A STUDY OF COMBINING ABILITY FOR GRAIN PROTEIN PERCENTAGE IN A DIALLEL CROSS OF FIVE SIX-ROW BARLEY CULTIVARS

Abstract

Grain protein percentage was assessed in F₁ and F₂ populations in two experiments involving a complete diallel cross among the barley (Hordeum vulgare L.) cultivars Bonanza, Conquest, Olli, Galt and Jubilee. Heterosis was absent in all crosses and a Griffing combining ability analysis showed that specific combining ability was nonsignificant in both F₁ and F₂ populations. General combining ability (GCA) for protein percentage was highly significant in both generations, with Conquest and Olli having major positive GCA effects. Galt produced a large negative GCA effect, while Jubilee and Bonanza caused small negative GCA effects. Significant differences between the hybrids were found only in F₁. Broad sense heritabilities for protein differences between the parents were 0.57 and 0.72 in the two experiments, and were significant at the 5 and 1% levels of significance, respectively. Conquest had significantly higher protein than Bonanza, with Olli being intermediate. Galt had lower protein than Jubilee, but this difference was significant in only one experiment. The differences among the five cultivars for mean grain protein percentage and general combining ability are significant in relation to breeding for malting and feed type barleys.