Effect of cutting frequency on above- and belowground biomass production ofRumex alpinus, R. crispus, R. obtusifoliusand theRumexhybrid (R. patienta×R. tianschanicus) in the seeding year

Summary Rumex species are important weeds in grasslands and on arable land. The Rumex hybrid (R. patienta × R. tianschanicus; cv. OK-2, Uteusha) has been planted as a forage and energy crop since 2001 in the Czech Republic, but its ecological requirements and its potential to become a new weedy species have never been investigated. In 2010 and 2011, we performed a pot experiment to investigate the effect of none, one and two cuts per year on biomass production of Rumex OK-2 and common broad-leaved Rumex species (Rumex obtusifolius, R. crispus and R. alpinus). The higher cutting frequency can reduce the belowground biomass, but no effect on the aboveground biomass was detected. Flowering in the seeding year was recorded in only 50% of R. obtusifolius plants. Non-flowering R. obtusifolius plants produced significantly more belowground biomass than flowering plants under no cutting or one cut treatments. The growth response of Rumex OK-2 to different cutting treatments was very similar to R. crispus. These similarities indicate the weed potential of the hybrid to become a troublesome weedy species, similar to R. crispus.