Allelopathic Properties of Tithonia diversifolia (Hemsl.) A. Gray (Asteraceae) Used in Sustainable Agriculture

Introduction. Allelopathy can be defined as the ability of plants to release secondary metabolites that can stimulate or inhibit biological processes of other plants. Tithonia diversifolia (Hemsl.) A. Gray, commonly known as Mexican sunflower, has gained interest for its allelopathic effects, both positive —by promoting crop growth, yield, and defense —and negative, due to its invasive character (Kato-Noguchi, 2020). Responses of plants to the allelochemicals produced by T. diversifolia vary widely, depending on the origin of the plant material, the method of application, and the concentration in allelochemicals. Nevertheless, the allelopathic potential of T. diversifolia remains partially unexplored, especially its effects on traditional legume species and cultivars such as lima bean (Phaseolus lunatus L.), which holds significant nutritional and cultural value (Salazar and Tun, 2016). Objective. To analyze the allelopathic effects of T. diversifolia on cultivated and weedy plant species, with a particular focus on legumes. Methods. A systematic review was conducted, compiling 76 studies published between 1982 and 2024 that evaluated the allelopathic effects of T. diversifolia on 50 cultivated species from 19 botanical families. Results and discussion. A total of 186 biological processes in crops were identified as being affected by the allelopathic compounds of T. diversifolia. In legumes (Fabaceae), the majority of effects were positive (67.3 %), followed by neutral (17.3 %), negative (13.5 %), and variable (1.92 %) responses. These findings highlight the potential of T. diversifolia as an agroecological tool, with specific applications for the management of leguminous crops such as beans (Mkindi et al., 2020). Conclusion. The use of allelopathic plants like Tithonia diversifolia represents a promising strategy to promote more sustainable agricultural practices in legume cultivation.