Monterey Bay Aquarium Research Institute
Marine Botany

Porphyra Cultivation of Porphyra yezoensis

(Conchocelis stage)

    As mentioned previously, the farming of nori occurs in two stages. The first occurs indoors, from May to October, where the Conchocelis stage is cultivated along with the production of conchospores. The second stage occurs from October until May or April, where the framer focus on the cultivation of the thallus in the field. The following will provide a timeline sketch of how nori is farmed in China.

    Cultivation of Conchocelis

    Early and mid-May

    • Carpospores are collected and seeded on mollusc shells (Meretrix meretrix). The cultivation occurs in large elongated shallow concrete tanks with 20-30 cm of seawater in depth. The seawater has been subjected to sedimentation and the addition of nitrogenous and phosphate nutrients. At this stage, the temperature is not controlled and allowed to flunctuate with the air temperature. However, optimal growth occurs between the temperatures of 20-25 degrees Celsius.
    • The carpospores develop to the Conchocelis phase, which is responsible for creating conchospores. The conchospores will develop into the thallus stage, which is then ready for harvesting.

    shells with filaments

    © 1999, Prof. Michael D. Guiry. Reuse of picture not permitted without prior consent. http://seaweed.nuigalway.ie

    Mid-May to early June

      Water temperature is raised to 22-23 degrees Celsius to encourage vegetative growth of the Conchocelis phase.

    Early July to late August

    • The water temperature is raised again from 22-23 degrees Celsius to 27-28 degrees in mid-August. After mid-August, the water temperature is gradually decreased.
    • In July, light intensity is reduced to encourage formation of conchosporangia, which will eventually release conchospores.

    Late August to late September

    • Water temperature is dropped to 23 degrees during this period of conchosporangium formation.
    • Light intensity is held the same to encourage the formation of the conchospores in conchosporangia.
    • The light period is reduced to 8-10 hours by darkening the culture rooms.

    Late September to mid-October

    • Conchospores are present in late September.
    • The mass discharge of conchospores occurs in early and mid-October.
    • Once the conchospores are released, they are seeded on special cultivation nets which are placed in the tanks.
    • When 50,000 spores are being released a day, the light intensity is increased slightly to encourage thallus germination.
    • The water in the tanks are also agitated to move the spores and to obtain an even distribution of conchospores on the cultivation nets.

    After the release of the conchospores, the cultivation processes now focuses on the cultivation of the thallus of Porphyra. These processes now occur outdoors, in the field, where the seaweed is now subject to natural environment conditions.

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© 1999 Lisa Chen. All rights reserved. Use for educational purposes permitted with acknowledgment and notice.  

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