Study On Tissue Culture And Regeneration Of Populus × Canadensis ’Aurea’

Populus×canadensis‘Aurea’,a color-leafed poplar cultivar bred by bud mutation breeding,has golden leaves in three seasons,which gives it high ornamental value,wide potential in landscape uses and good cultivation prospects.At present,the main breeding methods of Populus×canadensis‘Aurea’are grafting and cutting,which are susceptible to seasonal and other factors,resulting in low reproductive coefficient.The content of photosynthetic pigments in leaves was low,which led to slow growth.At the same time,there are some safety problems such as low healing and easy breaking of scions during grafting,which make Populus×canadensis‘Aurea’unable to achieve sustainable production and effective utilization.In this paper,stem segment with bud and leaf explants of Populus×canadensis‘Aurea’were used as experimental materials for tissue culture and rapid propagation system construction.The induction of aseptic seedlings,induction and differentiation of leaf callus,multiplication of cluster buds,rooting and seedling transplantation of Populus×canadensis‘Aurea’were studied.Combined with orthogonal experiment design and variance analysis,the key factors affecting in vitro culture of Populus×canadensis‘Aurea’were explored,in order to obtain the best culture formula and culture procedure,and to establish an efficient regeneration system of Populus×canadensis‘Aurea’,so as to provide technical guarantee for its further large-scale application in landscape greening.The main results are as follows:（1）The mid-March is the best time to take explants of Populus×canadensis‘Aurea’.（2）The best sterilization methods for explants of Populus×canadensis‘Aurea’were stems sterilized with 75%alcohol for 20 seconds and 0.1%Hgcl₂ for 6 minutes and leaves disinfected with 75%alcohol for 5 seconds and 0.1%Hgcl₂ for 4 minutes.（3）Primary culture:MS+6-BA 0.75 mg/L+NAA 0.05 mg/L+IBA 0.20 mg/L was the best formulation for stem segment,the initiation rate was 83.33%;MS+6-BA 0.50mg/L+NAA 0.10 mg/L+2,4-D 0.10 mg/L was the best formulation for induction of leaf callus,and the induction rate was 85%.（4）Subculture:The best formulation for stem subculture was 6-BA 0.05 mg/L+NAA0.20 mg/L+IBA 0.10 mg/L;the best formulation for leaf subculture was MS+6-BA 0.50mg/L+NAA 0.05 mg/L+2,4-D 0.30 mg/L,and the proliferation multiple was 4.0;the best formulation for differentiation of leaf callus was MS+6-0.50 mg/L+NAA 0.05 mg/L+IBA0.5 mg/L.（5）Rooting culture:1/2MS+NAA 0.20mg/L+IBA 0.20mg/L formulation was the best,rooting rate was 91%,average root number was 4.70,average root length was 7.75cm.（6）Mixing seedlings in transplanting:The optimum proportion of transplanting media was Humus:River Sand:Vermiculite=1:2:1,the survival rate of the plant is the highest,70.93%,growing well.