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Genetics

Inheritance of Slow Rusting of Barley Infected with Puccinia hordei and Selection of Latent Period and Number of Uredia. Dennis A. Johnson, Assistant professor, Texas A & M University, Vernon, TX, St. Paul, MN 55108; Roy D. Wilcoxson, professor, Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108. Phytopathology 69:145-151. Accepted for publication 31 August 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-145.

The inheritance of slow rusting was studied using nine crosses among fast- and slow-rusting barley cultivars or lines infected with Puccinia hordei. Progenies from the crosses were advanced by single seed descent, and 100 F₅ families and parents of each cross were planted in replicated hill plots at St. Paul and Rosemount, MN. The area under the disease progress curve was used to indicate the degree of slow rusting. The slow-rusting character behaved as a quantitatively inherited trait in that the progenies were distributed continuously from slow to fast rusting and transgressive segregation occurred in most of the crosses. Estimates of heritability for slow rusting ranged from 53 to 89% among the various crosses tested at Rosemount, indicating that selection for the slow-rusting character should be effective. Selection experiments with F₃ plants from three crosses among fast- and slow-rusting barleys indicated that selection for latent period was effective but selection for relative numbers of uredia per square centimeter of leaf surface was not, probably because the plants could not be inoculated uniformly.