Development of a Brazilian Maize Core Collection.

The objective of this study was to evaluate methods for the development of a Brazilian Core Collection from the Maize Active Collection of the Embrapa Maize & Sorghum. A previous survey of the active collection considered passport information, characterization and evaluation of the accessions, and then divided the accessions in accordance with the geographic regions and the kernel types, which constituted 21 extracts. Multiple methods of sampling were evaluated, including constant, proportional, logarithmic, random, and multivariate, using a sampling intensity of 10 to 30% of the active collection. The criteria used to define the adopted core collection were a smaller size, a greater variability retention index, low alteration in the frequency and average number of extract accessions and greater variance among the accession traits. The strategy of constant sampling generated great alterations in the frequency of extract accessions. The multivariate strategy, with dispersion graphs and principal components associated with Tocher’s method, was considered efficient for the identification of the most divergent genotypes in each extract. The multivariate strategy generated greater alterations in the variance of traits. The average number of traits showed few modifications with various sampling strategies. Thus, the Active Collection of Germoplasm of the Embrapa Maize & Sorghum possesses a satisfactory amount of information for most of its accessions and the multivariate strategy generated more modifications in the variance of the traits, independent of the sampling intensity.