| Castanopsis hystrix A. DC?family Fagaceae?, a genus of superior, valuable evergreen trees, predominates as one of forming species of broad-leaved forest trees in south subtropical regions of China. Moreover, this species is an important component of high-efficiency, multi-purpose non-commercial forests. Through shoot induction, shoot multiplication, rooting of shoots and transferring of well-rooted plants, this paper describes a systematic research on in vitro rapid propagation techniques of Castanopsis hystrix A.DC., which is of important practical significance and application prospects for speeding up popularization and application of the superior strains and alleviaing the seed supply and demand situation. Seed was employed as initial explant, origins of which were superior individuals. The results obtained were as follows:Establishment of aseptic strain. The disinfection procedure III?that was, the outer seed coat and subsequent tissue was removed to expose intact embryos. Subsequently, the embryos were disinfected with 75%?v/v? ethanol for 40 s followed by one rinse?1 min? with sterile distilled water, and then surface disinfected with an aqueous solution of 0.1% of mercuric chloride?w/v? for 67 min followed by five or six rinses?1 min each? with sterile distilled water.? was the best for Castanopsis hystrix A. DC. seed, yielding 82.2%contamination-free germinated buds with only 16.7% contamination rate. Modified-MS supplemented with 3.0 mg.l-1 gibberellic acid?GA3? was found to be best for seed germination, seed began to germinate the next day after being put into the medium, and the germination frequency reached up to 93.3%. Modified-MS containing 2.0-3.0 mg.l-16-benzyladenine?6-BA?, 0.2 mg.l-1 1-napthyl acetic acid?NAA?, 3.0 mg.l-1 GA3 was proved to be optimal for adventitious shoot induction with average 6.01 buds per explant.Proliferation medium and culture conditions. Through a sequence of tests, modified-MS supplemented with 1.5 mg.l-1 6-BA, 0.2 mg.l-1 1-napthyl acetic acid?NAA?, 30 g.l-1sugar,6.2 g.l-1 agar?p H 5.8-6.2?was found to produce maximal multiple shoots. And the better culture conditions were that all cultures were maintained at 25±2°C with a 12-h photoperiod, 1000-1500 lx provided by cool-white fluorescent lamps. Natural light with appropriate intensity was necessary in improving the growth of in vitro cultures.The subculture cycle should be within approximately 25 d. The multiplication rate was up to 3.25, and the effective buds were more than 19.28 per culture vessel.Induction of rooting in shoots. The most effective rooting medium was half-strength modified-MS containing 0.8-1.0 mg.l-1 NAA or 1.0-1.5 mg.l-1 IBA, which initiated rooting at a frequency of 96.7% after about 10-15 d, and the average root number was 3.01 each plant. Shoot rooting was significantly influenced by genotype, and seedlings from seed(Z3-1) had a high rooting rate of 98.9%.Transfer of plantlets to soil. Well-rooted plants were transferred to non-woven bags containing peat soil, perlite, coconut chaff?3:1:1, v/v? with above 90% survival, and the seedlings were strong and tidiness. |
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