Yields of willow biomass crops across a range of sites in North America

Abstract

Yield is an important factor in determining the economic feasibility of willow biomass crops. Over the past 18 years a series of yield trials have been established across North America with older clones from the Ontario Ministry of Natural Resources and the University of Toronto and new genotypes from the SUNY-ESF breeding programme. One trial that has been harvested four times showed that the yield of four commercial clones increased by 23.0 % from the first to second rotation and by 30.8 % from the first to fourth rotation. Quantifying these changes is important when modeling production and cash flow of these perennial systems. Across all yield trials, those with new willow clones have produced 38 % more biomass than trials with the older clones. The top three new clones in each of the nine trials that have been harvested produced a mean yield of 11.5 odt ha-1 yr-1, which was 13.9 % better than the three older reference clones in these trials. Key words: Breeding, Salix, short rotation woody crops, yield