Fig. 2.

Total harvestable yield (tonnes dry matter per hectare per year (t DM ha⁻¹ yr⁻¹)) for the four willow varieties grown at Harpenden (Harp) and Aberystwyth (Aber) during the first rotation (a) and second rotation (b). Data are means + SE of four replicates. Different letters indicate significant differences between the genotypes (P < 0.05), with differences at Harpenden indicated by the lower case letters and differences at Aberystwyth the underlined lower case letters.