Estimation of Genetic Parameters for Biomass Yield in Lowland Switchgrass (Panicum virgatum L.)

Switchgrass (Panicum virgatum L.) is an important herbaceous species for use in biofuel production. Genetic improvement of biomass yield and related traits of switchgrass will help ensure efficient feedstock production. To understand the genetics of biomass yield and related traits, 46 full-sib families, including 30 derived using a nested design, were evaluated during 2008 and 2009 in spaced-plant nurseries at Ardmore and Burneyville, OK, following a honeycomb design. Parental genotypes were evaluated adjacent to the family nurseries at Ardmore. Mean biomass yields of full-sib families ranged from 1.32 to 2.18 kg plant(-1). One family outperformed checks, while 16 other families performed as well as checks. Results showed a preponderance of additive genes in controlling biomass yield, tillering ability, and spring regrowth. Narrow-sense heritabilities for biomass yield were estimated to be 0.17, 0.14, and 0.24, based on half-sib families, full-sib/half-sib families, and midparent-progeny regression, respectively. Tillering abilities showed similar heritability estimates (0.20-0.24) using either method. For heading and flowering and spring regrowth, the heritability estimates were larger using midparent-progeny regression than using variation among half-sib or full-sib/half-sib families. Heritability for plant height and stem thickness were larger when estimated using half-sib families than full-sib/half-sib families, while the reverse held true for plant spread. Rigorous family evaluation and use of tillering ability, plant height, and stem thickness could be helpful in improving biomass yield in switchgrass.