Allelopathic effects of Paulownia tomentosa and hybrid P. elongata × P. fortunei on Sinapis alba, Festuca pratensis and Poa pratensis

To determine the influence of Paulownia tomentosa, new hybrid, P. elongata × P. fortunei, on the native flora, its allelopathic properties were analysed and compared to those of P. tomentosa. Dry-leaf extracts from Paulownia trees growing in southwestern part of Poland were used to derive allelochemicals, which were applied to seeds and seedlings of white mustard and two grass species which co-occur with P. tomentosa in urban areas. Water extracts had the strongest inhibitory effects on germination and growth of Sinapis alba seedlings. Extracts used in lower concentrations were stimulatory to seedlings growth of Festuca pratensis, but higher concentrations were inhibitory. The effects of the extracts on seeds germination and initial seedlings growth of Poa pratensis were not significant.