Inter-annual variation in biomass combustion quality traits over five years in fifteen Miscanthus genotypes in south Germany

• M. x giganteus genotypes have shown consistency in mineral concentrations especially for K, Cl and dry matter yield.
• The factors of variation were rainfall, harvest date, genotype selection and plant age.
• March was an appropriate harvesting time for optimal biomass quality and yield.

In recent years, miscanthus has emerged as a very promising alternative energy crop predominantly due to its low input requirements and high dry matter yield potential. In this study, inter-annual variation in biomass yield and composition between 2004 and 2010 was studied in a multi-genotype trial planted in south Germany. The main factors of interest in the inter-annual variation were climatic conditions (rainfall and temperature) and different harvest dates (January/February/March/April). The multivariate regression analysis showed that the interactions of harvest date–aging and harvest date–rainfall have significant effects on the stability of biomass quality characteristics over the productive growth period. In M. sacchariflorus the harvest date–aging interaction improved the combustion quality by reducing the Mg concentration by 29% and ash by 18%, whereas the harvest date–rainfall interaction contributed by decreasing the concentrations of Ca, Si and N by 8%, 4% and 6%, respectively. The M. x giganteus genotypes showed more consistency in mineral concentrations, especially K and Cl, and dry matter yield in comparison to M. sinensis over the productive growth period.