Tomatoes are a highly prized crop all over the U.S, but consumers are seeking more flavorful and high-quality produce. Tomatoes are also popular with growers and consumers in colder regions as well. Short and cold growing seasons provide a significant challenge to tomato production while most breeding and research on tomatoes has been done in warmer climates. In an effort to provide research relevant to growers and breeders in colder regions, this project conducts a germplasm screening of over 80 heart-shaped, indeterminate tomato varieties, many of which were bred in colder regions, in order to provide information on specialty, open-pollinated tomatoes that may be better suited for a shorter season. These tomatoes are characterized by their large size, heart-shape, fleshiness, and fewer seeds. Varieties were obtained from a number of seed catalogs as well as from the USDA Germplasm Repository. In the first year of the project, the varieties were screened for yield, earliness and fruit size measurements as well as dry matter, Brix, pH, and titratable acidity. Genotypes were planted in an augmented design and managed organically in an unheated high tunnel. Based on this year of data, some of the high yielding varieties with the mentioned satisfactory quality traits included ‘German Red Strawberry’, ‘Cuore di Toro’, ‘Russian 117’, ‘Upstate Oxheart’, and a GRIN variety ‘G32329’. None of the varieties exceeded acceptable levels of acidity, but there was much variability in both yield and Brix within the experiment. We also found that a number of varieties categorized as “heart-shaped” were not morphologically heart-shaped. This experiment will be conducted over another growing season in order to collect further data and insights on this project.
Strawberry (Fragaria × ananassa) production has grown significantly in recent decades, increasing demand for specialty crops. Despite improvements in management practices and breeding, maintaining soil health and minimizing environmental impact remain a challenge for agricultural systems. Biochar production and application have been proposed as one effective strategy to mitigate climate change, improve soil health, and promote plant growth. This study, done at the University of Maryland Eastern Shore (Princess Anne, MD), investigated the effect of biochar on the growth and root associated microbial communities of two selected day-neutral strawberries, Monterey and Seascape, under greenhouse conditions. A pot experiment was conducted with three treatments: No biochar (control), 5% biochar, and 10% biochar. Growth parameters including plant height, number of leaves, number of flowers, runner production, and chlorophyll content were measured at 30, 60 and 90 days after transplanting. The 5% biochar treatment enhanced leaf development, runner production, and yield in Monterey, whereas biochar at 10% improved chlorophyll content in both cultivars. The microbial analysis revealed higher Amplicon Sequence Variants (ASVs) with 10% biochar. Cyanobacteria and Proteobacteria were the dominant microbial taxa across all treatments at the phylum level, with no significant differences between biochar treated groups and control. Alpha diversity metrics showed no significant differences (p > 0.05) between treatments, whereas the beta diversity showed a slight shift in microbial community composition in the biochar amendments. A more diverse microbial community was observed in the control group, nevertheless, the biochar amendment demonstrated a more stable and functionally enriched microbiome. These findings contribute to the growing body of knowledge on biochar’s role in optimizing crop production and supporting sustainable farming practices.
As our understanding of the microbiome’s importance to agriculture improves, questions surrounding effective microorganism inoculants as crop treatments continue to arise. These products purportedly increase nutrient bioavailability and enhance plant growth. However, these vary in contents by producer and can be costly, especially given the inconsistent results on their efficacy. Local effective microorganisms (LEM) are alternative formulations produced with local forest litter and carbon sources that can be produced at scale on-site by farmers using local ingredients. LEM application has previously been shown to alter the dynamics of nitrogen availability and soil microbial populations when added to soil amendments, and may influence crop quality and microbial community resilience. However, long-term research on its relevance to organic vegetable rotations is still in its early stages. This project sought to determine the impacts of LEM application on the yield and quality of organic vegetable crops, and to compare soil nitrogen dynamics of these systems to a controlled laboratory incubation. In the field component, a vegetable rotation consisting of kale, carrot, or crimson clover (spring) and green beans (fall) was grown at three different organic farms in the Georgia Piedmont region for two years, and received either a control, low, or high LEM application rate twice per year. Soil samples were taken periodically for inorganic nitrogen, and at harvest total and marketable yields were taken. Subsamples of each harvested plot were juiced and analyzed for sugar content via %Brix. The laboratory incubation was performed on samples obtained from each plot from the field study, which were incubated for 120 days at a standard water content. Each microcosm received either no treatment or an LEM treatment analogous to its respective field plot at time zero. Sulfuric acid traps were used to measure ammonia volatilization, and samples were periodically taken from each microcosm to be analyzed for inorganic nitrogen and pH. At Day 28 of incubation, the average total inorganic nitrogen across treatments was 5.68 ppm. At the end of incubation, the average pH across all treatments was 5.97. The average %Brix for the beans across all locations was 3.5; plants that received high LEM showed higher Brix in plots where crimson clover was the winter crop in two of the three locations, and in plots where kale was the winter crop in one of the locations. These results indicate that LEM may influence produce quality metrics in some common vegetable crops.
