Physiological plasticity of beech (Fagus sylvatica L.) under contrasting light conditions

In this work pigment composition and chlorophyll fluorescence characteristics were studied in seedlings of Fagus sylvatica regenerating in contrasting light environments of forest understory, forest edge and deforested area. The results have shown that the survival of beech seedlings under high light conditions in the forest edge and deforested area, as well as their acclimation to excess light require effective functional plasticity of the photosynthetic apparatus and protective mechanisms. Physiological acclimation of beech seedlings to high light involves significantly the carotenoids both in the short-term through the reversible conversion of violaxanthin to zeaxanthin and in the long-term through the increase of total carotenoid content and the size of xanthophyll cyc e pool

Responses of some ecophysiological traits of sessile oak (Quercus petraea) to drought stress and heat wave in growing season of 2003

The effects of drought and heat wave appeared in growing season of 2003 on some physiological traits of Quercus petraea were studied at the Sikfôkút research site. There were comparative measurements in the subsequent humid growing season of 2004. Drought reduced significantly the leaf mass increment of Quercus petraea in the dry year (2003) which was reflected in lower SLM too as compared to 2004. Chlorophyll content showed inter-annual and within-canopy variability. Carotenoid content was 1,5-2 times larger in spring than in summer. In summer of 2003 VAZ pool was larger especially in sun leaves than in 2004. Values of Fv/Fm were lower in 2004 than 2003 which indicated lasting drought effects on the photochemical activity of leaves of sessile oak

Effects of supplemental UV-B radiation on photosynthesis performance and UV-B absorbing compounds in leaves of two oak species

The aim of this work was to compare the photosynthetic responses of two tree species (Quercus petraea, Quercus robur) and to determine the leaf level protection under enhanced UV-B radiation in outdoor experiments. Three year old seedlings of both species were exposed to enhanced UV-B radiation (supplementing the ambient level with 40%) from bud break until leaf senescence. Under enhanced UV-B, increases of specific leaf mass (SLM) and reduction of leaf chlorophyll content per dry weight basis were observed but the total carotenoid content remained high. Both oak species responded with an increase of VAZ pool to enhanced UV-B. High values of potential photochemical efficiency of PS2 (Fv/Fm) were observed in both species during the growing season. On clear sunny days loss of Fv/Fm was observed from morning till midday which was larger under enhanced UV-B for both species suggesting that UV-B exposure enhanced the sensitivity of seedlings to photoinhibition. The enhanced UV-B induced increases in the amount of UV-B absorbing compounds in leaves of Q. robur but it slightly affected these traits of leaves of Q. petraea

Synthesis of Zinc Ferrites in RF Thermal Plasma Reactor

Formation of nanosized zinc ferrite spinels was studied from iron- and zinc oxide powders and corresponding nitrate solutions, respectively in a radiofrequency thermal plasma reactor. From the viewpoint of applications, the research was motivated by the potential use of these materials in advanced magnetic devices on the one hand, and by their biomedical applications such as drug carriers or agents for cancer treatment by hyperthermia on the other. In this work effects of synthesis conditions on properties of products were studied in details. The products were characterised for chemical composition, phase conditions, particle size distribution, morphologies and saturation magnetisation. Most products exhibited ferrimagnetic behaviour. Correlations among domain- and particle sizes were also investigated. Conditions for the synthesis of nanosized, inverse zinc ferrites of high saturation magnetisation were established. It was proved that in thermal plasma conditions normal and inverse ferrites could be produced in a single step process

Synthesis of Spinel Ferrites in Radiofrequency Thermal Plasma Reactor

Formation of nanosized zinc-ferrites and nickel-zinc ferrites from iron- and zinc oxide powders and corresponding nitrate solutions, respectively, was studied in RF thermal plasma conditions. The products were characterized for chemical composition, phase conditions, particle size distribution, morphologies and saturation magnetization. Effects of synthesis conditions on properties of products were studied in details

A nevelő-oktató munka a társulati iskolákban a két világháború között

Der Verfasser stellt das Bildungsseptem, besonders die Bildung und Lehrlinsbildung der von Gesellschaften und Industrie magneten begründeten Schulen im Zeitraum zwischen den zwei Weltkriegen vor. Zum Untersuchungsbereich dieser Studie gehören in erster Linie die Schulen des Hüttenwerkes Diósgyőr, das Stahlwerkes Salgótarján und des Hüttenwerkes Ózd, auch deshalb, denn in den Schulen von Ózd und Diósgyőr wurde das derzeitige Grundschulsegstem mit 8 klassen das erste. Mal eingeführt. Im Rahmen der neuen Konzepte des Ministeriums und der Reformen funktionieren immer mehr Privat Schulen, die den Schülern mehr, bessere und persönliche Bildungsmöglichkeiten bieten können. Zur Umwandlung ist aber auch ein Mäzenatentum nötig. Laut den Erfahrungen wird vom Verfasser festgestellt, daß die gegenwartige bildungspolitische Lage und das Anforderungs - und Beding ungsystem der Schulen heutzutage im Verhältnis zu dem untersuchten Zeitraum ahnlich, dadurch sehr aktuell ist

