Genetic Diversity among Yam (Dioscorea cayenensis Lam. Complex) Landraces using Morphological Traits

Yams ( Dioscorea cayenensis Lam. complex ) are the fourth most economically important tuber crop next to Irish potatoes, cassava, and sweet potatoes. The study was conducted to estimate the magnitude of genetic variation, association between tuber yield and related traits and to identify the most influential character(s) involving twenty landraces collections of yam for effective selection and conservation. The experiment was conducted at Hawassa University's main campus research farm using a randomized complete block design in three replications. Data were collected for growth and yield parameters. Mean values were used to determine characters' phenotypic and genotypic variances, phenotypic, genotypic and environmental coefficients of variation. Broad sense heritability and genetic advance percentage of mean were estimated for each trait. Analysis variance of characters revealed significant differences (p < 0.01) among the landraces. Estimate of phenotypic and genotypic coefficients of variation showed variability among the farmers’ varieties. The difference between phenotypic and genotypic coefficients of variation was low for traits studied, which indicates the lower environmental influences on these traits. The highest genotypic and phenotypic coefficients of variations and the maximum heritability were recorded for leaf lobe length. A significant positive phenotypic correlation was recorded between tuber fresh weight and seven characters. Selection of farmers’ varieties based on high genotypic coefficient variation coupled with high heritability and genetic advance as percent mean value are useful tools in yam improvement programs. In this regard, leaf lobe length, number of stems, tuber fresh weight and tuber dry weight should be given due importance in yam breeding programs.