Agronomical Evaluation of Aerial Yam/ Dioscorea bulbifera/ Accessions collected from South and Southwest Ethiopia

The experiment was conducted at Jimma Agricultural Research center. The objectives of the study were to estimate the level of diversity within collected accessions based on key agronomic trait(s) that can be used for selection of aerial yam accessions for high root yield and evaluate the accessions based on root yield and other related trait. A total of 47 accessions of aerial yam were tested in randomized complete block design with three replications. Both qualitative and quantitative data collected were subjected to multivariate analysis using principal component (PCA), cluster analysis and analysis of variance to determine the variability of accessions. The results of PCA based on qualitative traits indicated that traits have good contribution to the variability. The two-dimensional plot of the first two PCs showed a separation between accessions in big sized. Cluster analysis based on qualitative characters showed the creation of six distinct groups with different sizes and presence of variability, based on their above and below ground plant parts. The result of Shannon-Weaver diversity index (H’=0.18) showed low levels of diversity between aerial yam accessions. Analysis of variance indicated that tuber length, tuber diameter and vine length have highly significant (P>0.01) differences exists for most of the characters studied. Estimate of phenotypic and genotypic coefficients of variation also showed the presence of variability among the accessions for the a limited number of the characters namely, vine length, vine dry weight, tuber length and tuber diameter. Relatively high phenotypic (53.96, 44.99 and 26.07 %) and genotypic coefficients of variation (12.44, 22.81 and 11.18%) were observed for vine dry weight, tuber dry weight and vine fresh weight in the order of magnitudes. Heritability (39.69% and 25.70%) coupled with genetic advance as percent of mean (12.42% and 23.83%) were recorded for vine length and tuber dry weight per plot, respectively. Path coefficient analysis revealed that that vine dry weight (p =1.203) and leaf length (p =1.1949) was more important than other traits, hence can be used as a criterion for indirect selection. Therefore, selections based on vine dry weight and leaf length are vital to increase the yield and the genetic improvement of this crop. The overall results of this study showed that aerial yam accessions collected from south and southwestern Ethiopia have an enormous wealth of traits variation, indicating huge potential for its genetic improvements through selection and hybridization