Biological plant strengthener (bio-strengthener) formulated as a wettable powder based on vesicular-arbuscular mycorrhizae and plant nutrients to improve crop yield. The formulation of the biological strengthener is designed with a consortium of spores belonging to vesicular-arbuscular mycorrhizal fungi strains Glomus geosporum, Gigaespora margarita, Glomus fasciculatum, Glomus constrictum, Glomus tortuosum, and Glomus intraradices.