Divergências morfológicas em Stylosanthes spp. ocorrentes em Pernambuco

Abstract

The potential use of native herbaceous legumes from the Northeast of Brazil as forage are large, among them the genus Stylosanthes spp. is highlighted for its adaptability to the semiarid conditions and for its high nutritive value. This research aimed to identify morphological differences among genotypes and to estimate genetic parameters, also identify characteristics correlated with high production of dry matter with the degree of reliability in the genotypic discrimination above 80% in plants of the Stylosanthes spp. genus. Two trials were made, the first one was developed in the Universidade Federal Rural de Pernambuco (UFRPE), in the experimental field from the Academic Unit of Serra Talhada (UAST). Were used morphological descriptors to help in the identification of the differences among thirteen accessions of Stylosanthes spp. from the germplasm bank from UAST, these were collected in different areas from the semiarid. In the analyses of main components, was verified that plant size (PS), width of the central petiole (WCP), length of spitule attached to the petiole (LEAP), petiole length (PL) were the descriptors that showed more importance in the eigenvectors. The second trial was developed in a greenhouse in the central campus of UFRPE, were used eight accessions of Stylosanthes scabra Vog. collected in the city of Bom Jardim-PE, also was used morphological descriptors, the data were submitted to the analyses of variance, genetics parameters, Pearson’s correlation and repeatability coefficient. Were observed significant difference (P< 0.05) among the accessions for all characters evaluated, except for the plant height (PH). The characteristics showed values for heritability from 62.78 to 97.70, and for repeatability 0.19 to 0.57. The descriptors: growth habit (GH), flowering (FLO), length of spitule attached to the petiole, branching (BCH), stem diameter (SD), number of leaves (NL), demonstrated positive correlation with dry matter production. Were observed genetic differences among the accessions of the Stylosanthes spp. when in field conditions, expressing the existence of the variability among them. To identify the accessions with better dry matter production at greenhouse conditions, the descriptors: growth habit, length of spitule attached to the petiole, stem diameter, number of leaves, length of central petiole, length of lateral foliole (LLF), hairiness of leaf (HL) and petiole length, were effective, requiring no more than five evaluations to predict its real value (R²=0.80).