Predicting productivity: A trait-based analysis of variability in biomass yield among switchgrass feedstock cultivars

•Traits differed among 12 cultivars of Panicum virgatum in a common garden experiment.•Composite trait variables correlated with variability in productivity over eight years.•Composite trait variables better predictors of yield than cultivar ecotype or climate.•Taller cultivars with more leaf nitrogen had highest yield only in establishment years.•Composite traits had highest explanatory power during severe drought year.