Genetic variability of the Embrapa-cerrados cassava germoplasm collection accessed by morphological descriptors

Abstract

Germplasm collections may represent excellent sources of genes for plant breeding programs, since they bring together genetic compositions from different origins and from different breeding levels. Therefore, it is essential for plant breeders to be informed about the genetic variability and agronomic performance of the available germplasm of a given species. The aims of the present work were to estimate the genetic variability of 356 cassava accessions from the Embrapa-Cerrados germplasm collection in relation to 27 morphological descriptors, find out which of them show the highest entropy levels and to group the accessions in terms of genetic dissimilarity. Based on the data, the entropy level of the characters and the genetic dissimilarity were estimated. Later, the accessions were grouped according to Tocher's grouping method. The cassava accessions were organized in 34 different groups which presented high genetic variability. The characters showing the highest entropy levels were stem external colour, petiole colour, shape of the central lobule, and colour of the apical leaf. The characters presenting the lowest entropy levels were stem growth habit, flowering, texture of the root epidermis, and the occurring of constrictions in roots. Additional keywords: Manihot esculenta Crantz; genetic distance; entropy; genetic resources; plant breeding.