A determination criterion was proposed for the number of replications, r, and of evaluated progenies, Nr, given P experimental plots, with Nr=P/r, and n progenies to be selected; its application was discussed in the selection of progenies of bulk populations, derived from two homozygous parents. For a known heritability at the plot level, h²0, there is a critical n below which the gain is greater with selection evaluating P/(r+1) progenies in r+1 than P/r progenies in r replications. Different h²0 scenarios were simulated in the F2 and F∞ generations, assuming no dominance. It was demonstrated that at any h²0 , if n > 18.5% of P, larger gains are obtained by assuming Nr = P, showing that the augmented block design could be used in the early stages of breeding programs. The higherh²0, the higher must be the selection intensity to justify the use of additional replications.
Selection gains; population sample size; number of selected progenies; selection limits
