Stahlheber, K. A., J. Lindquist, P. D. Drogosh, D. Pennington, and K. L. Gross. 2020. Predicting productivity: A trait-based analysis of variability in biomass yield among switchgrass feedstock cultivars. Agriculture, Ecosystems & Environment 300:106980.
Plant trait variation in bioenergy crops is hypothesized to affect crop biomass production. The extent of this trait variation and its relationship to production should be explored to inform cultivar selection in different environments and with environmental change. Switchgrass (Panicum virgatum L.) is an important prospective bioenergy crop in North America because it has the potential for high productivity, a wide geographic range, and distinct ecotypes that differ in a number of traits likely to be associated with production. Commercial cultivars of switchgrass have been developed for specific traits, but few studies have assessed if variation in multiple distinct traits relates to productivity and if this relationship differs with environmental conditions. To determine how trait variation affects biomass production in switchgrass we sampled a field trial of 12 switchgrass cultivars of two ecotypes (eight upland, four lowland) being grown in a common garden at the W.K. Kellogg Biological Station, Michigan State University, Michigan, USA. Yield was measured annually for eight years (2010–2017). Between 2014 and 2016, we measured physiological, morphological, and system-level (weed suppression and recovery from drought) traits of these cultivars in the common garden. We used principal components analysis to summarize these traits into composite trait variables and developed linear models to assess the relationship between composite traits and yield across and within years. The 12 cultivars exhibited considerable trait variation that did not align entirely with ecotype. Composite trait axes representing height, phenology, and leaf nitrogen content were strong predictors of yield during stand establishment (years one to three) and in drought years, but were less predictive after stand maturation. Variation in yield across the eight years of the study was better explained by traits than growing season precipitation or drought severity. Interestingly, despite differences in traits, overall ecotype was not a strong predictor of interannual variation in yield especially during stand establishment. The results suggest that traits should be incorporated into agronomic decisions for planting and managing switchgrass cultivars in bioenergy production.
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