Variance components and heritability of biomass yield in switchgrass (Panicum virgatum L.) grown in the Southern Great Plains

• The lowland ecotype produced greater biomass, increasing up to 526% over a two-year period (2008–2010).
• Switchgrass biomass yield decreased 13–88% during a drought year compared to the previous year (2010–2011).
• Accessions accounted for 49 and 37% of the total variation in the lowland and upland ecotypes.
• Biomass yield was moderately heritable in switchgrass (0.50).

Switchgrass (Panicum virgatum L.) is an important feedstock for biofuel production and also used for rangeland restoration and as a forage crop. Wide variability has been observed in switchgrass at both ecotypic and population levels. Variance component analysis can identify the relative contribution of different factors which can be used as guidance in selection of genotypes in breeding programs. The objectives of this study were to estimate and partition the sources of variance components and to estimate heritability of biomass yield in switchgrass. A total of 36 accessions including 31 plant introduction accessions collected from the Germplasm Resources Information Network (GRIN) and five improved populations developed at the Samuel Roberts Noble Foundation were used for estimating the variance components. Fourteen of these were lowland and 22 upland accessions. The accessions and populations were evaluated in Ardmore, Oklahoma from 2007 to 2011. Average biomass yield of lowland accessions was 2.41 ± 0.05 kg plant−1 and that of upland accessions was 0.57 ± 0.01 kg plant−1. Biomass yield increased up to 526% from 2008 to 2010; however, it decreased up to 88% from 2010 to 2011 growing seasons due to severe drought. Variance component analysis revealed that accessions accounted for 48.5 and 37.2% of the total variation in the lowland and upland ecotypes, respectively. Biomass yield was moderately heritable for switchgrass (0.5) and for lowland (0.6) and upland (0.44) ecotypes, indicating that biomass yield could be improved through selection. In general, lowland ecotypes are more productive; however, a few upland accessions (e.g., PI 476294, PI 657660, PI 642193) were found productive even during dry years, albeit less biomass was produced than lowland ecotype.