This work aimed to study the plant conditioning effect and mode of action of a plant-based biostimulant used in organic farming. This new generation plant biostimulant, named ELICE16INDURES®, is rich in plant bio-active ingredients containing eleven supercritical botanical extracts encapsulated in nano-scale liposomes. The dose–response (10 to 240 g ha−1) relationship was tested in a field population of autumn barley (Hordeum vulgare) test crop, and underlying molecular mechanisms were studied. Applying nanotechnology, cell-identical nanoparticles may help the better uptake and delivery of active ingredients increasing resilience, vitality, and crop yield. The amount of harvested crops showed a significant increase of 27.5% and 39.9% interconnected to higher normalized difference vegetation index (NDVI) of 20% and 25% after the treatment of low and high dosages (20 and 240 g ha−1), respectively. Illumina NextSeq 550 sequencing, gene expression profiling, and KEGG-pathway analysis of outstanding dosages indicated the upregulation of pathogenesis-related (PR) and other genes—associated with induced resistance—which showed dose dependency as well.