|Price, David -|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 12, 2013
Publication Date: N/A
Interpretive Summary: Switchgrass is undergoing transformation to become a perennial bioenergy crop. Breeding for increased biomass yield per acre is a significant component of this transformation. Because most switchgrass breeding is done in large nurseries, containing tens of thousands of plants that are visually evaluated under relatively non-competitive conditions, breeding for biomass yield is relatively inefficient. This research showed that tillering (spreading) traits are typically the most important for predicting biomass yield of plants grown under non-competitive conditions, but that plant height and leaf area traits are more important for plants grown under real-world competitive conditions. These results will help to refine the objectives of switchgrass breeding programs, improving their efficiency, and increasing the rate of progress toward higher yielding varieties.
Technical Abstract: Switchgrass (Panicum virgatum) has many valuable characteristics as a biofuel feedstock, but commercial viability will require further improvements of biomass yield to improve sustainability. Direct selection for biomass yield in switchgrass has proven difficult due to the many factors influencing biomass yield. The identification of morphological traits associated with biomass yield could increase the efficiency of breeding efforts if these traits can be used as indirect selection criteria. By allowing increased screening and greater intensity of selection for biomass yield within spaced-plant nurseries, these results may impact how phenotypic selection is used for switchgrass cultivar development. The objective of this research was to identify morphological traits in parental plants that are predictive of biomass yield in progeny swards. Results of this research demonstrate the challenges of selecting for increased biomass yield in switchgrass within spaced-plant nurseries. Limited predictive ability was observed using individual and combinations of plant morphological traits. Comparisons of models with varying subsets of traits revealed common traits among the best predictive models including plant height, single-plant dry biomass, and second leaf width. Predictions of single-plant biomass, using the same set of morphological traits, revealed a large effect for tillering-related traits. The observation that different traits affect biomass yield differently in the two planting types may indicate an effect of plant competition on the relationship of these traits with biomass yield. While these traits can help guide selections for a preferred plant ideotype, additional efforts to improve selection schemes for increasing biomass yield will be necessary for sustained genetic gain in switchgrass.