Nevena Stoeva

Bio: Nevena Stoeva is an academic researcher. The author has contributed to research in topics: Phaseolus & Chlorophyll. The author has an hindex of 9, co-authored 24 publications receiving 697 citations.

Effect of arsenic on some physiological parameters in bean plants

Abstract: The objective of the study was to investigate the effect of different arsenic concentrations on some physiological parameters of bean (Phaseolus vulgaris L.) cultivars Plovdiv 10 and Prelom in the early growth phases. Seedlings, grown in sand with Hoagland-Arnon nutrient solution in a climatic box, were treated with 0, 2, 5 mg(As) dm−3 as Na3AsO4 (pH 5.5). After 5 d of As treatment, the changes in leaf gas-exchange, water potential, chlorophyll and protein contents, peroxidase activity and lipid peroxidation in roots were recorded. Physiological analysis showed a minor negative effect of arsenic at concentration 2 mg(As) dm−3, but at the higher dosage of 5 mg(As) dm−3 growth, leaf gas-exchange, water potential, protein content and biomass accumulation were reduced in both cultivars. The peroxidase activity and lipid peroxidation increased considerably at 5 mg(As) dm−3, which is a typical reaction of the plants to a presence of oxidative stress.

Oxidative changes and photosynthesis in oat plants grown in as-contaminated soil

Abstract: Summary. The effect of different arsenic concentrations on some physiological parameters in oats cultivar Hanza 152 was studied. Arsenic was applied as H 3 AsO 4 at concentrations of 40, 80 and 160 mg (As) per kg soil. The plants were grown in pots with 5 kg soil/pot. Physiological analysis showed a small negative effect of arsenic at concentration of 40 mg (As) per kg soil, but the higher dosages of 80 and 160 mg (As) per kg soil, generated stress in oats plant and as a consequence leaf gas-exchange was suppressed (14% and 25% for photosynthesis rate and 13% and 20% for transpiration intensity). The chlorophyll fluorescence ratio F v /F m decreased. The chlorophyll and protein content also decreased. The peroxidase activity and lipid peroxidation increased, considerably at 160 mg arsenic, per kg soil, which is a typical plant reaction to the oxidative stress.

Physiological Response of Maize to Arsenic Contamination

Abstract: The objective of the study was to investigate the effect of As on some physiological parameters of maize in the early growth phases. Seedlings grown in a climatic box in a Hoagland-Arnon nutrient solution were treated with 0, 2 and 5 mg(As) dm−3 (pH 5.5). After 5 d of As treatment the changes in growth, leaf gas-exchange, chlorophyll (Chl) content, Chl fluorescence, peroxidase activity and lipid peroxidation in roots were recorded. The applied As decreased the growth, leaf area, and biomass accumulation, induced lipid peroxidation and increased peroxidase activity, especially at concentration 5 mg(As) dm−3. It also decreased the Chl, carotenoid (Car) and protein contents. A decrease in the variable to maximum fluorescence ratio (Fv/Fm) indicated lower photosynthetic efficiency.

Effect of salt stress on the growth and photosynthesis rate of bean plants (Phaseolus vulgaris L.).

Abstract: The effect of salt stress оn some physiological parameters in young bean plants (cv. Lody) was studied under controlled conditions in a climatic room. The plants were grown in pots as hydroponic cultures in half-strength Hoagland nutrient solution. The plants were treated for 7 days with 50 and 100 mM NaCl and Na2SO4 , starting at the appearance of the fi rst trifoliate leaf unfolded. The salts were added to the nutrient solution. It was established that the applied doses of both salt types caused stress on the young bean plants, which found expression in the suppression of growth, photosynthesis activity and the plastid pigment content. The amount of proline in the tissues of the salt-treated plants was increased, while the cell water potential was reduced.

Effect of paclobutrazol on wheat seedlings under low temperature stress

Abstract: Wheat (Triticum aestivum L., cv. Beloslava) seeds were imbibed for 24 h in a water solutions containing 0, 25 and 50 mg.l–1 of paclobutrazol. The seedlings were grown as a substrate culture under controlled climatic conditions. Seven-day-old plants were exposed to low temperature stress by placing them in a cold room at a temperature of 2±1oC for 10 days – the first phase of hardening, -4±1oC for 3 days – the second phase of hardening and freezing, -10±1oC for 1 day – the third phase of hardening and freezing. After exposure to stress, the seedlings were returned to a climatic chamber with controlled climatic conditions. Under stress conditions the growth rates of the PBZ-treated seedlings measured by height, fresh and dry weights were greater than the control. Low temperature stress (LTS) induced lipid peroxidation and increased peroxidase activity. It was also found that LTS decreased the chlorophyll and carotenoid levels. A decrease in fluorescence ratio (Fv/Fm) indicated lower photosynthetic efficiency. These deteriorative symptoms in the control seedlings were ameliorated by the PBZ treatment. Based on the results of triazoles studies, we presume that the stress protection caused by PBZ probably contributes to some extent to the enhanced activity of the free-radical scavenging systems.

