Factors affecting sporulation of Gracilaria cornea (Gracilariales, rhodophyta) carposporophytes from Yucatan, Mexico

Carpospore shedding was studied in Gracilaria cornea in order to determine maximum spore output potential for mariculture purposes. The combined effec ts of temperature (23, 26 and 29 degrees C), daylength (8:16, 12:12 and 16: 8 light:dark), photon irradiance (darkness, 20 and 40 mu mol m(-2) s(-1)) a nd spore release method (spontaneous release, osmotic shock and drying) wer e tested. Maximum spore shedding in cystocarpic G. cornea occurred within t he first three days depending on temperature. A reduction in spore release periodicity was more evident at 29 degrees C. Carpospore shedding was mainl y affected by temperature and daylength. A higher number of carpospores was released per cystocarp at 26 degrees C than at 23 or 29 degrees C. Short d ay conditions (8:16 L:D) produced a higher number of carpospores at 26 degr ees C, even at the lowest irradiances tested (darkness and 20 mu mol m(-2) s(-1)). A combination of 26 degrees C and short days (8:16) gave the highes t carpospore discharge per cystocarp. There was no significant difference b etween the spore release methods. These results could be applied to promote the establishment of extensive cultivation of G. cornea from spores as an alternative to vegetative propagation in Yucatan coast.