Characterizing phenotypic diversity, genotype by environment interactions, and optimizing selection efficiency of a miscanthus germplasm collection

Increasing concerns over energy security and the environmental effects of conventional fuels has spurred interest in alternative avenues of energy production, with biomass feedstocks emerging as a promising source of sustainable renewable energy needs. Miscanthus is a largely unimproved crop and current biomass production focuses on a single sterile clonal cultivar of M. ×giganteus. Although highly productive, the sterility and genetic uniformity M. ×giganteus complicates crop improvement. Evaluation of available Miscanthus germplasm is necessary in order to create additional improved cultivars for biomass production. The overall objective of this project was to evaluate available Miscanthus breeding resources in the U.S. and determine how to best maximize breeding efficiency for Miscanthus. Multiple studies were conducted to: 1) determine low temperature thresholds for damage and death of Miscanthus seedlings in a controlled environment chamber, 2) quantify the effect of early planting dates for Miscanthus seedlings in the field on survival, growth and yield, 3) assess genotypic differences in biomass yield, putative yield-component traits, and spring and autumn frost tolerance, 4) determine the predictive value of three putative yield-component traits for estimating yield, and 5) quantify the relative importance of genotype × environment and error variances for estimating genotypic values. We found that Miscanthus seedlings and mature plants have exceptional cold tolerance for a C4 grass. M. ×giganteus, the industry standard for biomass production, exhibited low tolerance to frost relative to other Miscanthus genotypes, indicating the potential for genetic improvement. We observed large and significant differences among genotypes for all biomass traits. The commercially important biomass cultivars, M. ×giganteus ‘Illinois’ and ‘Freedom’, produced the greatest yields. Estimates of G × E interactions and repeatabilities indicated that selection efficiency would benefit more from increased sampling of locations rather than years and that effective selection of Miscanthus for yield could be accomplished in year 2 before the planting reaches maximum yield potential in subsequent years, thus reducing the time between selections. For a long-lived perennial grass such as Miscanthus, minimizing the number of years per selection cycle will be critical for maximizing genetic gain per unit time. Genetic variation for cold tolerance in Miscanthus can be used to optimize planting dates for specific cultivars, to breed new Miscanthus biomass cultivars with improved cold tolerance, or even introgress genes for cold tolerance from Miscanthus into Saccharum