Figure 1.

Aboveground biomass (d.w.) of Reynoutria × bohemica grown in pots with various substrates based on miocene clay from coalmine spoil banks with (black columns) and without (open columns) Melilotus alba (significant differences are indicated by asterisks) in 2006 (a - left) and 2007 (b - right). ClayC = clay enriched with slow-release biofertilizer Conavit; ClayCS = clay enriched with Conavit and arbuscular-mycorrhizal product Symbivit, both produced by Symbiom Ltd. Equal letters indicate non-significant differences between the substrates; lower case - without melilot, upper case - with melilot.