Valtcho D Jeliazkov (Zheljazkov)

Valtcho D Jeliazkov (Zheljazkov)
Oregon State University | OSU · Department of Crop and Soil Science

PhD University of Massachusetts - Amherst

About

253
Publications
111,306
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Introduction
Research interests: Long-term effects of agricultural practices on crop production systems. Hemp, oilseeds, essential oil and medicinal plants, and native plants containing plant chemicals. Bioprospecting of promising chemicals for new drug development. Organic food production. Program director of new program 'Online Graduate Certificate in Organic Agriculture'
Additional affiliations
December 2010 - November 2014
University of Wyoming
Position
  • Associate professor in Plant Sci., Director of Sheridan R&Ext Center

Publications

Publications (253)
Article
Pinus heldreichii and P. peuce are Balkan endemics, Tertiary relicts, while Pinus mugo is an edificator in the phytocenoses in the Alpine mountain range. The chemical profile and essential oil (EO) yield and composition of these three species as a function of distillation time (DT) was the subject of this study. The working hypothesis was that EO o...
Article
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Winter savory (Satureja montana L.) is a well-known spice and medicinal plant with a wide range of activities and applications. Two subspecies of S. montana, subsp. montana and subsp. variegata, were used for the preparation of seven different extracts: steam distillation (essential oil (EO) and hydrolate (HY)), subcritical water (SWE), ultrasound-...
Article
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Satureja pilosa and S. kitaibelii (Lamiaceae) are Balkan endemic plant species, and the composition of their essential oil (EO) is highly variable. The aim of the present study was to establish: (1) the EO variability in two populations of S. pilosa (the intrapopulation), and (2) the EO variation in S. kitaibelii between nine populations (interpopu...
Article
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Sagebrush (Artemisia spp.) are dominant wild plants in large areas of the U.S., Canada and Mexico, and they include several species and subspecies. The aim was to determine if there are significant differences in essential oil (EO) yield, composition, and biological activity of sagebrush within the Bighorn Mountains, U.S. The EO yield in fresh herb...
Article
Background: Solvent-free microwave-assisted extraction (MAE) is a green extraction capable of boosting the yield and quality profile of hemp essential oil when compared with other conventional extraction techniques. During this process, two by-products are produced, namely the aqueous residue containing bioactive phenolics, and the residual deterp...
Article
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Phytogenics are plant extract additives used for their bioactive properties. The objective of this study was to assess the effect of plant extracts, wheat grass juice (WGJ) and barley grass juices (BGJ) addition to fish diet on growth and meat quality of common carp. Fish (51 ± 33 g initial weight) were fed for four weeks with three plant-based die...
Article
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Steam distillation was used for the isolation of Dracocephalum moldavica L. (Moldavian dragonhead) essential oil (DMEO). This aromatic herbaceous plant is widespread across the Northern Hemisphere regions and has been utilized in health-improving studies and applications. In addition to the DMEO, the hydrolate (DMH), a byproduct of the distillation...
Article
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This study compared the essential oils (EO) composition of Helichrysum arenarium (Bulgarian populations) with that of the cultivated species H. italicum. The EO composition of H. arenarium and H. italicum were analyzed via gas chromatography. In general, 75 components were identified in H. arenarium EO and 79 in H. italicum EO. The predominant cons...
Article
Plant essential oils (EOs) are often used as ingredients in the development of new biopesticides. The objective of this study was to investigate the allelopathic effects of three EOs of two juniper species against weed seeds. The EOs were extracted from Juniperus sabina L. Male (M) and Female (F) and J. excelsa Bieb. by means of steam distillation...
Article
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Periodic removal of sediment from aquaculture ponds is practiced to maintain their productivity and animal welfare. The recovery of sediment as a plant fertilizer could alleviate the costs of sediment removal. The objective of this study was to test the effects of a dried sediment, extracted from an aquaculture pond used for common carp cultivation...
