Baby Leaf Research Articles

The use of UV-A radiation for biofortification of lettuce and basil plants with antioxidant phenolic and flavonoid compounds

Stable plant production is a crucial concern of modern agriculture facing increasing food demands and the risk of less predictable weather conditions in the open field. Alternative approaches for plant production are greenhouses and indoor farming. Modern LED-based artificial lighting indoor facilities allow not only to fill the gap in the supply chain of food production, but to produce plants characterized with higher concentration of essential phytochemicals. Thus, in this study, we attempt to analyse the efficiency of short-term supplementation of spectrum within ultraviolet A light (UV-A, 365 nm) to increase the antioxidant potential of leafy plants, assessed by total phenolic (TPC) and flavonoid (TFC) content. To this end, two distinct cultivars of baby leaf lettuce (Lactuca sativa var. crispa L.) and microgreens basil (Ocimum basilicum L.) plants were grown under red-green-blue spectrum supplemented prior to harvest with low doses of UV-A radiation. Analyses showed that UV-A exposition enhanced TPC and TFC with green leaf cultivars, compared to dark-pigmented ones. The analysis also proved that plants exposed to UV-A presented higher overall antioxidant potential measured with 1,1-diphenyl-2-picrylhydrazil (DPPH). Results are crucial for better understanding the potential of UV-A supplementation to produce functional plants which are natural sources of dietary antioxidants.

An Overview on the Use of Artificial Lighting for Sustainable Lettuce and Microgreens Production in an Indoor Vertical Farming System

With the global population projected to reach 8.6 billion by 2050 and urbanization on the rise, sustainable food production in cities becomes imperative. Vertical farming presents a promising solution to meet this challenge by utilizing space-efficient, controlled-environment agriculture techniques. In a vertical farming system, high quality, high nutritional value products can be produced with minimum water consumption, using LEDs as energy-efficient light sources. Microgreens are a new market category of vegetables among sprouts and baby leaf greens. The most critical challenge in their cultivation is the choice of growing medium, lighting, and light spectrum, which affect photosynthesis, plant growth, and yield. This review explores various cultivation methods, including hydroponics, within the context of vertical farming. Using current research, it investigates the effect of LED lighting on the physiological properties and growth of microgreens and baby leaf lettuce, but further research is needed to determine the response of the varieties and the optimal light spectrum ratios to meet their needs.

Greenhouse production of baby leaf vegetables using rainbow trout wastewater in a high-tech vertical decoupled aquaponic system

IntroductionAquaponics is an integrated food production system that links recirculating aquaculture with hydroponics, leading to higher water use efficiency than conventional food production systems while also saving on fertilizers. In the present study, baby lettuce and baby rocket plants cultivated hydroponically in a deep water culture system using wastewater from rainbow trout were evaluated as part of a vertical decoupled aquaponic system.Materials and methodsMore specifically, three different nutrient solutions were supplied: a) using fish wastewater only (designated as Fish); b) fish wastewater enriched with synthetic fertilizers (Mix); and c) a typical nutrient solution (Hoagland) as the control. Both lettuce and rocket plants were monitored in these nutrient solutions and in two different substrates, peat and perlite, as an organic and an inert substrate, respectively. The purpose of this study was to assess a vertical decoupled aquaponic system with regard to the resource use efficiency, such as water, land, and energy, while evaluating plant cultivation in the different treatments in terms of yield, growth, nitrate concentration on the leaf tissue, and foliar analysis. The photosynthetic rate and leaf color indices were also considered in the plant evaluation.ResultsThe Mix–Peat treatment was the most efficient growing combination in terms of land and water use efficiency, with approximately 7% better land use efficiency while using 38% less water and 10% less fertilizer than Hoagland–Peat. Moreover, lettuce plants had the highest yield in the Mix–Peat treatment, at 2,497 g m−2, which was approximately 6% higher than that of Hoagland–Peat while not being inferior in the quality measures. On the other hand, the yield of rocket was significantly higher in the Hoagland–Peat treatment, being 18% higher than that of Mix–Peat and 30% higher than that of Fish–Peat. Overall, the study confirmed that aquaponic systems could lead to higher water use efficiency and savings in fertilizers without undermining the yield and quality of lettuce, while the vertical arrangement developed within the scope of this study can increase the land useefficiency of the system.

