Algal Resources
Online ISSN : 2423-8473
Print ISSN : 1883-3284
Growth and metabolic responses of the tropical red alga Gracilaria blodgettii Harvey under different abiotic factors
Rhea Joy CARTONMasahiro NOTOYA
ジャーナル フリー

2008 年 1 巻 1 号 p. 9-16


Carposporelings of Gracilaria blodgettii Harvey were exposed to different temperature (20℃, 25℃, 30℃ and 35℃), salinity (20‰, 25‰, 30‰ and 35‰) and irradiance (60 µmol photons m-2s-1 and 100µmol photons m-2s-1) levels to determine effects on growth and photosynthetic performance using a series of factorial experiments. Growth was significantly affected by variations in temperature and irradiance levels with highest growth rates obtained at 25℃ (13.1% d-1) and 100µmol photons m-2s-1 (12.7% d-1). No significant difference was found at all salinity levels tested. Photosynthesis-irradiance (P-I) parameters were directly proportional with increasing temperature. Significantly higher net photosynthesis (Pmax) was obtained at 30℃ and 35℃ than at 25℃ and 20℃ but were complemented with higher respiration rates (1.19 for 30℃ and 1.32 for 35℃) ( p < 0.05). The high photosynthetic efficiency (α) which suggests its ability to maximize low-light conditions was also significantly higher at 25℃ to 35℃ (0.04 to 0.05) than at 20℃ ( p < 0.05). This is further shown by the low compensation point photon fluxes (Ic) (19-27µmol photons m-2s-1) and saturation photon fluxes (110-159µmol photons m-2s-1). Salinity did not produce significant differences on the photosynthetic responses of the seaweed. This study concludes good culture conditions for Gracilaria blodgettii at 25℃ and 100µmol photons m-2s-1 based on high growth rates and high photosynthetic rates with low respiration.

© 2008 The Japanese Society of Applied Phycology
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