bluuebunny/crossref_metadata_2025_split huggingface dataset:
Der Einfluß der Expositionszeit auf die Höhe der Bodenatmung bei Anwendung der Lundegardhmethode
Authors: Kleber Markus , Stahr Karl , Henning‐Müller I. 
Published: February 2007

AbstractZur Beurteilung der Rolle, die speziell kohlenstoffreiche Böden bei einer potentiellen Klimaveränderung spielen werden, sind weit mehr Daten erforderlich, als bisher verfügbar. Nicht an jedem Standort kann jedoch ein beliebig hoher technischer und personeller Aufwand getrieben werden. Es wurde daher in der vorgelegten Untersuchung das alte und einfach anzuwendende Lundegardh‐Verfahren zur Messung von Kohlendioxidemissionen aus Böden, das für Zeiträume bis zu 24 Stunden allgemein als Standard akzeptiert ist (Anderson, 1982), daraufhin geprüft, ob es auch bei längeren Installationszeiten verwertbare Information liefert Zu diesem Zweck wurden an sieben aufeinander folgenden Tagen je sechs Lundegardhglocken für jeweils einen Tag installiert (Behandlung B) und die Mittelwerte aus den sechs Wiederholungen zu einem Wochenwert addiert. In unmittelbarer räumlicher Nähe wurden parallel dazu je 6 Glocken für die Dauer von einem bis zu sieben Tagen installiert (Behandlung A). Dies wurde sowohl in der warmen, als auch in der kalten Jahreszeit vorgenommen. Der Vergleich der Variante A mit der Variante B ergab einen linearen Zusammenhang, der es erlaubt, kumulierte Tagesdaten durch Werte von mehrtägig installierten Glocken zu substituieren. Dies setzt die Berücksichtigung des “Kammereffektes”, einer vonTesarovaundGloser(1976) gefundenen Überschätzung der Respiration durch die längerfristig installierten Glocken voraus. Die dort angegebene Überschätzung um 16% pro Tag wurde im Sommer in der identischen Höhe gefunden, während im Winter, bei wesentlich niedrigeren Absolutwerten und damit einhergehend größerer statistischer Bedeutung von Ausreißern, eine Überschätzung von 46% auftrat.
Small Scale Heterogeneity of Soil Chemical Properties. I. A Technique for Rapid Aggregate Fractionation
Authors: Kayser Achim T. , Wilcke Wolfgang , Kaupenjohann Martin , Joslin John D. 
Published: February 2007

AbstractSeveral recent studies have observed physical, chemical and microbiological heterogeneities on the scale of soil aggregates. The publications emphasize the ecological importance of these small scale gradients. This paper introduces a method for the rapid fractionation of soil structure units into a surface fraction and a core fraction. The technique combines a rapid freezing in liquid N2 and standardized wet sieving of the structure units. During the sieving process the aggregate surfaces begin to thaw and are consequently washed through the sieve. The soil passing the sieve during a specified time is termed aggregate surface fraction, the remainder is the aggregate core fraction.Samples from 18 forest soil profiles were taken to study the precision and accuracy of the method, as well as factors determining the efficiency of fractionation. The precision of aggregate fractionation as determined by parallel fractionations yielded coefficients of variability of 5.3 to 7.5% and 6.5 to 11.4% for the amount of core and surface fraction, respectively. Furthermore, the proposed technique yielded results comparable to those obtained by manual razor‐peeling of the aggregate surfaces. The variation of concentrations of chemical parameters in water extracts of both aggregate fractions was up to six times greater than in soil solutions obtained from mixed samples. Increasing soil organic C resulted in a decrease in the proportion of the aggregate surface soil collected under fixed sieving conditions, while clay content correlated positively with the amount of the aggregate surface fraction collected.
Regulation of enzymes involved in the sulphur‐assimilatory pathway
Authors: Hawkesford Malcolm J. , Schneider Andrea , Belcher Ann R. , Clarkson David T. 
Published: February 2007

AbstractThe regulation of enzymes involved in sulphate assimilation in plants has been investigated. Extractable activity of ATP sulphurylase (the first enzyme of the assimilatory pathway) has been shown to be regulated by sulphate availability and O‐acctylserine (OAS) supply. OAS addition to the medium increased extractable activity and was able, at least partially, to overcome the repression of extraclable activity observed by supply of sulphate and cysteine. Cysteine synthase, the final enzyme of the cysteine biosynthetic pathway, was not regulated under these conditions.
Ermittlung bodenphysikalischer Kennwerte in Abhängigkeit von Bodenart, Lagerungsdichte und Humusgehalt
Authors: Krahmer Ulrich , Hennings Volker , Müller Udo , Schrey Heinz‐Peter 
Published: February 2007

