Abstract
Artificial culture of the laver thalli of the genus Porphyra sp. was carried out using a 2m3-tank and the following results were obtained.
1. Through floating culture using bubbling-stirring tank provided with draft, the layer thallishowed favorable growth with maximum culture density of layer thalli: 600g(dry)/m3; maximum productivity of laver per unit volume: 60.3g(dry)/m3•day; minimum electric power consumed for lighting: 0.80 KWH/g(dry); and maximum daily growth: 30%/day.
2. As the source of light, mercury lamps, particularly, thallium mercury lamps were used and experiments were carried out with strong light at a illumination intensity of up to 350 klx. Under this condition, the growth was lowered to 70% due to hindrance by storng light but still adaily growth of 10%/day could be maintained.
3. Mechanical stirring was attempted in place of bubbling-stirring and it was revealed that with a gentle stirring at 75 rpm, it was possible to substitute mechanical stirring for bubbling-sturing.
4. Use of artificial seawater for a long period was studied and 100 days continuous use was achieved.
5. Germling culture in a large tank was also studied using the spore collection method usingshell meal as the substrate. It was confirmed that a large scale germling culture can be utilized without substantial problem.
6. Amethod of measuring the speed of CO2-uptake based on the pH change of the culture liquor in the tank was devised and using this method, periodical change of the ability of photo-synthesis during the light and dark periods was pursued or the light saturation was measured. The ability of photosynthesis during the light period is lowered with time, while it tends to recoverduring the dark period.
7. The quality of the artificially cultured layer thalli was compared with that of a maricultured product by means of elemental analysis. As the result, it was recognized that the layer of artificial culture was comparable to the maricultured product of superior quality.
