Effects of natural leachates of Acacia dealbata Link in Galicia (NW Spain)

A systematic collection of throughfall (rain passing through the canopies), stemflow (rain flowing over the stems), and soil percolates was carried out in a Acacia dealbata plantation during one year, and its allelopathic capacity was biotested using Lactuca sativa L. var. Great Lakes. The results showed an allelopathic effect related to flowers: Germination of L. sativa was inhibited 30% by throughfall, 60% by stemflow, and 75% by soil percolates during the blossoming of A. dealbata, while radicle growth of L. sativa was inhibited 23%, 33%, and 48% by the same solutions. Climatic factors, particularly rainfall some days before, were also important. The three types of samples showed significant toxicities during some periods of the year, particularly percolates, which retained toxicity for a longer time, due perhaps to the decomposition of flowers fallen on the ground.