Allelopathic effects of silverleaf nightshade (Solanum elaeagnifolium Cav.) aqueous extracts on germination and early growth of wheat, broad bean and flax

Silverleaf nightshade (Solanum elaeagnifolium Cav.) is one of the most problematic invasive plants threatening agricultural lands in the northern Middle East. Its recent widespread occurrence has raised serious concern, as one of the major problems associated with lands infested by this weed is its allelopathic effect on successive crops. Therefore, the present study aimed to evaluate the allelopathic effect of different concentrations of its aqueous extracts on the germination and seedling development of three potential successive crops, wheat (Triticum aestivum L.), broad bean (Vicia faba L.) and flax (Linum usitatissimum L.) and to screen its chemical components. All tested concentrations of the plant extract had a negative impact, inhibiting germination and suppressing seedling growth. The highest concentration (12.5 %) inhibited germination of wheat and broad bean by 100 %, while flax seeds showed complete germination inhibition at concentration of 7.5 % and above. Furthermore, the lower concentrations exhibited an inhibitory effect on growth over time, likely due to the accumulation of active substances within seedlings, preventing normal germination and development. The results of the chemical composition analysis also indicated that the residues of this plant contain a considerable amount of bioactive secondary metabolites known to inhibit seed germination, particularly glycosides and terpenes. The study's findings demonstrate the adverse impact of this plant’s spread and recommend implementing all possible measures to limit its further expansion. Conversely, the study highlights the potential use of its bioactive compounds as natural agents for biological control.