AbstractDie Neuauflage der Bodenkundlichen Kartieranleitung als 4. Auflage enthält ein neues Bodenartendiagramm mit 31 zum Teil neu definierten Bodenarten. Sie verzichtet auf die vorher frei wählbaren alternativen Bezeichnungen bei Ton‐Schluff‐Gemengen, trägt neueren bodenkundlichen Erkenntnissen Rechnung und soll für die neuen und alten Bundesländer verbindlich sein. Da die Bodenart für nahezu alle bodenkundlichen Bewertungen eine elementare Ausgangsgröße ist, mußten einige aus ihr ableitbaren bodenphysikalischen Kennwerte neu berechnet und auf eine breitere Datenbasis gestellt werden. Für die vorliegende Auswertung standen 6352 Datensätze aus acht Bundesländern zur Verfügung. Aus ihnen wurden für die meisten Bodenarten repräsentative, statistisch gesicherte Werte der Luft‐, Feld‐, nutzbaren Feldkapazität und Wasserdurchlässigkeit als Funktion der Rohdichte, trocken, effektiven Lagerungsdichte sowie des Humusgehaltes zugeordnet und in tabellarischer Form dargestellt.
Luftkapazität, nutzbare Feldkapazität und Feldkapazität von Substrat‐Horizontgruppen ‐ eine statistische Auswertung von Labordatenbanken
Authors: Riek Winfried , Wessolek Gerd , Renger Manfred , Vetterlein Eberhard 
Published: February 2007

AbstractDie vorliegende Auswertung basiert auf mehr als 6000 Bodenhorizontdaten, die den Labordatenbanken der geologischen Dienste mehrerer Bundesländer entstammen. Zur statistischen Bearbeitung wurden Dateien mit einer gezielten Differenzierung nach geologischen Ausgangssubstraten bzw. petrographisch‐genetischen Angaben angelegt. Die Abschätzung des Einflusses von Bodenart, Humusgehalt und Trockenrohdichte auf die Kennwerte Feldkapazität, nutzbare Feldkapazität und Luftkapazität erfolgte regressionsanalytisch für Substrat‐Horizont‐Gruppen. Unter geogenetischen Aspekten konnte ein Vergleich mit den bodenphysikalischen Angaben der Bodenkundlichen Kartieranleitung (AG Bodenkunde 1982) angestellt werden. Zur Ableitung der Kenngrößen FK, nFK und LK wird exemplarisch für Lößböden ein Schätzrahmen vorgestellt, der die Bodenhorizontierung berücksichtigt.
Migration of Cesium‐137 in typical soils of North Germany ten years after the Chernobyl accident
Authors: Giani Luise , Helmers Heinz 
Published: February 2007

AbstractTen years after the Chernobyl disaster the Cs‐137 migration of typical soils of North Germany (Folic Histosol, Haplic Podzol, Dystric Gleysol, Eutric Fluvisol) has been investigated and compared to their Cs distribution in 1986. In 1986 nearly 90% of the Cs‐137 occurred in the upper 1–5 cm soil sections, whereas it was 50–70% in 1996. The more regular distribution ten years after the accident shows that migration processes have taken place. The Podzol presented a high migration with marked Cs‐137 losses in the top soil. The Gleysol showed the lowest migration down to 10 cm depth. A nearly similar pattern at the top was found within the Histosol, however, a ratio of 10% Cs‐137 in the 10–15 cm section indicated a deeper migration. Despite the large clay content, the Fluvisol showed a regular Cs distribution within its profile, probably resulting from cattle steps and/or peloturbation.
Estimation of ammonia losses after application of liquid cattle manure on grassland
Authors: Braschkat Jörg , Mannheim Thomas , Marschner Horst 
Published: February 2007

AbstractField experiments under various conditions were carried out in Hohenheim and the Allgäu to measure the effects of liquid manure properties and meteorological factors on ammonia losses. The micrometeorological method (IHF) and the wind tunnel method were used. Depending on the prevailing conditions the ammonia losses varied between 14 and 99% of the applied ammonium nitrogen. The relationship between the ammonia loss and the logarithm of the dry matter content of liquid manure was highly significant. The dry matter content also influenced the time course of the ammonia loss. Solar radiation was the other major factor affecting ammonia loss. Compared to dry matter content and‐solar radiation, effects of other factors such as ammonium content and pH of liquid manure, air temperature, relative humidity and wind speed were small in the given range tested. Based on the relationships between the various parameters a simple model for estimation of ammonia loss was developed.
Ammoniakemissionen aus alternden Pflanzen und bei der Zersetzung von Ernterückständen
Authors: Mannheim Thomas , Braschkat Jörg , Marschner Horst 
Published: February 2007

