Hem S. Bhandari

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.

Switchgrass (Panicum virgatum L.) is a main herbaceous species projected for use as feedstock in biofuel production. Understanding the nature of genetic variation for biomass yield and other important traits in switchgrass would aid cultivar development. The aim of this study was to estimate the genetic component of variation and narrow‐sense heritability for biomass yield and several morphological and phenological traits in lowland switchgrass. Thirty‐seven half‐sib families were evaluated during 2007–2009 at two south central Oklahoma locations, Ardmore and Burneyville. Half‐sib families were different for biomass yields and other traits, suggesting the presence of additive gene action in controlling these traits. Family × location effects were observed for biomass yield and days to spring regrowth. Stem thickness, plant spread, and spring regrowth showed family × year interaction effects. Days to flowering showed a significant family × location × year interaction. Narrow‐sense heritability for biomass yield was 0.13 based on half‐sib family variation and 0.29 based on parent–progeny regression, suggesting a complex genetics of biomass yield. Stem thickness also had low (≤0.27) and plant height and tillering ability had low to moderate (0.26–0.48) heritability. Heritabilities were moderate (0.47–0.70) for heading, flowering, and plant spread and relatively high (≥0.82) for spring regrowth. The biomass yield was positively correlated with tillering ability, plant height, and stem thickness. Rigorous family evaluation procedure and use of tillering ability as an indirect measure to improve biomass yield could enhanced gain from selection.