Outdoor culture of agar yielding red alga Gracilaria edulis (Gmelin) Silva

Abstract

Agar yielding red alga Gracilaria edulis was successfully cultured in fibre glass tanks with running seawater at out door environment. The biomass of cultured seaweed showed a crop growth rate ranging between 3.9 - 8.0 g/day after different days of culture. The tanks stocked with lesser quantity of seed material showed better growth rate. Experiments were also conducted by providing the seed material with different quantities of NPK, Urea, Ammonium sulphate + Sodium phosphate and Potassium nitrate + Phosphate + EDTA at weekly intervals. Higher crop growth rates (CGR) of 4.3 g/day with 700 mg NPK and 5.2 g/day with 80 mg urea were attained respectively. The growth rate recorded was 3.6 g/day in the tanks provided with Ammonium sulphate + Sodium phosphate and 3.7 g/day in the tank provided with Potassium nitrate + Phosphate + EDTA. Data on the environmental and hydrological parameters from seaweed culture tanks were recorded.