Combining abilities and elite germplasm enhancement across U.S. public sorghum breeding programs

Abstract

For mature breeding programs, maintaining genetic variation in elite germplasm requires a continual assessment of the most efficient methods to maximize functional genetic variation while improving productivity. This research assessed the relative value (defined as population means and variances) derived from elite germplasm exchange between distinct public breeding programs. Ten elite A-and R-lines from Texas A&M and Kansas State sorghum (Sorghum bicolor L. Moench) 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 10 environments over 2 yr. Combining abilities and their interactions with the environment were assessed. Combined analysis detected significant effects for all traits, but genetic effects for grain yield were not consistently significant within each group of hybrid combinations. Hybrids derived from only Texas inbreds had limited genetic variation for grain yield but the highest mean of all four groups; hybrids derived from only Kansas inbreds produced moderate genetic variation but lower grain yield potential. Maximum genetic variation for grain yield and plant height occurred when Kansas A-lines were crossed to Texas R-lines, whereas hybrids between Texas A-lines and Kansas R-lines maximized variation for days to antheses. Results demonstrated the potential benefit from crossing elite inbred parents derived from distinct breeding programs to increase genetic variation and enhance agronomic performance.

Mega-environment analysis to assess adaptability, stability, and genomic predictions in grain sorghum hybrids

“…The grain sorghum hybrids utilized in this study are as previously described by Fonseca et al (2021a). In brief, 100 hybrids were generated from crossing ten female with ten male lines in a factorial mating scheme (Comstock and Robinson 1952).…”

“…Hybrids were planted in a randomized complete block design (RCBD) with sets in replicate adjustment; each set was composed of one of the four groups of 25 hybrids (Figure 1), with randomization occurring within and between sets. In 2018 trials, each location had test, agronomic practices standard to the location were followed (Table 2) (Fonseca et al, 2021a). GPS coordinates of each environment were used to collect weather data from the NASA POWER database (NASA 2021).…”

“…Many studies have reported on the benefits of using linear mixed models to assess MET (Piepho 1997(Piepho , 1998Smith et al 2001Smith et al , 2019Resende and Thompson 2004;Piepho and Möhring 2005;Burgueño et al 2008;Balestre et al 2010;Hu 2015;Jarquin et al 2020). Bayesian models have also demonstrated their advantages for analyzing genotypic data (Sorensen and Gianola, 2007;Crossa et al, 2010;Alves et al, 2019;Fonseca et al, 2021a). For instance, Lian and de los Campos (2016) reported the stability of wheat varieties using a novel approach of the Finlay and Wilkinson stability test under a Bayesian framework.…”

“…Although this approach is still generally applicable, breeding pipelines are being modified to accommodate predictive breeding technologies (Crossa et al 2021). For instance, genomic-enabled prediction is most effective if it replaces the first phase of hybrid trials in grain sorghum breeding schemes (Fonseca et al, 2021a). Further, MET permit the development of genomic-enabled prediction models to include GxE, and results indicate better prediction accuracy (Burgueño et al 2012;Lopez-Cruz et al 2015;Lado et al 2016;Cuevas et al 2016;Acosta-Pech et al 2017;Basnet et al 2019;Costa-Neto et al 2020).…”

“…Studies have demonstrated the potential advantages of utilizing this strategy in hybrid crops (Podlich and Cooper, 1998;Technow et al, 2020). This strategy is less common in public institutions (Fonseca et al 2021a), because these programs have more limited target area with fewer genetic resources. Nevertheless, the exchange of germplasm between distinct breeding programs could foster a collaborative system between public institutions and mitigate the decrease in number and funding of public breeding programs (Shelton and Tracy, 2017;Coe et al, 2020;Fonseca et al, 2021b).…”