Received: 24-10-2023 / Accepted: 23-05-2024
The aim of this study was to advance grow-out cultivation techniques of slender red seaweed (Gracilaria tenuistipitata)in experimental conditions, serving as basis for experimental farming on a commercial scale, contributing to improving productivity and ensuring the quality of raw material seaweed. Four experiments were conducted: (1) culture density, (2) fertiliser doses, (3) depth for cultivation and (4) biomass of seaweed seedlings left after harvesting. Each experiment was repeated three times from May to December 2022 in Thai Thuy District, Thai Binh Province. Research results show that the optiml initial density of seaweed seedling was 600 ± 50 g/m2; basal fertilizer with a dosage of 0.2 kg/m2and inorganic fertilizer as nutrient supplement with a dosage of 0.02 kg/m2were most appropriate in commercial slender red seaweed farming; the depth for cultivation of Gracilaria tenuistipitataof 60 ± 5cm was best for control of the algae fouling; and the appropriate biomass of algae seedlings left after harvesting was 550 ± 50 g/m2.