Zinc and iron biofortification of crops grown in a vertical farm

With the growing global population and climate change, achieving food security is a pressing challenge(1). Vertical farming has the potential to support local food production and security. In the UK population females and younger adults appear to be particularly vulnerable to micronutrient shortfalls from food sources alone. Levels of micronutrient intakes including zinc and iron are below the recommended daily intake(2). As a Total Controlled Environment Agriculture (TCEA) system, vertical farming employs hydroponics using a nutrient solution which offers opportunities to modulate nutrient uptake, and thus influence plant mineral and vitamin composition(3).In this study we aimed to determine the suitability of different crop types for soilless agronomic biofortification with zinc and iron to achieve biofortified crops.In this study, we investigated the effect of the addition of 20ppm (+20 mg L−1) of zinc (ZnSO4) or iron (Fe-EDTA) to the nutrient solution on the growth and nutritional components in pea microgreens, kale microgreens and kale baby leaf plants. The growth conditions were kept identical throughout the treatments with photoperiod 18 h d-1, temperature 20-22°C and relative humidity at 70-80%. Plant growth, mineral composition, glucosinolate content and protein content were evaluated. Results were analysed using ANOVA (p<0.05, Tukey’s test).It was determined that higher amounts of zinc in the nutrient solution resulted in significantly higher levels of zinc in all three crops (p<0.05), with increases of 205% in pea microgreens, 264% in babyleaf kale and 217% in kale microgreens compared to the control plants. Higher amounts of iron in the nutrient solution resulted in significantly higher levels of iron only in pea microgreens, with an increase of 38% (p<0.05). Neither dosing regimen negatively influenced the overall crop performance.These results suggest that the three different crops are suitable for soilless biofortification with zinc and iron, although pea microgreens were the only crop that had a significant increase in iron upon iron-dosing.

Effects of the Mixed Seeding Rate of Milkvetch on Fertilizer Substrate, Growth, and Carotenoid Levels of Baby Leaf Vegetables in Vertical Indoor Farming

During this study, an indoor experiment was conducted to determine the effect of mixed seeding rates of legumes used as green manure on the substrate fertilizer, growth characteristics, and bioactive compounds of baby leaf vegetables. The mixed seeding treatment was designed for milkvetch (Astragalus sinicus L.), tatsoi (Barassica rapa L.), kale (Brassica oleracea var. sabellica L.), and spinach (Spinacia oleracea L.) using five rates for each. Accordingly, a total of 15 treatments (3 baby leaf species × 5 mixed seeding rates) were constructed using a randomized complete block design with three replications for each treatment. During the baby leaf vegetable harvest, we evaluated the macronutrient levels (nitrogen, phosphorus, and potassium) in the substrate as well as the growth parameters and carotenoid contents. The substrate in the treatment mixed with milkvetch showed significantly higher levels of nitrogen, phosphorus, and potassium compared with those of tatsoi and kale sown alone (P ≤ 0.05). However, there were no significant differences in macronutrients observed in substrate-sown spinach with or without the milkvetch mixture. The growth and carotenoid levels of each baby leafy vegetable sown alone were significantly higher than those of each baby leafy vegetable sown with the mixed seeding treatment (P ≤ 0.05). Sowing the milkvetch–vegetable mixtures did not result in a significant increase in the growth and carotenoid levels of the three baby vegetables. The results showed that planting milkvetch with tatsoi and kale had a significant impact on substrate fertilization. However, regarding short-term vertical indoor farming, the growth and carotenoid responses of the three greens may be different. Nonetheless, we still believe that the combined interactions of legumes can provide long-term benefits by enhancing the biological functionality of the growing medium for balanced indoor agriculture production.

Modification of the existing maximum residue levels in various plant commodities resulting from the use of potassium phosphonates.

In accordance with Article 6 of Regulation (EC) No 396/2005, the applicants De Sangosse SAS and Tilco-Alginure submitted two requests, respectively, to the competent national authorities in France and Germany to modify the existing maximum residue levels (MRLs) for the active substance potassium phosphonates in various plant commodities. The data submitted in support of the requests were found to be sufficient to derive MRL proposals for the commodities under assessment. For the derived MRL on baby leaf crops, further risk manager consideration is required to decide between two MRL options. Adequate analytical methods for enforcement are available to control the residues of potassium phosphonates in accordance with the residue definition 'phosphonic acid and its salts expressed as phosphonic acid' in the commodities under consideration. Based on the risk assessment results and assuming that the existing MRLs will be amended as proposed by EFSA in previous outputs, EFSA concluded that the long-term intake of residues resulting from the existing uses of fosetyl and phosphonates (previously assessed in a joint MRL review) and new proposed uses of potassium phosphonates is unlikely to present a risk to consumer health. Considering the toxicological profile of the active substance, a short-term dietary risk assessment was not required. The risk assessment shall be regarded as indicative because some MRL proposals derived by EFSA in the framework of the MRL review according to Articles 12 and 43 of Regulation (EC) No 396/2005 require further consideration by risk managers.

