Laminaria gametophyte clone culture and its application in sporeling cultivation

In China,the total annual production of cultured Laminaria japonica reached half million tons in dry weight these few years.The routine sporeling culture technique conducted in the greenhouse took aF least three and half months.In such a case,sometimes the sporelings died within a few days due to destructive diseases.In order to overcome the mentioned problems,a new sporeling culture technique,the clone technique,is developed.The method includes three steps:(1)Gametophyte clone culture.The spores and the gametophytes are cloned in flasks under favorable environments.(2) Sporeling cultore.Male and female clones are crushed and spread onto a frame to allow the gametophytes to attach to the substrata.The frames are cultured in tanks,and the sporophytes reach 1 cm in length within one and a half months.(3) Outgrowing of the plant.The frames are put in the open sea when seawater temperature decreased to 20℃.After one month,the sporelings are large enough to be transplanted.It is concluded that the clone technique has the following advantages:(1) Large amount of clones can be produced in a short period of time.(2) Clone seeding method makes it free from the biological rhythm.one can seed the plant anytime all the year round.(3) It takes only one and a half months to complete the process of sporeling cultivation in the greenhouse.At present,this technique is used in the breeding of new strains of Laminoria.