Evolution of mildew resistance in a hybrid bulk population of barley

Abstract

Inbred lines derived from successive generations of a composite cross population of bar'ey, CCV, by single seed descent were screened for variation in mildew resistance with the aim of investigating the effect of natural selection on the population. A significant increase in the frequency of plants resistant to the open-air mildew spores over 10 generations was observed. Tests of reaction to selected mildew isolates of known virulence genotypes showed a similar shift towards increased resistance to single and combined isolates. These results are discussed in relation to the effect of selection on inbreeding species and the usefulness of composite crosses as dynamic reservoirs of genetic diversity. © 1991 The Genetical Society of Great Britain.