Photoperiod and temperature regulation of the life history ofPorphyra columbina(Rhodophyta, Bangiales) from central Chile

摘要

The effects of temperature (10, 15, 20 deg;C) and photoperiod (8:16, 12:12, 16:8 (hours of light: hours of dark)) on the growth and reproduction of different stages in the life history ofPorphyra columbinaMontagne were assessed. The conchocelis phase had higher growth rates at 12ensp;h light:12ensp;h dark, 45ensp;mu;molensp;mminus;2ensp;sminus;1, and 15 deg;C. Under all the temperatures and photoperiods tested, the conchocelis phase could propagate either by monospores or vegetative fragmentation. Conchosporangia were formed only at 10 deg;C and 8ensp;h light:16ensp;h dark or at 15 deg;C and either 8ensp;h light:16ensp;h dark or 12ensp;h light:12ensp;h dark. Long photoperiods inhibited conchosporangia formation at all temperatures tested with the exception of 20 deg;C and 16ensp;h light:8ensp;h dark, where sporangia was formed once. Conchospores were released when the temperature was decreased (15 to 10 deg;C) maintaining the photoperiod. Conchospore germination occurred under the three photoperiods and temperatures tested. Growth of juvenile fronds was maximum at 15 deg;C and either 12ensp;h light:12ensp;h dark or 16ensp;h light:8ensp;h dark. Fronds formed carpospores and spermatia at 15 deg;C and 16ensp;h light:8ensp;h dark only. With optimum conditions the life history was completed in 60 days. Spermatia had three chromosomes (nensp;=ensp;3).