Comparison of manganese tolerance and accumulation among 24 Salix clones in a hydroponic experiment: Application for phytoremediation

• Significant clonal differences in Mn tolerance and accumulation among Salix clones
• Phytoextraction potential of Mn varied 5.8-fold among Salix clones.
• Clonal selection improves Mn phytoremediation efficiency.

Willows (Salix spp.) are excellent candidates for phytoremediation owing to their large biomass, high metal tolerance and accumulation capacity. In this study, manganese tolerance and accumulation capability in 24 Salix clones were evaluated exposed to 1 mM Mn by a hydroponic system for 21 days. Results suggested that there were wide variations in Mn tolerance and accumulation capability among the clones. Clonal variation in biomass production ranged from growth reduction to growth stimulation. The clonal differences in Mn concentrations (μg g− 1, dry weight, DW) ranged from 3183.10 to 5827.7 in leaves, from 1840.48 to 4572.17 in stems, and from 2733.33 to 10,253.88 in roots exposed to excess Mn. The total Mn contents in shoots (including leaves and stems) varied 5.8-fold among clones under Mn treatment. Five clones exhibited high Mn tolerance and accumulation capacity, and clone J333 (Salix babylonica × Salix matsudana) had a relatively high Mn tolerance index and the highest Mn content in aboveground tissues. Consequently, further evaluation of the Salix clones for Mn tolerance and phytoremediation potential is recommended in field experiments.