| Castanopsis hystrix A.DC,a precious timber with multipurpose and belonging to the family Fagaceae,is one of the important Southern planting tree species in subtropical broad-leaved forest and conifer-broad leaved mixed forest.Using annual half-lignified branches from 25 mature C.hystrix A.DC.superior trees as explants,based on adventitious buds initiation to select the appropriate condition of induction,subculture and rooting culture,this paper studies on establishing a s ystematic research about in vitro rapid propagation technique of mature C.hystrix A.DC.superior trees,which is as technological support for extension of its vegetative propagation.We draw the following conclusions:1.Establishment of Regeneration System of C.hystrix A.DC in Vitro(1)It can greatly reduce the amount of pollution materials and increase the inducing rate of axillary bud by spraying stock plant with 40% carbendazim(0.1% dilute)three times and collecting the eugenic twigs from mature trees in October.The best stem segments as explants were 3~6 internodes below apical buds,whose suitable length is 0.5~1.5cm.(2)The best disinfecting scheme is as follow: the explants were disinfected by shaking in 1% benzalkonium bromide(v/v)for 2 min plus 1~2 drop tween,followed by 0.1% mercury chloride(w/v)for 3~4 min.WJ medium supplemented with 1.0~1.5 mg/L 6-benzyladenine(6-BA),0.1 mg/L 1-napthyl acetic acid(NAA)and 8 g/L carrageenan was proved to be the optimal medium for shoots generation and induction,on which,most were germinating with single bud.The highest induction rate is over 82%.Each individual plant has obvious difference in induction rate.Some of them have got the best results,which are numbered 42B?27?29?9A.2.Proliferation medium and culture conditions.The better proliferation medium was WJ medium fortified with 0.5 mg/L 6-benzyladenine(BA),0.1 mg/L 1-naphthaleneacetic acid(NAA)and additives(p H5.8~6.2).It's better to control the light intensity in 1000~1500 lx and culture temperature between 23~27 ?.Appropriate natural light can significantly improve the growth of tissue-cultured plantlets.The subculture cycle for 30 days,can guarantee the quantity and the quality of the adventitious buds.The multiplication coefficient was up to 2.78.The proliferation of the trees numbering 42B?27?29 has the highest coefficient.3.Induction of rooting in shoots.The half-strength WJ medium supplemented with 0.6 mg/L 1-naphthaleneacetic acid(NAA),15 g/L sugar,6.0g/L agar and additives(pH5.8~6.2)turned out to be the best medium for in vitro rooting,which has a highest root rate of 85% after 20 to 25 days,and everage roots number was 2.19 each plant.It's better to control the light intensity in 2000~3000 lx and the culture temperature at 23~27 ?.4.The mechanism of adventitious root formation.By anatomic research,we found that the adventitious roots induced by auxin begin from the cortex of the plantlets.The primordium of adventitious root originated from division and differentiation of medullary ray cell.After cultured for 11 d,the root primordium will develop as tiny adventitious root out of periderm.5.Transfer of plantlets to soil.Well-rooted plants were transferred to plastic cups containing peat soil,perlite,coconut chaff(3:1:1,v/v).The survival rate reached 90% and the plantlets are growing well. |
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