Combined nitrogen deposition and Cd stress antagonistically affect the allelopathy of invasive alien species Canada goldenrod on the cultivated crop lettuce

Abstract

Allelopathy of invasive alien species on seed germination and seedling growth (SGerSGro) of coexisting plant species play a critical role in their effective invasion. Currently, atmospheric nitrogen deposition and heavy metal pollution has become more and more serious globally. Significant changes may occur for the allelopathy of invasive alien species on SGerSGro of coexisting plant species under the increasing nitrogen deposition and heavy metal stress. This study aims to evaluate the allelopathy of the notorious invasive alien species Canada goldenrod (Solidago canadensis L.; using leaf extracts) on SGerSGro of the cultivated crop lettuce (Lactuca sativa L.) under the independent and combined nitrogen deposition and cadmium (Cd) stress. Canada goldenrod recruit distinctly allelopathy on SGerSGro of lettuce and remarkably upsurge with increasing concentration of leaf extracts. Nitrogen evidently enhanced SGerSGro of lettuce and dramatically alleviated the allelopathy of Canada goldenrod on SGerSGro of lettuce. Cd notably suppressed SGerSGro of lettuce and distinctly enhanced the allelopathy of Canada goldenrod on SGerSGro of lettuce. The combined nitrogen deposition and Cd stress antagonistically affect the allelopathy of Canada goldenrod on SGerSGro of lettuce. Consequently, the weakened allelopathy of Canada goldenrod may prevent its further invasion process speculatively, especially under the combined nitrogen deposition and Cd stress.