INHERITANCE OF EARLINESS IN BARLEY

Abstract

The F1, F2 and F3 of seven crosses between spring barley varieties of differential maturity periods were grown in the same year. Genetic analyses were largely based on F3 breeding types, six of which were distinguishable among frequency distributions of F3 hybrids classified in days-to-heading categories. Each breeding type was determined by characteristic variance and mean days-to-heading values. It was hypothesized that parents in each late × early cross differed by additive, increaser alleles at two loci, giving aiaibibi × a a b b. Theoretically, such a cross produces six F2 breeding types, viz., late, intermediate, and early homozygotes, and late, intermediate, and early heterozygotes; the ratio being 1:2:1:4:4:4. Observed frequencies being in good agreement with these expectations, it was concluded that the hypothesis accounted satisfactorily for the main features of inheritance. Minor discrepancies were attributed to modifying genes, the nature of which could not be determined.