Studies On Vegetative Micropropagation And Rejuvenation In Vitro Of Cryptomeria Fortunei Hooibrenkex Otto EtDietr

Cryptomeria fortunei Hooibrenkex Otto etDietr is one of the most precious plants in China. A large number of trees over 2000 years old with big trunk of this species are growing on the mountain in Zhejiang province, which are also rare ecologically in the world. However, these trees are speedly dwindled, due to human being destruction and nature environmental disasters. In order to overcome the decline problems of Cryptomeria fortunei trees two major methods were selected, first by carrying out micropropagation via tissue culture, the second by repeated graftings in vitro with adult shoot tips from the field as scions onto juvenile rootstocks, i.e., rejuvenation of adult or old and mature trees.This paper adopted Cryptomeria fortunei as a model plant subjected on large scale propagation by tissue culture and induction rejuvenation in vitro At this time the obtained results are presented as follows:1. Initially the seeds are required in flushing in running water for 12-16 h, followed by immerging in 0.5%NaClO solution with tween 20 for 10min in a vacuum as seed disinfestation procedure. Seed contamination rate was about 5% and germination rate about 75%. Cultureed in MS medium after seven days,green embryo germination and continue to cultivate in the MS medium, growth as a small bud.2. The optimaum shoot multiplication medium was established, i.e., in MS basic medium (containing MS salts, white’s vitamins, myo-inositol and 3% sucrose) was supplemented with 0.3-1 mg /L cytokinin ZT or BA and 1g /L Malt extract on induction axillary bud proliferation.3. Two-step rooting of shoots was adopted, the first step used 100mg/L IBA for 10 days in lack of salts but inclueded white’s vitamins, myo-inositol and sucrose 15g /L, followed by transferring into 1/3MS macro-salt medium as second step. Ratio of rooting was above 80%. Rooted shoots were transplanted to potting mixtures i.e., peat: vermiculite: perlite = 1:1:1. After acclimatization the survival rate was above 85 percent with vigorous growth in green house.4. The 30 years old trees were first choosed as scion donor mother plants with scion size about 1.0 cm in length were subjected to graft onto1.5cm long rootstock in vitro. Compared the rootstock with absent or present roots on the rootstocks demonstrated that the presence of roots on rootstock make survival rate be higher.Wrapping with parafilm for 10-day will help improve the survival rate.5. Repeated 3 times of grafting with presence of roots on rootstocks would significantly restore the juvenile traits of adult shoots. Rooting of shoots after 3 times repeated shoot-tip grafting from 30-year-old adult trees was increased to above 55% by now which was nil in adult shoots. And demonstrated that the presence of roots on rootstock was prerequisite for rejuvenation of adult trees. More times of repeated grafting of adult shoots will be required to continue till 100% rooting of adult shoots was attained.