Efficiency of indirect selection in sorghum breeding for target production environments in moisture deficit areas of Ethiopia

Abstract

The success of crop breeding program ultimately hinges on developing, disseminating, and integrating suitable varieties into the production system. A critical challenge in variety development process is whether indirect selection in one environment is more effective than direct selection in the target environment. Hence, the efficiency of direct vis-à-vis indirect selection was compared, and recommendations are provided to support more objective breeding strategies. Thirty-six series of variety trials conducted between 1994 and 2020 at the pre-national and national levels, and evaluated under selection and target environments were used for analysis. Grain yield, heritability, predicted genetic gain, and genetic correlations varied significantly across environments. The mean yield was 3565.6 kg ha − 1 in the selection environment (SE) Melkassa, and 3627.6, 5079.1, 5059, and 4200.9 kg ha − 1 , respectively in target environments/TEs/ Miesso, Kobo, Srinka, and Zema. Similarly, for SE (Miesso), the mean yield in the TE (Kobo, Zema, Erer, Shewarobit, and Sheraro) were 3802.1, 1450.1, 2819.2, 6172.5, and 2366.5 kg ha − 1 , respectively, with the SE itself yielding 3165.8 kg ha − 1 . Heritability estimates ranged from 5% to 96% with the majority (84.7%) of the trials exhibited medium to very high, while genetic correlations ranged from 0.002 to 0.62 indicating substantial genotype-by-environment interaction. The correlation suggests that the alleles controlling physiological mechanisms in the SEs are at least partially different from those controlling in the TEs. When Melkassa was used as SE the efficiency of indirect selection relative to direct selection was 0.23, 0.21, 0.33, and 56 for Miesso, Kobo, Srinka, and Zema, respectively. When Miesso was used as SE, the efficiency of indirect selection was 0.14, 0.08, 0.16, 0.17, and 0.06 for Kobo, Zema, Erer, Shewarobit, and Sheraro, respectively. This indicated that indirect selection under SE can identify superior genotypes for TEs to some extent, however, the relative efficiency of indirect selection was consistently lower than direct selection under the TEs themselves. These results highlight limitations in the current sorghum breeding approach and suggest that the selection strategy requires refinement to better predict performance across diverse growing conditions and to maximize genetic gains.