Genetic diversity evaluations in Turkish onion (Allium cepa L.) genotypes: principal component analyses (PCA) for breeding strategies

Sustainable plant breeding relies on available germplasm and genetic diversity. Analysis of genetic diversity in germplasm collection aids in classification of genotypes and identification of core collections with possible utility for specific breeding strategies. In the present study, principal component analysis (PCA) was used to evaluate resources of variation among some Turkish onion (Allium cepa L.) genotypes. Onion germplasm covering 96 accessions collected from different regions of Turkey were evaluated for 31 quantitative traits through principal component analyses. According to PCA results, eigenvalue was maximum in PC-I (7.74) followed by PC-II (3.25) and PC-III (2.33). Total variance percentage was maximum in PC-I (24.98) followed by PC-II (10.50) and PC-III (7.52). The first nine PCs with Eigen values >1 contributed 71.84% of the variability amongst accessions. The characters contributing more positively with PC1 were the bulb weight (0.33) and diameter of the pseudostem (0.30).