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Title: Effect of hybrid choice and soil and foliar elicitor treatments on powdery mildew disease severity, crop performance and/or expression of disease resistance mechanisms in tomato and courgette plants
Author: Toufexi, Eleftheria
Awarding Body: University of Newcastle Upon Tyne
Current Institution: University of Newcastle upon Tyne
Date of Award: 2011
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This aim of the study was to investigate the effect of using less susceptible hybrids, and sailor foliar applied elicitor treatments (Milsana, chitin/chitosan) on powdery mildew disease severity and crop performance parameters in greenhouse grown tomato and courgette. The second aim of the study was to investigate potential mode of actions of elicitors against powdery mildew. Two glasshouse experiments were performed with tomato plants under environmental conditions which resulted in the absence of powdery mildew infection; this allowed the effects of elicitor treatments on tomato plant growth and fruit yield and quality parameters to be determined in the absence of confounding effects of mildew infection. These data were then combined with data sets from identical trials carried out under contrasting environmental conditions and mildew disease pressure and used in multivariate analyses designed to identify associations between a environmental and agronomic drivers on tomato performance. Tomato yield and sugar content were only affectcd by hybrid choice, with the less susceptible tomato hybrid Elpida showing higher yield and higher sugar fruit content. Truss and leaf numbers were reduced by the use of Milsana and the sulphur fungicide treatment, which was included in the study as a positive control. Leaf chlorophyll was found to be higher in plants of the less susceptible hybrid Elpida and those treated with Milsana. Total antioxidant activity was not significantly affected by elicitors, but there was a trend towards higher antioxidant levels where standard Milsana treatment \vas applied. Multivariate analyses suggest that the environmental factors, relative humidity, mean and maximum daily temperature, were significant drivers. Powdery mildew severity was strongly positively associated with relative humidity and negatively with mean and maximum daily temperature. Leaf chlorophyll content was strongly negatively associated with relative humidity and positive ly with mean and maximum daily temperature. The drivers non-use of chitin soil amendment and foliar treatment (untreated control) were also identified as highly significant. Total fruit yield, number of fruits and fruit diameter were strongly positively associated with these drivers.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available