Allelopathic potential of selected woody species growing on fly-ash deposits

摘要

The objective of this study was to determine the allelopathic potential of Robinia pseudoacacia L., Ailanthusaltissima (Mill.) Swingle and Amorpha fruticosa L. that grow on the fly-ash deposits at the “Nikola Tesla – A” thermoelectric power plant in Obrenovac. The chemical characteristics of fly ash, such as pH, electrical conductivity (EC), contentof carbon (C) and nitrogen (N), contents of available phosphorus (P2O5) and potassium (K2O), the contents of total andavailable Fe, Cu, Mn, Ni and Zn as well as of phenolic acids (3,5 dihydroxybenzoic acid (3,5-DHBA) and ferulic acid) andflavonoids (rutin and quercetin) were analyzed in control fly ash (bare zones without vegetation cover) and plant rhizospheric fly ash. In order to determine the allelopathic activity of phenolic compounds in fly ash, modified soil sandwichallelopathic biotests were performed, and Trifolium pratense L. (red clover) was used as the indicator species. A. fruticosashowed the highest allelopathic activity, followed by A. altissima whereas R. pseudoacacia showed the lowest allelopathicpotential. Negative correlation was noted between radicle and hypocotyl growth inhibition of red clover and the pH of flyash. Positive correlations were found between radicle growth inhibition and the content of C, P2O5, total concentrations ofCu, available concentrations of Mn and Ni, the contents of ferulic acid, 3,5-DHBA, and rutin. Our results indicate that A.fruticosa and A. altissima increased the content of phenolics in fly ash, which can act as allelochemicals leading to radiclegrowth inhibition of red clover in the pioneer plant community on fly-ash deposits. These woody species that colonizedfly-ash deposits can initiate the beginning of pedogenetic processes altering the ecosystem processes at degraded sites.