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A multi-environment evaluation of sorghum genotypes was conducted across six environments in the 2021 main growing season in a randomized complete block design with three replications. The objectives of the study were to estimate the magnitude of genotypes by environment interaction (GEI) and grain yield stability of drought-tolerant sorghum genotypes across different environments. Data were subjected to analysis of variance, Additive Main Effects and Multiplicative Interaction (AMMI), and GGE biplot analysis. Combined analysis of variance revealed significant variations among genotypes, environments, and GEI for yield and yield-related traits, indicating that these factors significantly affected grain yield. The maximum mean grain yield value of genotypes due to the mean effect of the environment was obtained from G1 (5119.93kg ha-1), followed by G14 (4834.57 kg ha-1), and G18 (4801.20 ha-1), while the least mean grain yield was obtained from G3 (3314.50 kg ha-1). The multiplicative variance of the treatment sum of squares due to GEI was partitioned into four principal component axes (PCA). Sum squares of the first and second interaction principal component axis (IPCA) explained 71.07% and 17.50% of the GEI variation, respectively. The IPCA12 mean squares were highly significant (P0.01), indicating the adequacy of the AMMI model with the first two IPCAs for cross-validation of grain yield variation. The magnitude of the GEI sum squares was 3.9 times that of the genotype sum squares for grain yield, indicating the presence of substantial differences in genotypic responses across environments. The results of cultivar superiority measure (Pi), yield stability index (YSI), AMMI stability value (ASV), regression coefficient (bi), and deviation from regression (S2di) depicted that genotypes G18, G22, G31, and 32 were the most stable genotypes for grain yield and biomass yield, respectively. AMMI2 biplot showed Jinka, Alduba, and Kako were the most discriminating environments as indicated by the long distance from the origin; whereas testing locations Meioso and Gato with short vector length indicated that these locations had less discriminating power on the genotypes' performance. The study has provided precious information on the yield stability status of the sorghum genotypes and the best environments for future improvement programs in Ethiopia.
Gebre et al. (Wed,) studied this question.