Lateral floret development in barley as influenced by recessive int genes in a heterozygous state

Effects of gene interaction between heterozygous recessive intermedium genes and the semidominant Int‐d gene on lateral floret development in barley were studied in various F, constellations with I, 2, or 3 int genes added to a heterozygous Int‐d gene. The study was based on 13 recessive intermedium mutants belonging to the three most frequently mutated int loci, int‐a (5 alleles), int‐c (5 alleles), and int‐e (3 alleles); and 5 alleles of the semidominant locus Int‐d . The different loci were represented by the alleles a 9 a 10 a 14 a 27 a 30 ; c 3 , c 13 , c 29 c 62 c 63 ; e 20 e 23 e 65 ; and d 12 , d 22 d 24 d 25 d 36 . Comparisons between the different constellations were made on data for lateral floret awn length, fertility, and kernel size. The recessive int genes were able to enhance the expression of Int‐d . The degree of enhancement may differ among allelic states of Int‐d and among characters of lateral floret development, and there is progressive enhancement when two or three recessive int genes are added as potential enhancers to the initial effector. Differences among the three int loci in their enhancing potentials are shown at higher levels of the basic effect caused by the initial effector. Locus int‐c is indicated to be the superior enhancer.