Nitrogen Deposition Elevated the Allelopathic Effects of Three Compositae Invasive Species on Indigenous Lactuca sativa

It is essential to understand the ecological role and importance of allelochemicals on the growth of native plants. Our study hypothesized that nitrogen (N) intimidation would influence the secretion of allelochemicals in invasive plants, impacting native plants. In the experiment, the root and aboveground aqueous extracts of three invasive compositae (Soildago Canadensis L., Erigeron Canadensis L. and Erigeron annuus) were used to treat the native compositae (Lactuca sativa) seeds under different N concentrations 0 mgL(-1), 50 mgL(-1), 100 mgL(-1), 200 mgL(-1) and distilled water added as an additional control (CK). The results showed that the Lettuce seeds (germination rate, germination potential, germination index, and vigor index) and seedlings (root height, plant height, fresh weight, and Malondialdehyde (MDA)) had different responses to different aqueous extracts. Allelochemicals were also varied with different exotic invasive plants and different parts of the plants. At the same time, N addition elevated the allelopathy effects of three Compositae invasive species and affected the growth of the seedling of native Lettuce. This approach offered the opportunity to study the influence of allelochemicals of exotic plants with an additional N source and explain the mechanism of a successful invasion.

Automated summary

This study found that the aqueous extracts of root and aboveground parts of invasive plants have different effects on the seeds and seedlings of native plants. The allelochemicals also vary depending on the invasive plant species and plant parts. In addition, the addition of nitrogen fertilizer enhances the allelopathy effects of invasive plants and affects the growth of native plants.