M. Guimaraes et al., Life history, reproduction and growth of Gracilaria domingensis (Gracilariales, Rhodophyta) from Brazil., BOTAN MARIN, 42(5), 1999, pp. 481-486
The life history, reproduction and impact of fertilization on growth rate o
f Gracilaria domingensis (Kutzing) Sender ex Dickie were studied in vitro.
The life history is of the Polysiphonia-type, and was completed in six mont
hs. Carpospores developed into plants which produced tetraspores in 60 days
. The gametophytes originated from the released tetraspores became fertile
after 101 days with a sex ratio of 1:1. Spermatangia were found in single d
eep conceptacles, verrucosa-type, as well as confluent ones, henriquesiana-
type. Mature cystocarps have a conspicuous fusion cell and tubular nutritiv
e cells formed from the gonimoblast to both pericarp and cystocarps floor.
Non-fertilized female gametophytes showed a higher number of new apices dur
ing cultivation. Fertilized female branches grew similarly to the unfertili
zed branches during the first three weeks, but much slower from that time o
n. The reproductive cost, expressed as growth differential was around 55% s
maller than the control.