Application of Sodium Alginate Extracted from Brown Algae: Sargassum ilicifolium to Encapsulate Indole-3- Acetic Acid

Abstract

Alginate is a natural polymer widely used in textile, food and pharmaceuticals industries due to its properties of viscosity, stabilizing and gelling ability. Although alginate can be extracted from brown algae species such as Sargassum sp, characterization together with potential value addition to extracted alginate is yet to be explored, and the present study was designed to fill this information gap. Sargassum ilicifolium were collected from the Southern coast of Sri Lanka to extract alginate. Percentage yield, moisture content, and ash content were determined, while the FT-IR analysis was performed to determine the structural properties of the extracted alginate. As a value addition to extracted alginate, Indole Acetic Acid (IAA) encapsulated alginate beads (IAA-beads) were prepared by using the Ionotropic gelation method and they were characterized. The impact of IAAbeads on shoot growth & biomass were evaluated using Mung bean (Vigna cylendrica) against pure IAA. The percentage yield, moisture content and the ash content of the extracted alginate were 15.92±0.04%, 8.91±0.14% and 43.53±0.03% respectively. The moisture content of the alginate beads was 87% and the mean weight and mean diameter of the alginate beads were 4.99±0.01 mg, and 1.05±0.01 mm respectively. There was a significant difference (p < 0.05) between two treatments where the shoot length and dry weight of the plants grown in IAA-beads were superior to its counterpart. The highest shoot length (18.90 ± 0.47 cm) and maximum dry weight (45.70 ± 1.27 mg) were found in 20 ppm and 40 ppm IAA concentrations respectively. As the shoot growth and dry weight of plants were enhanced by the slow release of hormones by the IAA beads, this product will have a promising application in nurseries to grow seedlings.