Changes in biochemical composition during the transition from vegetative to reproductive phases in Ulva ohnoi

The cultivation of Ulva lags behind that of red and brown seaweeds despite its high growth rate and richness in nutrients. This study aimed to investigate the biochemical changes that occur during the transition of Ulva ohnoi from vegetative to reproductive (determination and differentiation) phases. Changes in proximate content, pigments, antioxidant activities, hormones, metabolites, and minerals were analyzed during the phase transition. Through the vegetative to determination phase, lipid decreased from 0.85 to 0.61 %, while chlorophyll a increased from 184.23 to the 244.89 μg g⁻¹. Catalase activity increased from 1079 to 7017 units mg⁻¹ protein, while indole acetic acid raised from 0.004 to 0.027 μg g⁻¹ during the transition from the vegetative to the differentiation phase. Among minerals, carbon (35.08 %), sulphur (0.32 %), phosphorus (4.53 mg 100 g⁻¹), and calcium (6.20 mg 100 g⁻¹) increased in the differentiation phase compared to that in the preceding phase. It is essential to understand these biochemical changes as this might help in both cultivation and natural resource management.