Allelopathic Potential of Coniferous Species to Old-Field Weeds in Eastern Quebec

Abstract

Phytotoxicity of Abies balsamea (L.) Mill., Picea mariana (Mill.) BSP., Pinus resinosa Ait., Pinus divaricata (Ait.) Dumont, and Thuya occidentalis L. fresh leaf and leaf litter leachates were evaluated on the germination and growth of four weed species: Phleum pratense L., Poa pratensis L., Agropyron repens (L.) Beauv., and Epilobium angustifolium L. Three dilutions of leachates were used for the germination tests. Germination of all weed species was inhibited in proportion to the dilutions used. Fresh leaf leachates of A. balsamea and P. resinosa were most inhibitory to germination. P. pratense was usually less affected by the treatments than were the other three species. Germination or E. angustifolium and P. pratensis was delayed by the different solutions; germination of P. pratense was delayed only by fresh leaf leachates of A. balsamea and P. divaricata. Height growth and root elongation of A. repens, P. pratensis and P. pratense were inhibited by most extracts. P. mariana leaf leachates were the most inhibitory to height growth and root elongation. All seedlings treated with P. mariana leaf leachates exhibited severe root necroses which affected normal root development. Laboratory experiments suggested that allelopathic weed control, using coniferous leaf litter or fresh leaves, could aid in reforestation of abandoned fields by reducing undesirable competition. Forest Sci. 32:112-118.