Article
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Marrubium friwaldskyanum Boiss (Lamiaceae) is a Bulgarian endemic species. Overall, the essential oil (EO) composition of M. friwaldskyanum was different from that of the other Marrubium species reported in the literature. The main EO constituents of M. friwaldskyanum were (E)-caryophyllene, germacrene D, and caryophyllene oxide. The effect of the...
Article
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In this study, we evaluated the allelopathic effects of essential oils (EOs) from six different plant species, namely, lavender (Lavandula angustifolia), hyssop (Hyssopus officinalis), English thyme (Thymus vulgaris), lovage (Levisticum officinale), costmary (Chrysanthemum balsamita), and cumin (Cuminum cyminum), on seed germination and seedling gr...
Article
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The objective of this study was to assess the biological activity of essential oils (EOs) of four Juniperus species obtained via two different distillation methods and their potential as biopesticides. The studied factors were juniper species (Juniperus communis L., J. oxycedrus L., J. pygmaea C. Koch., and J. sibirica Burgsd), plant sex (male (M)...
Article
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Hemp (Cannabis sativa L.) synthesizes and accumulates a number of secondary metabolites such as terpenes and cannabinoids. They are mostly deposited as resin into the glandular trichomes occurring on the leaves and, to a major extent, on the flower bracts. In the last few years, hemp for production of high-value chemicals became a major commodity i...
Article
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H. italicum essential oil (EO) is one of the most popular ingredients utilized by the cosmetic industry, and it is also used as natural antioxidant and as a value-added ingredient in food products. The chemical composition of the EO H. italicum cultivated in Serbia was analyzed by gas chromatography–mass spectrometry. The quantitative structure–ret...
Article
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Juniperus excelsa M. Bieb and J. sabina L. contain essential oil (EO), while J. sabina also contains podophyllotoxin, which is used as a precursor for anti-cancer drugs. Two studies were conducted. The first assessed the variability in the EO profile and podophyllotoxin concentration of the two junipers, depending on the location and tree gender. T...
Article
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The extraction of coalbed methane produces a significant amount of coalbed methane co-produced water (CBMW). Coalbed methane co-produced water is often characterized by high levels of pH, total dissolved solids (TDS), sodium (Na) and bicarbonate (HCO−3) and if used for irrigation without treatment, it may be detrimental to the surrounding soil, pla...
Article
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The development of organic farming as a result of increasing consumer preference for organic food has led to the development and registration of new pest-control products for certified organic production. In this study, the effects of three biocontrol products containing spores and mycelium of Arthrobotrys oligospora—Artis®, Beauveria bassiana—Bora...
Article
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The objective of this study was to evaluate wild growing Satureja kitaibelii, Thymus serpyllum, Origanum vulgare, Achillea millefolium and Achillea clypeolata with respect to their essential oil (EO) content, composition and antimicrobial activity. The five species were collected at Mt. Rtanj and the village of Sesalac, Eastern Serbia. The main EO...
Article
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Laurel (Laurus nobilis L.) is a plant species from Lauraceae family, and is native to the Mediterranean region. The goal of this study was to compare chemical composition of laurel leaves and antibacterial activity of its essential oil (EO) from wild-grown trees in Greece and Georgia. The laurel leaves from the two native habitats had dissimilar co...
Article
Juniperus oxycedrus L. (Cupressaceae Bartlett) sensu lato is a species of high phenotypic and phytochemical variability. There is interest in the development of this species into cultivated crop because wild collection of galbuli or leaves result in significant variation in the essential oil (EO) profile and bioactivity. The objectives of this stud...
Article
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Hemp (Cannabis sativa L.) is currently one of the most controversial and promising crops. This study compared nine wild hemp (C. sativa spp. spontanea V.) accessions with 13 registered cultivars, eight breeding lines, and one cannabidiol (CBD) hemp strain belonging to C. sativa L. The first three groups had similar main essential oil (EO) constitue...
Article
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Grecian juniper (Juniperus excelsa M. Bieb.) is an evergreen tree and a rare plant found in very few locations in southern Bulgaria. The aim of this study was to evaluate the phytochemical content and antioxidant potential of J. excelsa unripe and ripe galbuli from three different locations in Bulgaria. The essential oil content ranged between 1.9%...
