Effects of desiccation, diurnal temperature changes and irradiance on archeospore production of Pyropia yezoensis

The archeospore is an asexual reproduction strategy for some red algae, including Pyropia. Since cultivation of Pyropia yields important economic returns, whether or not it forms archeospores that can reseed nets becomes a key feature for this commercial seaweed. In this paper, desiccation, diurnal temperature changes and irradiance were tested for their effects on archeospore production by Pyropia yezoensis Ueda. Our results first showed that 2–3 h of daily, rhythmic desiccation and diurnal temperature changes strongly induced archeospore production, especially for the group with an increased temperature during the light period and a decreased temperature during the dark. The results also confirmed that a short photoperiod and a relatively higher light intensity benefitted the production of archeospores.