Problems in the Estimation and Utilization of Genetic Variability

Progress in either plant or animal breeding is de-pendent upon genetic variability. In spite of this dependence definite information on the extent of genetic variability is limited and quite inadequate. From observations of populations of open-pollinated varieties of corn, one is impressed by the extreme variability observed. However, a portion of this vari-ability is environmental rather than genetic. Several ines of evidence may have a bearing on the extent of genetic variability in open-pollinated varieties of corn. Possibly one of the most intrigu-ing of these is the Illinois selection experiments for chemical composition and for yield. Superficially, at least, these experiments give quite conflicting an-swers as to the magnitude of genetic variability.