Assessing Contents of Sugars, Vitamins, and Nutrients in Baby Leaf Lettuce from Hyperspectral Data with Machine Learning Models

Lettuce (Lactuca sativa) is a leafy vegetable that provides a valuable source of phytonutrients for a healthy human diet. The assessment of plant growth and composition is vital for determining crop yield and overall quality; however, classical laboratory analyses are slow and costly. Therefore, new, less expensive, more rapid, and non-destructive approaches are being developed, including those based on (hyper)spectral reflectance. Additionally, it is important to determine how plant phenotypes respond to fertilizer treatments and whether these differences in response can be detected from analyses of hyperspectral image data. In the current study, we demonstrate the suitability of hyperspectral imaging in combination with machine learning models to estimate the content of chlorophyll (SPAD), anthocyanins (ACI), glucose, fructose, sucrose, vitamin C, β-carotene, nitrogen (N), phosphorus (P), potassium (K), dry matter content, and plant fresh weight. Five classification and regression machine learning models were implemented, showing high accuracy in classifying the lettuces based on the applied fertilizers treatments and estimating nutrient concentrations. To reduce the input (predictor data, i.e., hyperspectral data) dimension, 13 principal components were identified and applied in the models. The implemented artificial neural network models of the machine learning algorithm demonstrated high accuracy (r = 0.85 to 0.99) in estimating fresh leaf weight, and the contents of chlorophyll, anthocyanins, N, P, K, and β-carotene. The four applied classification models of machine learning demonstrated 100% accuracy in classifying the studied baby leaf lettuces by phenotype when specific fertilizer treatments were applied.

Effect of Far-Red Light on Biomass Accumulation, Plant Morphology, and Phytonutrient Composition of Ruby Streaks Mustard at Microgreen, Baby Leaf, and Flowering Stages.

Far-red (FR) light influences plant development significantly through shade avoidance response and photosynthetic modulation, but there is limited knowledge on how FR treatments influence the growth and nutrition of vegetables at different maturity stages in controlled environment agriculture (CEA). Here, we comprehensively investigated the impacts of FR on the yield, morphology, and phytonutrients of ruby streaks mustard (RS) at microgreen, baby leaf, and flowering stages. Treatments including white control, white with supplementary FR, white followed by singularly applied FR, and enhanced white (WE) matching the extended daily light integral (eDLI) of FR were designed for separating the effects of light intensity and quality. Results showed that singular and supplemental FR affected plant development and nutrition similarly throughout the growth cycle, with light intensity and quality playing varying roles at different stages. Specifically, FR did not affect the fresh and dry weight of microgreens but increased those values for baby leaves, although not as effectively as WE. Meanwhile, FR caused significant morphological change and accelerated the development of leaves, flowers, and seedpods more dramatically than WE. With regard to phytonutrients, light treatments affected the metabolomic profiles for baby leaves more dramatically than microgreens and flowers. FR decreased the glucosinolate and anthocyanin contents in microgreens and baby leaves, while WE increased the contents of those compounds in baby leaves. This study illustrates the complex impacts of FR on RS and provides valuable information for selecting optimal lighting conditions in CEA.

Innovative Cultivation Practices for Reducing Nitrate Content in Baby Leaf Lettuce Grown in a Vertical Farm

The aim of this research is to introduce innovative cultivation practices that result in reduced nitrate levels in baby leaf lettuce grown under vertical farming conditions while maintaining high productivity. For this reason, three experiments were conducted. The first experiment focused on the impact of two “white” light spectra with a blue:green:red:far-red ratio of 14:32:43:10 (BlowRhigh) and 21:34:36:7 (BhighRlow). The second experiment assessed the effects of two nitrogen supply conditions: sufficient total nitrogen (N15) and limited total nitrogen (N5), and foliar biostimulant application. In the third experiment, the impact of replacing the nutrient solution in the N15 treatment with tap water for an additional 24 h (TW24) on leaf nitrate content was examined. Results from the lighting experiment revealed no significant effects on agronomical parameters or nitrate content between the two light spectra. Reducing nitrogen content in the nutrient solution reduced leaf nitrate content but negatively influenced agronomical characteristics. Biostimulant application and replacing the nutrient solution with water reduced leaf nitrate content compared to the control and positively affected growth. The most favorable outcomes were observed in plants supplied with sufficient nitrogen and foliar biostimulant but also cultivated for an additional 24 h with tap water (Sp-N15-TW24).

