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Resistance

Reselection for Improved Resistance of Wheat to Stripe Rust. J. M. Krupinsky, Biological technician, Agricultural Research Service, U.S. Department of Agriculture, Montana State University, Bozeman, MT 59717, Present address of senior author: Research plant pathologist, Science and Education Administration, USDA, Northern Great Plains Research Center, Box 459, Mandan, ND 58554; E. L. Sharp, professor, Department of Plant Pathology, Montana State University, Bozeman, MT 59717. Phytopathology 69:400-404. Accepted for publication 13 September 1978. 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, 1979. DOI: 10.1094/Phyto-69-400.

Ten acceptable commercial cultivars of spring wheat with resistant, intermediate, and susceptible reactions to stripe rust were intercrossed. The most resistant seedlings (10–20%) were selected in each of four segregating generations, transplanted, and grown to maturity. When evaluated as seedlings in controlled environment chambers, 45 spring wheat crosses showed transgressive segregation. Transgressive segregation was demonstrated in later generations in nine spring wheat crosses that lacked resistant progeny in the F₂ and F₃ generations. Ten commercial cultivars of winter wheat with acceptable agronomic performance and either intermediate or susceptible reactions to stripe rust also were intercrossed. When evaluated as seedlings in controlled environment chambers, 38 winter wheat crosses showed transgressive segregation. Transgressive segregation also was clearly shown in later generations of 17 winter wheat crosses even though the F₂ and F₃ generations of these crosses were totally susceptible. Under field conditions of natural infection, progeny of 27 winter wheat crosses were selected for increased resistance. More resistance was found in the F₃ than in the F₂ progeny. Many F₄ plant progeny were more resistant than the parental cultivars.