Genotype by Environment Interaction and Stability of Pod Yield of Elite Breeding Lines of Groundnut (Arachis hypogaea L.) in Eastern Ethiopia

Abstract

Groundnut (Arachis hypogaea L.) yield under small scale farming of eastern Ethiopia is low (1.04 t ha-1) and highly variable over years and locations. Eleven elite breeding lines of groundnut were tested at Babile and Likale, eastern Ethiopia, in 2007, 2008 and 2009 to identify high yielding and stable genotypes. Additive main effect and multiplicative interaction (AMMI) model, cultivar-superiority measure, and genotype plus genotype by environment variation (GGE) were used to analyze multi-environment data. In the analysis of variance, all sources of variations showed statistically significant differences except year by genotype interaction indicating the possibilities for identification of best performing genotypes with specific and broad adaptability in the tested sites. AMMI analysis showed highly significant (P<0.01) effect of genotypes, environments and their interactions on dry pod yield. Similarly, the first and the second interaction principal component axis (IPCA 1 and IPCA 2) were highly significant (P<0.01) and explained 58.57 and 23.18 % of the G×E sum of squares, respectively. The environment had 84.7% effect, thereby explained high differences in genotype response to the tested environments. Genotype and genotype by environment interaction (GEI) accounted 6.6 and 8.7 %, respectively. Genotypes BaHa-jidu (-0.099), ICG-9251 (0.013), ICG-8644 (0.055) and Roba (0.057) with the lowest IPCA 1 showed the general adaptation in the mega-environment-1 (Ba2007, Ba2008 and Ba2009) and mega-environment-2 (Li2007, Li2008 and Li2009). BaHa-gudo had the highest mean dry pod yield (t ha-1) in a mega-environment-2 and highest PCA 1 score (0.343). Genotypes BaHa-jidu and BaHa-gudo had the smallest superiority measure values and had the highest dry pod yield and stability. In GGE bi-plot, PC 1 and PC 2 explained 51.2 and 30.6% of genotype by environment interaction, respectively. ICGV-8749 and BaHa-gudo were vertex genotypes at mega-environment-1 and mega-environment-2, respectively, whereas BaHa-jidu was vertex genotype in both mega-environments.

Keywords: AMMI; GGE bi-plot; Groundnut; Mega-environment; Stability; Environment; Eastern Ethiopia