Article
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Industrial hemp (Cannabis sativa L., Cannabaceae) is an ancient cultivated plant originating from Central Asia and historically has been a multi-use crop valued for its fiber, food, and medicinal uses. Various oriental and Asian cultures kept records of its production and numerous uses. Due to the similarities between industrial hemp (fiber and gra...
Research
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A review and explanation of the long-term experiments at the Columbia Basin Agricultural Research Center (CBARC) over many years. The goals are how to work and protect the dryland soil over time so that healthy crops can continue to grow there. Their research shows that certain techniques work best to achieve that goal.
Article
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The hypothesis of this study was that we can modify the essential oil (EO) profile of hemp (Cannabis sativa L.) and obtain fractions with differential composition and antimicrobial activity. Therefore, the objective was to evaluate the effects of grinding of hemp biomass before EO extraction and fractionation during distillation on EO profile and a...
Article
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For the first time the volatile fraction of coffee silverskin has been studied focusing on odor-active compounds detected by gas chromatography-olfactometry/flame ionization detector (GC-O/FID) system. Two approaches, namely headspace (HS) analysis by solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) and odor-active comp...
Article
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The genus Nicotiana (Solanaceae) includes over 70 species, with a long history of traditional use; many of them are nowadays used in bioengineering, biosynthesis, molecular biology, and other studies, while common tobacco, N. tabacum L., is one of the most economically important industrial crops worldwide. Although Nicotiana species have been exten...
Article
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The Balkans endemic species Alkanna primuliflora Griseb., A. stribrnyi Velen., and A. graeca Boiss. & Spruner have limited distribution in the Balkan Peninsula and a large variation in the morphological characteristics. The populations of the three Alkanna species in the Bulgarian flora are small and fragmented. There are no previous reports on the...
Article
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Studies on the impact of agricultural practices on plant diversity provide an important information for policy makers and conservation of the environment. The aim of the present work was to evaluate wild plant diversity across the agroecosystems in two contrasting regions of Bulgaria; Pazardzhik-Plovdiv (representing agroecosystems in the lowlands)...
Article
Aims: To conduct a biological investigations and to evaluate the antimicrobial and antioxidant activities of the essential oil extracted from Juniperus communis, J. scopulorum and J. horizontalis; to screen their mechanisms of action by conducting the cell membrane permeability assay (CMP); and to determine the possible cytotoxicity of the three e...
Article
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Previous studies in the long-term experiments at Pendleton, OR (USA), were focused on organic matter cycling, but the consequences of land management for nutrient status over time have received little attention. Soil and wheat (Triticum aestivum L.) tissue samples were analyzed to determine the macronutrient dynamics associated with residue managem...
Article
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Satureja pilosa Velen. senso lato is a Balkan endemic plant that is not well characterized and is found on rocky outcrops of limestone base in Stara Planina (the Balkan Mountains) and the Rhodope Mountains. The objective of this study was to assess the variability of essential oil (EO) content and composition of S. pilosa collected at 33 locations...
Article
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The intent of this study was to utilize distillation timeframes (DT) of nutmeg (Myristica fragrans) essential oil (EO) to generate fractions with differential chemical compositions and bioactivity. Ten fractions were captured at the following distillation timeframes: 0.0–0.5, 0.5–1.0, 1.0–2.5, 2.5–5.0, 5.0–10, 10–30, 30–60, 60–90, 90–120, and 120–2...
Article
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N. glutinosa L. is a relatively less studied Nicotiana species (Solanaceae), although there are data about its importance as a model plant in viral control studies, as a gene donor in tobacco hybridization and as a source of agents with insecticidal or fungicidal effects. The biological activities of the species were associated mostly with the pres...
Article
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Genus Galanthus (Amaryllidaceae) includes 19 species in Europe and the Middle East. The Flora of Bulgaria recognizes two species: G. nivalis L. and G. elwesii Hook. Galanthus elwesii is characterized by relatively high morphological variability, leading some authors to identify some populations as G. gracilis Celak. However, the occurrence of G. gr...
