Der Online-Leitfaden für Praxisversuche

In northern America on-farm research has been successfully performed for many years either by the farmer himself or with the support of extensions. Accordingly, many written guides on how to carry out on-farm research are available. The opportunities of the internet can be used to guide the practical user with his decisions better than written guides can do. Furthermore, so called online guides may support the user with statistical analysis tools and be of help improving the knowledge exchange between scientists and people in practice. In this contribution the first online guide for on-farm research is outlined in its basics

European perspectives of organic plant breeding and seed production in a genomics era.

For further optimisation of organic agricultural systems, more focus is required on organically produced seeds and the development of better adapted varieties. Organic plant breeding and seed production need to comply with the concept of naturalness as applied in organic agriculture, which not only includes the nonchemical and agro-ecological approaches, but also the integrity of life approach. As organic environments are less controllable and are more variable, breeding should aim at improved yield stability and product quality by being adapted to organic soil fertility as well as sustainable weed, pest and disease management. Also the ability to produce economicacceptable seed yield avoiding seed-borne diseases should be included. On the short term, organic plant production can gain better yield stability by increasing within-crop diversity by the use of mixtures of conventionally bred varieties or crop populations. Because of expected genotype by environment interaction more research is needed to define the best selection environment for selecting organic varieties. To arrive at better adapted varieties for organic farming systems the role of practical participatory plant breeding may be crucial. Although organic farming is clear on excluding the use of genetically modified organisms and their derivates, the use of molecular markers is still under debate. Questions arise with respect to their efficiency in selecting the most important organic traits, such as yield stability, and on the compounds and substances to produce and apply them. A major concern for a GM-free organic agriculture is an increasing contamination with genetically modified organisms in organic production and products, i.e., the problems related to co-existence of GM and non- GM agriculture. This paper discusses some important factors with regard to possible impact of co-existence on organic farming. Perspectives to a global scale of organic plant breeding and seed production are given from a European point of view

Leitfaden Saatgutgesundheit im Ökologischen Landbau - Gemüsekulturen

Im "Leitfaden Saatgutgesundheit im Ökologischen Landbau – Gemüsekulturen" werden ausgewählte saatgutbürtige Krankheiten von ackerbaulichen Kulturen samt vorbeugenden und direkten Regulierungsmöglichkeiten vorgestellt

Strategien zur Bekämpfung von Streifen- und Netzfleckenkrankheit der Gerste im Ökologischen Landbau

Barley leaf stripe (Drechslera graminea) and net blotch (Drechslera teres) are important seed transmitted diseases in organic barley cultivation in Europe. In the poster different measures and agents to control both diseases are investigated and discussed. Our research reveals that barley leaf stripe as well as net blotch can be sufficiently controlled in organic farming by physical methods (warm water and hot air treatment) or by the alcoholic plant strengtheners Lebermooser and - less effectively - by Milsana®. The plant protection product Cedomon® was not always sufficiently effective to control barley leaf stripe and net blotch. Depending on the imposed measure and on the barley type (hulless, hulled), variety and seed origin more or less adverse side effects on germination were observed and should thus be considered

Leitfaden Saatgutgesundheit im Ökologischen Landbau - Ackerkulturen

Im "Leitfaden Saatgutgesundheit im Ökologischen Landbau – Ackerkulturen" werden ausgewählte saatgutbürtige Krankheiten von ackerbaulichen Kulturen samt vorbeugenden und direkten Regulierungsmöglichkeiten vorgestellt

Vermeidung von saatgutbürtigen Krankheiten: Strategien für den Öko-Landbau

Due to legal provisions on the use of organic seed and the generally occurring expansion of organic agriculture the significance of healthy seed in organic farming is increasing. In a project the currently available as well as promising methods and substances shall be tested and evaluated for their use in practice. Results of exemplary investigations concerning the control of Ustilago nuda in spring wheat and spring barley by thermal treatment as well as the control of Tilletia caries in spring wheat by different plant strengtheners are presented

Strategien zur Bekämpfung von Brandkrankheiten bei Getreide im Ökologischen Landbau

