Seleção de descritores morfológicos e divergência Genética em acessos de mandioca

Abstract

The cassava (Manihot esculenta Crantz) is one of the most important tropical species grown. The genus Manihot has 98 species and among them, there are no barriers to reproductive isolation, therefore, there is an immense gene pool available to the breeders of cassava. Many scientists have emphasized the importance for the development of improved cultivars, using the accessions of wild species of Manihot. The objective of this work was Selection of descriptors morphological and agricultural traits and analysis of genetic diversity of accesses active bank of cassava of Embrapa Cassava and Tropical Fruits. For characterization of cassava germplasm accessions were used 35 morphological and agronomic descriptors, being 19 qualitative and 16 quantitative. It was carried out the identification of redundant descriptors, by means of the methodology proposed by Jollife and taking into account the relative contribution of each characteristic for genetic divergence, according to the method proposed by Singh. It is concluded that the descriptors length and root diameter, number of roots per plant, root weight per plant, starch content and hydrocyanic acid in root, distance between leaf scars, number of stems from the manioc cuttings mother, height of the first branch, length of the middle lobe and the petiole, color of the film from root, color of the root bark without film, form of root, stem color, branching habit, color, shape of the terminal branches of the lobe, color of the petiole are important in the characterization of germplasm of cassava. The method of Gower was efficient in discrimination of germplasm of cassava. The method of Gower was efficient in discrimination of groups whereas the joint analysis of descriptors studied, demonstrating that the simultaneous analysis of qualitative data, quantitative is viable and can allow a greater efficiency in the knowledge of the genetic divergence among accessions of germplasm banks by consider the influence resulting from the interdependence between their respective characteristics.