Cadmium-induced turion formation of Spirodela polyrhiza (L.) Schleiden

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Cadmium-induced turion formation of Spirodela polyrhiza (L.) Schleiden

Spirodela polyrhiza (L.) Schleiden (giant duckweed) is an extensively studied representative of duckweeds (Lemnoideae subfamily, Araceae). Despite its widespread application in numerous research areas and well-known capability for producing turions, the effects of various toxicants on turion production are sporadically discussed in the scientific literature. Our aim was to study the growth of S. polyrhiza under cadmium stress and to test its potential interference with turion production. Effects of cadmium were assessed in axenic cultures of a local S. polyrhiza clone in 7-days-long duckweed growth inhibition tests. Our results indicated that higher cadmium concentrations decreased the relative growth rates of cultures within 3 days and growth inhibition reached its maximum between the 3rd and 5th days with 0.080 mg l-1 IC50. Parallel with slowed frond production - by mirror image pattern - induction of turion formation was observed. The first turions protruded by the 5th day of treatments in the 0.075-0.75 mg l-1 concentration range. Such rapid onset of turion formation is indicative of an almost immediate switch between normal and turion mode of meristem function upon cadmium stress. The consideration of this mechanism in practical applications of S. polyrhiza is recommended

Photosynthesis-ecophysiological properties of beech (Fagus sylvatica L.) under the exclusion of ambient UV-B radiation

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Az erdődegradáció és szukcesszió ökofiziológiai háttérfolyamatainak kutatása Bükk-hegységi ILTER területeken = Study of ecophysiological background processes at two ILTER Sites in Bükk Mountains

A síkfőkúti cseres tölgyes erdőben a 80-as évek közepétől fellépett fapusztulás következtében a kocsánytalan tölgy egyedszáma 60 %-kal, a csertölgy állománya jóval kisebb mértékben (20 %-kal) csökkent. A lombkorona mérete a kocsánytalan tölgyfák esetében 14 %kal, a csertölgynél azonban 33 %-kal növekedett. Az erdőállomány két fafaj közül a csertölgynél nagyobb a WUE, a levélnövekedés és a fotoszintetikus hatékonyság kisebb szárazságérzékenységet mutat, ami száraz termőhelyeken a kocsánytalan tölggyel szemben előnyt jelent. A csertölgy leveleinek nagyobb VAZ ciklus pigment készlete és nagyobb VAZ ciklus aktivitása hatékonyabb fényvédelmet jelez. A rejteki mintaterületen a bükkös erdő tarvágását (1981) követő szukcesszió során az irtás és az erdőszegély növényzetének az össz-denzitása a korábbi stádiumokhoz képest 20-25 %-ra csökkent. Mindkét élőhelyen a Fagus sylvatica, Fraxinus excelsior, Carpinus betulus újulat előretörése következett be. E fajok CO2 fixációs rátája a korai szukcesszionális fajokétól jóval alacsonyabb, ez magyarázhatja a lassú regenerációjukat az irtott területen a szukcesszió korábbi stádiumaiban. A regenerálódó fásszárúaknál a két tölgyfajhoz hasonlóan a fényakklimáció a fotoszintetikus apparátus felesleges fényt disszipáló kapacitásával és a VAZ ciklus működésével szoros összefüggést mutat. A két tölgyfaj esetében ezen kívül egy másik xantofill-ciklus, a lutein-epoxid ciklus működését is feltártuk. | In the Sikfőkut forest area the number of trees of sessile oak decreased by 60 % from 80ies, while the population of Austrian oak changed more slightly. The size of canopy and basal area of the remained sessile oak trees increased by 14%, and by 33% in case of Austrian oak. From the two species leaf growth and photoynthetic apparatus of sessile oak was more sensitive to the climatic fluctuations, than that of Austrian oak. The photosynthetic apparatus of both tree species show a high degree of susceptibilty to abiotic stresses in spring. The larger water use efficiency, the smaller sensitivity of leaf growth and photosynthetic efficiency of Austrian oak provide advantage against sessile oak in the dry habitat conditions. In the Rejtek research site the total density of vegetation significantly decreased to 20-25 % of the former succession stages.. In both habitats the regenerating woody species (Fagus sylvatica, Fraxinus excelsior, Carpinus betulus) became dominant. The CO2 assimilation rate of these species is significantly lower than that early-successional species. The light acclimation of the invesigated woody species is in a close correlation with the capacity for dissipating excess light and the activity of VAZ cycle. Beside the VAZ cycle in case of both oak species the operation of another xanthophyll cycle was also revealed, the luetin-epoxide cycle