AbstractDie unter naturnahen Bedingungen mit der Windtunnelmethode gemessenen NH3‐Emissionen aus Pflanzenbeständen betrugen zwischen Blüte und Reife 0,8 bis 1,4% des Nt‐Gehaltes der oberirdischen Pflanzenmasse, entsprechend 1,1 bis 2,9 kg NH3‐N ha−1. Die höchsten Emissionen wurden bei Ackerbohnen gefunden; die Emissionen aus Winterweizen, Sommerraps und Senf lagen auf niedrigerem Niveau. Durch Entfernen eines Teiles der Ähren (Sink‐Reduktion) wurde die Höhe der NH3‐Emission nicht verändert, jedoch vorverlegt ebenso wie die Seneszenz. Dies läßt darauf schließen, daß die NH3‐Emission in enger Beziehung zur Seneszenz steht.Die NH3‐Emissionen aus Ernterückständen betrugen zwischen 0,9 und 3,7% des Nt‐Gehaltes. Während aus wasserreichen Zuckerrübenblättern und aus Kartoffelkraut Verluste von 8,6 bis zu 12,6 kg NH3‐N ha−1 auftraten, emittierte aus N‐reichem Ackerbohnenstroh, wahrscheinlich aufgrund des hohen Trockensubstanzgehaltes, verhältnismäßig wenig NH3 (3,1 kg N ha−1; 0,9% des Nt‐Gehaltes). Durch Einarbeitung von Zuckerrübenblatt in den Boden konnte die NH3‐Emission um 81% reduziert werden, durch Mulchen um 63%.
Specific surface area and surface charges of some argentinian soils
Authors: Sánchez R. M. Torres , Falasca S. 
Published: February 2007

AbstractThe specific surface areas of nine argentinian soils obtained by adsorption followed the order N2 < ethylene glycol < H2O, attributed to the presence of smectites (verified by XRD analysis) and some organic coating. The H2O2 treatment of these soils modified the former order of surface area determined by different absorbents. This order was modified because the mineral surface was evidenced and an increase of cation adsorption was produced by organic matter removal. This fact was supported by the decrease of PZC values of soils after H2O2 treatment.The specific surface area of initial soils obtained by water and ethylene glycol adsorptions showed a good correlation with carbon content and CEC of untreated soils and with the PZC of protonated soils.
Ammonium fluxes into plant roots: Energetics, kinetics and regulation
Authors: Glass Anthony D. M. , Erner Yair , Kronzucker Herbert J. , Schjoerring Jan K. , Siddiqi M. Yaeesh , Wang M.‐Yuan 
Published: February 2007

AbstractAmmonium uptake across the plasma membranes of seedling roots of intact rice plants is thermodynamically active at low external concentrations, and consequently, electrogenic uniport is an unlikely mechanism for influx. At higher NH4+ concentrations uptake is passive and electrogenic uniport is a possibility. While passive permeation of NH3 is also possible at high external [NH4+], influx measurements at 10 mM NH4+ demonstrated a pH dependence which was inconsistent with significant NH3 permeation. Kinetic studies using 13NH4+ established that influx at low external [H4+] occurred via high affinity transport systems (HATS) in rice and spruce, while at higher [NH4+], influx was mediated by low affinity transport systems (LATS), that showed linear concentration dependence. Ammonium influx via the HATS was shown to be up‐regulated or down‐regulated in response to changes of N status, whereas influx in the LATS was insensitive to N status. The identity or identities of the regulatory signals responsible for controlling influx are discussed.
Manipulating the pathway of ammonia assimilation in transgenic non‐legumes and legumes
Authors: Hirel Bertrand , Phillipson Belinda , Murchie Erik , Suzuki Akira , Kunz Caroline , Ferrario Sylvie , Limami Anis , Chaillou Sylvain , Deleens Eliane , Brugière Norbert , Chaumont‐Bonnet Muriel , Foyer Christine , Morot‐Gaudry Jean‐François 
Published: February 2007

