Abstract

Though a recent introduction, rice is becoming the most important food and cash crop in Ethiopia. However, its productivity is being constrained mainly by lack of improved varieties. Identification of high yielding and stable genotype(s) and desirable environment(s) has been the most important objectives of multi-environment trials. The objectives of the present study were to explore the effect of genotype and genotype × environment interaction on grain yield of upland rice genotypes and to examine the possible existence of different mega environments. Grain yield performances of 13 upland rice genotypes were evaluated under rainfed conditions at three locations (Woreta, Pawe, Metema) in North Western Ethiopia from 2011 to 2013. The study was laid out in a randomized complete block design with three replications. The first two principal components (IPC1 and IPC2) were used to create a twodimensional GGE biplot that accounted for 76.80% and 20.05%, respectively. A combined analysis of variance showed that both main effects (environment and genotype) and GE interactions were highly significant. The polygon tool of the biplot suggested the existence of two upland rice mega-environments with wining genotypes G3, G9, G8 and G12. Visualizing the mean and stability parameters of the genotypes in the biplot indicated that genotypes NERICA-13 (G3), FOFIFA-3730 (G11) and NERICA-12 (G2) are adapted to rainfed upland rice growing areas of North Western Ethiopia. According to the ideal-genotype biplot, genotypes G3 followed by G2 and G11 were better genotypes demonstrating their high mean yield and stability performance.Based on discrimination and representation, Woreta was identified as the ideal location for generally adaptable upland rice genotypes and Metema for selecting specifically adaptable upland rice genotypes. Finally, it was concluded that genotypes; G2, G3 and G11 showed high grain yield and stability performance across environments and were promoted to variety verification. Of which, G2 has been officially released for large scale production with the common name “NERICA-12’’.

Keywords: G × E interaction; GGE biplot analysis; Mega environment; Multi-environment trials; NERICA rice