Physiological aspects of N nutrition in saline and waterlogged soils.

The present work highlights a few physiological aspects of NO3-nutrition and closely related issues in Magnoliopsidae growing slaine and waterlogged soils. The main interest was to study the effect of high NaCI concentrations in the root zone on NO3 uptake. Soil salinity is a major agricultural problem in many semiarid and arid regions of the world and NaCI induced reduction in NO3-uptake had occasionally been assumed to contribute to the negative effects on growth and development in crops. ... Zie: Summary

Die Lawinensituation am Lahnsattel in integrativer geographischer Perspektive

Die Zentralanstalt für Meteorologie und Geodynamik hat die Aufarbeitung eines Archives, das die außergewöhnlichen Lawinenkatastrophen Ende des 19. / Anfang des 20. Jahrhunderts am Lahnsattel dokumentiert, in Form einer Masterarbeit in Auftrag gegeben. Ziel dieser Arbeit ist es die Katastrophenereignisse aufzuarbeiten, die Zusammenhänge zwischen intensiver forstwirtschaftlicher Nutzung und physischer Geographie im Untersuchungsgebiet herzustellen sowie anhand der gesammelten Daten eine Beurteilung der gegenwärtigen Lawinensituation durchzuführen. Das Untersuchungsgebiet ist das Gebiet am Lahnsattel und der 1766 m hohe Göller. Die Lage des Göllers im Nordstaugebiet bildet die Grundlage für eine ausgeprägte Lawinentätigkeit. Die steilen zum größten Teil waldfreien Hänge stellen ideale Einzugsgebiete für Lawinenabgänge dar. Integrativ geographische Methodiken erlauben historische Quellen, Klimadaten, Befragungen und Eigenrecherche als Arbeitsmittel heranzuziehen. Bereinigte Klimadaten werden in Excel Datenbanken verknüpft und in definierten Klimanormalperioden dargestellt, um entsprechende Grundlagen für eine Beurteilung der Lawinenereignisse bereitzustellen. Allen außergewöhnlichen Lawinenereignissen sind zwar Perioden mit überdurchschnittlichem Niederschlag vorausgegangen, allerdings kann die Niederschlagsmenge allein nicht als einziger Parameter zur Beurteilung und zur Prognose herangezogen werden. Von 1844 bis 1944 wurden 6 Lawinen dokumentiert, die den Talboden im Bereich des Lahnsattels erreichten. Drei Lawinen, 1844, 1878 und 1923 forderten insgesamt 27 Menschenleben. Anhand der analysierten Daten ist ein Bedrohungsszenario in der Gegenwart durchaus denkbar. Katastrophen wie 1878 oder 1923 wären heute allein durch die Tatsache, dass sich in den damals betroffenen Gebieten heute keine Siedlung mehr befindet, allerdings nicht mehr möglich. Die Ablagerungsgebiete dieser Katastrophenlawinen wurden zu roten Zonen erklärt. Faktoren für die unmittelbare Auslösung derartig katastrophaler Lawinenereignisse im Untersuchungsgebiet lassen sich mit dem erarbeiteten Datenmaterial nicht treffsicher beschreiben. Im Rahmen der integrativ-geographischen Methodik, der Zusammenschau von Lawinendisposition, geschichtlichem und wirtschaftlichem Hintergrund, sowie meteorologischen Daten, lassen sich die Einflüsse für eine prinzipielle Lawinentätigkeit am Lahnsattel aber gut darstellen.The intensive use of land for forestry purposes between the 18th and 19th century has resulted in serious interferences with nature. The aim of this thesis is to examine the catastrophic events, to investigate the connections between forestry and physical geography in the investigation area and to use the collected data to assess the current avalanche situation The Central Institute for Meteorology and Geodynamics has commissioned the processing of an archive in the form of a master's thesis, which deals with extraordinary avalanche disasters at the end of the 19th and the beginning of the 20th century on the Lahnsattel. The investigation area is the area at Lahnsattel and the 1766 m high Göller. The location of the Göller around the area of Nordstau is the reason for an intense avalanche activity. The steep mostly forest free slopes are perfect catchment areas for avalanche events. An integrative geographical methodology allows to consult historical sources, climate data, surveys and self-research. Adjusted climate data are connected in Excel databases and represented in defined climate normal periods as basis for analysing the avalanches. All exceptional avalanche events have been proceeded by periods of above average precipitation, however the precipitation is not the only parameter for the evaluation and the forecast for avalanches. From 1844 to 1944, six avalanches were documented that reached the valley floor of Lahnsattel. Three avalanches, 1844, 1878 and 1923, claimed a total of 27 lives. The analyzed data shows, that a threat scenario still can happen today. But catastrophes like 1878 or 1923 will not happen today, because there is no settlement in the affected area. The deposit area of the catastrophes were declared as red zones. It wasnt possible to find clear reasons and factors for the extraordinary avalanche disasters in the available data. With the integrative geographical method, an overview of the avalanche disposition, the historical and economical background and the meteorologic data, the influences for avalanche activity can be found.Roman RubiniggAbweichender Titel laut Übersetzung des Verfassers/der VerfasserinZusammenfassungen in Deutsch und EnglischKarl-Franzens-Universität Graz, Masterarbeit, 2018(VLID)258164

