Miklós Fári

Selenium and nano-selenium in agroecosystems

Selenium (Se) is an essential health element becoming rare in food as a result of intensive plant production. Indeed, several enzymes contain selenium in the form of the unusual selenocysteine amino acid. Selenium was found an essential nutrient in the late 1950s, when selenium was found to replace vitamin E in the diets of rats and chicks for the prevention of vascular, muscular, and hepatic lesions. At that time, selenium was considered solely as a toxic element in the northern Great Plains of the USA, because selenium was associated with the ‘alkali disease’ of grazing livestock. The major source of Se in soils is the weathering of Se-containing rocks. Secondary sources are volcanic activities, dusts such as in the vicinity of coal burning, Se-containing fertilizers, and some waters. Se cycles through the food system; Se is first removed from soils by plants and soil microorganisms, which can take up Se into their proteins and produce volatile forms such as dimethylselenide. Dimethylselenide enters the atmosphere to be brought down with precipitation and airborne particulates. Here, we review Se in agroecosystems. We focus on the production, biological effects, and use of nano-selenium particles.

Selenium and nano-selenium in plant nutrition

Abstract Selenium (Se) is a naturally occurring metalloid element which occurs nearly in all environments. Se is considered as a finite and non-renewable resource on the Earth. The common sources of Se in earth’s crust occur in association with sulfide minerals such as metal selenide, whereas it is rarely found in elemental form (Se0). While there is no evidence of Se need for higher plants, several reports show that when Se added at low concentrations, Se exerts beneficial effects on plant growth. Se may act as quasi-essential micronutrient through altering different physiological and biochemical traits. Thus, plants vary considerably in their physiological and biochemical response to Se. This review focusses on the physiological importance of Se forms as well as different Se fertilizers for higher plants, especially plant growth, uptake, transport, and metabolism.

Postharvest Management of Fruits and Vegetables Storage

Sustainable agriculture is a core part of the concept of sustainable development. Given the forecast in population increase, sustainable agriculture has to achieve food security in combination with economic viability, social responsibility and have as little effect on biodiversity and natural ecosystems as possible. Based on Agenda 21, signed at the world summit in Rio de Janeiro 1992, sustainable agriculture takes a truly global perspective. This concept requires a thorough understanding of agro-ecosystem functions. The protection of soil and water is one necessary prerequisite as well as the efficient use of mineral and organic fertilizers. This might be achieved by means of improved technology and better understanding of the basic processes in soils. Solving the persistent hunger problem is not simply a matter of developing new agricultural technologies and practices. Most poor producers cannot afford expensive technologies. They will have to find new types of solutions based on locally-available and cheap technologies combined with making the best of natural and human resources. Sustainable intensification is the use of the best available technologies and inputs such as best genotypes, best agronomic management practices and best postharvest technologies to maximize yields, while at the same time minimizing or eliminating harm to the environment. Clearly, over the next 50 years we will need to learn to do just this. Therefore, this review will be focused on the postharvest physiology and management including harvesting, handling, packing, storage and hygiene of fruits and vegetables to enhance using of new postharvest biotechnology. The postharvest biology including biochemical parameters of horticultural crops quality, postharvest handling under extreme weather conditions, potential impacts of climate changes on vegetable postharvest and postharvest biotechnology will be also highlighted.

Selenium and its Role in Higher Plants

Selenium (Se) is a naturally occurring metalloid element which occurs nearly in all environments in the universe. The common sources of Se in earth crust occurs in association with sulfide minerals as metal selenide whereas, it is rarely seen in elemental form (Se0). Furthermore, Se is considered a finite and non-renewable resource on earth, and has been found to be an essential element for humans, animals, micro-organisms and some other eukaryotes; but as yet its essentiality to plants is in dispute. Thus, plants vary considerably in their physiological and biochemical response to Se. Therefore, this review focuses on of the physiological importance of Se for higher plants, especially plant growth, uptake, transport, metabolism and interaction of selenium with other minerals. Biogeochemistry of Se, its relationship with S, application of Se-containing fertilizers, Se in edible plants and finally, red elemental Se nanoparticles in higher plants will be highlighted.

