Cyanobacterial Allelochemicals as Natural Bioherbicides: Opportunities and Challenges for Sustainable Weed Management

ABSTRACT Cyanobacteria are prolific producers of secondary metabolites with a range of biological activities, including allelopathic effects. This review explores the chemical classes, ecological roles, and herbicidal potential of allelochemicals derived from cyanobacteria. The main types of these compounds include fatty acids, peptides, phenolic compounds, and toxins, which inhibit the growth of competing plants and microorganisms. They achieve this by inducing oxidative stress, disrupting hormone levels, and interfering with the processes of photosynthesis and cell division. Recent advancements in molecular biology and metabolomics have shed light on the specific mechanisms of action of these allelochemicals, facilitating the discovery of new compounds through omics‐based approaches. Additionally, the complex interactions among these allelochemicals can lead to synergistic or antagonistic effects, impacting their bioactivity and formulation as bioherbicides. While these natural compounds hold promise for sustainable agriculture and reducing reliance on synthetic herbicides, several challenges persist. These include regulatory barriers, environmental persistence, potential toxicity, and public acceptance. Regulatory frameworks in the United States and the European Union increasingly require thorough environmental risk assessments and standardized safety evaluations. Despite these obstacles, cyanobacterial allelochemicals represent a promising avenue for natural weed control. Further interdisciplinary research is essential to optimize the extraction, formulation, and integration of these products into effective weed management programs.