Allelopathic effects of Poa pratensis on other grassland spp.

We estimated the allelopathic potential of water leachates from Poa pratensis leaves, sampled each month from May to September. The seeds of test species were irrigated daily with Poa pratensis leaf water leachates (1.25, 2.50, 5.00%). The distilled was used as control. The content of phenolic compounds was determined in the plant material. The effects of leaf water leachates of Poa pratensis on tested grass species, depended on the sampling dates of leaves. This implies that the accumulation and release of phytotoxins from plant tissues was affected by weather conditions as well as by plant developmental phase. The leaf leachates collected in July were most inhibitory to the growth of the studied species, because these leachates had the highest content of phenolic compounds. White clover proved the most and perennial ryegrass the least susceptible to allelopathic influence of P. pratensis.