Kartoffelanbau im ökologischen Landbau – Stand des Wissens und gegenwärtige Forschungsarbeiten

Die Kartoffel ist aus pflanzenbaulicher und ökonomischer Sicht eine wichtige Kultur im ökologischen Landbau. In den vergangenen Jahren wurden Anbaustrategien für Speisekartoffeln im Hinblick auf die Ertragssicherung und Qualitätsverbesserung erarbeitet und in die Praxis eingeführt. Forschungsbedarf ist für diesen Sektor vor allem bei der Regulierung von Krankheiten wie Phytophthora infestans oder Rhizoctonia solani zu sehen. Die Verarbeitung von ökologisch erzeugten Kartoffeln zu Chips oder Pommes frites spielt bislang eine untergeordnete Rolle. Diese könnte jedoch im Hinblick auf eine Ausweitung des ökologischen Landbaus zukünftig eine größere Bedeutung erlangen. Bislang liegen hierzu lediglich erste orientierende Anbauversuche mit einer produktspezifischen Qualitätsbewertung vor. Forschungsbedarf besteht in der Erarbeitung von Anbaustrategien im Hinblick auf die von der Verarbeitungsindustrie geforderten inneren und äußeren Qualitätsansprüche

Determination of islet cell antibodies using an ELISA system with a preparation of rat insulinoma (RIN A2) cells

An enzyme-linked immunosorbent assay (ELISA) was established for the detection of islet cell antibodies in human sera. The antigen was prepared from rat insulinoma (RIN A2) cells. Cells were dissociated in lysis buffer and the lysate was centrifuged at 100,000 x g. The supernatant was used to coat microtiter ELISA plates (10 micrograms protein/ml in PBS pH 7.2). Non-specific binding sites on the plates were blocked with 2% PBS-BSA. Human test sera were preabsorbed on separate plates using 2% PBS-BSA and incubated on precoated plates at an optimal dilution of 1/10 in 60 mM PBS for 60 min at 37 degrees C. Phosphatase-labeled anti-human IgG serum and phosphatase substrate were applied and the reaction was stopped by adding 3 M NaOH. Out of 90 sera from type I diabetic patients, 47 (52.2%) reacted in the new ELISA whereas none of 15 type II diabetics, 50 sera containing non-islet specific antibodies or 100 normal controls were positive. In the same group of patients, ICA were positive in 63.3%. When both, the ELISA and conventional ICA testing were applied, the number of positives was increased to 83%. The ICA-ELISA with the above described antigen preparation provides a well standardized and reproducible test method which is highly specific for type I diabetes. It may therefore be useful for large screening procedures

Complex collective states in a one-dimensional two-atom system

We consider a pair of identical two-level atoms interacting with a scalar field in one dimension, separated by a distance $x_{21}$. We restrict our attention to states where one atom is excited and the other is in the ground state, in symmetric or anti-symmetric combinations. We obtain exact collective decaying states, belonging to a complex spectral representation of the Hamiltonian. The imaginary parts of the eigenvalues give the decay rates, and the real parts give the average energy of the collective states. In one dimension there is strong interference between the fields emitted by the atoms, leading to long-range cooperative effects. The decay rates and the energy oscillate with the distance $x_{21}$. Depending on $x_{21}$, the decay rates will either decrease, vanish or increase as compared with the one-atom decay rate. We have sub- and super-radiance at periodic intervals. Our model may be used to study two-cavity electron wave-guides. The vanishing of the collective decay rates then suggests the possibility of obtaining stable configurations, where an electron is trapped inside the two cavities.Comment: 14 pages, 14 figures, submitted to Phys. Rev.

Evaluation of water balance components in the Elbe river catchment simulated by the regional climate model CCLM

For investigations of feedbacks between the hydrological cycle and the climate system, we assess the performance of the regional climate model CCLM in reconstructing the water balance of the Elbe river catchment. To this end long-term mean precipitation, evapotranspiration and runoff are evaluated. Extremes (90th percentile) are also considered in the case of precipitation. The data are provided by a CCLM presentday simulation for Europe that was driven by large-scale global reanalyses. The quality of the model results is analyzed with respect to suitable reference data for the period 1970 to 1999. The principal components of the hydrological cycle and their seasonal variations were captured well. Basin accumulated, averaged daily precipitation, evapotranspiration and runoff differ by no more than 10% from observations. Larger deviations occur mainly in summer, and at specific areas

Hysteresis of Backflow Imprinted in Collimated Jets

We report two different types of backflow from jets by performing 2D special relativistic hydrodynamical simulations. One is anti-parallel and quasi-straight to the main jet (quasi-straight backflow), and the other is bent path of the backflow (bent backflow). We find that the former appears when the head advance speed is comparable to or higher than the local sound speed at the hotspot while the latter appears when the head advance speed is slower than the sound speed bat the hotspot. Bent backflow collides with the unshocked jet and laterally squeezes the jet. At the same time, a pair of new oblique shocks are formed at the tip of the jet and new bent fast backflows are generated via these oblique shocks. The hysteresis of backflow collisions is thus imprinted in the jet as a node and anti-node structure. This process also promotes broadening of the jet cross sectional area and it also causes a decrease in the head advance velocity. This hydrodynamic process may be tested by observations of compact young jets.Comment: 9 pages, 5 figures, accepted for publication in ApJ

Auswirkungen der Beregnung von Kartoffeln in Abhängigkeit der Stallmistdüngung auf den Ertrag, die Qualität sowie die Verarbeitungseignung zu Pommes frites und Chips

Ökologisch erzeugte Kartoffeln, die zur Verarbeitung zu Pommes frites oder Chips genutzt werden sollen, müssen besondere Qualitätseigenschaften aufweisen. So wird beispielsweise ein mittlerer bis hoher Stärkegehalt bei gleichzeitig niedrigen Gehalten an reduzierenden Zuckern gefordert. Um den von der verarbeitenden Industrie geforderten Qualitätsansprüchen gerecht zu werden, ist neben einer ausgewogenen Düngung gerade auf leichten Böden auch eine ausreichende Wasserversorgung entscheidend, die oft nur über Beregnung sichergestellt werden kann. Unter den Fragestellungen, ob organischer Dünger (Stallmist) durch die Beregnung besser von den Verarbeitungskartoffeln ausgenutzt werden kann und inwiefern Ertragsstruktur und die Qualitätsparameter von Verarbeitungskartoffeln beeinflusst werden, wurde auf einem leichten Standort bei Hamburg im Jahr 2003 ein Feldversuch durchgeführt

Einfluss unterschiedlicher Kleegrasnutzungssysteme auf Ertrag, Sortierung und Qualität ökologisch erzeugter Verarbeitungskartoffeln

The most organic produced potatoes are used for direct marketing or home requirements. But due to the growing demand for “Convenience-products” like potato crisps and chips the production of processing potatoes offers farmers an alternative. In contrast to conventional agriculture the nutrient supply in organic potato production must be secured by preceding crops or organic fertilization. Clover grass as preceding crop is common in praxis. But as the case may be how the clover grass is utilized (mulching, cut mowing) a different nitrogen fixation and mineralization is possible. In a period of two years (2003/2004) the effect of different clover grass management systems on yield, grading and quality of processing potatoes was under examination on the experimental farm of the University of Kiel in Northern Germany. The tested management systems showed only a low effect on yield and quality on the following crop potato. In 2003 a small yield increase was achieved by the mulch system