|Munkvold, Gary - IOWA STATE UNIVERSITY|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 2, 2001
Publication Date: N/A
Interpretive Summary: Crown rust disease is the most damaging disease of oat in the U.S. and worldwide. Epidemics of the disease occur almost every year in most oat growing areas in the U.S. Selection for crown resistance in oat sometimes results in lower yielding oats. We used a method to simultaneously improve crown rust resistance, grain yield, and grain quality in oat. We showed that the method is predicted to result in improvements in all traits. Demonstrating the usefulness of the breeding method may help other oat breeders to improve disease resistance at the same time as they improve yields. In addition, we identified some experimental lines that may be useful in developing improved oat cultivars.
Technical Abstract: Host plant resistance to crown rust (Puccinia coronata) of oat based on single genes that completely prevent infection has been used extensively by breeders, but has not been durable. Partial resistance may be more durable, but has not been widely used because of its polygenic inheritance and the difficulty in measuring it. In order to integrate selection for partial resistance to crown rust with selection for increased grain yield and grain quality, we developed an oat population derived from 20 lines and cultivars selected to contribute alleles for partial resistance to crown rust, or for grain yield and grain quality potential. Partial resistance to crown rust, as measured by area under the disease progress curve (AUDPC), was highly heritable (H = 0.89 on an entry-mean basis), and was favorably correlated with grain yield, seed weight, and test weight measured in crown rust-inoculated plots. AUDPC was unfavorably correlated or uncorrelated with grain yield and quality traits measured in fungicide- treated plots. In order to simultaneously select for improved partial resistance and higher grain yield and seed weight both under low and high levels of crown rust infection, we estimated the parameters required to develop an optimum selection index for these traits.