Selection for winter survivorship in lowland switchgrass

Authors: POUDEL, HARI - Aafc Lethrdge Research Center; LEE, DOKYOUNG - University Of Illinois; Casler, Michael

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2020
Publication Date: 1/30/2020
Citation: Poudel, H., Lee, D., Casler, M.D. 2020. Selection for winter survivorship in lowland switchgrass. BioEnergy Research. 13/109-119. https://doi.org/10.1007/s12155-020-10091-1.
DOI: https://doi.org/10.1007/s12155-020-10091-1

Interpretive Summary: Development of switchgrass into a dedicated biomass feedstock for conversion to bioenergy requires breeders to increase biomass yield of new varieties. Collection of late-flowering lowland ecotypes from the southern USA is one strategy to accomplish this, because moving them into northern climates, extends the growing season almost up to the time of killing frost. However, these southern ecotypes have low levels of winter survivorship, requiring significant selection and breeding efforts to make improvements. This study reports gains from selecting and breeding 14 different lowland populations for winter survivorship. Gains were made in 7 of 14 populations, resulting in significant improvements over existing cultivars. The best population had an average survivorship greater than 90% at four northern locations, indicating that selection broadened its adaptation to cold climates. These results and this population will be of value to breeders, agronomists, and producers with interests in biomass production from perennial crops.

Technical Abstract: Development of switchgrass (Panicum virgatum L.) as a sustainable biomass crop for conversion to bioenergy requires substantial increases in biomass yield. Because switchgrass is highly photoperiodic, one approach toward this goal is to collect, screen, and select germplasm populations from the southern USA in northern environments where they represent a delay in flowering time of up to 6 weeks compared to local ecotypes. This delay in flowering has been linked to increases in biomass yield of up to 50%. The objective of this study was to conduct and evaluate selection progress for winter survivorship in 14 southern lowland populations of switchgrass. The populations originated from USDA Plant Hardiness Zones (PHZ) 7 or 8 and the selection and evaluation were conducted in PHZ 4 or 5. Seven of the 14 populations responded to selection, with increases in winter survivorship and/or biomass yield across four evaluation locations. Winter survivorship and biomass yield were highly correlated with each other, so that increases in survivorship usually translated to increases in biomass yield. The top-ranked population represented the third cycle of selection within the cultivar Kanlow, indicating that the greatest gains from selection represented longer-term efforts than a single generation of field-based selection. This study verified that alleles for winter survivorship and plants capable of surviving in PHZ 4 or 5 can be found across a broad geographic area in the southern USA, albeit at very low frequencies in most populations.