured using a mini-rhizotron. Six months after the initial treatment application, treatment differences were not visually apparent and VWC was below 10% for the majority of measurements captured at all depths. Rooting data at this stage was minimal. Palm trees may grow very slowly and under these environmental conditions, it may take the palm over a year to replace an entire crown. Therefore, yearly updates will be presented for this three-year trial to best determine which treatment provides the best solution to establish transplanted palms in the landscape and maintain palm health.