Nordic microalgae produce biostimulant for the germination of tomato and barley seeds

Abstract

AbstractMicroalgal biomass may have biostimulating effects on plants and seeds due to its phytohormonal content, and harnessing this biostimulating effect could contribute to sustainable agriculture. Two Nordic strains of freshwater microalgae speciesChlorella vulgarisandScenedesmus obliquuswere each cultivated in a photobioreactor receiving untreated municipal wastewater. The algal biomass and the supernatant after algal cultivation were tested on tomato and barley seeds for biostimulating effects. Intact algal cells, broken cells, or harvest supernatant were applied to the seeds, and germination time, percentage and germination index were evaluated. Seeds treated withC. vulgaris, in particular intact cells or supernatant, had up to 25 percentage units higher germination percentage after 2 days and an overall significantly faster germination time (germinated on average between 0.5 and 1 day sooner) than seeds treated withS. obliquusor the control (water). The germination index was higher inC. vulgaristreatments than in the control for both tomato and barley, and this was observed for both broken and intact cells as well as supernatant. The Nordic strain ofC. vulgariscultivated in municipal wastewater thus shows potential for use as biostimulant in agriculture, adding novel economic and sustainability benefits.