Study of genetic diversity in some populations of cultivated alfalfa (Medicago sativa L.) using morphological traits

genetic diversity assessment and core collection establishment is useful for facilitation of germplasm management and better evaluation of genetic resources in breeding programs. In spite of high level of morphological diversity in alfalfa germplasm, it has not been intended enough in breeding programs. Hence, a field investigation based on a completely randomized block design with three replications was conducted to study the genetic diversity of 110 alfalfa (Medicago sativa L.) genotypes, belonging to 11 populations, using 13 morphological traits. The analysis of variance showed significant differences (P < 0.01) among studied populations for all studied traits. Genetic and phenotypic coefficients of variation were high for most of theevaluated traits, indicating high amounts of both phenotypic and genotypic variation in the studied traits amongst populations assessed. Analysis of correlation coefficients among traits showed that increased stem weight is correlated with greater leaf weight. Principal component analysis (PCA) revealed that the first three components account for 88.1 % of the total variation observed. The first component was positively related to total wet weight, total dry weight, leaf wet weight, stem wet weight and stem dry weight. The second component was affected by the ratio of leaf dry weight to stem dry weight as well as number of leaves. Chlorophyll content and plant height had positive correlation with the third component. Cluster analysis using Ward’s method grouped the studied populations in two main groups; each one fall into two subgroups. Assessment of available phonotypic variation could provide useful information in germplasm management and identification of suitable populations for different breeding purposes in alfalfa