Strain selection in Kappaphycus alvarezii var. alvarezii (Solieriaceae, Rhodophyta) using tetraspore progeny

A brown strain of Kappaphycus alvarezii from the Philippines produced tetra spores in the summer and autumn (December 1995 to May 1996) in cultivation experiments in the sea at Ubatuba, Sao Paulo State, Brazil. In vitro tetras pore release and germination experiments showed a mass mortality two to fou r days after release. Only 20 plants derived from tetraspores were grown su ccessfully for over a year in the laboratory. Large differences in morpholo gy, colour, size and growth rates were observed amongst these plants. The i ndividual plants differed from one another in one or more characteristic. D ifferences appeared in the early developmental stages and persisted through time. After ten months, the plants that grew best in laboratory culture we re transferred into the sea, but the others remained very small (3 to 5 mm) , even after two years. In the sea, the plants also showed individual diffe rences in their ability to survive and grow. These results emphasise the po tential of the tetraspore progeny for strain selection in K. alvarezii. The results also suggest that the tetrasporophyte used in these studies is of hybrid origin.