Male Sterility for Increased Outbreeding in Populations of Barley

Abstract

IN recent years several interesting mechanisms have been investigated which enable many plant species to maintain a mixed mating system with its variable proportions of outbreeding and inbreeding adaptively adjusted to the optimal requirements of recombination potential, hybridity and reproductive economy^1–3. In the predominantly self-fertilized species such mechanisms seem to be of particular evolutionary significance. Using a theoretical model, Jain⁴ showed that male sterility factors, occurring in their populations might be favoured for an effectively increased rate of outcrossing on the male-sterile individuals. The adaptive role of cytoplasmic male sterility in the case of gynodioecious species was discussed earlier by Lewis⁵. The composite cross-bulk populations of barley in which a recessive male sterility gene (ms) has been introduced to facilitate continued recombination⁶ provide suitable material for examining the consequences, of Jain's model. In this communication an analysis of two such populations is briefly discussed in relation to the regulation of breeding system.