Sortenmischungen bei Getreide: Eine Chance für die ökologische Qualitätsproduktion

Um eine hohe Backqualität vor allem auch für Weißmehlprodukte zu erreichen, muss der Weizen optimal mit Nährstoffen versorgt werden. Dies bedeutet im ökologischen Landbau, dass das N-Angebot erhöht werden muss. Während dies einerseits Erträge und/oder Qualität steigern kann, erhöht es andererseits auch die Anfälligkeit des Bestandes vor allem gegenüber obligaten Pathogenen, wie Rost und Mehltau. Außerdem nimmt der Fusariumbefall bei erhöhtem N-Angebot deutlich zu. Fusariumbefall beeinflusst die Qualität durch die Produktion von Mykotoxinen sowie durch eine unmittelbare Verminderung der Backqualität

Erhaltung und Generierung genetischer Ressourcen durch die Entwicklung moderner Landrassen unserer Kulturpflanzen: Wozu wir die Ko-Evolution im Feld brauchen

Over the past 100 years, the biodiversity within varieties and species of field crops in agriculture has been reduced drastically through plant breeding approaches favouring genetic uniformity for all traits. This has practically eliminated all co-evolutionary proc-esses between hosts and their pests and pathogens. It also does not allow for dy-namic adaptation of plant populations to changing environment e.g. climatic change. Breeders and pathologists have all along pointed out the danger of this approach. Alternative approaches to the pure line breeding have been developed by using com-posite crosses, top crosses and population breeding. These have also been termed “evolutionary breeding”. The need for the reintroduction of diversity within our varieties by producing modern landraces that combine the advantages of the breeding success of the last 120 years and genetic variation is presented and discussed using the ex-ample of a modern composite cross population of wheat

N-uptake in winter wheat pure line varieties and winter wheat composite cross populations in the F11

Introduction In order to be able to adapt to changing environmental conditions, crop plants need a certain degree of diversity (Stevens 1942, Finckh 2008). The development of genetically diverse populations (composite cross populations, CCPs) instead of breeding entirely homogeneous pure line varieties by standard pedigree breeding methods is a strategy that aims at creating flexible varieties. Material and Methods Three winter wheat CCPs from the UK based on 20 modern wheat varieties (A) or a subset of either 12 high quality varieties (Q) or 9 high yielding parents (Y) were used. Since the F5 the CCPs have been grown under organic (O) and conventional (C) conditions in two parallel sets at the University of Kassel without artificial selection applied. In addition, since the F8 two A populations have been maintained as broadcast sown populations without mechanical weed control. In 2011/12 the F11 of all 14 populations were compared in a replicated field trial to the mixture of the 20 parents and the three commercial wheat cultivars Achat, Akteur, and Capo. N-uptake of the plants was measured at the beginning of stem elongation, at the flowering stage and in the ripe seeds and straw. Samples of fresh plants were cut and dried for 72 hours at 60 °C. Seeds and straw were dried after harvesting and all samples were milled and analyzed for N-content using a CHN analyzer. Nmin in the soil was measured in early spring, at the flowering stage and after harvest. Results and Discussion Overall, the differences among the populations in N-uptake appeared small. However, when comparing the conventionally and organically grown populations as two groups, in 2011, at flowering O- populations had taken up approximately 6% more N than the C-populations. These differences were not visible in early cut samples or in seeds and straw. Comparing N-uptake and the amount of available Nmin in the soil, no strong relationship appears. Sufficient seeds of the F10 were saved and a second year of field trials is on-going with the same populations in 2012/13. Detailed data including the second years data will be presented

Auswinterung im Jahr 2011/12: Auswirkungen auf Winterweizen-Liniensorten und Winterweizenpopulationen in der F10

TThree winter wheat composite cross (CC) populations were created in 2001 in the UK consisting either of 20 modern wheat parents (called A population), a subset of 12 high quality parents (Q), or a subset of 9 high yielding parents (Y). Seed of the F4 was transferred to the University of Kassel in 2005 and the populations were grown since then under organic and conventional conditions in well separated large (>100 m2) plots in two parallel sets (12 populations total) without conscious selection applied. In the conventional system fungicides and insecticides were not applied to expose the populations to natural pest and disease pressure. In addition, since the F8 two A populations have been maintained as broadcast sown populations without mechanical weed control. In the F10 all 14 populations were compared in a replicated field trial to the mixture of the 20 parents and the three wheat cultivars Achat, Akteur, and Capo. The parents were also grown in unreplicated plots for seed increase. A serious frost period of 3 weeks in February after an unusually mild winter resulted in winterkill in 16 out of the 20 parent varieties to the point that the plots had to be given up. In contrast, the populations, the mixture of the 20 parents, and the three reference varieties recovered, resulting in low but acceptable yields

Prävention der Kraut- und Knollenfäule ohne Kupfer - Möglichkeiten durch Diversifikation?

