Integrating Genomic Selection and Accelerated Generation Advancement to Improve Genetic Gain in a Winter Wheat Breeding Program

Winter wheat (Triticum aestivum L.) is a cold-hardy crop with higher yield potential compared to spring wheat, making it more desirable to Ontario farmers. The economic importance of winter wheat makes it imperative that innovative breeding tools, including genomic selection (GS) and accelerated generation advancement (AGA) protocols, are introduced to allow for the rapid generation and selection of value-added traits for cultivar development. Development of improved cultivars is limited by the rate of genetic gain. Genetic gain can be optimized by increasing selection accuracy and decreasing generation time. The objectives of the research presented in this thesis were to examine the feasibility of integrating GS and an AGA protocol in a winter wheat breeding program by, (1) determining the accuracy of predicting the performance of optimal breeding lines for advancement through the program; (2) evaluating the effects of maximized photoperiod on generation time; and (3) providing recommendations for the optimization and integration of new breeding tools into the program. Genotypes in the advanced and elite yield trials were used to train GS models to predict performance of the genotypes in a testing population for a number of agronomic and disease-related traits resulting in a prediction accuracy (r) for grain yield (r = 0.34) and Fusarium head blight (FHB) incidence (r = 0.59). The inclusion of genotype-by-environment interaction effects in the Elite University of Guelph Winter Wheat Breeding Program (Elite-UGWWBP) population showed its importance as a covariate in GS models. Genetic gain through the reduction of cycle time using an AGA protocol was also tested. The lengthening photoperiod while controlling temperature and total light received, daily light integral, led to a 7% decrease in generation time, indicating that temperature or light levels may be more important for accelerating maturation rate than previously reported. A cost-benefit analysis is necessary before determining if AGA is viable on a program basis. The ability to increase selection accuracy and decrease generation time will lead to increased rates of genetic gain annually, an increase in program efficiency and the development of successful winter wheat cultivars.