Vermicompost as Substrate Amendment for Tomato Transplant Production

Vermicompost may be a promising substitute for peat especially in transplant production. Vermicomposting is a sustainable solution for management of organic wastes. However, due to variability of organic wastes, vermicomposts might have varying nutrient content levels. The study compared vermicomposts from different sources on growth and nutrition of tomato (Solanum lycopersicum L.) transplants. Chemical composition of vermicomposts differed. Common characteristics were high pH and very high electrical conductivity. All vermicomposts stimulated growth of tomato transplants, with up to a 2.2-fold increase occurring in shoot biomass. Differences in growth were attributed mainly to differences in nutrient content of the potting mixtures, but some changes in physical and biological properties of the substrate could also be responsible

Population Response of Rhizosphere Microbiota of Garden Pea Genotypes to Inoculation with Arbuscular Mycorrhizal Fungi

This study of a legume’s rhizosphere in tripartite symbiosis focused on the relationships between the symbionts and less on the overall rhizosphere microbiome. We used an experimental model with different garden pea genotypes inoculated with AM fungi (Rhizophagus irregularis and with a mix of AM species) to study their influence on the population levels of main trophic groups of soil microorganisms as well as their structure and functional relationships in the rhizosphere microbial community. The experiments were carried out at two phenological cycles of the plants. Analyzes were performed according to classical methods: microbial population density defined as CUF/g a.d.s. and root colonization rate with AMF (%). We found a proven dominant effect of AMF on the densities of micromycetes and actinomycetes in the direction of reduction, suggesting antagonism, and on ammonifying, phosphate-solubilizing and free-living diazotrophic Azotobacter bacteria in the direction of stimulation, an indicator of mutualistic relationships. We determined that the genotype was decisive for the formation of populations of bacteria immobilizing mineral NH4+-N and bacteria Rhizobium. We reported significant two-way relationships between trophic groups related associated with soil nitrogen and phosphorus ions availability. The preserved proportions between trophic groups in the microbial communities were indicative of structural and functional stability

Assessment of Balkan Pepper (<i>Capsicum annuum</i> L.) Accessions for Agronomic, Fruit Quality, and Pest Resistance Traits

To maintain the continuous genetic variation and increase the genetic gain, appreciable germplasm diversity and its comprehensive characterization is necessary to further utilize gene sources for pre-breeding. The diversity of pepper forms, cultivation traditions and diverse fruit usages are typical for Balkan countries. Considering this rich diversity, 21 pepper accessions from the Balkan region were evaluated for morphological, biochemical, and insect resistance traits during 2018 and 2019 at Maritsa Vegetable Crops Research Institute, Plovdiv, Bulgaria. Among the studied accessions, the highest productivity was observed in pumpkin shape K1115 and kapia type K1081 accessions, with 0.74 kg and 0.70 kg per plant, respectively. Concerning fruit quality, the highest total polyphenols and ferric reducing antioxidant power (FRAP) were observed in pumpkin shape K712 (203.44 mg GAE/100 g FW) and K1103A (11.49 µmol Fe2+/g FW) accessions, respectively. Concerning insect resistance, 38% of studied accessions showed no infestation of green peach aphid. The kapia type K697 accession was seen as the most reliable resistance source, as it was not infested by aphids and had the least thrips (20% on plants) and cotton bollworm (6.67% on plants and 8.34% on fruit) damage. Based on examined traits, accessions were identified for enhanced fruit quality and promising insect resistance and have been included in further pre-breeding efforts

Organic Production of Snap Bean in Bulgaria: Pests and Diseases Incidence and Control, Soil Fertility and Yield

