Study On Tissue Culture Techniques Of Three Acacia Species

Acacia. mangium, A. auriculiformis and A. mangium×A. auriculiformis is belong to Mimosaceae family and Acacia general. A. mangium×A. auriculiformis is a cross between A. mangium and A. auriculiformis. With properties of fast-growing, high-yield and symbiotic nitrogen fixation with Rhizobium, three Acacia species are excellent material source of pulp and furniture upholstery, able to improve soil fertility. Because of their important economic benefits and ecological values, all three are most valuable fast-growing broadleaf species in the south of our country. While, the utilization of fine varieties of three Acacia spices are relatively low because of the lacking of effective vegetative propagation techniques. It can improve the utilization and planting of three Acacia spices by building the tissue culture system. Tissue culture techniques of three Acacia species have been reported at home and abroad. But there are some disadvantages still.1) Seeds and stock plants with unknown characteristics were used as explants, which result in poor qualities of plantlets, low survival and shooting rate of explants after being sterilization.2) Tissue culture systems with mere adjustment of medium and single cultural method were incomplete, which cause low proliferation rate, rooting rate, transplanting rate, long proliferation and rooting time.Perennial elite trees of A. mangium, A. auriculiformis and A. mangium×A. auriculiformis, which were planted by Research Institute of Tropical Forestry Chinese Academy of Forestry, were selected as material. This study perfected the tissue culture system through direct organogenesis, which mainly include selection of explants and establishment of sterilizing system, selection of primary culture medium, selection of proliferation medium and method, selection of rooting medium and method, selection of acclimatization method and transplantation matrix. In addition, this study also improved the survival and shooting rate of explants by constructing cutting orchard, acquired stable proliferation rate and improved proliferation efficiency by researching the effects of proliferation medium on several subcultures, economized cost and space on industrialized production by building the ex vitro rooting system. Results showed as follows: 1. Selection of explants and establishment of sterilizing system:Cutting orchards of excellent clones were constructed by using branches of three Acacia species elite trees via cutting propagation. Semi-ligneous stems from the middle part of branches, which were collected in the summer day with high temperature and less rain, were used as material of tissue culture. The survival rate and shooting rate of A. mangium can reach85.33%and83.33%respectively after being sterilized by0.1%mercury bichloride and75%alcohol with9min and15s separately. The survival rate and shooting rate of A. auriculiformis can reach90.00%and91.67%respectively after being sterilized by0.1%mercury bichloride and75%alcohol with18min and15s separately. The survival rate and shooting rate of A. mangiumxA. auriculiformis can reach93.33%and92.00%respectively after being sterilized by0.1%mercury bichloride and87.5%alcohol with15min and30s separately.2. Primary culture:The optimal primary culture medium of A. mangium is improved MS+6-BA0.5mg-L-1’+sucrose20g-L-1. The optimal primary culture medium of A. auriculiformis is MS+6-BA1.0mg-L-1+sucrose40g-L-1. The optimal primary culture medium of A. mangiumxA. auriculiformis is MS+sucrose30g-L-1. Shooting rate of all three Acacia species can reach90%above.3. Proliferation culture:The proliferative rate of A. mangium can reach3.08and remain stable after being subcultured on MS+6-BA0.5mg-L-1+NAA0.1mg-L-1+Ac0.05g-L-1+sucrose30g-L-1with7times. The proliferative rate of A. auriculiformis can reach2.63and remain stable after being subcultured on MS+6-BA1.0mg-L-1+NAA0.1mg-L"’+Ac0.05g-L-1+sucrose30g-L-1with7times. The proliferative rate of A. mangium×A. auriculiformis can reach2.52and remain stable after being subcultured on Improved MS+6-BA1.5mg-L-1+NAA0.1mg-L-1+Ac0.04g-L-1+sucrose30g-L-1with7times.4. In vitro rooting:The rooting rate and average root number of A. mangium can reach94.36%and2.24separately after being culture on1/2MS+IBA0.5mg-L-1+NAA0.5mg-L-1+sucrose30g-L-1within15days. The rooting rate and average root number of A. auriculiformis can reach93.44%and1.37separately after being culture on1/2MS+IBA0.5mg-L-1+NAA0.25mg-L-1+sucrose30g-L-1within15days. The rooting rate and average root number of A. mangium×A. auriculiformis can reach99.43%and3.17separately after being culture on1/2MS+IBA1.0mg.L-1+NA0.5mg-L-1+sucrose30g-L-1within15days. 5. Ex vitro rooting:The optimal ex vitro rooting system of A. mangium is dipping in400mg-L-1ABT with0.5h. The optimal ex vitro rooting system of A. auriculiformis is dipping in200mg-L-1IB A with0.5h. The optimal ex vitro rooting system of A. mangium×A. auriculiforms is dipping in100mg-L-1ABT with1h. The rooting rate of all three Acacia spices can reach90%above after being culture on yellow soil in the greenhouse with60days.6. Acclimatization and transplantation:After being cultured on rooting culture medium with15days and acclimated with5days in greenhouse, the survival rate of A. mangium can reach97.22%when transplanted on the matrix of yellow soil:sand=1:3. After being cultured on rooting medium with15days and acclimated with5days in greenhouse, the survival rate of A. auriculiformis can reach97.96%when transplanted on the matrix of yellow soil:sand=1:3. After being cultured on rooting medium with10days and acclimated with5days in greenhouse, the survival rate of A. mangium×A. auriculiformis can reach99.44%when transplanted on the matrix of yellow soil.