Root-derived allelochemicals from Moringa oleifera regulate germination and early seedling growth in New Zealand pasture, native, and weed species.

Moringa oleifera L. (moringa) is not currently commercially cultivated in New Zealand, but there is growing interest in its integration into farming systems. However, there are questions regarding its ecological impacts. One area of interest is its allelopathic traits, which may affect native and other introduced plant species. Hence, this study evauated the effects of root-derived moringa allelochemicals on the germination and seedling growth of pasture, weed an native species and employed untargeted metabolomics to identify potential bioactive compounds responsible for the observed effects, and their biosynthetic pathways. . Root extracts from two moringa provenances were assessed across concentration gradients (1-100%) in laboratory bioassays, while potted plant experiments were conducted under semi-controlled conditions to evaluate allelochemical-mediated plant-plant interactions.. Metabolomics analysis revealed several bioactive compounds with potential allelopathic activities dominated by phenylpropanoids and benzenoids, with relatively small contributions from organoheterocyclics, oxygenated compounds, and organic acids. Statistical analyses demonstrated a dose-dependent and species-specific response to moringa root allelochemicals, with white clover, a key pasture species in New Zealand, being the most adversely affected. Therefore, the utilisation of moringa within white clover pastoral systems may not be advised. Isolating and testing individual compounds will be essential for determining how moringa may influence plant growth and population dynamics in New Zealand pastoral and native ecosystems.