Diallelic crosses were made involving the standard height cultivars BH-1146 and Atlas-66, the semidwarf cultivar Siete Cerros and the dwarf source Tordo. Parents, F1's, F2's and reciprocal backcrosses were tested for grain yield, plant height, number of heads per plant, number of kernels per head, and for weight of 100 kernels, in an experiment carried out at Hyslop Farm, Oregon, U.S.A., in 1978. Narrow sense heritability estimates for plant height were moderately high for the crosses BH-1146 x Atlas-66 (0.55), BH-1146 x Siete Cerros (0.60) and Atlas-66 x Siete Cerros (0.74), moderate for the crosses Atlas-66 x Tordo (0.43) and Tordo x Siete Cerros (0.41) and low for the cross BH-1146 x Tordo (0.24). Moderate values (0.43 to 0.58) were estimated for number of heads per plant for all crosses with exception of the crosses BH-1146 x Atlas-66 and Atlas-66 x Tordo which presented low values for the narrow sense heritability. The heritability values for weight of 100 grains were low for all crosses with exception of the crosses BH-1146 x Atlas-66 and BH-1146 x Siete Cerros which presented moderate levels (0.40 and 0.45, respectively). In relation to grain yield the narrow sense heritability estimates were low with exception of those for the crosses BH-1146 x Tordo (0.73) and BH-1146 x Siete Cerros (0.62). The phenotypic correlations between grain yield and number of heads per plant, plant height, number of grains per head and weight of 100 grains were positive and mostly highly significant, except for the correlation between grain yield and weight of 100 grains for the population BH-1146 x Atlas-66, which was not significant. The results suggested that it would be possible to select semidwarf plants, with high yield potential, with high number of kernels per head and heads per plant, and 100 kernel weight if large segregating populations are used to identify desired genotypes originated from eventual genetic recombinations. This procedure is being used for selections of semidwarf wheat cultivars in the State of São Paulo, Brazil.
wheat; dwarf; semidwarf and tall types; grain yield