Effects of temperature and irradiance on filament development of Grateloupia turuturu (Halymeniaceae, Rhodophyta)

Grateloupia turuturu Yamada is an economically valuable red alga with great potential in nutraceuticals and pharmaceuticals. Filaments of G. turuturu are of primary importance in germplasm preservation and sporeling culture, although filaments were not present in its life cycle. In this study, effects of temperature (10, 15, 20, 25, and 30 °C) and irradiance (10, 30, 60, and 90 μmol photons m⁻² s⁻¹) with photoperiod 10:14 h (light/dark) on filament development were investigated. Our results indicated that 25 °C was the optimal temperature for the formation of discoid crusts regardless of the irradiance. Conditions of 20 °C and 60 μmol photons m⁻² s⁻¹ promoted the development of discoid crusts and formation of upright thalli.