Role of open-pollinated populations in the development of maize lines with commercial value

Abstract

If hybrids with better yield potential than that of currently grown hybrids are to be developed, new lines will be required with better genes and gene combinations. New character combinations only arise in populations. The probability of developing lines suitable for the development of commercial hybrids from heterozygotic populations is always extremely low. This is probably due to the fact that the linkage groups of the genotype carrying favourable properties are not fixed. The method by which linkage groups can be fixed has been known for several hundred years: continual selection aimed at stabilising and standardising the desired characters, and partial inbreeding. A great deal of breeding experience provides evidence of the fact that the linkage groups containing the desired characters are not necessarily confined to a single chromosome. The joint inheritance of several chromosomes over a number of generations suggests the presence of an as yet unknown mechanism which helps to preserve the favourable characters tested and accumulated by breeding or natural selection in a system offering a number of alternatives.