Effects of Anaerobic Soil Disinfestation for Soilborne Disease and Weed Management on Baby Leaf Lettuce Performance in a High Tunnel Organic Production System

The use of high tunnels, which allows growers to extend their season and improve yields, is increasing in the Southeastern U.S., yet growers face challenges related to weed and disease management, particularly in organic systems. On-station experiments were conducted during fall 2021 and spring 2022 in a split-plot design to assess the efficacy of anaerobic soil disinfestation (ASD) in high tunnels for the organic production of direct-seeded baby leaf lettuce. Soil treatments (ASD, Compost, and Control) and lettuce types (romaine and oakleaf cultivars) were included in whole plots and subplots, respectively. The ASD-treated soils received molasses and granular organic fertilizer as carbon and nitrogen sources. The Compost treatment involved the application of yard waste-based compost and the same organic fertilizer, while the Control soils received organic fertilizer only. The ASD treatment period lasted 8 days rather than the typical 21-day period evaluated in Florida. Crop yield, biometrics (leafy dry matter content, specific leaf area, specific leaf weight), and lettuce quality attributes (leaf color, soluble solids content, total titratable acidity, ferric reducing antioxidant power, ascorbic acid content, total phenolics) were assessed following harvest. In both trials, numerical differences in lettuce fresh weight yield between soil treatments were evident, though not statistically significant. Differences in leaf quality attributes were driven by lettuce cultivar rather than soil treatments. Bottom rot incidence caused by Rhizoctonia solani was reduced by 93% and 87% in the ASD-treated plots compared with the Compost- and Control-treated soils during the spring 2022 trial. The ASD-treated soils had a reduced population density of broadleaf weeds in both baby leaf lettuce production trials. The current study presents novel evidence of the potential of integrating ASD into HT organic production systems without reducing the yield and quality attributes of direct-seeded baby leafy greens compared with common grower practices.

Effect of Compost from Cardoon Biomass, as Partial Replacement of Peat, on the Production and Quality of Baby Leaf Lettuce

The use of peat, the standard substrate used for soilless cultivation of horticultural crops, is becoming of increasing concern as peat is a non-renewable resource and its extraction can degrade wetland ecosystems, creating a strong environmental impact. For this reason, the search for organic materials that can totally or partially replace peat has become increasingly important. In this research, three types of composts (C1, C2, C3), derived from cardoon biomass mixed in different volumes with woody and/or fruit wastes, were utilized as the constituents of growing media, at two dilution rates with peat (60:40 and 30:70 v:v), to assess their effect on the growth and quality of baby leaf lettuce in a greenhouse trial. The two cultivars Imperiale and Verde d’Inverno, belonging to the butterhead and romaine lettuce types, respectively, were employed. Plant performance and yield were unaffected or were positively affected by compost-containing growing medium compared to the control. The cultivars responded differently to the growing medium; the Imperiale showed the highest yield with C1 compost at a 60% rate while the Verde d’Inverno with the C2 was at 30%. The total chlorophyll, carotenoids, and ascorbic acid were found higher in the Verde d’Inverno than in the Imperiale variety while the total polyphenols, flavonoids, and antioxidant activity were lower. Also, the content of chlorophylls as well as of antioxidant compounds and antioxidant activity were differently affected by the growing medium, depending on the lettuce cultivar. The results obtained indicate that cultivated cardoon waste-based compost is a promising constituent of the growing media for baby leaf production. The specific varietal response observed should be considered to optimize both yield and product quality.

Rain splash-mediated dispersal of Escherichia coli from fecal deposits to field-grown lettuce in the mid- and south Atlantic U.S. regions is affected by mulch type.

