Allelopathic effects of Solidago canadensis L. between the leaf litter and green leaf

The aqueous extract of invasive Solidago canadensis L leaf has significant allelopathic effect on the coexisting native plants. To test whether S. canadensis leaf litter also had similar effects, a pot experiment was done to study the allelopathic effects of S. Canadensis (green leaves and leaf litter) on the seedling growth of recipient specie Lactuca sativa. Gas chromatography- mass spectrometry (GC-MS) was used to identify the differences in the allelochemicals present in green leaf and leaf litter. In leaf litter and green leaves of S. Canadensis 27 and 34 compounds were identified, respectively. The chemical compounds and their relative contents were higher in green leaves of S. canadensis than in leaf litter. The seedling growth of L. sativa was significantly inhibited by leaf litter and green leaves, however the green leaves extract was more inhibitory than leaf litter. Malondialdehyde (MDA) content and peroxidase (POD) activity of L. sativa increased with the increase in extract concentrations of green leaf and leaf litter, while catalase (CAT) activity decreased at 0.2g/g soil. This suggests that the accumulation of reactive oxygen species (ROS) may damage the membrane lipids, which consequently inhibited the growth of L. sativa