Getreidebrände als saatgutübertragbare Erkrankungen der Ähre haben im Ökologischen Landbau stärkere Bedeutung erlangt, weil eine Beizung mit hochwirksamen Fungiziden unterbleibt. Eine Bekämpfung ist jedoch zwingend notwendig, weil in der Regel Ertragseinbußen eintreten und die Sporen toxikologisch bedenklich sind. Zudem droht der Saatgutvermehrung Schaden, denn bereits mehr als drei bzw. fünf befallene Pflanzen pro 150 m² führen zur Aberkennung des Basis- bzw. Z-Saatgutes. Resistente Sorten stehen kaum zur Verfügung, denn wegen der Saatbeizung bestand für die Züchtung seit Jahrzehnten keine Notwendigkeit, sich einer Resistenzzüchtung zu widmen. Das spiegelt sich auch in den Zulassungskriterien des Bundessortenamtes wider, wo die Anfälligkeit der Sorten auf Brandkrankheiten nicht berücksichtigt wird. Bei den relevanten Brandkrankheiten handelt es sich bei allen Triticum-Arten um Steinbrand (Tilletia tritici), Zwergsteinbrand (Tilletia controversa) und Flugbrand (Ustilago tritici), bei Gerste um Flugbrand (U. nuda) und Hartbrand (U. hordei) sowie bei Hafer um Flugbrand (U. avenae). Die Bekämpfung der Getreidebrände im Öko-Landbau ist spätestens seit der EU-Verordnung Nr. 1452/2003, welche die Verwendung von Saatgut aus ökologischem Anbau vorschreibt, eine vordringliche Aufgabe der Forschung. In Deutschland werden derzeit verschiedene Forschungsvorhaben zu dieser Problematik durchgeführt (Wilbois et al. 2005; Spieß 2006)

Nucleon-Nucleon Correlations and Two-Nucleon Currents in Exclusive (e,e′NNe,e'NN) Reactions

The contributions of short-range nucleon-nucleon (NN) correlations, various meson exchange current (MEC) terms and the influence of $\Delta$ isobar excitations (isobaric currents, IC) on exclusive two-nucleon knockout reactions induced by electron scattering are investigated. The nuclear structure functions are evaluated for nuclear matter. Realistic NN interactions derived in the framework of One-Boson-Exchange model are employed to evaluate the effects of correlations and MEC in a consistent way. The correlations correlations are determined by solving the Bethe-Goldstone equation. This yields significant contributions to the structure functions W_L and W_T of the (e,e'pn) and (e,e'pp) reactions. These contributions compete with MEC corrections originating from the $\pi$ and $\rho$ exchange terms of the same interaction. Special attention is paid to the so-called 'super parallel' kinematics at momentum transfers which can be measured e.g. at MAMI in Mainz.Comment: 14 pages, 8 figures include

Consistent Treatment of Relativistic Effects in Electrodisintegration of the Deuteron

The influence of relativistic contributions to deuteron electrodisintegration is systematically studied in various kinematic regions of energy and momentum transfer. As theoretical framework the equation-of-motion and the unitarily equivalent S-matrix approaches are used. In a (p/M)-expansion, all leading order relativistic $\pi$-exchange contributions consistent with the Bonn OBEPQ model are included. In addition, static heavy meson exchange currents including boost terms, $\gamma\pi\rho/\omega$-currents, and $\Delta$-isobar contributions are considered. Sizeable effects from the various relativistic two-body contributions, mainly from $\pi$-exchange, have been found in inclusive form factors and exclusive structure functions for a variety of kinematic regions.Comment: 41 pages revtex including 15 postscript figure

Meson exchange currents in electromagnetic one-nucleon emission

The role of meson exchange currents (MEC) in electron- and photon-induced one-nucleon emission processes is studied in a nonrelativistic model including correlations and final state interactions. The nuclear current is the sum of a one-body and of a two-body part. The two-body current includes pion seagull, pion-in-flight and the isobar current contributions. Numerical results are presented for the exclusive 16O(e,e'p)15N and 16O(\gamma,p)15N reactions. MEC effects are in general rather small in (e,e'p), while in (\gamma,p) they are always large and important to obtain a consistent description of (e,e'p) and (\gamma,p) data, with the same spectroscopic factors. The calculated (\gamma,p) cross sections are sensitive to short-range correlations at high values of the recoil momentum, where MEC effects are larger and overwhelm the contribution of correlations.Comment: 9 pages, 6 figure