Microalgae grown on biogas digestate as biostimulants for cropsResman, Lara (Avtor) Mihelič, Rok (Mentor) Acién Fernández, Francisco Gabriel (Komentor) microalgaebiogas digestateopen raceway pondsmicroalgae productivitydecision support protocolbiostimulantsmicroalgae extractionplant bioassaysbiostimulant effectsSinapsis albaCurcumis sativusCannabis sativacannabinoidsIn a study conducted in the ALS6 region of Europe (Ljubljana, Slovenia), the production of a microalgae consortium, primarily Scenedesmus dimorphus and S. quadricauda, on anaerobic digestate from food waste was investigated in three ponds (P1, P2, and P3) within a greenhouse. The impact of digestate quality and quantity, as well as seasonal variations, on microalgae productivity was examined. Based on measurements and observations, a simple Decision Support Protocol (DSP) was developed, based on easily measurable parameters (pH, temperature, electrical conductivity, dry matter, ammonium, nitrate, and nitrite nitrogen, delayed fluorescence index, and optical density). The produced microalgae biomass was tested for biostimulatory effects on plants using various bioassays: germination of white mustard (Sinapis alba) and auxin- and cytokinin-like efficiency tests with cucumber (Cucumis sativus) cotyledons. The biomass from the most productive pond (P2) was further processed through high-pressure homogenization and enzymatic hydrolysis to obtain cell extracts. These extracts were also tested with plant bioassays under controlled laboratory conditions and later in pot experiments in a greenhouse at different stages of cannabis (Cannabis sativa) development. Under optimal conditions, an average microalgae production of 11±1.5 g m-2 day-1 and a nitrogen use efficiency of 28±2.6 g biomass g-1 nitrogen input were achieved, following the DSP procedure. Positive effects on seedling germination and root formation in tested plants were observed, but no effect on plant growth or secondary metabolite production in cannabis was found. Valuable insights were gained into the potential of digestate-grown microalgae as biostimulants, though further optimization of cultivation conditions is needed to achieve specific biostimulatory effects.20252025-07-02 14:03:36Doktorsko delo/naloga170183VisID: 257693COBISS_ID: 241188355sl