Artificial pores attract barley roots and can reduce artifacts of pot experiments

Soil compaction is a severe agricultural problem. It is characterized by an increased resistance to root penetration and by a decreased amount of porosity in the soil. Until today it is not clear whether crop roots are able to actively detect remaining pores in compacted soil. Moreover, little is known about the capability of roots to leave pores again if the mechanical resistance of the bulk soil allows so. The aim of this study was to investigate the root growth response of spring barley (Hordeum vulgare L. cv. Ascona) in different configurations of a compacted loamy soil containing pores. The three‐dimensional configurations of the root systems from three well watered and fertilized treatments were analyzed with X‐ray computed tomography. All soil‐filled cylindrical plastic pots (diameter: 60 mm, height: 210 mm) contained loose topsoil but differed in subsoil structure. In treatment ‘Loose' [L] the pots were entirely filled with loose soil. Treatment ‘Lower part compacted' [C] contained compacted soil in the lower part of the pots. Likewise, treatment ‘Pores' [P] contained compacted soil in the lower part too, but here 16 artificial pores (1 mm diameter) were generated in the central part of the compacted subsoil zone. Comparison of the two treatments with compacted soil [C] and [P] showed that the roots were able to detect pores. However, the roots frequently grew across the pores or left the pores again after having grown into them, leading to a significantly higher fraction of roots exploring the compacted soil in the treatment with pores compared to the treatment without pores. These findings are useful for designing controlled experiments in pots of limited size that can mimic root growth in relatively complex soil structures which are more similar to field situations than usual pot experiments.     

Capillary forces in suspension rheology

The rheology of suspensions (solid particles dispersed in a fluid) is controlled primarily through the volume fraction of solids. We show that the addition of small amounts of a secondary fluid, immiscible with the continuous phase of the suspension, causes agglomeration due to capillary forces and creates particle networks, dramatically altering the bulk rheological behavior from predominantly viscous or weakly elastic to highly elastic or gel-like. This universal phenomenon is observed for a rich variety of particle/liquid systems, independent of whether the second liquid wets the particles better or worse than the primary liquid. These admixtures form stable suspensions where settling would otherwise occur and may serve as a precursor for microporous polymer foams, or lightweight ceramics.     

Thermal degradation studies of glucose/glycine melanoidins

Nondialyzable and water-insoluble melanoidins, isolated from a glucose/glycine model reaction mixture, which was prepared in a standardized way according to the guidelines of the COST Action 919, were heated at different temperatures ranging from 100 to 300 degrees C. Among the volatile compounds, which were analyzed by SPME and GC-MS, pyrazines, pyridines, pyrroles, and furans were detected. In general, total amounts of volatile compounds increased with the temperature. When water-insoluble melanoidins were heated, especially at higher temperatures, this resulted in a higher diversity of isolated compounds. For furans, pyrroles, pyrazines, and carbonyl compounds a maximum was observed in the case of high molecular weight melanoidins around 200-220 degrees C. Pyridines and total oxazoles, however, were generated in higher yields with increasing temperatures. These results demonstrate the possibility of producing some flavor-significant volatiles from heated standard melanoidins at temperatures relevant to food preparation and contribute to the flavor aspects originating from melanoidins.     

Root production and root mortality of winter wheat grown on sandy and loamy soils in different farming systems

Winter wheat was grown over 2 years (1995, 1996) in an organic and integrated cropping system on sandy and loamy soils. Root growth was measured on five to six occasions each year with an auger sampling procedure and the ingrowth core method. The first resulted in an estimate of net root development, while the latter revealed gross root growth (GG) or root production. Total root production was about 80-150 km m^-2 (0- to 30-cm soil layer) between April and July and exceeded the net size of the root system at harvest by a factor of between 2 and 4. The C input into the soil could be estimated as 1.4-2.6 t ha^-1 by this root production. The cropping systems had nearly no influence on root production. The largest differences occurred between the years. The net root length tended to be lower on sandy soils compared to the loam, but total root production was higher. Root mortality, which is the difference between GG and net root growth, was also higher on sandy soils. The turnover index, which is the mean of the relative root production rates and relative root mortality rates, was positively related to the soil sand content in both years.     

Manipulating the pathway of ammonia assimilation in transgenic non-legumes and legumes

In 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.     

Estimation of dry matter and starch concentration in potatoes by determination of under-water weight and near infrared spectroscopy

Summary Potato food and non-food industries need information about dry matter (DM) and starch concentration of tubers. Therefore, calculation of dry matter concentration and starch concentration via under-water weight were optimised. Determination coefficients (R²) were 0.92 and 0.83 (starch concentration between 13 and 23%), and 0.94 and 0.88 (starch concentration ≥13%) for dry matter and starch concentration, respectively. In a second attempt, near infrared spectroscopy models for both constituents were calculated (R² of validation set was 0.98 and 0.96 for dry matter and starch concentration, respectively). Results pointed out superiority of the near infrared technique with less divergence than the techniques of under-water weighting.     