Giant reed for selenium phytoremediation under changing climate

At very low concentrations selenium is an essential micronutrient for humans, animals and some lower plants including algae and bacteria, whereas Se is extremely toxic at higher doses. Living organisms can be exposed to high selenium concentrations from both natural and anthropogenic sources. Climate is a major factor governing the biogeochemistry of Se. Climate change can indeed modify Se uptake by plants and the rhizosphere and the volatilization of Se by plants. High precipitation rates and low temperatures can reduce Se accumulation by plants. Se-hyperaccumulator plants such as giant reed thus appear as a means to regulate Se flow in ecosystems. Se-hyperaccumulator plants can indeed be used to clean Se-contaminated agricultural soils and wastewaters and as a source of dietary Se. Those plants are also converting mineral soil Se into volatile organic Se that is released in the atmosphere.

Giant Reed (Arundo donax L.): A Green Technology for Clean Environment

In recent years, biomass plants have gained considerable public attention and interesting of environmental policy makers as important renewable source for energy. In addition, exploitation of biomass plants as promising phytoremediation candidates was proposed since these plants can produce huge biomass production under low-cost conditions as well as its ability to survive in contaminated and poor soils (marginal lands). Giant reed (Arundo donax L.) has been recognized as one of the most important energy plants as a consequence of its huge dry biomass production that can reach more than 60 t ha-1 under optimal growth conditions. Nowadays, giant reed becomes promising tool for phytoremediation purposes where it shows great ability to grow in different soils with wide ranges of pH, salinity and trace metal contents. Giant reed is a tall perennial rhizomatous grass (Poaceae family), native to the freshwater regions of Eastern Asia, but nowadays considered as a sub-cosmopolitan species given its worldwide distribution. It is a hydrophyte, growing along lakes, streams, drains and other wet sites. The genus Arundo can reach the height of 14 m and is among the fastest-growing terrestrial plants. Giant reed displays unique physiological features whereby it readily absorbs and concentrates toxic chemicals from contaminated soil with no appreciable harm to its growth and development. It is one of the mostly used plants as a trace element bio-accumulator, especially via phytoremediation processes, due to its capacity of absorbing contaminants such as metals that cannot be easily biodegraded. Many reports documented well that giant reed can efficiently decontaminate polluted soils with Cu, Cd, As, Pb Ni, high content of salts bauxite-derived red mud. Microbial component in soil is considered one of the most sensitive indicators for soil contamination especially with trace metals. Where, many microbial species significantly reduce directly after exposure to such pollutants except tolerant species. However, giant reed showed capability for healing and restoring the soil microbial community within phytoremediation process. Moreover, in autoclaved soil samples, giant reed was able not only to maintain soil chemical properties, but also to induce the microbial growth of different groups such bacteria, fungi and actinomycetes in a short period. These data encourages using giant reed for phytoremediation purposes as well as for recovering steaming soil as in natural fires. This chapter reviews the scientific literatures and presents innovative findings on the ability and utilization of giant reed biomass feedstock for phytoremediation and other uses.

Plant Nutrition: From Liquid Medium to Micro-farm

Soil fertility and plant nutrition have played an important role in the agricultural science during the twentieth century in increasing crop yields. In the twenty-first century, importance of this field is still expanding due to the limitations of natural land and water resources, sustainable agriculture, and concern about environmental pollution. Under these conditions, improving food supply worldwide with adequate quantity and quality is fundamental. Supply of adequate mineral nutrients in adequate amount and proportion to higher plants will certainly determine such accomplishments. Further, in developing crop production technologies, research work under field and controlled conditions is necessary to generate basic and applied information. In addition, research is very dynamic and complex due to variation in climatic, soil, and plant factors and their interactions. This demands that basic research information can only be obtained under controlled conditions to avoid or reduce effects of environmental factors on treatments. Hence, the objective of this review article is to discuss basic principles of research in soil fertility and plant nutrition under different conditions from to liquid or solid media, micro-farm, green house and field experiments. These information will be included the management of different tools of plant nutrition even on the small or large scale i.e., Petri dishes (in case of medium) or hectare unit (in case of fields). Topics discussed are soil and solution culture experimental techniques including, fertilizer application and planting, experimental duration and observations, considerations of pot or field experimentations.