Water spinach (Ipomoea aquatica) is classified as a noxious weed by the USDA. However, it remains a popular vegetable in Southeast Asia. Water spinach thrives in warm, moist conditions. Demand for water spinach is increasing in the state of Georgia. The present study assesses the effects of planting date and organic fertilization rate on water spinach yield. The study was conducted in an organically certified high tunnel at the University of Georgia Tifton Campus. Organic fertilizer was applied and incorporated into the soil before planting. Water spinach seedlings were grown in a greenhouse. Within the high tunnel, plants were cultivated on drip-irrigated raised beds (1.8 m apart center to center), covered with white-on-black film mulch. Plants were grown in two rows per bed, with 45 cm between rows and 30 cm between plants. The experimental design was a split-plot arrangement with three replications. The main plots consisted of three planting dates—T1 (16 May), T2 (9 July), and T3 (3 Oct.)—while the subplots included four fertilization rates: 0, 56, 112, and 224 kg/ha of nitrogen (N) applied as organic fertilizer. Plants (shoots) were harvested by cutting 5 cm above the soil surface: four times for T1, three times for T2, and once for T3, with the final harvest conducted on 22 Nov. Shoot fresh weights (FW) were recorded. Results showed that cumulative shoot FW was highest at the earliest planting date (T1; 2.77 kg/m²), followed by T2 (2.36 kg/m²), and lowest at the latest planting date (T3; 0.062 kg/m²). The reduced cumulative shoot fresh weight observed in the latest planting suggests that cooler fall conditions significantly limited plant growth. Regarding the fertilizer rate, the cumulative shoot FW was highest at the 224 kg/ha N fertilization rate (2.03 kg/m²) and lowest at 0 kg/ha N (1.41 kg/m²). However, the relatively high shoot growth at 0 kg/ha N is notable and may indicate the presence of confounding factors. Plants exhibited vigorous shoot and root development, including the formation of adventitious shoots, which likely allowed them to explore soil beyond the experimental plot boundaries (the separation between plots was 30 cm). Visually, plants appeared to grow more actively when provided with ample soil moisture and organic fertilizer. In conclusion, the optimal planting window for water spinach in South Georgia appears to be from April to July. The effect of fertilizer rate on water spinach growth could not be conclusively determined from this study.
Sustainable agricultural practices are essential to mitigating the impact of climate-induced stresses on crop production. Enhancing photosynthetic efficiency is a key strategy to boost yield, productivity, and resilience to stress, especially in organic farming. This study aimed to identify natural variation in leaf photosynthesis and uncover key genetic regulators of physiological and molecular responses in USDA spinach (Spinacia oleracea) germplasm under organic cultivation. 314 USDA organic spinach accessions and commercial checks were planted in an augmented design within an organic field in Uvalde, Texas. Gas exchange traits—including CO2 assimilation rate (A), carboxylation efficiency (CE), CO2 concentration in leaf air spaces (Ci), transpiration (E), CO2 efflux, stomatal conductance (gsw), and water use efficiency (WUEi)—as well as chlorophyll fluorescence metrics such as the efficiency of energy harvesting by oxidized (open) PSII reaction centers (Fv’/Fm’), quantum yield of PSII, electron transport rate, non-photochemical quenching, and photochemical quenching were measured using the LI-6800 portable photosynthesis system. The genome-wide association study (GWAS) was conducted on photosynthesis traits in 299 spinach accessions using 50,873 SNPs. Several SNP markers associated with different traits and candidate genes were identified. Our findings emphasize the value of combining high-throughput photosynthesis measurements with GWAS to reveal the genetic basis of photosynthetic variation in crop species.
