Evaluation of maize genotypes using parametric and non-parametric stability estimates
Cereal Research Communications
Department of Plant Sciences, University of the Free State, P.O. Box 339, Bloemfontein 9300, South Africa
High and stable yield is very desirable in maize (Zea mays L.) genotypes. Stable yield of a genotype means that its rank relative to other genotypes remains unchanged in a given set of environments. Grain yield of 10 maize genotypes was tested in a randomised block design with four replications across 15 environments (five locations in three years) in Ethiopia. The combined analysis of variance for environment (E), genotypes (G) and GE interaction was highly significant, suggesting differential responses of the genotypes and the need for stability analysis. The parametric stability measure of Wricke's ecovalence (Wi) and the regression coefficient (bi) showed that BH-660 was the most stable genotype. Nassar and Huehn's non-parametric measures S(1) and S(2), were significantly and positively correlated with Eberhart and Russell's Sdi2 and Wi. The stability measures are useful in characterising cultivars by showing their relative performance in various environments. Results revealed that high-yielding cultivars can also be stable cultivars. The stability statistics generally identified BH-660, L2 and Gibe-1 as the most stable genotypes, whereas Kulani and BH-140 were the least stable.