Amelioration of tomato plants cultivated in organic-matter impoverished soil by supplementation with Undaria pinnatifida

Rising demands of food together with modern practices in agriculture require the inclusion of areas with sub-optimal soil qualities for cultivation and the replacement of contaminant chemical fertilizers. In this work, we evaluated the use of the seaweed Undaria as a soil amendment of organic-matter impoverished soil. We demonstrated that Undaria supplementation to a substrate containing vermiculite:organic soil mix (95:5) promotes the growth of tomato plants evidenced in increases in aerial and root biomass and the restoration of redox status. By means of chemical and functional analysis we identified in Undaria extract the presence of plant nutrients, minerals, vitamins, antioxidant capacity and phytohormone-like activities. All together these compounds would be able to promote growth and contribute to redox homeostasis in early plant developmental stages which are critical for tomato production yield. We propose Undaria supplementation as an efficient way to provide nutritional and growth promoter compounds to tomato crops growing on impoverished soils. •Undaria amendment improves growth parameters of plants cultivated in poor soils.•Undaria extract contains nutrients, minerals, vitamins and antioxidant capacity.•Undaria extract contains hormone-like activities auxin, cytokinin and gibberellin.•Undaria is a suitable supplement intended to organic-matter impoverished soils.