Krautfäuleresistenz und der Beginn des Knollenansatzes von Kartoffeln sind sehr wichtige Kriterien für die Sortenwahl und somit vorbeugende Maßnahmen gegen P. infestans. Diversifikationsstrategien könnten einen Beitrag zu einer Gesamtstrategie zur Prävention der Kraut- und Knollenfäule leisten und müssen weiter überdacht werden. Zukünftige Forschungsarbeiten sollten größere schmale Felder unter Praxisbedingungen einbeziehen, um einerseits Interferenzen zwischen den Versuchsgliedern zu reduzieren, andererseits die Wirksamkeit unter Praxisbedingungen zu prüfen. Zusätzlich müssen Fragen der Sortenwahl, was Resistenzen betrifft und die Anpassung der Pathogenpopulationen an Sorten mit einbezogen werden. Erste Untersuchungen finden derzeit statt. Pathogenisolate werden auf Virulenzen, Aggressivität und genetische Vielfalt hin untersucht, um eine Aussage über die langfristigen Auswirkungen verschiedener Management Strategien auf die Krankheitsentwicklung treffen zu können

Faktoren für die Integration von Mischkulturen in die landwirtschaftliche Praxis

In diesem Beitrag präsentieren wir die ersten empirisch fundierten Hypothesen über die Faktoren, die den Einsatz von landwirtschaftlichen Mischkulturen (Gemengen) in der Praxis bedingen. Die wichtigsten ermittelten Faktoren sind: (1) psychosoziale Faktoren, (2) argrar-systemische Faktoren, ernährungs-systemische Faktoren, (3) technologische Faktoren und (4) bio-ökologische Faktoren. In geplanten zukünftigen Interview-Studien werden diese Faktoren validiert und weiter differenziert

Populationszucht auf Anpassungsfähigkeit durch Diversität und partizipative on-farm Selektion am Beispiel Winterweizen

Das Projekt beschäftigt sich mit dem dynamischen Management genetischer Ressourcen. Am Beispiel von Winterweizen-Evolutionsramschen (auch Composite Crosses (CCs) genannt), wird die Auswirkung von unterschiedlichen Selektionsumwelten auf heterogene Weizenpopulationen untersucht. Zusätzlich wird in einem partizipativen Züchtungsansatz Saatgut der CC-Populationen an verschiedene Praxisbetriebe abgegeben, die Entwicklung der Populationen an den Standorten verfolgt und die Selektionskriterien der Landwirte dokumentiert. Anhand der Parameter Pflanzengesundheit, Stickstoffaneignungsvermögen, Backqualität, Ertrag und morphologische Diversität wird im Vergleichsanbau untersucht, wie sich ökologische und konventionelle Anbaubedingungen auf die Entwicklung der Populationen ausgewirkt haben. Die Ergebnisse deuten darauf hin, dass bereits die Auswahl der Sorten, aus denen die Populationen erstellt werden, von ausschlaggebender Bedeutung ist und in vielen Fällen auch nach etlichen Jahren in unterschiedlichen Selektionsumwelten die Populationseigenschaften noch maßgeblich prägt. Langfristig ermöglicht die Arbeit aber auch, Antworten auf die Frage zu geben, wie sich Anpassungsprozesse und damit auch Zuchtziele in der ökologischen und konventionellen Landwirtschaft unterscheiden und auf dieser Basis eine klare Definition und Abgrenzung ökologischer Zuchtziele vorzunehmen

Yield stability in winter wheat composite cross populations under organic and conventional conditions from the F5 to the F13.

The use of Composite Cross Populations (CCPs) as an alternative breeding approach, has gained significant interest, particularly due to the potential adaptability of evolving populations to specific locations. Three winter wheat (Triticum aestivum L.) CC populations were created in 2001 through collaboration between Elm Farm Research Centre (ORC) and the John Innes Institute in the UK. The populations were created through the inter-crossing of 20 parental varieties, in order to create a high yielding (Y) population; a high baking quality (Q) population and a population consisting of the 9 x 12 (YQ) intercrosses. Since 2005/6 (F5), the populations have been maintained at Kassel University without conscious selection. The objectives of the study are to increase the resilience, adaptability and performance of winter wheat through increased genetic diversity, as well as the improvement of breeding efficiency and the introduction of a novel breeding method that has the potential to provide an alternative source of germplasm in the form of CCPs. The adaptation of CCPs into mainstream practice is hampered by a number of factors including legal and quality aspects, but yield performance and stability of the CCPs are important criteria in view of increasing climatic unpredictability and for farmers (Finckh et al. 2000). Actual yields, as well as the yield stability of the populations relative to a common reference variety will be presented

Fruchtresistenz von Tomaten gegen P. infestans

Resistance of tomato fruits to Phytophthora infestans Late blight, caused by Phytophthora infestans (Mont) de Bary, is one of the important diseases in organic potato and tomato production. While some information on foliar disease resistance of tomatoes is available, virtually no information exists on the relation of leaf to fruit resistance. The central parameters of the infection chain, incubation and latency period were determined for 40 tomato varieties using three isolates of P. infestans. A total of 2858 fruits were drop inoculated in the lab and assessed daily for symptoms or sporulation for 16 days. There were significant variety by isolate interactions for incubation period, latency period and the interim time suggesting race specific interactions with tomato fruits. A Manteltest showed that the distance matrix of the isolate x variety interaction of leaf and fruit reactions were not correlated. Thus, it appears that fruit and leaf resistance are independent characters

Beziehung von Blatt- und Fruchtbefall mit Braunfäule bei Freilandtomaten

There is virtually no information available on the relationship between the reaction of tomatoes to Phytophthora infestans on leaves and fruits. Late blight and brown rot of tomatoes were assessed in outdoor conditions in 2005 on 15 tomato varieties and in 2006 for 41 varieties. Leaf disease expressed as area under the disease progress curve (AUDPC) and the proportion of healthy fruit of the total fruit were used as meas-ures. In 2005, the two varieties that were most susceptible to leaf blight produced the least healthy fruit while the most resistant variety produced the highest proportion of healthy fruit. However, for the varieties with more intermediate reactions to leaf blight there was great variation in the proportion of healthy fruit with an overall insignificant rank correlation for the two parameters (Spearman). The independence between leaf blight and brown rot was confirmed for the year 2006. While these data are an indica-tion that there is a need to assess leaf and fruit resistance independently, this will have to be done under controlled conditions or the fruit from the field has to be incu-bated after removal from the mother plants to determine if there were latent infections