Growth, agar yield and quality of selected agarophyte species from the Philippines

Abstract

Three local agarophyte species (Gracilaria firma, Gracilaria sp. and Gracilariopsis bailinae) were grown under controlled outdoor flow-through culture conditions. Growth rates and agar characteristics of the three species were determined. Gracilaria firma showed superior growth and agar quality among the three species. It exhibited the highest growth rate, highest agar gel strength and was observed to be highly resistant to epiphytes. Growth experiments under various light and ammonium combinations showed that the highest photon flux density level (900 μ mol m⁻²s⁻¹) and moderate ammonium (150 μM NH₄Cl) concentration gave the highest growth rates for all species. The single and interactive effects of light and ammonium enrichment on growth and agar characteristics of the three species were highly significant.