Heritability of Biomass Yield and Yield Components in Lowland Switchgrass.

Switchgrass (Panicum virgatum L.) breeding in the recent days has focused primarily on improving biomass yield for use in biofuel production. Understanding of heritability of biomass yield would help adopt an appropriate approach in cultivar development.  The objective of this study was to estimate the narrow sense heritability for biomass yield and yield components in lowland switchgrass. Using a broad based elite breeding population of lowland switchgrass as a reference population, we generated 37 half-sib and 14 full-sib families. The half-sib and full-sib families were evaluated separately at two Oklahoma locations, Ardmore and Burneyville . The seedlings were planted in May 2007 in space plant nurseries following honeycomb design with 1.5 m plant spacing.  The biomass was harvested from each individual plant separately after the killing frost in 2007 and 2008. The plant height and stem thickness scores were recorded after anthesis and the tillering ability was scored after harvesting in both years. The narrow sense heritability estimates for biomass yield was 0.13 and 0.23 based on variation among half-sib and full-sib families, respectively. The heritability estimates based on half-sib and full-sib families, respectively, were 0.20 and 0.39 for plant height, 0.27 and 0.27 for tillering ability, and   0.21 and 0.37 for stem thickness. The low heritability for biomass yield and its component traits warrants a rigorous family evaluation procedure in cultivar development. The tillering ability and stem thickness were associated with biomass yield indicating that these traits could be used for indirect selection for biomass yield.