AbstractIn this paper we discuss the ways in which our understanding of the nature of the molecular controls of nitrogen assimilation has been increased by the use of non‐leguminous and leguminous plants with genetically‐altered capacities for ammonia assimilation. Using tobacco or Lotus as model plants, Glutamine synthetase (GS) and glutamate synthase (GOGAT) activities have been altered by stimulating or inhibiting in an organ‐ or tissue‐specific manner the expression of the corresponding genes. In a few selected examples, the physiological impact of these genetic manipulations has been studied on plants grown under different nitrogen regimes. The use of such genetically‐modified plants will allow us to better understand the molecular control of this metabolic pathway. It is also potentially of great importance in agriculture if such internal and stable modifications are beneficial in terms of nitrogen use efficiency, thus avoiding an excessive utilization of fertilizers or herbicides (GS inhibitors). Our current knowledge and prospects for future development are explored.
Aluminum and iron(III) species in the soil solution including organic complexes with citrate and humic substances
Authors: Gerke Jörg 
Published: February 2007

AbstractThe solubility of Al and Fe in soil is of relevance for their toxicity and availability, respectively, to plant roots. Humic substances as the main part of stable soil organic matter and citrate which is often excreted by P deficient plants are strong complexants of Al and Fe(III). Therefore, equations were developed to calculate the Al and Fe(III) species distribution in the soil solution in the presence of humic substances and citrate as organic ligands.Calculations in the pH range 4.0–7.0 showed that at higher pH humic‐Al complexes were the most important species whereas AlOH‐citrate− dominated between pH 4.0 and 5.4. Free monomeric Al and AlSO4+ were of minor relevance.Iron(III) species calculations showed that humic‐Fe complexes were the main species in the pH range 4.0–7.0. But if mugineic acid, a Fe complexing phytosiderophore released into the rhizosphere by graminaceous plant species, was present in the soil solution (10−6 M), Fe‐mugineic acid complexes accounted for most of the Fe in solution. Fe‐citrate− was relevant at lower pH but contributed little to Fe(III) species at pH > 6.0.The results demonstrate the strong importance of the considered organic ligands for Fe and Al in the soil solution.
Changes of Al and Heavy Metal Concentrations in Slovak Soils During the Last 25 Years
Authors: Berghofer Ralf , Wilcke Wolfgang , Linkeš Vladimír , Nestroy Otmar , Zech Wolfgang 
Published: February 2007

AbstractThe objective of this study was to investigate changes of total concentrations and various extract‐defined Al and heavy metal fractions in Slovak agricultural soils during the last 25 years. We compared 7 stored soil samples collected between 1966 and 1970 with samples collected in 1994 at the same sites. Seven fractions of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were determined with a sequential extraction procedure in all samples. Total concentrations of Cd, Zn, Mn, Ni, and Cu were lower in the 1994 samples; those of Al, Fe, Pb, and Cr were higher. Based on the initial concentrations, the average total concentration changes were: Cd(‐10,3%)<Zn(‐7,2%)<Mn(‐4,8%)<Ni(‐2,3%)<Cu(‐1,4%)<Al(+2,1%)<Fe(+2,9%)<Cr(+7,4%)<Pb(+8,3%). This row is consistent with the decrease in metal mobility. The differences in salt‐extractable metals showed the same pattern; however, changes were more pronounced than for total concentrations. The results suggest that decreases during the last 25 years are caused by higher leaching than deposition rates and increases vice versa. The highest increase in Cr and Pb concentrations is observed in the EDTA‐extractable fraction, which mainly characterizes organically bound metals.
Cd translocation into generative organs of linseed (Linum usitatissimum L.)
Authors: Becher Monika , Wörner Annke , Schubert Sven 
Published: February 2007

AbstractLinseed is able to accumulate considerably high concentrations of Cd in generative organs, the dietary critical value of 0.3 μg Cd/g seed often being exceeded. Differences between genotypes of linseed in this respect, however, have been observed but the underlying mechanisms responsible for these differences are unknown. The aim of the present work was to identify these mechanisms by studying the Cd accumulation of the linseed genotypes Antares and McGregor which differ in their ability to accumulate Cd in the seeds. Cultivar Antares is a high and cv. McGregor a low Cd accumulator which was confirmed in a pot experiment. It was found that the differences between these genotypes were Cd‐specific and were caused neither by single seed weight nor by Cd translocation into the shoot. The distribution pattern of Cd within mature capsules between the pericarp and the seeds differed from that of Ca which was used as a phloem‐immobile reference ion. From these results we conclude that Cd was translocated from the pericarp into the seeds via the phloem. This conclusion was supported by direct Cd determination in collected phloem sap from linseed stems. As sources of seed‐Cd we identified the pericarps of capsules and the leaves. The genotype differences concerning the Cd concentrations in the seeds may be explained in terms of differences in phloem translocation of Cd.
Relationship of apple vitamin C and antioxidant contents to harvest date and postharvest pathogen infection
Authors: Davey Mark W , Auwerkerken Annemarie , Keulemans Johan 
Published: February 2007