Among factors affecting snap bean production in organic growing systems, pests and diseases are of paramount importance. The current study was aimed to determine the impact of organic production practices on snap bean pests and diseases infestation, soil fertility and yield. Five treatments of plants during the whole growing season with a Bordeaux mixture at a dose of 3000 g/ha, provided more than 50 percent protective effect against the development of the bacterial blight Xanthomonas axanopodis pv. phaseoli and anthracnose Colletotrichum lindemuthianum. In organic fields, commercial bioproducts containing pyrethrins or entomopathogenic fungi Beauveria bassiana can be successfully applied to control the black bean aphid (Aphis fabae Scop.). To limit the attack of bean weevil (Acanthoscelides obtectus Say), phytopesticide containing pyrethrins can also be used. Against the two-spotted spider mite (Tetranychus urticae Koch.), products containing the active ingredient azadirachtin were seen to be effective five days after treatment. Soil amendment with vermicompost at a dose of 2850 L/ha slightly increased the amounts of water-soluble nutrients; however, soil remained nutrient deficient across the growing season. Among the tested Bulgarian varieties, Evros possessed higher yield, and appear to be suitable for organic system than the Tangra variety

Characterization of Tomato Accessions for Morphological, Agronomic, Fruit Quality, and Virus Resistance Traits

Characterization of local germplasm is an effective way to identify elite breeding material and develop improved varieties. This study was aimed to assess 52 tomato accessions comprised of local varieties (28), landraces (8), breeding lines (14), and wild relatives (2) and its characterization for 30 morphological/agronomic, four fruit quality, and Tomato Mosaic Virus (ToMV) resistance traits. Morphological, quality, and ToMV traits were evaluated using phenotyping, biochemical assays, and molecular markers, respectively. Fruit shape and size showed appreciable variation with fruits varied from rounded to heart shape and small to big size. Significant variation was observed for fruit weight (1.6g to 564.8g), fruits per plant (6.0 to 174.7), productivity (130.5g to 5146.5g), soluble solids (4.1% to 8.4%), vitamin C (9.5 mg/100g to 46.4 mg/100g), antioxidant activity (2.5 μmol Fe2+/g FW to 9.6 μmol Fe2+/g FW), and total polyphenols (23.9 GAE/100g FW to 124.2 GAE/100g FW). All accessions were phenotypically screened for the virus resistance in the growth chamber and CAPS molecular markers were used to identify accessions with ToMV Tm-22 resistant alleles and accessions LYC-13, LYC-15, LYC-17, LYC-26, and LYC-52 were identified as resistant. Multivariate analysis of morphological and quality traits showed that 35 principal components (PCs) contributed to the total variation and the first two and twelve PCs explained 47.2% and 90% variation, respectively. The evaluated tomato collection appears to have breeding potential and around 20% accessions of the collection (LYC-6, LYC 17-18, LYC 26-31, LYC 33) are promising genetic resources for variety development that are enriched with enhanced fruit quality and high yield.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

A step towards Balkan Capsicum annuum L. core collection: Phenotypic and biochemical characterization of 180 accessions for agronomic, fruit quality, and virus resistance traits.

Region-specific local landraces represent a germplasm diversity adapted and acclimatized to local conditions, and are ideal to breed for targeted market niches while maintaining the variability of heirloom traits. A collection of 180 pepper accessions, collected from 62 diverse locations across six Balkan countries, were characterized and evaluated for phenotypic and biochemical variation during a multi-year environment. An assortment of 32 agro-morphological, fruit quality, and virus resistance traits were evaluated, and the top 10% accessions were identified. A wide range of trait variation concerning plant architecture, inflorescence and fruit traits, yield and fruit quality was observed, and appreciable variation was noticed. According to hierarchical clustering, six distinct clusters were established based on pre-defined varietal groups. Divergence among accessions for phenotypic and fruit compositional variability was analyzed, and eight principal components were identified that contributed ~71% of the variation, with fruit shape, width, wall thickness, weight, and fruit quality traits being the most discriminant. Evaluation of the response to tobacco mosaic virus (TMV) and pepper mild mottle mosaic virus (PMMoV) showed that 24 and 1 accession were resistant, respectively while no tomato spotted wilt virus (TSWV) resistance was found. Considerable diversity for agro-bio-morphological traits indicates the Balkan pepper collection as good gene sources for pre-breeding and cultivar development that are locally adapted