Combining Ability Effects for Mineral Elements in Forage Sorghum Hybrids1

Abstract

The concentrations of minerals in forages are important in satisfying animal requirements, but little attention has been given to determining these concentrations in forage sorghum [Sorghum bicolor (L.) Moench.] breeding programs. In this 2‐yr study, the objectives were to determine the contents, genetic variability, combining ability effects, and correlations for 12 mineral elements in 49 experimental hybrids of forage sorghum. Mineral elements studied were N, Mg, Si, P, S, Cl, K, Ca, Mn, Fe, Cu, and Zn. General combining ability (GCA) effects exceeded specific combining ability (SCA) effects for all elements except P, Cl, and Fe in females, and S and Cl in males. The GCA and SCA effects in females were low for both Fe and Cu. Genetic ratios, resembling heritability, were higher for GCA than SCA except for Cl and Fe in females, and S and Cl in males. Thirty phenotypic correlations among the 12 elements were statistically significant. Some of the highest values were from the relationships of N with P, S, Cu, and Zn; Mg with Si and Cu; Si with Ca; P with Cu and Zn; S with K; and Cu with Zn. Some of the highest phenotypic correlations calculated among the mineral elements and 12 agronomic and quality traits were the positive association of protein with P, and the negative relationship of height with N and P, Brix of stem juice with K, and neutral detergent fiber with P. Data obtained in these studies show the feasibility of altering the mineral content of forage sorghum by breeding.