Development of dual purpose sorghum: correlation and path-coefficient analysis of grain yield and stem sugar traits

Abstract

Information on the relationship between grain yield, stem sugar and biomass is important in developing dualpurpose sorghums. The objective of this study was to determine, correlations and path-coefficients between grain yield and stem sugar traits. The study was conducted using 100 sorghum genotypes evaluated in six environments in southern Africa. Grain yield, the dependent variable, was positively and significantly (P<0.05) correlated with stem sugar, stem biomass, days to 50% flowering, number of leaves per plant, plant height and stem diameter. Grain yield was negatively significantly (P<0.05) correlated with stem juice score (r = -0.049), suggesting that high grain yielding cultivars are generally low in stalk juice. However, the significance of the positive correlation coefficient between grain yield and stem sugar (r = 0.071) suggested that the traits are not mutually exclusive. The identification of hybrids that combined high performance for both traits supported this. Path-coefficient analysis revealed that the number of leaves per plant had high, positive direct effect on grain yield, implying that selection for high performance in this trait improves grain yield. In contrast to the overall correlation coefficient, stem sugar had a negative direct effect on grain yield; suggesting that selection for high stem sugar content directly reduces grain yield. However, this was masked by the indirect effect, hence the significant positive and significant (P<0.001) correlation coefficient between the two traits.

Key Words: Plant height, stem biomass, stem juice