Chemical profiling and effects of extracts from Laminaria japonica and Ulva prolifera on rooting and seedling development of common bean

Seaweed extracts are rich in diverse bioactive compounds that can stimulate growth and metabolism of plants. Thus, this study aimed to chemicallly characterize Laminaria japonica (LLE) and Ulva prolifera (ULE) liquid extracts, two formulated commercial products, and to assay their impact on seed germination and seedling development of common bean (Phaseolus vulgaris). Ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS) identified 10 and 17 chemical compounds in liquid extracts of L. japonica and U. prolifera, respectively. Soaking common bean seeds with LLE or ULE increased the germination and seedling vigour. Both seaweed treatments also resulted in increased rooting, fresh weight, and length of roots and shoots in common bean seedlings. Soaking common bean seeds with LLE or ULE modified the carbohydrate, protein and amino acid content of common bean roots and shoots, as well as the α-amylase activity in roots. Sugars (mannitol and sucrose), organic acids (malic acid), and amino acids found in both seaweed extracts may exert effects on common bean seeds and seedlings, particularly on root development. Additionally, gibberellin, which is also found in ULE, could play a role in these effects. These results accurately describe the biochemical compounds present in two seaweed biostimulants and their effects on common bean seeds and plants.