Assessment of Morphological Variation in Irish Brassica oleracea Species

This study aimed at assessing the morphological variation in 25 accessions of an Irish collection of Brassica oleracea using 44 morphological traits. The morphological traits showed a pronounced variation among accessions. Vegetative preflowering and maturity traits revealed higher variation than seedling traits. Of the 44 morphological descriptors used, 28 were significantly different and proved useful in examining diversity and differentiating among accessions studied. Principal component analysis (PCA) showed variation among accessions, where 87.24% of the total variation in the morphological data was separated on the first five components, indicating a high degree of correlation among traits studied. Cluster analysis grouped the 25 accessions into 4 main groups, corresponding to kales, cauliflowers, cabbages and sprouts, and also showed a sort of correlation between clustering pattern and eco-geographical distribution of the accessions. Furthermore, this study identified 9 highly diverse accessions, providing opportunities for optimising parental sources in future breeding programs to develop new or more productive Brassica varieties. Morphological traits were deemed useful for assessing the diversity and relationships in Irish Brassica oleracea species.