Traits Evaluation And Genetic Analysis Of Main Cultivars Of Laminaria In China

China is the biggest country of Laminaria cultivation. Genetic improvement played a crucial role in the development of Laminaria cultivation of China. Genetic improvement of Laminaria began in 1950s and more than 20 varieties have been bred and used. Their popularization promoted the development of Laminaria cultivation industry drastically.Morphological characteristics, economic traits, production quality and DNA fingerprints are important sections of germ plasm data-base. In this study, traits eveluation and genetic analysis of 12 main cultivars were conducted. Moreover, traits and components of 4 dominat commercial varieties were compared and analysed in different sites. Our results will enrich the basic data of Laminaria germplasm on a greater extent. It will play an important role in elite varieties protection, utilization, identification and supervision. Furthermore, it will provide reference for breed purification and rejuvenation as well as new varieties developing. The following are our major findings:1.Traits eveluation of 12 cultivars of Laminaria were conducted in Yantai Zhifu Bay.The results of morphological observation show that Dongfang No.2 hybrid Laminaria has the most robust holdfast in 12 varieties; The shape of blade basis of 860,1170 and 901 kelp is cuniform. That of L japonica, Yuanza NO.2 and Dongfang No.2 hybrid Laminaria is near circular and that of Rongfu, 201, Benniu, Zaohoucheng and Dongfang No.3 hybrid Laminaria is rounded. 1170 and Fujian Laminaria have not middle grooves in blade, but other varieties all have middle grooves or deep or shallow. Respect to economic traits, 901and Dongfang No.3 hybrid Laminaria show obvious advantage in blade length. Fujian, 201 and Benniu Laminaria have wide blade and the blade thickness of Dongfang No.2 hybrid Laminaria, Benniu and Zaohoucheng is satisfactory. As to fresh weight, Rongfu, 901, 201, Dongfang No.2, Benniu and Dongfang No.3 hybrid Laminaria are superior to other varieties. Rongfu, 901, Dongfang No.2, Benniu and Dongfang No.3 hybrid Laminaria attained higher yield.2. DNA fingerprints of 12 varieties were set up and genetic analysis was carried out using AFLP technology.Totally, 431 loci were obtained after PAGE electrophoresis using 20 combinations of selective primers. Of these loci, 69.6% were polymorphic, 33 characteristic loci were selected and they can be used to distinguish different varieties.The calculation results indicate that the genetic distance of 12 varieties is from 0.1553 to 0.4066.The genetic distance between 860 and Dongfang No.2 hybrid Laminaria is furthest, that of Yuangza No.2 and Benniu is nearest.From the mapping of UPGMA, 12 varieties can be clustered into two major groups. One is composed by Fujian, Dongfang No.2, Rongfu, Yuanza No.2, Benniu, 201 and Dongfang No.3 hybrid Laminaria, the other one is make up of 901, 860, Zaohoucheng, 1170 and L. japonica. 3. Traits and components of 4 dominant varieties were compared and analysed inYantai Zhifu Bay, Tuoji Island, Rongcheng Chudao Bay and Dalian Longwangtang.Comparison of economic traits support that suitable cultivars in Chudao Bay are Dongfang No.2 hybrid Laminaria, 901 and Benniu kelp. In Yantai Taozi Bay, the yeild of Dongfang No.2 hybrid Laminaria is highest, followed by 901 kelp and that of Zaohoucheng is lowest. Dongfang No.2 hybrid Laminaria and 901 kelp are appropriate for cultivation in Tuoji Island. In Dalian Longwangtang, the economic traits of Zaohoucheng and Benniu kelp are better than those in other location, so these two varieties can be regarded as the proper cultivars.Results of components analysis show that carbohydrate, calcium, copper and nickel contents of Zaohoucheng kelp in Dalian Longwangtang are highest. Iodine and phosphorus contents of 901 kelp are highest in Taozi Bay. Crude fat and zinc contents of 901 kelp are highest in Tuoji Island. Crude protein, iron, manganese contents of 901 kelp are highest. Crude fiber content of Dongfang No.2 hybrid Laminaria is highest and the highest content of mannitol was obtained from Benniu kelp in Chudao Bay.