Culture of the kelp Undaria pinnatifida in subtropical waters using clonal seedlings: A pilot study in China

The temperate-water kelp Undaria pinnatifida (wakame) was successfully farmed in subtropical coastal waters of Fujian, China using clonal sporophyte seedlings. The clonal sporophytes acclimated effectively to subtropical conditions, achieving mean frond lengths of 190.7 ± 18.4 cm and fresh weights of 353.4 ± 58.5 g per individual sporophyte in early March. Cluster-clipping cultivation method yielded 10.20 ± 0.43 kg m⁻¹ cultivation rope, surpassing the traditional northern cultivation counterpart Liaoning province (8.63 ± 0.27 kg m⁻¹) by 19 % and demonstrating 101 % greater biomass than individual-clipping method (5.07 ± 0.25 kg m⁻¹). The subtropical-grown Undaria blades had higher protein content (2.08 ± 0.06 %) and umami-associated amino acid levels (glutamate: 2.46 ± 0.07 g kg⁻¹; aspartate: 1.97 ± 0.06 g kg⁻¹) than blades grown in Liaoning. The success of this subtropical cultivation trial shows the feasibility of expanding the cultivation further down to the southern province to meet the uprising market demands. • Clonal seedlings enabled successful cultivation of U. pinnatifida in subtropical Fujian. • Undaria sporophytes showed rapid winter growth and commercial-grade biochemical quality. • Findings support southward expansion of the temperate kelp aquaculture.