Wildlife feces can contaminate vegetables when enteric bacteria are released by rain and splashed onto crops. Regulations require growers to identify and not harvest produce that is likely contaminated, but U.S. federal standards do not define dimensions for no-harvest zones. Moreover, mulching, used to retain soil moisture and maximize crop yield may impact rain-mediated bacterial dispersal from feces. To assess Escherichia coli dissemination from a fecal point source to lettuce grown on various mulches, lettuce cv. 'Magenta' was transplanted into raised beds with plastic, biodegradable plastic, straw, or left uncovered at field sites in Maryland and Georgia. Eleven days post-transplant, 10g of rabbit manure spiked with ~8 log CFU g-1 E. coli were deposited in each bed. One day following natural or simulated rain events, lettuce was sampled along 1.5m transects on either side of fecal deposits. Lettuce-associated E. coli was semi-quantified with an MPN assay and dependence on fecal age (stale or fresh), lettuce age (baby leaf or mature head), distance from point source, mulch and post-rain days were statistically evaluated. Distance (p<0.001), fecal age (p<0.001) and mulch (p<0.01) were factors for E. coli transfer from point source to lettuce. The highest and lowest E. coli estimates were measured from lettuce grown on biodegradable plastic and straw, respectively, with a 2-log MPN difference (p<0.001). Mulch and distance were also significant factors in E. coli recovery 3 days post-rain (both p<0.001), where plastic mulches differed from bare ground and straw (p<0.01). For all treatments, fewer E. coli were retrieved from lettuce at 0.3m, 3 days post-rain compared to 1 day (p<0.001). Fitting the data to a Weibull Model predicated that a 7-log reduction in E. coli from fecal levels would be achieved at 1.2-1.4m from the point source on plastic mulches, 0.75m on bare soil (p<0.05) and 0.43m on straw (p<0.01). Straw and bare ground limited rain-mediated E. coli dispersal from feces to lettuce compared to plastic mulches. Fecal age was negatively associated with E. coli dispersal. These findings can inform harvesting recommendations for measures related to animal intrusion in vegetable production areas.

Optimising Sowing Density for Microgreens Production in Rapini, Kale and Cress

Microgreens represent a valuable agrifoods niche. Their cropping cycle is shorter than that of baby leaf greens, but the sowing density is typically much higher, and this has important cost implications for the grower. The current research demonstrates that the choice of sowing density strongly influences yield, as well as developmental stage and other quality parameters. Results also depended on the choice of the species and landrace. Considering the cost of seed, the option of accessing locally available landraces becomes particularly intriguing, again with relevant implications in choosing seed density. Rapini (landraces Cima grande and Fasanese), kale (landraces Barese and Altamura), and commercial cress were grown in an indoor environment. The effects of the three sowing densities (from 3 to 5 seeds∙cm−2) and the growing cycle (earlier harvest, 11 days from sowing, or later harvest, 14 days from sowing) on the microgreen yield and quality were studied. Sowing density affected yield (+19% at highest vs. lowest density), dry matter (but only with a longer cycle, and variable by landrace, with Fasanese rapini landrace 7% more than the Cima grande landrace), developmental stage, and soil coverage. The effects of sowing density can be modulated by cycle duration. Crop heights were 25% and 44% greater for the longer cycle of the Cima grande and Fasanese rapini landraces, respectively. In conclusion, the choices of the species/landrace and seed density must be carefully evaluated given costs and outcomes, with potential for the production of different final products (e.g., microgreens at earlier or later stages, other characteristics) and also for control over costs.

Life cycle assessment of baby leaf spinach: Reduction of waste through interventions in growing treatments and packaging

Salad vegetables are an important dietary nutrient source, but are prone to spoilage, and actions to reduce waste are being explored and assessed. The Leaf No Waste project aims to reduce food and packaging waste in Ireland, by extending the shelf life of leafy vegetables through growing treatments and packaging choices. This LCA study assessed environmental impacts of a silicon foliar treatment and packaging choices - Oriented Polypropylene (OPP) and Polylactide Acid (PLA) for baby leaf spinach, focussing on climate change, terrestrial acidification, freshwater eutrophication, fossil resource scarcity, and water use. The production of spinach, storage, packaging, retail, and waste management of the spinach supply chain are included in the system boundary, for 1 kg packed baby leaf spinach. The results illustrate that the silicon foliar treatment reduces waste, and LCA of the silicon foliar treatment for baby leaf spinach in OPP packaging under 3-day shelf life demonstrates limited effects on climate change (323 vs 321 g CO2-eq/kg), freshwater eutrophication (21.4 vs 20.9 mg P-eq/kg), and water use (10.2 vs 10 L/kg), increased impact on fossil resource scarcity (98.6 vs 91.4 g oil-eq/kg) and lowers impact on terrestrial acidification (3573 vs 3997 mg SO2-eq/kg). PLA packaging has a greater impact than OPP packaging in all impact categories, except fossil resource scarcity. The 7-day shelf life causes more impacts than the 3-day shelf life, except for the scenario with PLA packaging in the impact category of fossil resource scarcity. The results of this study identify environmental hotspots of an Irish spinach supply chain and are preliminary evidence to support actions to reduce waste in fresh leaf spinach supply chains from packaging to retail.

