Muna Kadariya

Document Type

Thesis - University Access Only

Award Date

2006

Degree Name

Master of Science (MS)

Department / School

Agronomy

Abstract

Fusarium head blight (FHB), caused by fungus Fusarium graminearum Schwabe, has reemerged worldwide as disease of economic importance. Some effort aimed at the improvement of resistance to FHB has been practiced within spring wheat breeding programs for many years. With the advent of the US Wheat & Barley Scab Initiative, however, such efforts have become major resource expenditures. As such, it seems worthwhile to periodically monitor progress from such endeavors. In our first attempt to gauge progress, the objective ofthis study was to determine whether FHB resistance in a random sample of spring wheat germplasm selected has increased. A secondary objective was to test the association between several agronomic and FHB resistance traits. A study which included 36 spring wheat varieties and breeding lines originated from both the South Dakota State University and North Dakota State University spring wheat breeding programs was conducted. All the experimental lines were evaluated for agronomic (yield, test weight, heading days and height) and FHB resistance parameters for two consecutive seasons (summer of 2004 and 2005) at Brookings, SD and Prosper, ND. Artificial inoculation with Fusarium graminearum isolates were done to measure FHB resistance parameters. Analyses of variance revealed that entries were significantly different (P < 0.01) for the expression of agronomic and FHB resistance parameters at both locations. A significant interaction effect (P < 0.01) between entry, year and location for yield and test weight suggested that entry performance was inconsistent across locations and years. Also, significant interactions (P<0.01) between location, year and entry for severity explained the variability of expression of disease resistance. A simple linear regression analysis done with year of advancement, (i.e., when entries were first entered into the Advanced yield trials) and mean severity ratings at each locations, as independent and dependent variables, respectively, revealed that the slope was not statistically different from zero (b=-0.45; P=0.36). These results suggest that much phenotypic variation for FHB severity was present within this germplasm. At the same time, it appears that the entries sampled from the 5-year time span are still too variable, with respect to FHB severity, to begin monitoring progress in the advancement of FHB resistance. Results from Pearson's correlation coefficients revealed that yield and test weight were negatively correlated with FHB resistance parameters. Plant height was negatively correlated (r=-0.34, P<0.04; r=-0.40, P<0.01; r=-0.40, P=0.01) with incidence, severity, and disease index. Heading date was, however, not significantly associated with any of the FHB resistance parameters. This further supports that progress in FHB resistance will have impacts on yield and quality of wheat.

Library of Congress Subject Headings

Wheat -- Disease and pest resistance

Fusarium diseases of plants

Format

application/pdf

Number of Pages

63

Publisher

South Dakota State University

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