Contribution à l’étude du potentiel biostimulant de l’ortie (Urtica dioica) et du potentiel préventif des extraits d’ortie et de chrysanthème (Chrysanthemum coronarium) sur la culture du poivron (Capsicum annuum) : vers des alternatives écologiques aux intrants agricoles

Abstract

This thesis research, conducted at the experimental farm of the University of Mostaganem, focused on evaluating the biostimulant and bio-insecticidal effects of nettle (Urtica dioica) and chrysanthemum (Chrysanthemum coronarium) extracts on greenhouse-grown sweet pepper (Capsicum annuum, Majister variety). The experimental design assessed different concentrations of nettle extract (25%, 50%, and 100%) as well as the protective effects of the extracts applied individually or in combination against major pests. The results showed that 100% nettle extract optimally stimulated plant growth, as evidenced by increased stem length and leaf number, and significantly enhanced fruit production. From a phytosanitary perspective, nettle extract alone effectively controlled whitefly infestations, while complete acaricidal activity against spider mites was observed across all treatments. However, the combination of nettle and chrysanthemum extracts exhibited an antagonistic effect against aphids. Furthermore, the highest yield was recorded with the nettle-only treatment (1.87 kg). These plant extracts therefore represent a promising and sustainable alternative to synthetic chemical inputs in agricultural production.