Mainly within organic and low-input cropping systems, evolutionary breeding based on the creation of heterogeneous evolving composite cross populations (CCPs) has been gaining attention. The aim of this dissertation is to assess the agronomic potential and yield stability of wheat CCPs in comparison to pure line varieties under differing management systems. Three winter wheat CCPs were created in the UK in 2001, based on parental varieties that were selected for either their high yield or baking quality. The baking ...

Ziel dieser Arbeit war es, die Bedeutung phytotoxischer Sirodesmine in Interaktionen von Phoma lingam mit Brassica napus und Brassica juncea zu untersuchen. Ein weiteres Interesse galt dem Einfluß einer induzierten Seneszenz auf die Resistenzeigenschaften. Zur Isolierung von Sirodesmin PL wurde ein Säulenchromatographieverfahren auf Kieselgelbasis entwickelt. Mit dieser Methode konnten bis zu 100 µg Sirodesmin PL in reiner Form pro Arbeitsgang chromatographiert werden. Sirodesmin PL wurde in verschiedenen Dosierungen ...

This thesis combines experimental work on heterogeneous crop populations (HP) and species mixtures (SM) with a social scientific and participatory approach. Chapter 1 introduces crop communities as a concept to integrate multiple approaches to diversify farming systems. HPs provide intraspecific and SM interspecific diversity in crop communities. A key challenge for the genetic improvement of HPs, especially for root traits is to combine effective selection to improve HPs while maintaining intraspecific diversity. ...

In the past 10 to 15 years, there has been a tendency in Europe to switch from cereal based cropping systems, with winter and summer fallow, to cropping systems which combine greater crop diversity with maximum soil cover. Increasing the opportunities of including legumes into crop rotations to be grown as cover crops, intercropped or under-sown with cereals can provide multiple beneficial services to agro-ecosystems. A major concern is however, that many of the leguminous species of interest share important soil-borne ...

Potato cyst nematodes (PCN), Globodera rostochiensis and G. pallida are important potato pests responsible for high yield losses globally. The ability of PCN to persist in the soil for a long time makes their management challenging and therefore these nematodes are under strict quarantine regulations in many countries. Nevertheless, both PCN species have recently been reported in potato cropping systems in Kenya. Resistant potato cultivars reduce nematode densities in the field below damage threshold levels and thus ...

Parasitism caused by cereal cyst nematodes (CCNs) is a major limiting biotic factor in cereal cropping systems. CCNs attack cereal crops and can lead to significant yield reductions. Field observations in experimental wheat fields of the International Maize and Wheat Improvement Centre (CIMMYT) in Turkey had revealed a sharp decline in nematode populations of the cereal cyst nematode Heterodera filipjevi. Microscopic studies of the cyst samples obtained from these fields regularly demonstrated the presence of fungi ...

Durch die vermehrte Nachfrage von Biomöhren im Lebensmitteleinzelhandel ist die Anbaufläche ökologisch erzeugter Möhren in den letzten zehn Jahren deutlich angestiegen. Der Anbau konzentriert sich auf bestimmte Regionen und erfolgte damit zunehmend auf großen Schlägen in enger räumlicher und zeitlicher Abfolge. Mit der steigenden Wirtspflanzenpräsenz steigt auch der Befallsdruck durch die Möhrenfliege. Während der Schädling im konventionellen Anbau mit Insektiziden kontrolliert wird, stehen dem Ökologischen Landbau ...

Der Bodenschutz ist eine der wichtigsten Anforderungen an die Landwirtschaft im 21. Jahrhundert. Daher sind nicht-wendende Bodenbearbeitungssysteme, basierend auf dem Anbau von Untersaaten und Zwischenfrüchten, verstärkt in den Fokus der europäischen Agrarwirtschaft geraten. Allerdings können diese neuartigen Systeme das Spektrum und die Abundanz gewisser Krankheiten, Schädlinge und Unkräuter grundlegend verändern. Ein Beispiel ist die Zunahme von Unkräutern und ihren Samenbanken während der Übergangsphase von ...

Many plant strengtheners are promoted for their supposed effects on nutrient uptake and/or resistance induction (IR). In addition, many organic fertilizers are supposed to enhance plant health and several studies have shown that tomatoes grown organically are more resistant to late blight, caused by Phytophthora infestans to tomatoes grown conventionally. Much is known about the mechanisms underlying IR. In contrast, there is no systematic knowledge about genetic variation for IR. Therefore, the following questions ...

Parasitic weeds of the genera Striga, Orobanche, and Phelipanche pose a severe problem for agriculture because they are difficult to control and are highly destructive to several crops. The present work was carried out during the period October, 2009 to February, 2012 to evaluate the potential of arbuscular mycorrhizal fungi (AMF) to suppress P. ramosa on tomatoes and to investigate the effects of air-dried powder and aqueous extracts from Euphorbia hirta on germination and haustorium initiation in Phelipanche ramosa. ...