Dynamics of above-ground and below-ground biomass of Rumex crispus , Rumex obtusifolius and the new weedy species Rumex hybrid cv. OK-2 ( R. patientia x R. tianschanicus ) in the seeding year

Summary Docks can be serious weeds of arable land and permanent grasslands where they can persist through well-established root systems. A Rumex hybrid (R. patientia x R. tianschanicus; cv. OK-2, Uteusha) has been planted as a forage and energy crop since 2001 in Czechia and has now become a new weed species. As its ecological characteristics are unknown, there is a need for improved knowledge for developing control measures and strategies. In 2010 and 2011, we performed a tube pot experiment to investigate above-ground and below-ground biomass growth dynamics and below-ground biomass allocation of Rumex OK-2. We compared the hybrid with Rumex crispus and Rumex obtusifolius during the vegetation season in the seeding year. Above-ground and below-ground biomass of Rumex species tended to increase from July to September. In the seeding year, flowering was recorded only for one plant of Rumex OK-2 and 27.5% of R. obtusifolius plants, whereas R. crispus did not flower. The proportion of below-ground biomass of Rumex species in the upper 30 cm was about 70–80%. The growth dynamics and allocation of below-ground biomass of Rumex OK-2 were more like R. crispus than to R. obtusifolius. These similarities indicate the potential of Rumex OK-2 to become a troublesome weedy species, comparable with R. crispus.