Genotype-by-environment interaction and stability of sweetpotato genotypes for root dry matter, β-carotene and fresh root yield

Abstract

Abstract The study was conducted to estimate the magnitude of genotype x environment interactions (G x E) and to select stable and high yielding sweetpotato genotypes for root dry matter content (RDMC), β-carotene content and fresh root yield, and to identify the most discriminating and representative test environments in Ethiopia. The study was conducted across six environments (Halaba, Kokate, Areka, Arbaminch, Hawassa and Dilla) in southern Ethiopia. Twenty four selected genotypes and one check variety (Tula) were evaluated using a 5 × 5 simple lattice design. Stability analysis was conducted using Genotype plus Genotype by Environment Interaction (GGE bi-plot). Environment, genotype and G × E interaction variances were significant (p < 0.001) for the three traits. The magnitude of environment and G x E interaction was 66.8% for fresh root yield, 44.0% for RDMC and 7.6% for β-carotene content. Three genotypes designated as G1, G6 and G20 were identified as having above average RDMC of 31.82, 32.60 and 30.06%, high β-carotene content of 12.48, 14.27 and 13.99 mg 100 g-1 and, stable and high fresh root yields of 25.09, 26.92 and 25.46 t ha-1, respectively. These genotypes were selected for final evaluation and recommendations. Among the test environments, Arbaminch, Halaba and Areka better discriminated among genotypes for RDMC and fresh root yield while Areka, Dilla and Halaba were the environments better discriminated among genotypes for β-carotene content. Four environments, Arbaminch, Halaba, Areka and Dilla can be considered good environments for sweetpotato screening in southern Ethiopia. Kokate is not a good environment for sweetpotato testing in Southern Nation, Nationalities and People’s Regional State (SNNPRS). Generally, the current study demonstrated the possibility of breeding sweetpotato varieties with combined high RDMC, β-carotene content and a high fresh root yield, with wide adaptation for large scale production.