Growth Promotion of a Sea Water Algae with Sterile, Ulva pertusa Kjellman, Due to Supplemental Lighting

Ulva pertusa is widely used as human food and also to feed cultured fish. U. pertusa is expected to be used as a bio-filter for purification of breeding - circulation water in the terrestrial aquaculture of fish. Insufficient sunshine and lower temperature causes bad commercial production. In order to realize stable cultivation of U. pertusa throughout the year, experiments on the growth of a sea water algae with sterile, U. pertusa Kjellman, due to supplemental lighting were performed. An illuminance of 1×104 lx in the treatment areas and 2×104 lx in the control, when the illuminance was 8×104 lx in the greenhouse. Artificial lighting was added during the daytime in treatments 1∼3. The mounting height of each luminaire was adjusted to have a PPFD of 140 μmol m-2s-1. Each lamp had the R/FR PF ratio of 3.8, 1.2, 0.8. Considering of relationship between the growth and cumulative PPFD including daylight and supplemental lighting, the growth of the experimental area were superior to the control area. U. pertusa can be grown with warm sea water using supplemental lighting. But under the growth environment with daylight and supplemental lighting together, it is difficult to recognize whether the R/FR PF ratio influences photomorphogenesis.