Developmental consequences of two-row and six-row ear type in spring barley: 2. Shoot apex, leaf and tiller development

Abstract

Summary Leaf and tiller production, ear development and ear growth were measured on a two-row and a six-row spring barley genotype, on the F 1 between them and on the first backcrosses. Among the developmental differences between the parental genotypes the following appeared to be of particular significance: the two-row genotype bore more leaves on the main shoot than the six-row genotype and these were initiated more slowly, but emerged more rapidly; the two-row genotype had a proportionately longer ear initiation phase than the six-row; the apical dome was bigger in the six-row than in t he tworow; the two-row genotype produced more tillers. The association of characteristics with ear type may depend on a pleiotropic effect of the ear type ( V – v ) locus or, alternatively, some of these characteristics may be under independent genetic control. The latter hypothesis was supported by the developmental pattern of the F 1 . It may be that well-adapted two-row and six-row genotypes have patterns of development balanced for the particular ear type. Hybridization between ear types may disrupt these balanced developmental patterns producing a high frequency of poorly adapted genotypes in the progeny.