Variation and covariation of seed quality traits in Ethiopian mustard

Ethiopian mustard (Brassica carinata A. Braun), an oilseed crop of Ethiopian origin, is a less preferred source of edible oil due to its high erucic acid and glucosinolate contents. This study was undertaken to assess the variability for seed quality traits in the Ethiopian germplasm, determine their interrelationships and explore their pattern of genetic variation with respect to geographic origin. Seed of 913 selfed S2 plants derived from 36 germplasm accessions collected from eight different geographic regions of Ethiopia were analysed for seven seed quality traits by Near Infrared Reflectance Spectroscopy (NIRS). Large variability for oil, protein and glucosinolate contents was observed ranging from 16.4 to 54.7 %, 19.0 to 39.3 % and 28.2 to 171.8 μmoles g-1, respectively. Fatty acids varied as follow: Oleic, 0 to 20.3 %; linoleic, 5.4 to 29.5 %; linolenic, 10.1 to 22.9 %; and erucic acid 14.3 to 53.3 %. Correlation analysis showed a strong negative associations between oil and protein contents and oleic and erucic acids. Mahalanobis' dissimilarity index showed high diversity and the 913 S2 plants were grouped by the unweighted pair-group method using arithmetic mean (UPGMA) into 11 clusters, that varied in constellation from a cluster that contain a single plant to a cluster containing 332 plants. Factors other than geographic origin appeared to be a potent source of genetic diversity. The result demonstrated the usefulness of assessing genetic variation in segregating progenies to detect rare but desired traits like low glucosinolate content.