Unveiling the impact of antimicrobial-infused water on hydroponic baby leafy vegetables (lettuce, rocket, and watercress): Physiological effects and food safety

The uptake of antimicrobials by vegetables can reduce plant production and compromise food safety, as these compounds can disrupt plant physiology and accumulate in plant tissues. In this study, we investigated the effects of environmentally representative concentrations of ciprofloxacin (CIP, 1.5 µg L−1), erythromycin (ERY, 1.5 µg L−1), and/or sulfamethoxazole (SULFA, 0.3 µg L−1) on the physiology (growth and oxidative stress markers), nutraceutical characteristics (mineral composition and total phenolic content), and antimicrobial accumulation in hydroponically grown baby leaf lettuce, rocket, and watercress plants. Only watercress exhibited disrupted shoot growth. Furthermore, increased concentrations of total phenolic compounds were observed in rocket plants when exposed to the antimicrobials. The drugs also significantly impacted on mineral nutrition, altering the mineral-recommended daily intake (RDI) of all plants, with rockets and watercress being the most affected. Additionally, higher human health risks were observed in plants exposed to CIP, particularly concerning children. The presence of CIP in the growing water of hydroponic vegetables poses a notable risk to food safety due to the plant's ability to accumulate the drug in its edible parts. Moreover, beyond the adverse effects on human health, using antimicrobial-contaminated water in vegetable cultivation can also disrupt watercress production, leading to significant economic losses.

Productivity of baby leaf lettuce cultivars (Lactuca sativa (L.)) in different photoperiods in indoor hydroponic cultivation

Innovation in agriculture caused by 4.0 technologies has allowed significant advances in the way of production, in the quality of the final product and in sustainability. Thus, the objective of this work was to evaluate the effect of photoperiod on different lettuce cultivars in indoor hydroponic cultivation with artificial lighting for the production of baby leaves. For this, the lettuce cultivars BSAC0055, BSAC0155 and BSAL0071 were evaluated in an NFT hydroponic system, under a photoperiod of 14,16,18 and 20 hours with photosynthetically active radiation of 248 µmol m-2 s-1. The effects of the cultivar x photoperiod interaction were significant, with cultivars behaving differently for each photoperiod and vice versa. The BSAC0055 cultivar, regardless of the photoperiod, was superior to the others and adapted to indoor cultivation. For cultivars BSAC0055 and BSAC0155, the photoperiod was significant with a quadratic effect for the number of hours/day close to 16 hours and 45 minutes. It is concluded that cultivars have different management and it is possible to select specific cultivars for indoor production; cultivars respond differentially to photoperiods.

Effect of Different Substrates and Protected Environments on Growth, Chlorophyll, and Carotenoid Contents of Kale Microgreens and Baby Leaf

Effect of Different Substrates and Protected Environments on Growth, Chlorophyll, and Carotenoid Contents of Kale Microgreens and Baby Leaf

Assessing baby leaf kale (Brassica oleracea) waste production mitigation in the transition to sustainable packaging with the application of silicon through an integrative model of quality

This research builds a mathematical modelling to assess food waste production when designing sustainable packaging solutions integrated with an agricultural intervention in kale production. The model utilizes experimental data obtained from simulated retail and distribution storage conditions to assess the probability of the product to be found out of technical specification and becoming waste. The packaging design was made using a system of differential equations describing the gas exchanges inside the packaging. The waste was estimated fitting linear mixed effect models to the postharvest experimental data, accounting for the variability between and within groups. A field experiment with kale treated with silicon during growth as a bio stimulant was used with the aim to make the product more resilient to packaging conditions. The Kale was then packaged in polylactic acid and oriented polypropylene for postharvest testing. Technological thresholds that indicate out-of-specification product were used to estimate the percentage of product that would likely end up as food waste. In total 7.2% of the product was found to be out of specification with the PLA film after 7 days. Silicon treatment was able to reduce this value to negligible, demonstrating the ability of agricultural interventions to facilitate sustainable packaging and reducing food waste in horticultural products.

