Thesis (MScAgric (Plant Pathology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Maize is the most important cereal crop produced in southern Africa. Maize producers, processors, and consumers in the region, however, are affected by Fusarium ear rot, a disease caused primarily by the fungal pathogen Fusarium verticillioides that reduces grain quality and potentially contaminates the grain with mycotoxins (fumonisin). Due to the threat of fumonisin to human and animal health, and the economic losses associated with reductions in grain quality, strategies aimed at the prevention of Fusarium ear rot and fumonisin contamination are required. These preventative strategies should be focused on protecting the crop prior to harvest, as damage is known to occur in the field before storage.
Chapter 1 provides the reader with a broad overview of maize production in southern Africa, the disease Fusarium ear rot caused by F. verticillioides, and the contamination of grain with fumonisins. Potential disease management practices are summarised, and the role of host resistance and its underlying mechanisms emphasised. Finally, the use of plant breeding and resistance elicitors as methods to enhance host resistance in maize towards Fusarium ear rot and fumonisin contamination are discussed in detail.
The planting of maize genotypes with enhanced host resistance potentially offers the most efficient method to reduce Fusarium ear rot and mycotoxin contamination. If plant breeding is to be used to enhance resistance, sources of genetic resistance are required. These sources would ideally be in the form of locally adapted maize genotypes, such as inbred lines. In Chapter 2, maize inbred lines used in local breeding programmes, which are adapted to the production conditions in southern Africa, were evaluated as potential sources of resistance to Fusarium ear rot and fumonisin contamination. If inbred lines with good genetic resistance were to be identified they could be used by breeding programmes to develop commercial maize cultivars with resistance to Fusarium ear rot and fumonisin.
Activation of resistance responses in normally susceptible maize genotypes using resistance elicitors could provide a novel management strategy for Fusarium ear rot control, as no commercial cultivars with complete resistance to this disease have been identified in southern Africa. Elicitors have previously been found to induce resistance to plant pathogens, mostly in dicotyledonous crops, but the ability of a range of elicitors to reduce Fusarium ear rot and fumonisin contamination in maize has not been investigated. In Chapter 3, a variety of chemical elicitors that induced resistance in other plant-pathogen systems were selected based on the different defence pathways that they stimulate, and evaluated in field and greenhouse trials. Three commercial maize hybrids were included in the trial, conducted at two different field sites, and the elicitors were tested for their ability to reduce Fusarium ear rot and fumonisin contamination of grain, as well as for their effect on yield. These elicitors could be applied in the field as part of an integrated disease management programme, are environmentally friendly, and would be affordable to commercial producers that produce the majority of maize in South Africa.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/4803 |
| Date | 03 1900 |
| Creators | Small, Ian |
| Contributors | Viljoen, A., Flett, B. C., McLeod, A., Marasas, W. F. O., University of Stellenbosch. Faculty of AgriSciences. Dept. of Plant Pathology. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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