Impact of Angiosperm Tree-Derived Allelochemicals on Physiological Responses of Acceptor Plants—A Systematic Review

Allelopathy—the release of biologically active secondary metabolites by plants—is a key mechanism regulating plant community dynamics in forest and agro-forestry ecosystems, yet the physiological basis of allelochemical effects of angiosperm trees on acceptor plants remains insufficiently understood. This systematic review synthesises knowledge on the physiological effects of angiosperm tree allelochemicals, focusing on photosynthesis, respiration, water relations, mineral nutrition, and growth and development. Following PRISMA 2020 guidelines, five databases (Web of Science, ScienceDirect, SpringerLink, Wiley Online Library, and Scopus) were searched between October 2025 and June 2026 for English-language peer-reviewed articles on allelopathic effects on plant physiological processes; risk of bias was assessed via methodological transparency, and, given design heterogeneity, a qualitative narrative synthesis was performed. Of 7748 records identified, 99 met the eligibility criteria. Allelochemicals, including phenolic acids, flavonoids, naphthoquinones, terpenoids, alkaloids, and coumarins, were associated with disrupted photosynthetic efficiency, impaired mitochondrial electron transport, altered stomatal functioning, reduced nutrient uptake, and suppressed cell division, with oxidative stress—often linked to reactive oxygen species accumulation—recurring as a shared mechanism; effects were concentration-dependent, with synergistic interactions noted between allelochemicals. These findings advance mechanistic understanding of angiosperm tree allelopathy and highlight its relevance for sustainable agriculture and biological weed management.