Heavy metals in soils : trace metals and metalloids in soils and their bioavailability

Abstract: Preface.- Contributors.- List of Abbreviations.- Section 1: Basic Principles: Introduction.-Sources of Heavy Metals and Metalloids in Soils.- Chemistry of Heavy Metals and Metalloids in Soils.- Methods for the Determination of Heavy Metals and Metalloids in Soils.- Effects of Heavy Metals and Metalloids on Soil Organisms.- Soil-Plant Relationships of Heavy Metals and Metalloids.- Heavy Metals and Metalloids as Micronutrients for Plants and Animals.-Critical Loads of Heavy Metals for Soils.- Section 2: Key Heavy Metals And Metalloids: Arsenic.- Cadmium.- Chromium and Nickel.- Cobalt and Manganese.- Copper.-Lead.- Mercury.- Selenium.- Zinc.- Section 3: Other Heavy Metals And Metalloids Of Potential Environmental Significance: Antimony.- Barium.- Gold.- Molybdenum.- Silver.- Thallium.- Tin.- Tungsten.- Uranium.- Vanadium.- Glossary of Specialized Terms.- Index.

Arsenic toxicity: The effects on plant metabolism

Abstract: The two forms of inorganic arsenic, arsenate (AsV) and arsenite (AsIII), are easily taken up by the cells of the plant root Once in the cell, AsV can be readily converted to AsIII, the more toxic of the two forms AsV and AsIII both disrupt plant metabolism, but through distinct mechanisms AsV is a chemical analog of phosphate that can disrupt at least some phosphate-dependent aspects of metabolism AsV can be translocated across cellular membranes by phosphate transport proteins, leading to imbalances in phosphate supply It can compete with phosphate during phosphorylation reactions, leading to the formation of AsV adducts that are often unstable and short-lived As an example, the formation and rapid autohydrolysis of AsV-ADP sets in place a futile cycle that uncouples photophosphorylation and oxidative phosphorylation, decreasing the ability of cells to produce ATP and carry out normal metabolism AsIII is a dithiol reactive compound that binds to and potentially inactivates enzymes containing closely spaced cysteine residues or dithiol co-factors Arsenic exposure generally induces the production of reactive oxygen species that can lead to the production of antioxidant metabolites and numerous enzymes involved in antioxidant defense Oxidative carbon metabolism, amino acid and protein relationships, and nitrogen and sulfur assimilation pathways are also impacted by As exposure Readjustment of several metabolic pathways, such as glutathione production, has been shown to lead to increased arsenic tolerance in plants Species- and cultivar-dependent variation in arsenic sensitivity and the remodeling of metabolite pools that occurs in response to As exposure gives hope that additional metabolic pathways associated with As tolerance will be identified

Arsenic uptake, toxicity, detoxification, and speciation in plants : physiological, biochemical, and molecular aspects

Abstract: Environmental contamination with arsenic (As) is a global environmental, agricultural and health issue due to the highly toxic and carcinogenic nature of As. Exposure of plants to As, even at very low concentration, can cause many morphological, physiological, and biochemical changes. The recent research on As in the soil-plant system indicates that As toxicity to plants varies with its speciation in plants (e.g., arsenite, As(III); arsenate, As(V)), with the type of plant species, and with other soil factors controlling As accumulation in plants. Various plant species have different mechanisms of As(III) or As(V) uptake, toxicity, and detoxification. This review briefly describes the sources and global extent of As contamination and As speciation in soil. We discuss different mechanisms responsible for As(III) and As(V) uptake, toxicity, and detoxification in plants, at physiological, biochemical, and molecular levels. This review highlights the importance of the As-induced generation of reactive oxygen species (ROS), as well as their damaging impacts on plants at biochemical, genetic, and molecular levels. The role of different enzymatic (superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase) and non-enzymatic (salicylic acid, proline, phytochelatins, glutathione, nitric oxide, and phosphorous) substances under As(III/V) stress have been delineated via conceptual models showing As translocation and toxicity pathways in plant species. Significantly, this review addresses the current, albeit partially understood, emerging aspects on (i) As-induced physiological, biochemical, and genotoxic mechanisms and responses in plants and (ii) the roles of different molecules in modulation of As-induced toxicities in plants. We also provide insight on some important research gaps that need to be filled to advance our scientific understanding in this area of research on As in soil-plant systems.

Understanding water deficit stress-induced changes in the basic metabolism of higher plants – biotechnologically and sustainably improving agriculture and the ecoenvironment in arid regions of the globe

Abstract: Water is vital for plant growth, development and productivity. Permanent or temporary water deficit stress limits the growth and distribution of natural and artificial vegetation and the performance of cultivated plants (crops) more than any other environmental factor. Productive and sustainable agriculture necessitates growing plants (crops) in arid and semiarid regions with less input of precious resources such as fresh water. For a better understanding and rapid improvement of soil-water stress tolerance in these regions, especially in the water-wind eroded crossing region, it is very important to link physiological and biochemical studies to molecular work in genetically tractable model plants and important native plants, and further extending them to practical ecological restoration and efficient crop production. Although basic studies and practices aimed at improving soil water stress resistance and plant water use efficiency have been carried out for many years, the mechanisms involved at different scales are still not clear. Further understanding and manipulating soil-plant water relationships and soil-water stress tolerance at the scales of ecology, physiology and molecular biology can significantly improve plant productivity and environmental quality. Currently, post-genomics and metabolomics are very important in exploring anti-drought gene resources in various life forms, but modern agriculturally sustainable development must be combined with plant physiological measures in the field, on the basis of which post-genomics and metabolomics have further practical prospects. In this review, we discuss physiological and molecular insights and effects in basic plant metabolism, drought tolerance strategies under drought conditions in higher plants for sustainable agriculture and ecoenvironments in arid and semiarid areas of the world. We conclude that biological measures are the bases for the solutions to the issues relating to the different types of sustainable development.