Diallel Analyses of Grain Yield, Percent Protein, and Protein Yield in Grain Sorghum¹

Abstract

A six‐parent diallel cross, including reciprocals, of grain sorghum [ Sorghum bicalor (L.) Moench] was analyzed for grain yield, percent protein, and protein yield. Highly significant differences were observed among parents and F 1 hybrids for each trait. Reciprocal differences were not significant, but a partial failure of assumptions for the Jinks‐Hayman analysis was noted for all traits. Differences among the parents indicated an additive component of genetic variation for all traits. The estimates for non‐additive components suggested that dominance was important for all traits. The degree of dominance was estimated to be in the overdominance range, particularly for the yield traits. Dominance was in the direction of higher yields and lower percent protein. The positive and negative alleles were estimated to be equally frequent for yield; or percent protein, the negative alleles were estimated to be more frequent. These results suggest that improvement of percent protein requires selection for recessive alleles that have a low frequency; improvement of yield requires a method to cope with overdominance. Highly significant GCA and SCA effects were observed for all traits. A comparison of their relative magnitudes indicated SCA effects were much more important than GCA. Specified comparisons among the parents were made for GCA and among the parents and hybrids for SCA.