Although the traditional method of the cultivation of Porphyra (natural seeding of conchospores on bamboo sticks and nets) may still be practiced in some areas (especially Japan), the bulk of nori produced in Japan, China, and Korea depends on artificial seeding of con chospores from hatchery grown conchocelis. In these countries, 'seeding' commences in autumn when the water temperature begins to decrease to 18 °C but this can vary depending upon species. The nets are tradition ally 1.8 m wide and 18 m long and made ofsynthetic twine 3-5 mm in diameter. The nets may have a mesh size of about 15 cm. In Korea, nets 2 m x 100 m are now being routinely used in commercial cultivation. Artificial seed ing may be done outdoors in the sea or indoors in shallow hatchery tanks. Outdoor seeding is carried out in nursery grounds by setting up layers of (12-16) nets on support systems. Hatchery produced mature conchocelis (con chocelis that has gone through several developmental phases including fat filaments and conchosporangia) on shells or on artificial substrata are placed in plastic bags and hung under the nets. The released conchospores float on the water and are collected in the nets. Indoor seeding may be done by fixing the net either over a rotary wheel or a conveyor belt that is rotated in a seeding tank con taining mature conchospore inoculum from the free living conchocelis culture (Figure 1d). Another method, popular in China, is the indoor seeding of nets that are suspended in shallow seeding tanks about 25 cm in depth. The conchospores are inoculated by re circulating water via a submersible pump that is in the tank.
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