Phytotoxic potentials of Brocchia cinerea (Delile) Vis. on germinability and growth of two noxious weeds in Egypt

Weeds are among the main factors responsible for reducing crop yield by competing with cultivated plants for essential resources. This study aimed to evaluate the allelopathic potential of the donor species Brocchia cinerea (Delile) Vis. against two recipient weed species, Melilotus indicus L. and Vicia monantha Retz., by assessing their germination, growth, and selected physiological parameters. An aqueous shoot extract of B. cinerea at concentrations of 5, 10, 20, and 40% (along with a control) was applied in a Petri dish experiment to test germination responses. In a complementary pot experiment, the crude shoot powder of B. cinerea was mixed with soil at 4% and 8% (w/w) to verify its effects on seedling growth. Key parameters including shoot and root length, leaf area index, total pigments, protein, and carbohydrate contents were determined. The application of B. cinerea extracts significantly inhibited plumule and radicle elongation, germination percentage, and seedling dry weight. Similarly, the crude powder treatments markedly decreased shoot and root lengths and leaf area index in both recipient species. Physiological analysis revealed significant reductions in total photosynthetic pigments, protein, and carbohydrate contents. B. cinerea exhibits strong allelopathic potential and could serve as a promising natural weed management agent by suppressing the germination and growth of competing species.