Eckol Improves Growth, Enzyme Activities, and Secondary Metabolite Content in Maize (Zea mays cv. Border King)

The effects of eckol, a phenolic compound isolated from the seaweed Ecklonia maxima, on the growth of Zea mays cv. Border King were examined. Kernels were soaked in eckol solution (10(-6) M) for 18 h prior to planting. Additional treatments were water control and 10(-6) M phloroglucinol, a known phenolic plant growth regulator. Growth parameters, photosynthetic pigments, total proteins, alpha-amylase and malate dehydrogenase (MDH) activities, and secondary metabolite content such as total phenolics (TPC), total flavonoids, condensed tannins, and iridoid glycosides (IG) were determined in roots and shoots after 60 days. Generally, a considerable difference in growth, enzyme activities, and secondary metabolite content were observed between the treatments. The roots of eckol-soaked kernels yielded higher levels of proteins (124 +/- A 0 A mu g/g FW), TPC (7.0 +/- A 0.14 mg GAE/g DW), and IG (1.74 +/- A 0 mg HE/g DW) compared to the water control. The phloroglucinol treatment showed a significant (P < 0.05) increase in TPC and IG of maize roots. Kernels soaked with eckol and phloroglucinol solutions showed enhanced alpha-amylase and MDH activities. In this study, eckol treatment enhanced both growth and biochemical physiology of the maize cultivar used, possibly through synergistic effects with other plant growth hormones. The mechanism of action needs further evaluation.