Seaweed-Derived Biostimulant (Kelpak®) Influences Endogenous Cytokinins and Bioactive Compounds in Hydroponically Grown Eucomis autumnalis

The effect of a seaweed-derived biostimulant (Kelpak (R) at 1, 2.5 and 5 % dilution; v/v) on the growth, endogenous cytokinin (CK) and phytochemical content in Eucomis autumnalis (Mill.) Chitt. under hydroponic conditions was evaluated. After 4 months, the stimulatory effect of Kelpak (R) treatments was more noticeable in the underground organs than in the aerial organs. Total endogenous CK was also higher in plants treated with Kelpak (R) (c.a. 1000-1200 pmol g(-1) DW) compared to control plants (860 pmol g(-1) DW). Isoprenoid CKs (which mainly accumulated in the aerial organs) were more dominant than aromatic-type CKs across all the treatments. A total of 11 bioactive chemicals (8 phenolic acids and 3 flavonoids) and eucomic acid known for their diverse biological activities were quantified in the samples. The most abundant compound was p-coumaric acid (6.5 mu g g(-1) DW) and it was approximately sevenfold higher in 2.5 % Kelpak (R)-treated plants than in the control. It was also noteworthy that syringic acid only occurred in the underground organs of 5 % Kelpak (R)-treated plants. Eucomic acid which is a major bioactive compound in E. autumnalis was significantly enhanced in Kelpak (R) treatments, and the leaves accounted for more than 70 % of the overall content. Thus, Kelpak (R) elicited a significant influence on the growth, endogenous CK and phytochemical content in E. autumnalis. These findings provide additional evidence of the enormous potential of Kelpak (R) as a useful biostimulant with practical applications in various agricultural endeavours.