Solid–liquid extraction of bioactive compounds as a green alternative for developing novel biostimulant from Linum usitatissimum L.

Abstract Background The interest expressed by the agriculture in the category of innovative biostimulants is due to the intensive search for novel preparations based on natural substances i.a. allelochemicals. Scientific research into the design and testing of next-generation biostimulants marks advances for sustainable agricultural production. Results Our research represents an innovative and comprehensive approach to the use of Linum usitatissimum L. seed extracts in soybean cultivation using foliar treatments. A multi-tiered approach was adopted, involving both the assessment of soybean responses at the agronomic, morphological and biochemical levels. It was hypothesized that the extract would improve the growth and yield of soybean through mechanisms based on improved physiological and biochemical processes. The study showed that the extract was rich in micro- and macro-nutrients (in particular potassium and zinc), amino acids (with the largest proportion of glutamic acid), fatty acids (predominant oleic + elaidic acids) and carbohydrates (sucrose and glucose). Soybean responded positively by increased in plant height, number of pods and seed yield. The results confirmed that the tested biostimulant is not only an environmentally friendly product, but also is capable of increasing the growth and productivity of soybeans, thus increasing farmers' profit. The obtained yield was characterized by a lower total proteins pool (average decrease approx. 2%). The extract caused changes in the amino acid profile (especially in the case of proline and lysine) and fatty acid composition (significantly higher content of acids: heptadecanoic, octadecanoic, eicosanoic, eicosapentaenoic, docosanoic, erucic, tricosanoic). Conclusions All the observations made confirm that the extract positively affected the soybean crop. Based on the study, it was concluded that solid–liquid extraction could be considered as a green alternative for prototyping a novel and ecological biostimulant. Graphical Abstract