Evaluation of Spinach Cultivars for Resistance to Stemphylium Leaf Spot (Stemphylium vesicarium) and White Rust (Albugo occidentalis)

Stemphylium leaf spot, caused by Stemphylium vesicarium, and white rust, caused by Albugo occidentalis, can cause significant losses in spinach production. Management of these foliar diseases of spinach has become increasingly challenging with the development of fungicide resistance in some pathogen populations, high planting density and overhead irrigation used for baby leaf spinach production, and the fact that &gt;60% of fresh market spinach production in the United States is certified organic. To identify spinach cultivars with resistance to Stemphylium leaf spot and white rust, a field trial was performed near Crystal City, TX, USA, in 2021 (79 cultivars), 2022 (87 cultivars), and 2023 (63 cultivars). Each year, the plants were inoculated with S. vesicarium and rated for disease severity. Plants were also rated for white rust severity that resulted from natural infection during the 2021 and the 2022 trials. During each trial, 11% to 27% of the cultivars were identified as resistant to Stemphylium leaf spot, and another 29% to 48% had moderately resistant reactions. In contrast, only 5 of 79 cultivars (6%) in the 2021 trial did not develop symptoms of white rust, and all 87 cultivars evaluated in the 2022 trial had symptoms of white rust. Although there was no significant correlation between mean Stemphylium leaf spot ratings and mean white rust ratings during these trials, the cultivars Colusa, Kodiak, PV-1569, and PV-1664 displayed resistant or moderately resistant responses to both diseases in at least two trials. Therefore, processing and fresh market spinach growers have resistant cultivars from which to select to reduce the economic impacts of Stemphylium leaf spot and white rust.

Influence of Soil and Nutrient Management Practices on Crop Productivity and Quality in High Tunnel Organic Leafy Green Production

Despite the growing interest in high tunnel organic vegetable production, limited information is available regarding optimizing nutrient management for organic leafy greens. This 3-year study examined the impacts of cowpea cover crop as well as different organic fertilizers and composts on yield, leaf mineral nutrient content, and phytochemical properties of organic leafy greens produced in high tunnels under Florida sandy soil conditions. The experiment was arranged in a split-split-plot design with three replications. The whole plots consisted of a cowpea (Vigna unguiculata ‘Iron &amp; Clay’) cover crop and a weedy fallow control, with fertilization treatments in the subplots, including preplant application of granular fertilizer vs. weekly injection of liquid fish fertilizer at the same seasonal rates of nitrogen (112 kg/ha), phosphorus (9.8 kg/ha), and potassium (74.4 kg/ha). The sub-subplots included yard waste-based compost (22.4 Mt/ha), cow manure-based compost (22.4 Mt/ha), vermicompost (5.6 Mt/ha), and no compost control. Cowpea was broadcasted (112 kg/ha) in early July or mid-August and terminated 51 to 53 days after seeding. Pac choi (Brassica rapa var. chinensis ‘Mei Qing Choi’) was transplanted in mid-Sep. or mid-Oct. and harvested after 33 to 36 days. Baby spinach (Spinacia oleracea ‘Corvair’) or baby leaf lettuce (Lactuca sativa ‘Outredgeous’) was direct seeded subsequently as a catch crop. Each experimental unit remained in the same location across the 3 years of the study. Cover cropping had little influence on yields, leaf mineral nutrients, ascorbic acid content, total phenolics, and total antioxidant capacity of pac choi and baby spinach/lettuce. Compared with preplant application of the granular organic fertilizer, weekly liquid organic fertigation improved pac choi marketable yield and dry weight by 16.8% and 5.4% on average, respectively, and enhanced leaf nitrogen and phosphorus contents on a dry weight basis. Relative to the no compost control, yard waste compost consistently improved marketable yields of pac choi by 11.6% on average and led to higher yields of the baby spinach/lettuce catch crop in years 1 and 3, suggesting that compost applications may enhance seasonal nutrient availability to better meet crop demand. However, compost application exhibited inconsistent effects on crop mineral nutrient and phytochemical contents across the years, which could be attributed to the different nutrient compositions of the composts applied in each season, as well as the legacy effects from the previous season. Furthermore, the compost benefits may be influenced by the fertilization program as indicated by their interaction effects observed in this study.