Abstract

MAZZANI C, Elena; MARIN R, Carlos  and  ROMERO, José R. Classification of the bank of germoplasma of sesame of venezuela based on qualitative scales. Agronomía Trop. [online]. 2007, vol.57, n.1, pp.15-24. ISSN 0002-192X.

This study was conducted to classify 838 accessions of the Venezuelan sesame genbank according to 17 qualitative characters using multivariate analysis. Descriptions were performed for 42 agronomic and morphological characters using sesame descriptors. The collection was sown in Maracay, Aragua state, Venezuela. Groups of accessions were determined by hierarchical classification. The graphical representation was made by hierarchical dendrogram in a transformed scale. The hierarchical classification of 17 qualitative traits showed 20 classes. The grouping of accessions was based on ultrametric distance coefficients £ 0,05. The traits used for analysis were: number of days when 50% of plants reached emergence, flowering and harvest, number of nodes to first flower, number of flowers per axil, number of capsules per axil, extra-floral nectary development, capsule position in stem, length of capsule hair, leaves, stem shape and stem hairiness, branching habit, number of branches, mature plant color, seed shape and 1000 seed weight. These variables, quantitative as well as qualitative, were standardized in a categorized scale of 2 or 3 stages, to obtain qualitative data for analysis. The hierarchical classification of 17 qualitative variables explains 20 groups, consisting on 12 to 92 accessions. A higher variability was shown for: stem and capsules hairiness, color on mature plants, cycle, branching habit, number of flowers per axil, number of capsules per axil and extra-floral nectary development. Accessions did not show a clear differentiation among them. Duplications of accessions were identified for the traits taken into account.

Keywords : Sesamum indicum L; sesame germplasm; characterization; variability; core collection; clusteranalysis.