The Potential of Indonesian Macroalgae as Natural Biostimulants: Analysis of Phytohormone Composition and Its Effect on the Growth of Solanum lycopersicum
Mirnawati Dewinda Rumalean Ansanai1*, Rukman Hertadi1

1 Biochemistry and Biomolecular Engineering Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesha 10, Bandung 40132, Indonesia
*Corresponding author: mirnawatidewinda[at]gmail.com

Abstract

The mounting national demand for food necessitates the development of innovative and sustainable cultivation technologies, including the use of marine-based biostimulants. This study aims to characterize the phytohormone content of three Indonesian macroalgae species (Ulva sp., Sargassum sp., and Gracilaria sp.) and to evaluate their effects on the early growth of tomato plants (Solanum lycopersicum). Bioactive compounds were extracted using an optimized hot water extraction method (1:20 w/v ratio at 80 C for 4 hours). Quantitative analysis of phytohormones was conducted using colorimetric and spectrophotometric methods.
The results showed that Sargassum sp. extract (SE) significantly stimulated root growth (4.90 +/- 0.40 cm) at 20 percent concentration, associated with auxin content of 0.37 mg/L and gibberellin content of 1.32 mg/L. Meanwhile, application of 20 percent Gracilaria sp. extract (GE) produced the highest plant height (9.03 +/- 0.152 cm), corresponding to higher gibberellin levels (4.65 mg/L) and cytokinin contents, including zeatin (5.81 mg/L) and kinetin (5.44 mg/L). These physiological responses indicate that species-specific phytohormone composition plays an important role in regulating organ-specific plant growth. The findings highlight the potential of Indonesian macroalgae as effective organic biostimulant sources to support sustainable crop productivity.

Keywords: Biostimulants, Phytohormones, Macroalgae, Spectrophotometry, Solanum lycopersicum.

Topic: Biochemistry