Vol. 8(12), pp. 1033-1040, 4 April, 2013 DOI: 10.5897/AJAR2012.6648 ISSN 1991-637X ©2013 Academic Journals http://www.academicjournals.org/AJAR African Journal of Agricultural Research Full Length Research Paper Additive main effects and multiplicative interactions model (AMMI) and genotype main effect and genotype by environment interaction (GGE) biplot analysis of multi-environmental wheat variety trials Asnake Worku Negash 1 , Henry Mwambi 1 , Temesgen Zewotir 1 and Girma Taye 2 1 School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal Pietermaritzburg, South Africa. 2 CIMMIT, Ethiopia. Accepted 26 March, 2013 Genotype by environment (G×E) interaction is associated with the differential performance of genotypes tested at different locations and in different years, and influences selection and recommendation of cultivars. Wheat genotypes were evaluated in six environments to determine the G×E interactions and stability of the genotypes. Additive main effects and multiplicative interactions (AMMI) was conducted for grain yield of both year and it showed that grain yield variation due to environments, genotypes and (G×E) were highly significant (p <0.01). Stability for grain yield was determined using genotype plus genotype by environment interaction (GGE) biplot analysis. The first two principal components (PC1 and PC2) were used to create a 2-dimensional GGE biplot. Which-won- where pattern was based on six locations in the first and five locations in the second year for all the 20 genotypes. The resulting pattern is one realization among many possible outcomes, and its repeatability in the second was different and a future year is quite unknown. A repeatability of which- won-where pattern over years is the necessary and sufficient condition for mega-environment delineations and genotype recommendation. Key words: Additive main effects and multiplicative interactions (AMMI), genotype×environment (G×E) interactions, wheat, stability. INTRODUCTION The increase in population and the subsequent rise in demand for agricultural produce are expected to be greater in regions where production is already insufficient, in particular in Sub-Saharan Africa. The necessity and demand to increase agricultural production represents a huge challenge to local farming systems given it must come mainly from increased yield per unit area in addition to the limited extension of cultivated land in the country. To meet this requirement various crop improvement programmes have been initiated by the Ethiopian Institute of Agricultural Research (EIAR). Under any crop improvement programme a sample of promising genotypes are performance tested each year at a number of sites, representing major crop growing areas with the a view to identify genotypes which possess the dual qualities of high yield capacity and low sensitivity to *Corresponding author. E-mail: 208517201@stu.ukzn.ac.za.