ASSESSING THE GENETIC VARIATION, PERFORMANCE, AND GENOMIC PREDICTION OF GRAIN SORGHUM HYBRIDS DEVELOPED FROM U.S. PUBLIC BREEDING PROGRAMS

Abstract

Many independent events led by public institutions significantly increased grain sorghum yield in the US, including the development of grain sorghum hybrids and the introgression of exotic germplasm. Nonetheless, the rates of genetic gain have been modest, and hence new strategies should be explored. This study assesses alternatives to maximize genetic gain via elite germplasm enhancement based on exchanging inbred lines derived from distinct sorghum breeding programs. Additionally, it presents classical and genomic prediction models that explore combining abilities and their interaction with environments to predict the performance of grain sorghum hybrids. Lastly, it evaluates the adaptability and stability of grain sorghum hybrids within mega-environments. For that, ten elite A- and R-lines from Texas A&M and Kansas State sorghum breeding programs were crossed in a factorial design to generate 100 hybrids. Hybrid combinations were grouped to represent hybrids within and across programs. Grain yield, plant height, and days to anthesis were measured in ten environments over two years. Results indicate that crosses between elite inbred lines developed from distinct sorghum breeding programs can increase selectable variation and generate top performers. General and specific combining abilities and their interaction with the environment can effectively predict hybrid performance, and the inclusion of genomic information further increased the prediction accuracy of models. The mega-environment analysis identified the established subtropical and temperate sorghum production regions and suggested that hybrid combinations between Texas A&M and Kansas State sorghum breeding programs can generate high-performing and stable grain sorghum hybrids across target regions. Plant breeders, growers, and seed companies are encouraged to explore such crosses to produce promising new products. Finally, the opportunity the exchange elite germplasm across breeding programs could foster collaborative efforts between public institutions and enhance the rate of genetic gain in crops with limited public and private resources.