Inheritance of Resistance to Stem Rust (Puccinia graminis subsp. graminicola) in Six Perennial Ryegrass (Lolium perenne) Crosses. Crystal A. Rose-Fricker, Former Graduate Research Assistant, Crop Science Department, Oregon State University, Corvallis 97331. William A. Meyer, President, Pure Seed Testing Inc., P.O. Box 449, Hubbard, OR 97032; and Warren E. Kronstad, Professor, Crop Science Department, Oregon State University, Corvallis 97331. Plant Dis. 70:678-681. Accepted for publication 3 January 1986. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-678.

Differences were found among four perennial ryegrass parental sources for stem rust reactions. Frequency distributions based on reaction patterns among segregating populations suggested resistance was predominately quantitatively inherited with minor and possibly some major genes. There was considerable genetic variability for resistance between parental lines as evidenced by different reaction patterns among progeny. Transgressive segregation toward susceptibility and slow-rusting types were evident. Selection for resistance would be more effective in the boot stage before anthesis (when higher heritability estimates were observed). Seedling reactions differed from adult plant responses, indicating that selection for resistance may be more successful if carried out in later growth stages. Results indicated that cultivars with greater and more durable resistance to stem rust could be obtained from these parental sources.