Inheritance of harvest index in spring wheat (Triticuma estivum L.) crosses with different plant height

Abstract

The inheritance of harvest index trait in spring wheat has been studied in the analysis of parents and F1, F2, RC1F1 and RC2F1 generations, of nine crosses between the genotypes: Maringá, a tall cultivar; IPF55243, semi-dwarf (medium heigth) and IPF55245, D8006 and D8017, all of them dwarf (short). There was genetic variability of harvest index among the studied genotypes. The broad sense heritabilities were low or intermediary because of the great environment effect on the character expression. Additive variance has showed important participation in genetic variance, which indicates less influence of dominance and/or epistasis. Additive gene effects were important in most of the crosses, although dominance effects showed importance in specific crosses involving D8006. Besides the importance of additive gene action, selection for harvest index in early segregating genera-tions may be difficult because the high value of environmental variances, and it should be done in more advanced generations.