Nutritional Genetic Diversity On Stylosanthes guianensis.

Stylosanthes guianensis (Aubl.) SW. is a perennial tropical legume native from South America. It is used in grass–legume mixed pastures, protein banks and crop-pasture integrated systems. The Stylosanthes guianensis germplasm collection at Embrapa Cerrados comprises more than 500 accessions. The objective of this research was to characterize the genetic diversity of Stylosanthes guianensis germplasm accessions in terms of parameters associated with nutritive value. Three hundred and three accessions from the Embrapa Cerrados Germplasm Bank were planted on plots of single rows with seven plants spaced of 0.5 m. Forage samples were collected from all seven plants of each accession to assembly bulk samples. Samples were analyzed in duplicates to estimate DM, IVDMD, CP, ADF, NDF, EE, ASH and OM. The germplasm presented great nutritive value variability. A PCA was performed with the goal of discriminating among accessions and grouping even further. The goal of PCA is to provide a reduced dimension model that would indicate measured differences among groups. It also can contribute to a better understanding of the set of variables by describing how much of the total variance is explained by each one. The first five PC explained 88% of the variance. The PC1 was highly correlated with ASH and OM, PC2 was associated with ADF and NDF, PC3 with EE and DM, PC4 with IVDMD and PC5 with CP. The Ward's Minimum Variance Cluster Analysis was performed to group the germplasm. Five different groups were formed. Group 1 was composed by accessions with high values of IVDMD, Group 2 was formed by accessions with high values of EE, Group 3 was formed by accessions with high values of CP, Group 4 was formed by accessions with high values of NDF and Group 5 was formed by accessions with high values of ADF.