Interrelationship and path analysis of tuber yield and related traits in yam (Dioscorea spp.) from Ethiopia

Understanding the nature of associations among economically important traits is essential to improve selection efficiency in plant breeding programs. This study aimed to determine the magnitude of association between tuber yield and related traits and to identify the most influential character(s) involving 36 landrace collections of yams for effective selection and conservation. Field evaluations were conducted at Jimma Agricultural Research Center in Ethiopia using a 6x6 lattice design with two replications during 2015. Data on 12 qualitative and 19 quantitative traits were collected and subjected to analysis of variance, correlation and path analyses. Highly significant differences (p<0.01) were detected among collections for the studied traits. Significant and positive correlations were detected between tuber fresh weight (TFW) with vine length (VL), days to maturity (DM) and tuber diameter (TDi). Tuber length (TL) positively and significantly correlated with leaf length (LL), vine length (VL) and internodes length (IL). Tuber diameter (TDi) positively correlated with LL, TuL, IL, DM and leaf width (LW). Leaf color (LC), leaf size (LSi), petiole color (PC), vine color (VC), tuber skin color (TSC) and tuber flesh color (TFC) had significantly negative correlations with TFW and TuL. Path analysis revealed high direct path coefficient value (1.112) between LL and TuL. Also, positive direct path coefficient value (1.018) was exhibited between DM and TFW. Relatively high direct path coefficient value (0.356) was exhibited between leaf shape (LS) and TuL. This study revealed that selection for increased above ground biomass and days to maturity may improve genetic gain in storage tuber yield and length of tuber in yam breeding. Using the overall analyses, the following collections such as: 27/02, 56/76, 08/02, 10/002,39/87, 45/03,6/02,116, and 7/83 were selected for breeding and conservation.