Location: Dairy Forage ResearchTitle: Heterosis and reciprocal-cross effects in tetraploid switchgrass
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2014
Publication Date: 8/22/2014
Publication URL: http://handle.nal.usda.gov/10113/62845
Citation: Casler, M.D. 2014. Heterosis and reciprocal-cross effects in tetraploid switchgrass. Crop Science. 54:2063-2069.
Interpretive Summary: Switchgrass is a candidate for cellulosic bioenergy feedstock development in many parts of North America. Because production costs are generally considered too high for economic and sustainable production of switchgrass biomass, breeding for increased biomass yield is a viable and desirable research objective. In an effort to mimic the hybrid production system of commercial corn companies, 62 switchgrass hybrids were created between the 2 main types of switchgrass, upland and lowland. A small number of hybrids were higher in biomass yield than the average of their parents, but none exceeded their best parent. Although no superior hybrids were identified, the experiments verified that breeding the lowland type of switchgrass for improved cold tolerance was successful in creating a high-yielding candidate variety that is well adapted to northern climates. These results will be of value to switchgrass breeders and agronomists, as well as to future producers of switchgrass biomass.
Technical Abstract: Switchgrass is a candidate for cellulosic bioenergy feedstock development in many parts of North America. Because production costs are generally considered too high for economic and sustainable production of switchgrass biomass, breeding for increased biomass yield is a viable and desirable research objective. The objective of this study was to estimate heterosis and reciprocal-cross effects in three types of switchgrass hybrids: upland-by-upland (U×U), lowland-by-lowland (K×K), and upland-by-lowland (K×U) hybrids. A total of 62 hybrids and 2 parental populations (abbreviated K and U) were evaluated for 3 years at 2 Wisconsin locations. Mid-parent heterosis for biomass yield was observed in only four K×K hybrids and no K×U hybrids, suggesting that it is not a universal phenomenon between upland and lowland ecotypes. Maternal effects appeared to be more important than additive effects, as most hybrids were similar in performance to their maternal parent population. Flowering time was a strong driver of biomass yield, accounting for 67% of the variation among hybrids in biomass yield and increasing biomass yield by 0.47 Mg ha-1 for each day delay in anthesis.