Genetic evaluation of an Eucalyptus breeding program after two cycles of reciprocal recurrent selection

Empirical validation of the reciprocal recurrent selection (RRS) in Eucalyptus breeding is limited. Our study fills this gap by quantifying the realized response to selection achieved after two cycles of RRS in a breeding program of “urograndis”, the interspecific hybrid between E. grandis and E. urophylla. We also investigated the effects of the RRS on the genetic parameters of the breeding population. We evaluated 17 trials of different generations and employed a linear mixed model to estimate the general and specific hybridizing ability of the parents and hybrid combinations, respectively. The realized response to selection was calculated as the difference between the mean genotypic values of the first and second generations. The RRS scheme effectively improved wood volume in the breeding population, with the mean increasing by 28.5% from the first to the second generation. The genetic variability also increased. Considering the dominance effects is vital for a proper selection of the best genotypes. These findings provide insights for decision-making in the Eucalyptus breeding program.