Interaction of photoperiod and temperature in the development of conchocelis of Porphyra purpurea (Rhodophyta: Bangiales)

The indoor cultivation of the free-living conchocelis of a Porphyra purpurea (Roth) C. Ag. strain, isolated from Long Island Sound, was established, and the effects of both photoperiod and cultural temperature on conchosporangia development were studied. Statistical analysis revealed that temperatures between 10°C and 15°C and light phases between 12 and 16 h per day comprised an ideal growth “window” for both the vegetative growth and reproductive development of conchocelis. For vegetative growth, there was a significant interaction between temperature and photoperiod. Conchospores were released from mature conchosporangia under both neutral (12/12 h) and long (16/8 h) day lengths. Different seawater supplements, such as full- and half-strength Von Stosch enrichment, showed no significantly different effects on growth or development. This work provides a guideline for maintaining conchocelis cultures of P. purpurea, which is a type of the Porphyra genus.