The Performance of Five Willow Cultivars under Different Pedoclimatic Conditions and Rotation Cycles

A plant’s genotype, their environment, and the interaction between them influence its growth and development. In this study, we investigated the effect of these factors on the growth and biomass yield of willows in short-rotation coppice (SRC) under different harvesting cycles (i.e., two- vs. three-year rotations) in Quebec (Canada). Five of the commercial willow cultivars most common in Quebec, (i.e., Salix × dasyclados Wimm. ‘SV1’, Salix viminalis L. ‘5027’, Salix miyabeana Seeman ‘SX61’, ‘SX64’ and ‘SX67’) were grown in five sites with different pedoclimatic conditions. Yield not only varied significantly according to site and cultivar, but a significant interaction between rotation and site was also detected. Cultivar ‘5027’ showed significantly lower annual biomass yield in both two-year (average 10.8 t ha−1 year−1) and three-year rotation (average 11.2 t ha−1 year−1) compared to other cultivars (15.2 t ha−1 year−1 and 14.6 t ha−1 year−1 in two- and three-year rotation, respectively). Biomass yield also varied significantly with rotation cycle, but the extent of the response depended upon the site. While in some sites the average productivity of all cultivars remained fairly constant under different rotations (i.e., 17.4 vs. 16 t ha−1 year−1 in two- and three-year rotation, respectively), in other cases, biomass yield was higher in the two- than in the three-year rotation or vice versa. Evidence suggests that soil physico-chemical properties are better predictors of willow SRC plantation performance than climate variables