Abstract
Abstract The extract of red marine algae contained growth-enhancing properties which is associated to age and their morphotypes. Kappaphycus alvarezii cultured in Ekas Bay, Lombok, Indonesia was studied and aimed to determine the content of growth-promoting substances in the young and old thallus of brown and green morphotypes of K. alvarezii. The content of K. alvarezii thallus growth substances was determined by High Performance Liquid Chromatography (HPLC). This study showed that the old thallus in the brown K. alvarezii strain contained auxin 8.43 ppm and the young thallus 2.89 ppm, while the old thallus in the green strain K. alvarezii contained auxin 10.92 ppm and the young thallus contained 16.28 ppm. This study concluded that auxin was the only growth promoter detected in K. alvarezii seeds in both young and old thallus in green and brown morphotypes.