An augmented additive-dominance (AD) model for analysis of multi-parental spring wheat F2 hybrids

Many plant breeding trials often include a large number of genotypes with possibly no repeated field plots. Ineffective control of field variation could result in an inflated residual variance and/or biased estimation/prediction of genetic effects. Three hundred thirty seven (337) multi-parental spring wheat (Triticum aestivum L.) F2 hybrids were grown in two locations in South Dakota without repeated field plots in 2009. Two agronomic traits (grain yield and plant height) were measured. An augmented additive-dominance (AD) model including a sub-block component was proposed for analyzing the data. This augmented AD model was first investigated by simulated data followed by actual data analysis. Simulation results showed that the augmented AD models yielded unbiased estimates with and without presence of sub-block effect. Actual data analysis revealed that grain yield and plant height were significantly influenced by the systematic field variation. Additive effects were significant for grain yield and plant height, and dominance effects were significant for plant height. Results also showed that most spring wheat lines developed by South Dakota State University breeding program (SD lines) were good general combiners for increasing grain yield and reducing plant height. Thus, this augmented AD model can reduce the impact of field variation on estimation and/or prediction of genetic effects.