02064nam a2200169 a 450000100080000000500110000800800410001910000170006024501250007726001250020252014990032765000130182665000140183965300120185365300110186570000180187614764752018-07-19       1982    bl uuuu     u00u1 u    #d1 aVELLO, N. A.  aGanho genético esperado com seleção dentro de progênies e recombinação por policruzamentos.h[electronic resource]  aIn: CONFERÊNCIA INTERNACIONAL DE BIOMETRIA, 10., 1979, Guarujá. Anais. Brasília: EMBRAPA-DID, 1982. p. 522-531.c1982  aExpected genetic gain in breeding programs that imply within-progenie selection followed by recombination through polycrossing. Expression are developed in this study for predicting genetic gain in breeding programs that are based on within progeny selection followed by recombination through polycrossing. Expressions for variances and covariances are obtained by considering two populations with different gene frequencies, both in hardy-Weinberg equilibrium. If one considers p and r the frequency of favorable allele for populations 1 and 2, respectively, the allele frequency after crossing the two populations 1 and 2, respectively, the allele frequency after crossing the two populations will equal to t = (1/2) (p + r). A measure ^ of departure from Hardy-Weinberg equilibrium is considered as given by Crow & Kimura (1970). This factor affects the distribution of the genetic variance among and within progenies. Estimates of the genetic gain by means of variance components from experimental data are inderestimated because of some inherent properties of the breeding method. Firstly, the genetic variance among progenies decreases after polycrossing. Secondly, the gain is also a function of an unestimable component of genetic variance which includes the ^ parameter. If only one population is improved through this process estimates of genetic gain become more realistic since ^ is zero, in this case. Also, estimates of heterosis and genotype x environments interactions may (...)  agenetics  aGenética  aPlantas  aPlants1 aVENCOVSKY, R.