Characterisation of the morphological variation for seed traits among 537 germplasm accessions of common vetch (Vicia sativa L.) using digital image analysis

Common vetch (Vicia sativa L.) is an important forage legume crop. This species is widely distributed in China, and includes 5 cultivated and 36 wild species. Our study was focused on estimation of genotypic variation for seed traits within germplasm of each of three subspecies of common vetch; V. sativa (402 accessions), V. sativa subsp. Sativa (105 accessions) and V. sativa subsp. Nigra (30 accessions). The seed traits measured were straight length, straight width, width to length ratio, curved length, curved width, perimeter, hilum length, 100-Seed weight and seed shape. The seed trait data were analyzed using REML in GenStat and the resulting accession-by-trait BLUP mean matrices were summarized using a combination of cluster and principal component analysis, presented as biplots. There was significant (P<0.05) genotypic variation among germplasm accessions, within each subspecies for all the traits measured. The calculated seed trait repeatability (R) provided a rough estimate of the upper limit of genotypic variation among the accessions within each of the three subspecies. The magnitude and type of association among the seed traits shown in the biplots were supported by the estimated phenotypic correlation coefficients. The germplasm accessions within the groups identified in V. sativa, V. sativa subsp. sativa and V. sativa subsp. nigra, will provide valuable genetic diversity for taxonomic studies and breeding associated with the seed morphological traits reported in our investigation.