Selection of adaptable vetch genotypes based on dry matter yield and multi-trait stability index
Vetch, a highly valued herbaceous legume for livestock, was studied in Northern Ethiopia from 2021 to 2023 to analyze genotype by environment interaction (GEI) in multi-environment trials (MET) and identify adaptable vetch genotypes. Combined analysis of variance (ANOVA), AMMI ANOVA and Eberhart and Russell regression for forage yield were analyzed. GGE, AMMI1 and AMMI2 bi-plots for forage yield of vetch genotypes were created. Principal Component Analysis (PCA) and correlation network plots were created, along with the analysis of multi-trait stability index (MTSI) for agronomic traits. AMMI stability measures, Best Linear Unbiased Prediction (BLUP) based indexes; parametric and non-parametric statistics were computed using R-statistical software. AMMI ANOVA revealed significant effects of genotype (G) (28.35% SS), environment (E) (30.29% SS), and GEI (17.48% SS) for the dry matter yield. The likelihood ratio test (LRT) revealed significant genotypic effects for all agronomic traits except days to emergence and survival rate, while the LRT for GEI was significant for all traits except the number of branches. AMMI and GGE bi-plots selected G3 and G4 as the most adaptable genotypes. Stability parameters: ASTAB, ASI, ASV, AVAMGE, DA, FA, Shukla, Ecovalence, Wi_u, Pi_u, S2 N3, and MASI identified G4 and G1 as the most stability genotypes. SIPC, DZ, EV, MASV, Wi_g, HMGV, S3, S6, R2 and ZA ranked G4 and G3 as most stable genotypes. HMRPGV, HPGV, WAAS, WAASB, Wi_f, Pi_a, Pi_f and GAI also ranked G3 and G4 most stable genotypes. The average rank sum (ARS) of the stability statistics groups was considered. AMMI-based stability statistics identified G4 and G1 as the top two stable. The WAAS index, BLUP-based, and non-parametric statistics identified G3 and G4 as the most stable genotypes. In contrast, parametric statistics ranked G4 first and both G1 and G3 second in stability. Overall, G4 and G3 were identified as the most stable genotypes. The MTSI also selected G4 (MTSI = 1.65) and G3 (MTSI = 1.79), are recommended for further verification and demonstration before being recommended for wider forage production in Tigray.