Evaluation of the Biostimulant Activity of the Microalgae Chlorella sorokiniana and Scenedesmus sp. and Their Resistance to the Most Widely Used Agricultural Pesticides.

Microalgae are promising bioinputs for sustainable agriculture. This study is relevant because it was evaluated the biostimulant activity of live microalgae and the pesticide tolerance of Chlorella sorokiniana and Scenedesmus sp. Biostimulant assays revealed significant improvements in plant growth parameters: Scenedesmus sp. increased germination by 157% and root elongation, while C. sorokiniana induced the greatest cotyledon thickening. Both species enhanced the chlorophyll content at all doses. Pesticide tolerance varied by species and compound: herbicides caused moderate stress, whereas fungicides (especially Mancozeb) caused severe morphological damage. AFM and SEM confirmed membrane alterations under chemical exposure. Overall, these microalgae demonstrated strong biostimulant potential and tolerance to agrochemicals, highlighting their role as tools for crop productivity.