Application Of Heterosis In Kelp Breeding

Kelp is one of the most important marine algaes in our country. In the late fifties of last century, the research work on kelp breeding was begun. Some new varieties have appealed by traditional breeding means and the spread of these varieties has greatly promoted the development of kelp industry. But the traditional means have some shortcomings such as long selective cycle, degradation of variety and big labor intensity. The application of gametophyte clone technology injects new vigor into the study of kelp breeding and seed-rearing.Separated female and male gametophyte clone of two varieties are easy hybridized to bring a hybrid and some fine characteristics of its parents is combined. As a result of heredity recombination of hybrid is completely uniform, selective cycle is shortened and the breeding efficiency is improved.A male haploid clone of Laminaria longissima is used to cross a female haploid clone of Laminaria japonica Aresch.and the F1 hybrid (kelp 12) is obtained. Kelp 12 shows obvious heterosis. The results show as follows:1. The frond of Kelp 12 is large and thick. Its rhizoid is well-developed. Kelp 12 has strong ability of high light tolerance.2. The growth speed of Kelp 12 is fast. Mean daily growth is 4.52cm during growth fastigium. It is faster than that of the two control groups, 4.23cm and 2.71cm respectively.3. The slough ratio of total length of kelp 12 is lower and pure length is longer than that of two control groups. It is showing obvious heterosis on length.4. The harvest of kelp 12 is 15-20 days earlier than that of control I, 15-20 days later than that of control II.5. The fresh weight of kelp 12 is heavier than that of two control groups.6. The yield of kelp 12 is 20-35% and 50% higher than that of two control groups respectively.The mutation of sporophytes of kelp 12 is less than that of control groups on lengh andwidth by genetics analysis. Colony configuration is highly uniform and individual difference is a little. Kelp 12 has obvious heterosis compared with its parents.