EN
The biological activities of root exudates from Poa pratensis (donor) were examined in biotest in which germination and height and mass of seedlings of Dactylis glomerata, Festuca pratensis and Phleum pratense (acceptors) were evaluated. The experiment was performed using root exudate recirculating system (RERS). It was documented that root secretion of Poa pratensis circulating in a closed cycle considerably limited germination of Dactylis glomerata and Phleum pratense, but only slightly limited germination of Festuca pratensis. It also negatively influenced the height of Phleum pratense seedlings, in the first growth as well as during regrowth after first cut; in case of Dactylis glomerata only the height of the plants after first cut was influenced. They had no pronounced influence on the height of Festuca pratensis seedlings. The application of amberlit XAD-4 reduced negative influence of root secretion of Poa pratensis on the height of Phleum pratense and Dactylis glomerata seedlings. Dry matter accumulation by tested grass species was reduced significantly at the presence of Poa pratensis root exudate as compared to the control; exception was Festuca pratensis, which was not influenced. The highest effectiveness of XAD-4 in limiting negative influence of Poa pratensis secretion on biomass of the tested species was found in the case of Phleum pratense.