Variabilidade e divergência genética em cruzamentos dialélicos de soja / Variability and genetic divergence in soybean diallel crosses
Rosa María Alvarez Parra
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia
DATA DE PUBLICAÇÃO
Estimates of genetic divergence (DG) have not been used for parental selection in breeding programs, because of the inconsistence of the results. The objective of this study was to evaluate the possibility of predicting the genetic variability (VG) of soybean populations derived from two-way crosses, using DG data from AFLP markers (Bonato et al., 2006), and also to evaluate the possibility of improving the relationship between DG and VG by partitioning the genetic distance (GD) in general genetic distance (DGGi and DGGj) and specific genetic distance (DGEij), according to a diallel scheme. Ten populations derived from a diallel composed by adapted parents with different levels of genetic divergence (GD) were used: low ( 0,2 DG £ ), medium ( 0,4 DG @ ) and high ( 0,6 DG @ ). One hundred F2:3 progenies of each cross were evaluated in a simple lattice 10 x 10 design (two replications) during the 2009/10 growing season for the traits grain yield (PG) and plant height at maturity (AM). Genetic variance among F2:3 progenies ( 2 p s ), F2:3 progeny mean ( 3 : 2 F ), amplitude of individual F2:3 progeny means ( 3 : 2 F ), heritability among F2:3 progeny means ) h ( 2x , and responses to selection (Rs), with intensities of 20% and 40%, were estimated for each cross. For PG, the Spearman correlation between DG and 2 p s , 2 x h and Rs (20% and 40%) were positive, high and significant (P<0.05), indicating an increase of the parameter estimates following the genetic divergence (DG) increasing. For AM, the correlation were high and significant (P<0.05) only for DG and 2 x h . In general, the partitioning of DG did not increase the association with the parameters estimates, except for the correlation between DG with 3 : 2 F and 3 : 2 F for both traits. General results suggest that AFLP genetic divergence between the parents considered in this study expresses the true DG for PG, since they were consistent with the results of a previous work, using the same estimates of DG. Thus, these estimates of genetic divergence could be used in order to select high potential parents for grain yield in soybean breeding programs.
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