Bulb Yield Stability in Shallot: The Case of Eighteen Shallot Genotypes Evaluated under Southeastern Ethiopia Highlands

Study was carried out to identify stable shallot genotypes with better yield performance over range of environments during 2008-2009 cropping season at south eastern highlands of Ethiopia. Eighteen shallot genotypes were evaluated including standard check (Huruta) and Local check over six environments (2 years x 3 locations) using randomized complete block design with three replications. Data was analyzed using MSTATC and IRRSTAT statistical softwares for combined analysis of variance and stability study respectively. Additive Main Effect and Multiplicative Interaction (AMMI) model was employed to handle the interaction effects. Combined analysis of variance indicated that there was highly significant difference (p<0.01) between genotypes, environments and genotype x environment (G X E) interactions. AMMI analysis confirmed that genotypes S2-68-89, DZ-SHT-57, DZSHT-82, DZSHT-119 and P-403-OP-S1 were the most stable genotypes. Their regression slopes were not significantly different from one (p<0.01) and scores near zero when observed across the first Interaction Principal Component Axis (IPCA1). However, genotypes Waliso, DZ-SHT-21, DZSHT-93 and Huruta were relatively unstable when observed on AMMI bi-plots and had regression slopes significantly different from one (p<0.01). Genotype DZ-SHT-21 was the best with 17300 kg/ha mean bulb yields. Environments Shallo 2008, Sinana 2009, Shallo 2009 and Lower Dinsh 2009 had large positive scores indicating that they interacted in positive direction with the genotypes whereas environments Sinana 2008 and Lower Dinsho 2008 had negative score indicating that they interacted in opposite direction with genotypes. These environments are described as unpredictable that makes cultivar recommendation difficult or complex. This study revealed that breeding shallot genotypes for local or specific adaptation is highly important.