Article
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The aim of this study was to establish the kinetics regression models for yield and composition of Ruta graveolens fruit and Hyssopus officinalis subsp. aristatus aboveground biomass essential oil (EO), collected at different time intervals during the hydrodistillation process. The hypothesis was that collecting the EO fractions during specific tim...
Conference Paper
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The wastewater resulting from the recirculating aquaculture systems (RAS) is rich in nitrogen and phosphorus, which is why it could be used for plant cultivation, as a sustainable disposal management. The aim of this study was to test the effects of RAS wastewater on basil yield and essential oil quality. A green basil cultivar ‘Genovese’ was used...
Article
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Tobacco (Nicotiana tabacum L.) aroma is an important attribute of tobacco quality and is influenced by a variety of minor chemical components, including carotenoid degradation products. The objectives of this work were to determine the content of the most important fragrance-shaping carotenoid degradation products in the essential oils (EOs) of the...
Article
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Currently, wastewater treatment plants produce large amounts of sewage sludge. Due to the rich content of organic matter and minerals, sewage sludge can be used as soil amendments for eroded soils. The aim of this work was to assess sewage sludge (SS) in combination with an eroded soil (ES) collected from the North Eastern Romania as growth substra...
Article
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Crop residues are an important source of plant nutrients. However, information on the various methods of residue management on micronutrients in soil and wheat (Triticum aestivum L.) over time is limited. A long-term (84-year) agroecosystem experiment was assessed to determine the impact of fertilizer type and methods of crop residue management on...
Article
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Tillage and nitrogen (N) fertilization can be expected to alter micronutrient dynamics in the soil and in plants over time. However, quantitative information regarding the effects of tillage and N application rates on micronutrient dynamics is limited. The objectives of this study were (a) to determine the long-term effect of different tillage meth...
Article
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Tribulus terrestris L. (TT) (puncturevine) is a common weed that grows in many countries worldwide and in some places is considered as a noxious weed. The plant has been used in traditional Chinese and Indian medicines and is now considered as one of the most popular aphrodisiacs. It is known for its healing properties for sexual difficulties, impo...
Article
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Bay laurel ( Laurus nobilis L.) is an evergreen tree. The objective of this study was to determine the chemical composition (polyphenols, essential oil [EO], lipid fraction, cellulose, and protein content) of laurel fruits collected from Greece (Mount Athos) and Georgia (the village of Meria), and to evaluate the antimicrobial activity of laurel fr...
Article
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Soil, Seedbed Preparation and Seeding for Hemp
Article
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Tillage plays a major role in nutrient dynamics under dryland cropping systems, but there remains uncertainty regarding the long-term impacts of tillage on nutrient availability. The objective of this study was to examine the influence of tillage intensity and timing on micronutrient concentration of soils and winter wheat (Triticum aestivum L.) un...
Article
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Coal-bed methane (CBM), an important energy source, coproduces a vast amount of saline-sodic wastewater, CBM water (CBMW), with environmental and economic disposal issues. This research evaluated under a greenhouse production system the influence of gypsum (CaSO4·2H2O) and CBMW on yields, essential oil (EO) content and composition in lemongrass (Cy...
Article
A possible solution for improving the fertility of the eroded soils could be the use of biosolids because of their high content of organic matter (OM), micro- and macronutrients. However, limited information is available concerning the mineral nutrition, physiology, and synthesis of secondary compounds in plants in response to eroded soils and bios...
Article
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The insights gained from the long-term impacts of tillage and N fertilization on soil fertility are crucial for the development of sustainable cropping systems. The objectives of this study were to quantify the effects of 75 years of tillage and N fertilization on macronutrients in soil and wheat (Triticum aestivum L.) tissues grown in a winter whe...
Article
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The chemical profile and antioxidant capacity of Juniperus virginiana, J. excelsa, and J. sabina essential oil (EO) fractions as a function of time was the subject of this study. The hypothesis was that, capturing EO in sequential timeframes during hydrodistillation would generate fractions containing unique compositions and antioxidant capacity. I...