Effects of NaCl salinity on nitrate uptake and partitioning of N and C in Festuca rubra L. in relation to growth rate

The effect of salinity on nitrate net uptake rate was studied in the moderately salt tolerant halophyte Festuca rubra L., in relation to changes in relative growth rate, root weight ratio and nitrogen and carbon partitioning. Plants were grown for 21 days on nutrient solution containing 50, 100 and 200 Mol m(-3) sodium chloride. Control plants received no additional sodium chloride. Relative growth rate of Festuca rubra was reduced by exposure to a sodium chloride concentration as low as 50 mol m-3, resulting in a lower nitrogen 'demand' for plant growth and consequently in a lower nitrate net uptake rate. However, the accumulation of reduced nitrogen containing osmotic solutes increased the plant's nitrogen 'demand' slightly The decreased root weight ratio, caused by the stronger inhibition of root growth as compared to shoot growth upon elevated salinity levels complicated the interpretation of the effects of different salinity treatments on nitrate net uptake rates. Utilization of soluble sugars for osmotic adjustment did not divert significant amounts of carbohydrates from the carbon pool. To get insight into the physiological background of the interaction between sodium chloride salinity and nitrate uptake, additional complications in the growth analysis and N nutrition must be considered

Spatial patterns of radial oxygen loss and nitrate net flux along adventitious roots of rice raised in aerated or stagnant solution

Roots of rice (Oryza sativa L.) grown in stagnant de-oxygenated solution contain a 'tight' barrier to radial oxygen loss (ROL) in basal zones, whereas roots of plants grown in aerated solution do not. It is generally accepted that the barrier to ROL involves anatomical modifications in the apoplast of cell layers exterior to the aerenchyma. A possible drawback of this adaptation is a reduced capacity for nutrient uptake. Whether or not induction of a barrier to ROL influences the capacity of adventitious roots of rice to take up NO3- was determined in the present study, using NO3--selective microelectrodes. When transferred into O-2-free root medium, ROL from positions at 30-50 mm behind the tip of adventitious roots of plants raised in stagnant solution was only 4-6% of the rate from roots of plants raised in aerated solution, indicating the barrier to ROL was induced by growth in stagnant solution. For plants transferred into aerobic nutrient solution containing 0.1 mM NO3-, net NO3- uptake by these root zones, with or without a barrier to ROL, was the same. It is concluded that induction of a barrier to ROL had no effect on the capacity of adventitious roots of rice to take up NO3- from aerobic solution