Introduction of a seedling production method using vegetative gametophytes to the commercial farming of Laminaria in China

Laminaria is the main seaweed species under commercial cultivation in China, which utilizes 80 x 10(9) artificially cultured seedlings each year. This paper reports the large-scale application of seedling production using vegetative gametophytes in Laminaria cultivation. Key techniques, such as the attachment of gametophytes to the collectors and tank culture of seedlings in the hatchery, are examined. The problems of detachment and irregular dispersion of seedlings were also investigated. An efficient and practical seedling production technology was developed, which consists of seeding gametophytes on collectors, control of seawater flow in tanks, washing of collectors and regulation of ambient light, seawater temperature and nutrition supplement. After 2 months of culture, seedlings grown on woven palm rope collectors 0.5 cm in diameter measured up to the national technical standard of China (i.e., > 20 individuals cm(-1) at a length of > 1.5 cm, and > 100 individuals cm(-1) at a length of 0.2 cm-1.5 cm, desolation rate < 1% and detachment rate < 5%). Compared with spore-derived seedlings, no significant differences in sporophyte recruitment and dispersion pattern were observed. Large-scale production of seedlings for commercial cultivation of 4,000 ha from 2001 to 2006 was conducted successfully.