Studies On The Culture In Vitro And Sterile Seedling Estimating Cold-resistance Of Acacia Implex

Acacia implexa Benth is the one of main forestation tree species in the South of our country which was imported in recent years, it has good adaptation, high yield and grows fastly, and can improve soil fertility, and has many uses. The superior seedlings of Acacia implexa can not satisfy the demand for forestation now. Adapting in vitro propagate technique to achieve industrial seedling will be a good way to settle the question. As with the introduction and origin type of climate differences, low-temperature damage often become successful restrictive factors on introduced species.In this study, A.implexa was taken as test materials. With the tissue culture technique and rapid propagation, the isolated culture and regeneration system were established; one new avenue which can rapidly propagate the seedling with stable and favorable characters was expected to be obtained. With coldness assessment, researching the indicators of A.implexa physiological and biochemical change after different low temperature menace, Using of cluster analysis to screen the strong coldness resistance clones. The results were as follows:1. A.implexa explants disinfection. With 70% alcohol soaking for 30 s, 6% sodium hypochlorite solution for 8 min, then 0.1% mercuric chloride for 10 min, making the explants contamination rate down to 19.2 %.2. A.implexa explants adventitious buds induced and proliferation. The appropriate culture medium formula for adventitious bud induction from A.implexa explants was: 6-BA 1.0 mg/L +IAA0.2 mg/L +ZT0.3 mg/L, Adventitious buds intensive, strongly, fast. The appropriate culture medium formula for adventitious bud proliferation was: MS+0.9 mg/L 6-BA +0.3 mg/L ZT +0.4 mg/L IAA, Average proliferation coefficient of 3.14.3. A.implex rooting and transplanting. The appropriate culture medium formula for rooting was: 1/2MS+0.4 mg/L NAA+1.0 mg/L IAA+10 g/L Sugar +1.0 g/L AC. Average rooting rate of 82.47%. The appropriate matrix for transplanting was: Acacia surface soil: peat =1:1, survival rate of 87%, and seedlings intensive, leaf green, fast growth.4. After Low-temperature menace, the relative conductances of 12 clones of A.implex have different levels of increasing. Coldness resistant Clones were small increasing on the relative conductance. Electrical conductivity methods was used to determine the changes of cell membrane permeability after Low-temperature menace, and the inflectional points of logistic equations were taken as freezing lethal temperature.5. The activities of SOD and POD in 12 clones of A.implex were rising in early Low-temperature menace. Low-temperature may activate protection mechanisms, increase activity, remove toxics, protecting the plant from harm; when the temperature was lower than half of its lethal temperature, the cells cause serious damage to the structure, resulting in SOD, POD enzyme inactivation, activity dropped substantially.6. The content of MDA and soluble protein in 12 clones of A.implex was increasing in Low-temperature menace. Coldness resistant Clones, the greater increasing in soluble protein content, the lower increasing in the content of MDA.7. The content of soluble sugar and proline in 12 clones of A.implex is increasing first decline after in Low-temperature menace totally. Coldness resistant Clones increased fastly, declined slowly.8. In order to comprehensively evaluate the cold resistance of A.implex, this experiment conducted cluster analyses to the relative conductivity, SOD activity, POD activity, the content of MDA, the content of soluble sugar, the content of soluble protein and the content of proline, identifying the most Coldness resistant Clones of IM1, IM2 and IM3 in the genetic distance of 6.10.