Obtaining sufficient nutrients and fighting foliar diseases caused by pathogens such as Alternaria and Cercospora remain an on-going problem for many carrot (Daucus carota) growers. Spraying leaves with mixtures containing soluble nutrient sources and beneficial microbes have potential to help address these issues, but the benefits may depend on the responsiveness of individual carrot genotypes. To test this hypothesis, a field trial was conducted on an organic farm in northern Indiana using three diverse carrot genotypes (Napoli, Nb3999, and Bolero). Each genotype was sprayed with a mixture of four commercial products commonly used by many organic farmers in the area, or left untreated as a control. Soil samples were collected midseason and changes in soil chemical and biological properties were quantified using standard practices. The incidence and severity of foliar diseases was also evaluated visually during the growing season and leaf samples were collected for quantification of leaf microbiomes. At harvest, total shoot and root biomass was determined and carrot taproot samples were collected for analysis of nutritional quality and endophytic microbiomes. Preliminary results indicated that foliar diseases were not particularly problematic during the 2024 growing on this farm. The carrot genotypes varied significantly with respect to above and belowground biomass, however, the treatments did not have any effect on these parameters. There were also no differences in the impact of the foliar sprays on soil parameters, which was expected. We suspect that the lack of any effect of the foliar sprays on carrot biomass was due to the absence of disease pressure at this site, where changes induced in leaf and root microbiomes could have helped mitigate any disease pressure.
Vegetable transplant production is a critical phase that enhances the efficiency, sustainability, and profitability of vegetable cropping systems. In the U.S. Midwest, many organic vegetable growers produce their own transplants due to the limited commercial availability of certified organic transplants. A major constraint in this process is managing nutrient availability, which can compromise transplant quality. While a variety of organic amendments exist, there is limited empirical data on their comparative effectiveness and application strategies in transplant production. This two-year greenhouse study evaluated the effects of selected organic amendments on the growth, root system architecture, and nutritional composition of pepper (Capsicum annuum) transplants grown in 25-cell trays. The experiment was arranged in a randomized complete block design with four replications. Treatments included three dry organic fertilizers bone meal (3-15-0), blood meal (12-0-0), and feather meal (12-0-0) mixed at recommended label rates with growing media at the time of seeding. Additionally, treatments included a liquid fish emulsion (5-1-1 AquaPower™), compost amendment, conventional synthetic (15-5-15 Peters Excel®), and a no-fertilizer control. Data was collected on plant height, stem diameter, plant biomass, tissue nutrient content, and chlorophyll content of leaves. Root and shoot biomass were also collected followed by analysis of root architecture using WinRhizoTM software. Synthetic fertilizer treatment resulted in the highest plant biomass and height, followed closely by blood meal, with no statistically significant difference between the two in either year. Root surface area and volume were greatest in plants treated with feather meal, followed by those receiving blood meal. Weekly EC and pH data collected on the growth medium leachate samples showed that there was a strong negative correlation between them that is when EC was high, pH was low across the treatments, with compost treatment having the highest EC and pH overall. These findings underscore the influence of organic fertilizer source on pepper transplant growth and nutrient status, contributing to improved organic transplant production practices and enhanced transplant quality for vegetable growers.
Tomato (Solanum lycopersicum) growers report that foliar diseases are their biggest production challenge. The tomato organic management and improvement (TOMI) project was launched in 2014 with support from the NIFA-OREI program to address this challenge. We have applied a transdisciplinary approach, integrating studies aimed at 1) increasing biocontrol efficacy, 2) understanding mechanisms controlling induced systemic resistance (ISR), and 3) developing new varieties using a participatory breeding approach. In our biocontrol studies, we learned that combining products with different modes of action was not effective, however, if applied early and often, some biocontrol agents can reduce disease across diverse locations and years. Potting media and composts containing residues with high carbon to nitrogen ratios can increase survival and efficacy of a soil-applied biocontrol agent. In our ISR studies, we learned that not all tomato genotypes are responsive to this form of disease control. The most responsive are wild relatives (Solanum pimpinellifolium), which release distinct compounds from their roots to signal and support soil microbes with biocontrol capabilities. ISR responsiveness is associated with upregulation of brassinosteroid and phenylpropanoid pathways, and grafting appears to promote ISR activity. Identifying genetic markers will improve selection for this trait. Finally in our breeding program, we learned that engaging growers in the selection process aids in the development of new varieties with the most desirable set of traits. We made significant gains in advancing populations and some advanced lines are being considered for release by seed companies, though resistance in many populations is not effective in all ecoregions. Regionally-focused breeding programs are likely to be more effective in developing varieties best adapted to local environmental conditions and disease complexes. We are continuing to work closely with growers to advance these efforts. More information about our project and resources for growers can be found on our website: https://eorganic.info/tomi.
