Study On Induction, Propagation And Seedling Raising Of Unisexualfilaments Of Scytosiphon Lomentaria

A method of seedling raising using unisexual filaments induced from the parthenogenetic gametes of the valuable brown algae Scytosiphon lomentaria collected in Dalian coast was reported in the paper. We studied the effects of temperature, light intensity, and photoperiod on the induction, propagation, and seedlingraisingof the unisexual filaments, which also beingcultured in natural water temperature and farmed at sea. The results were as follows:(1) Unisexual gametes germination and unisexual crusts growth: Unisexual gametes germinated from a single thallus of S. lomentaria and developed into unisexual crusts. There were very significant differences among 10℃, 15℃, 20℃ on effects of germination rate of unisexual gametes and growth of unisexual crusts(P<0.01), which being sorted as follows: 15 ℃ >10 ℃ >20 ℃ and 20 ℃ >15 ℃ >10 ℃, respectively.The germination rate of unisexual gametes and growth of unisexual crusts becamelarger from 5 μmol·m-2·s-1up to 60 μmol·m-2·s-1andnearly remained the same from 60 μmol·m-2·s-1up to 80 μmol·m-2·s-1(P>0.05). The germination rate of unisexual gametes was largest at 12L:12D and the growth of unisexual crusts was fastest at 24L:0D.(2) Unisexual filaments induction and growth: Unisexual filaments germinated from the unisexual crusts. There were very significant differences among 10℃, 15℃, 20℃ on effects of induction rate and growthof unisexual filaments(P<0.01), which being sorted in same order as follows: 20℃>15℃>10℃. The induction rate and growthof unisexual filaments became larger from 5 μmol·m-2·s-1 up to 60 μmol·m-2·s-1andnearly remained the same from 60 μmol·m-2·s-1up to 80 μmol·m-2·s-1(P>0.05). The induction rate of unisexual filaments was largest at 12L:12D and the growth of unisexualfilaments was fastest at 24L:0D.(3) Unisexual filaments seedling and indoor culture: Juvenile gametophytes directly germinated from the unisexualfilaments. There were very significant differences among 10℃, 15℃, 20℃ on effects of germination rate and growthof seedlings(P<0.01). Seedlings were observed from the fragments of the unisexualfilaments after 5 days’ culture at 10℃ and after 10 days’ culture at 15℃. The seedling germination rate reached 100% at 10℃ and reached 50.0±3.0%at 15℃ after 30 days’ culture. There were no seedlings observed at 20℃. The seedlings grew best at 10℃, better at 15℃, and unhealthy at 20℃.The germination rate and growthof seedlings became larger from 5 μmol·m-2·s-1 up to 40 μmol·m-2·s-1andnearly remained the same from 40 μmol·m-2·s-1up to 80 μmol·m-2·s-1(P>0.05). The germinationrate and growthof seedlingswere both largest at 16L:8D.(4) Seedling raising in natural sea temperature and cultivation in open sea: The unisexualfilaments were spread to the nets after being cut into fragments on 20 October at 16℃and cultured indoor. The seedlinggerminated rate reached 45.0±3.0% and the averaged length of the seedlings reach 5.5±0.5mm after 22 days’ culture. The seedlings were transported to the open sea and cultivated on the rafts on 20 November at 13.0℃.Mature tubular gametophytes in length of 0.91±0.07 m were obtained after 4months’ open seacultivation.