Soil Quality and Plant Nutrition

Soils are dynamic ecosystems that support a diversity of life. Therefore, the concept of soil quality or health, like that of human health, is not difficult to understand or recognize when the system is viewed as a whole. The challenge is to manage soils such that they are able to perform the various uses they are put to without degradation of the soils themselves or the environment. While, this is simple in concept, there are definite complexities that make the idea of soil health difficult to quantify. Which soil functions should be considered, which soil properties are most important to measure, and how to best measure those properties are some of the tough questions that need to be considered when attempting to quantify soil health. The great challenge is to manage soils in a sustainable fashion so that they will provide for human needs in the future. However, the measurement of soil processes and of the soil properties linked to these also depend on the use and location of the soil. When evaluating soil quality, it is therefore common to explore a range of soil physical, chemical, and biological properties. The single most important property determining the soil quality is the soil organic system because of the profound influence it has on soil physical, chemical, and biological properties. Therefore, many steps already taken to improve soil quality are dealing with improving soil organic matter status and hence, the vitality of the soil organic system. Some of the common ways to improve soil quality include: reduced tillage, use of green manure, application of animal manures, crop rotations, strip cropping, use of cover crops, application of sludge or biosolids, and other additions of organic materials and nutrients. These management techniques enhance the activity of both the micro- and macro-biological soil organic system, whose activities also improve properties such as soil aggregation, infiltration, and water holding capacity, decrease bulk density, penetration resistance and soil erosion, and increase cation exchange capacity. Management for soil quality can also lead to reduced need for agrochemicals and tillage, reduced fuel consumption by farm equipment, and increased sequestration of CO2 in the soil, all of which benefit the environment. Modern agricultural science has the ability to correct many of the poor practices of the past and to maintain healthier soils that should sustain the uses they are put to.

Selenium Phytoremediation by Giant Reed

Selenium (Se) is an essential micronutrient for humans, animals and some lower plants at very low concentrations, whereas it is extremely toxic at higher doses. Furthermore, living organisms become exposed to high Se concentrations via both anthropogenic and natural releases of Se to the environment. Thus, Se may be released naturally into soils formed from Se-bearing shales. Hence, this in turn can lead to the production of large quantities of Se-contaminated irrigation and drainage water. About the anthropogenic sources of Se, they include coal ash leachates or mining production, aqueous discharges from electric power plants, industrial wastewater and oil refinery industry. In general, Se levels in most soils are very low (0.44 mg kg−1) and naturally Se occurs in certain Cretaceous shale sediments. Furthermore, seleniferous soils contain up to 100 mg kg−1 Se, and when fossil fuels derived from these soils are used, or when these soils are cultivated, toxic levels of Se may accumulate in the environment. Hence, using of Se hyperaccumulator plants can be thrived on seleniferous soils, providing another portal for Se into the agroecosystem. These plants could be alleviated both of these problems, either as a source of dietary Se or for phytoremediation of excess Se from the environment. On the other hand, these plants also have the ability to clean up agricultural soils and industrial wastewaters, due to their capacity to not only take up and then accumulate Se but also convert inorganic Se into volatilized forms that are released into the atmosphere.

Alternatives of bioenergy feedstock production based on promising new perennial rhizomatous grasses and herbaceous semishrub crops in Hungary

The world’s energy consumption continues to increase, which results in demographic changes, living standard increases and technical development. In the world and Hungary the interest in biomass crops also has increased considerably over the previous decades. This paper summarizes the most important biological, biotechnological and agronomical researches and results of our working group, in Department of Agricultural Botany, Plant Physiology and Plant Biotechnology, University of Debrecen. It represents our research group publications and introduces some efficient propagation possibilities of promising new perennial bioenergy crops, giant reed (Arundo donax L.) and Virginia fanpetals (Sida hermaphrodita Rushby).