Year of Publication

2004

Document Type

Thesis

College

Agriculture

Department

Crop Science

First Advisor

David A. Van Sanford

Abstract

Fusarium graminearum, the causative agent of Fusarium head blight, is an economically important pathogen of wheat (Triticum aestivum). Breeding Fusarium head blight (FHB) resistant wheat requires knowledge of the underlying genetic control of FHB resistance. Genetic parameters for FHB resistance and five related traits were estimated in three populations at two locations and in two years. Moderate broad sense heritabilities for FHB severity and Fusarium damaged kernels (FDK) were observed. Incidence of FHB and the toxin deoxynivalenol (DON) accumulation had low to moderate broad sense heritabilities. Correlations between FDK and severity and FDK and DON were moderate to high in the three populations and do support indirect selection for FHB severity or DON based on FDK data alone, but it is important to be cautious in years with a high disease pressure when FHB resistance could be masked. A cycle of among-family and within-family selection cycle was conducted in 2003. Actual selection gain was higher than predicted gain based on variance components in 2003 in the within-family selection study. One population had also a strong response for low DON in the among-family selection study. The observed results suggest that selection for FHB resistant genotypes could be achieved with a recurrent selection scheme. Along with conventional breeding, molecular techniques are being used in breeding for FHB resistance. A first genotypic screening of the three populations showed Population 2 had the presence of a resistance allele form the resistant Chinese cultivar Sumai 3. Although Populations 1 and 3 did not have the resistance allele, the results suggest other sources of resistance might be present in these two populations.

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