Genetic diversity in Ethiopian mustard (Bbrassica carinata a. braun)
A field experiment was conducted at Kulumsa Agricultural Research Center in order to estimate the extent of genetic variation in Ethiopian mustard (Brassica carinata A. Braun). In this study, genetic diversity in 60 Ethiopian mustard genotypes, collected from 16 regions of Ethiopia, were assessed using the techniques of cluster and principal component analyses based on 16 traits. All traits were significantly (P < 0.01) different and the genotypes were grouped into seven clusters. The largest and the smallest clusters comprised about 28.3 and 1.7%, respectively, of the studied genotypes. Genotypes in clusters II and VII showed better performance for the majority of traits of interest: seed yield/plot, seed yield/plant, biomass/plot, biomass/plant, plant height, number of pods/plant, 1000 seeds’ weight and oil content. The clustering pattern of the tested genotypes indicated no relationships between genetic diversity and geographic origins since genotypes from the same origin were grouped into different clusters or vice versa. The average inter-cluster distances were significant for all clusters. The D2 statistics analysis showed that the distance between clusters IV and V was minimum (D2 = 22.085) while distance between clusters VI and VII was maximum (D2 = 1239.00), suggesting the existence of diversity among the genotypes, and hence, parental materials can be selected and used for hybridization and subsequent improvement of Ethiopian mustard. Maximum variations in subsequent generations is expected if there is crossing of parents selected from clusters II and VII with those from clusters III, IV, and VI since the intercluster distances between these groups were large. On the other hand, crossing between clusters I, IV and V; I and II, and III and IV might not produce desirable recombinants since the inter-cluster distance between these groups was very small, indicating similarity of their genetic make-up. The first six principal components accounted for 92% of the total variations encountered. The first three principal components accounted for 36, 22
and 19% of the variations, respectively. Days to flowering, days to maturity, seed yield/plot, oil yield/plot and biomass/plot were the most important traits contributing to the total variation of the first principal component, implying the existence of great potential to improve these traits through selection.
Keywords: Brassica carinata; Cluster Analysis; Ethiopian Mustard; Genetic Diversity