AbstractA surprisingly strong correlation between the date of commercial harvest and the mean vitamin C (L‐ascorbate, L‐AA) contents of fruits from Belgian‐grown Malus × domestica cultivars was reported recently (Davey MW and Keulemans J, J Agric Food Chem 52:8031–8038 (2004)). The study has been extended to show that this correlation remains consistent over different production years and that harvest date is also significantly correlated with fruit L‐AA and total antioxidant activities but not with glutathione (GSH) levels or other physiological parameters of fruits. L‐AA concentrations were also found to be negatively correlated with mean preharvest daytime temperature; however, since preharvest temperature and harvest date themselves are closely linked, it was not possible to definitively separate the relative contributions of genetic and environmental factors to these traits. It is also shown that the susceptibility of fruits of different apple genotypes to postharvest infection with Botrytris cinerea decreases with increasing harvest date and that this susceptibility is correlated with fruit vitamin C but not GSH levels. There is no such relationship underlying the susceptibility of fruits to postharvest infection with Gloeosporium fructigenum. These results are discussed in the context of low‐input breeding for improved fruit quality and disease resistance via selection of fruits with improved antioxidant defence capabilities. Copyright © 2007 Society of Chemical Industry
Reproducibility of the Italian ISQ method for quality classification of bread wheats: An evaluation by expert assessors
Authors: Foca Giorgia , Ulrici Alessandro , Corbellini Maria , Pagani Maria Ambrogina , Lucisano Mara , Franchini Gian Carlo , Tassi Lorenzo 
Published: February 2007

AbstractThe great variety of different bakery products in Italy has led to the development of a method, the Synthetic Index of Quality (Indice Sintetico di Qualità, ISQ), for the classification of bread wheats in different quality categories. Based on chemical and rheological properties, each wheat sample is assigned to the most suitable class by an expert assessor. In many cases this procedure is not straightforward, making the class assignation uncertain, thus leading to the possibility of controversies during the trading phase. In the present study, in order to have a quantitative estimate of the validity and reliability of this procedure, a panel composed of nine expert assessors was utilised for the repeated evaluation of 100 samples of bread wheats of various qualities. The results suggest that the proposed approach can be used both to monitor the reliability of the single assessors, and to identify samples whose class assignation is reasonably indubitable, e.g. to be used for the development of automated classification methods. Moreover, the analysis of the most uncertain assignation cases can be useful in order to enhance the ISQ classification method itself. Copyright © 2007 Society of Chemical Industry
Carotenoid pigments in kale are influenced by nitrogen concentration and form
Authors: Kopsell Dean A , Kopsell David E , Curran‐Celentano Joanne 
Published: February 2007

AbstractThe objective of these experiments was to investigate the effects of N rate and form on the accumulation of lutein, β‐carotene and chlorophyll pigments in the leaf tissues of kale. Winterbor, Toscano and Redbor kale cultivars were greenhouse grown using nutrient solution culture. In the first study, N treatments were 6, 13, 26, 52 and 105 mg L−1 at a constant 1 NH4‐N:3 NO3‐N ratio. On a fresh weight basis, plant pigment concentrations (lutein, β‐carotene and chlorophylls) were not affected by N rate. When calculated on a dry weight basis, however, carotenoid pigments increased linearly in response to increasing N rate. In a second study, N rate was held constant at 105 mg L−1 and N form was changed as follows: 100% NH4‐N:0% NO3‐N, 75% NH4‐N:25% NO3‐N, 50% NH4‐N:50% NO3‐N, 25% NH4‐N:75% NO3‐N and 0% NH4‐N:100% NO3‐N. Increasing NO3‐N in nutrient solutions from 0 to 100% resulted in increases in both lutein and β‐carotene concentrations. Increases in carotenoid concentrations would be expected to increase the nutritional value of kale. Therefore N management should be considered in crop production programmes designed to increase the concentrations of nutritionally valuable carotenoids. Copyright © 2007 Society of Chemical Industry