Response to selection and changes in genetic parameters for 13 plant and ear traits in two maize recurrent selection programs
Lamkey, K. R.
Recurrent selection is a cyclical breeding procedure that focuses on improving the mean performance of a population by increasing the frequency of favorable alleles and maintaining adequate genetic variability for continued selection response. The Iowa Stiff Stalk Synthetic (BSSS) maize (Zea mavs L.) population has undergone continuous recurrent selection for more than 50 years as the base population for two independent selection programs. This study was designed to estimate the mean performance and important genetic parameters in BSSS before and after seven cycles of half- sib (I IS) progeny selection, six cycles of Srprogeny selection, and 11 cycles of reciprocal recurrent selection (RRS). A Design II (factorial) mating design was constructed to give direct estimates of additive and dominance variance in the individual populations. Progenies from each of the four populations were grown for two years in a randomized incomplete block experiment. The relative effectiveness of the three selection methods for improving the mean performance: for grain yield of the BSSS populations per se was 0.4'Vi1 cycle-1 for HS selection, 1.1% cycle-1 for Srprogeny selection, and 1.4% cycle- 1 for RRS. There were few changes in variance components after selection for most of the traits. Additive variance generally accounted for the largest portion of the total genetic variance for all traits except grain yield The importance of dominance variance for grain yield implied that interpopulation and testcross selection methods may give the greatest direct response to selection. The estimates of heritability and corresponding estimates of additive genetic variance indicated that continued response to selection is expected for each selection method. Selection pressure on the primary agronomic traits did not seem to affect the mean performance and genetic parameters of the other unselected agronomic traits.
This article is published as Holthaus, J. F. and K. R. Lamkey. 1995. Response to selection and changes in genetic parameters for 13 plant and ear traits in two maize recurrent selection programs. Maydica 40:357-370.