Evaluation of Commercial Fertilizer Based Medium for Desmodesmus abundans Cultivation and the Use of Microalgal Biomass as Biostimulant in Soybean Glycine max (L.) Merr.

Microalgae have emerged as a promising renewable resource due to their biomass production and cell composition. This study aimed to evaluate a commercial nutrient source for Desmodesmus abundans L2B Bold cultivation, analyzing its metabolome, photosynthetic pigments, and biomass potential as a biostimulant for soybean crops. Samples underwent metabolomics analysis via GC/MS after derivatization. Microalgal biomass produced in a commercial fertilizer medium (CF) was applied as a biostimulant at three concentrations in soybean crops at 30, 50, and 70 days post-sowing. Pigments and dry biomass levels were similar in BG11 and CF media, but CF reduced production costs by 31.8%. Distinct metabolite profiles were observed, with major classes being organic acids (19%), amines (14%), sugars (12%), fatty acids (11%), and esters (10%). Foliar application of 20% (v/v) D. abundans L2B Bold increased stem diameter (5.88 mm), leaf fresh and dry mass, and stem mass. Additionally, there were increases in nitrogen (26%) and protein (38.1%) in seeds, alongside higher pod (10.9) and seed numbers (25.2) and seed mass (3.43 g) per plant−1. These findings demonstrate the feasibility of using CF as a culture medium and the potential of D. abundans L2B Bold as a biostimulant for soybean production.