Identification and Selection of F₆ and F₇ Families of Wheat for High-Temperature, Adult-Plant Resistance to Stripe Rust Using Hillplots. T. R. Schultz, Former Graduate Student, United States Department of Agriculture, Agricultural Research Service, Department of Plant Pathology, Washington State University, Pullman 99164-6430. R. F. Line, Plant Pathologist, United States Department of Agriculture, Agricultural Research Service, Department of Plant Pathology, Washington State University, Pullman 99164-6430. Plant Dis. 76:253-256. Accepted for publication 2 October 1991. 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, 1992. DOI: 10.1094/PD-76-0253.

F₆ and F₇ populations of winter wheat (Triticum aestivum) from nine crosses among the high-temperature adult-plant (HTAP) resistant cultivars, Gaines, Nugaines, Luke, Daws, and Stephens, and a susceptible line, PS279, were evaluated for resistance to Puccinia striiformis. Initial selection among F₆ families of each cross was done using rowplots at Mt. Vernon, WA, in 1986, and subsequent identification and selection among and within F₇ families was done using hillplots at Pullman, WA, in 1987. Stripe rust development in the hillplots was sufficient to observe significant disease differences among families of each cross. Significantly different phenotypes for disease expression were observed among and within families, indicating that it is possible to select for increased HTAP resistance at the F₇ generation. Transgressive segregation for both increased resistance and increased susceptibility was more frequently observed within families than among families. The additional space required to evaluate breeding lines at the subfamily level is much less when using hillplots than with other designs. The hillplot design is a practical and effective method for evaluating late-generation families for HTAP resistance to stripe rust.

Keyword(s): durable resistance, nonspecific resistance.