Growth, tetrasporogenesis, and life history in culture of Caulacanthus okamurae (Gigartinales, Rhodophyta) from Korea

Effects of temperature, daylength, and irradiance on the growth and tetrasp orogenesis of Caulacanthus okamurae and its life history were examined in c ulture. Plants grew over a wide range of temperature (13 - 27 degreesC), da ylength (8 - 16 h light), and irradiance (20 - 160 mu mol photons m(-2) s(- 1)), and optimal growth occurred at 23 degreesC. 14:(10) over bar, L:(D) ov er bar and 60 mu mol photons m(-2) s(-1). Tetrasporangia were formed at the same ranges of daylength and irradiance as in the plant growth experiments but did not develop at 13 degreesC and 16 degreesC. Life history of C. oka murae was a Polysiphonia-type and it was completed in unialgal culture with in 4-5 months. Early developmental patterns of tetraspores and carpospores were similar; spores divided into two unequal cells each producing a single rhizoid. Cystocarps were formed at the end of branch tips of female plants . On the basis of physiological and morphological features, the taxonomic p osition of C okamurae is discussed.