Exposure to non‐ionizing electromagnetic radiation of public risk prevention instruments threatens the quality of spermatozoids

The use of artificial insemination in cattle breeding has evolved to global extent, and insemination doses are often shipped via air transport which requires strict radiation‐based examinations. For the determination of effect of non‐ionizing radiation (NIR), to which are beings frequently exposed due to protection of airport or cultural event security, freshly ejaculated and cryopreserved bovine spermatozoa were used as experimental model. Following radiation with hand‐held metal detector in various exposition times (0, 10 s, 15, 30 and 60 min—groups FR, FR10, FR15, FR30 and FR60) the spermatozoa underwent motility and DNA fragmentation analyses. Study on cryoconserved semen treated with NIR was performed in time intervals 0, 10 s, 1 and 5 min (insemination doses radiated before cryoconservation—CB, CB10, CB1, CB5; samples radiated after freezing—CA, CA10, CA1 and CA5). Fresh semen and insemination doses radiated after cryoconservation showed significantly lower total and progressive motility. No effect on motility parameters was detected in semen extended with cryopreservative medium and radiated prior to freezing. Surprisingly, NIR showed a potential to stimulate spermatozoa velocity; however, the effect was modulated throughout the post‐thawing incubation. Based on the DNA fragmentation assay, sperm DNA stayed intact. Present study underlines the potential harm of NIR, which is frequently used in everyday life, with overall adverse impact on human and animal reproduction. Current study also points out on interesting short‐term spermatozoa stimulation induced by NIR.     

ICT and Sustainable Mobility: From Impacts to Policy

ABSTRACT The question “Will using Information and Communication Technology (ICT) systems enable a more sustainable mobility?” is answered through analyzing current ICT policy in the EU and the United States of America (USA), through developing a conceptual model to structure the expected direct and indirect effects of ICT systems on mobility, and through building models for three selected ICT systems to estimate their quantitative effects on mobility. Based on the models, ICT systems seem to have limited mobility reduction potential (in terms of CO₂ emissions and kilometer savings). On the short term, because of efficiency gains, ICT systems have a positive impact. In the long term, better quality of mobility will attract new demand and this will again result in an increase of travel. For policymakers this implies that ICT systems in the short run can make mobility more efficient. In the long run, to prevent the more efficient mobility from attracting new traffic, the implementation of any ICT system should be accompanied by a stronger pricing policy.     

Markierungsversuche zur Analyse des Aktionsraums und der Ortsbewegungen des Bisams(Ondatra zibethica L.)

Zusammenfassung 1. Von 926 Bisam-Markierungen liegen 267 Wiederfänge vor. Aufgrund dieses Wiederfangergebnisses von rund 30% kann die Gesamtpopulation der Bisamratten in Bayern unter Vorbehalt auf etwa 360 000 Tiere geschätzt werden.2. In der Statistik der Distanzen zwischen Markierungs- und Wiederfangsort zeichnen sich vier Bereiche des Aktionsraums ab. Nur einzelne Tiere dringen über diesen hinaus vor und können als Emigranten angesehen werden.3. Der hohe Prozentsatz der in der Nähe ihres Markierungsortes wiedergefangenen Tiere ist Ausdruck einer stark ausgeprägten Ortstreue. Sie steht im Widerspruch zu der dem Bisam oft zugesprochenen Wanderlust.4. Eine Analyse der Wiederfangdaten unter Berücksichtigung des Zeitfaktors bestätigt die erkannten Bereiche und die Größe des Aktionsraums und zeigt, daß es sich bei den bisher als Wanderungen bezeichneten Ortsbewegungen nicht um Tierwanderungen, sondern um normale Ausbreitungsbewegungen handelt.

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Résumé 1. En 1966 à 1969 tous ensemble 926 rats musqués ont été marqués de quels 267 ont été rattrapés. Ce résultat permit une estimation de la population des rats musqués en Bavière avec précaution sur 360 000 têtes.2. La statistique des distances entre le lieu du marquage et de la capture destine quatre zones d'espace d'action. Seulement quelques-uns des rats musqués se montraient comme migrateurs.3. Le haut pourcentage des captures tout près de lieu du marquage est l'expression d'une très grande fidélité pour le domaine vital. Elle est en contradiction avec l'instinct de migration, attribué souvent aux rats musqués.4. Une analyse des indications de la capture en raison de la durée depuis le marquage, confirme les zones et la grandeur du domaine vital. En outre elle montre que les migrations soidisants du rat musqué, sont seulement des mouvements d'une propagation normale.