ABSTRACT: Allelopathic management involves the use of natural compounds produced by plants to suppress weed growth, offering an eco-friendly alternative to synthetic herbicides. Cosmos sulphureus has shown allelopathic potential, but one of the challenges is the typically low concentration of allelochemicals. Environmental stress, such as drought, may stimulate the production of these compounds. This study evaluated the effect of drought stress at 40% field capacity, for fifteen days, at the initial reproductive stage, on the increase of the allelopathic potential of C. sulphureus. The plants were subjected to drought stress. After this period, fresh leaves were collected for malondialdehyde and proteomic tests; and used to prepare a crude extract. Bioassays were performed on Lactuca sativa, Sorghum bicolor, Urochloa decumbens, Cucumis sativus, and Panicum maximum. All extracts significantly inhibited germination (5–90%), depending on the species, concentration, and treatment. Extracts from stressed plants showed lower bioactivity on germination (22,74%), shoot (43,91%) and root growth (35,60%) compared to non-stressed extracts (15,69, 44,70, 33,65% respectively) with no significant differences occurring between the treatment conditions. It is concluded that drought stress at 40% field capacity, for fifteen days, at the initial reproductive stage, in Cosmos sulphureus plants, does not induce an increase in the allelopathic potential of this species. These findings open avenues for further research into its bioherbicidal activity and the exploration of novel herbicidal mechanisms of action, contributing to the de-velopment of sustainable weed management strategies.
Felipe Silva 