2021 Volume 87 Issue 1 Pages 23-30
The discoloration of Pyropia thalli resulting from a shortage of nutrients is a serious problem for the Pyropia industry and has often occurred during cultivation in the Seto Inland Sea, Japan. Therefore, a new method was developed to fertilize areas of Pyropia cultivation. Pyropia thalli growing-nets placed in a calm area were enclosed by a fence, using a Kagawa-style “nori skirt” made from polypropylene sheets and cultivation nets. Nutrients were supplied to the area enclosed by the fence. The concentrations of nutrients in the enclosed area were kept higher than those in the open area (which acted as a control). The color of Pyropia thalli was improved by this new method and the quality of the product was well recognized at market. The salinity in the area enclosed by the fence was lower following rainfall, suggesting that nutrients were effectively supplied to the cultivated thalli not only with fertilizer but also rainwater, because rainwater contains a high concentration of dissolved inorganic nitrogen.
