Study On Cutting Rooting Physiology And Tissue Culture Of Vernicia Montana

Vernicia montana,a kind of deciduous trees in Vernicia L.,are a member of the family Euphorbiaceae.It has been considered as an economic species and potential energy plant growing specifically in China.Tung oil is often used as a coating in the manufacture of furniture,ships,automobiles,and semiconductors because of its excellent quality,such as,water resistance,heat resistance,and insulation.Tung oil can be developed into high-quality biomass diesel and other industrial raw materials because it has the characteristics of environmental protection and pollution-free.The common propagation method of V.montana is the seedling propagation,the genetic diversity of seedlings reproduced in situ is not conducive to the maintenance of excellent traits.There is a long period from seedling to fruit ripening and the input costs are very high which limits the development of the V.montana variety industry.So,this paper provides a scientific basis for asexual rapid propagation and introduction and domestication of V.montana.by studying the rooting physiology and tissue culture of V.montana cuttings.The research results are as follows:（1）The orthogonal experiment design of L₉（3⁴）with three factors and three levels was used to analyze the influence of different treatments on rooting,in order to explore the influence of plant growth regulators,concentration and treatment time on rooting.The rooting effect of each treatment of orthogonal test was significantly better than that of the control（P<0.01）.Among them,ABT-1 was significantly better than IBA and NAA,and 10 minutes and 30 minutes was significantly better than 1 minute（P<0.05）.The concentration of plant growth regulators had no significant effect on rooting.The optimal treatment T₁ was soaking with 500 mg/L ABT-1 for 30minutes,whose rooting rate reached 43.97%.（2）The cuttings were soaked with 800 mg/L IBA,NAA and ABT-1 for 10 min respectively,whose rooting morphology and anatomical structure were photographed and observed with microscope.In addition,adventitious roots and phloem tissues about 2 cm long were cut off,whose endogenous hormone,SOD and POD activity were measured.The rooting morphology of cuttings was observed by taking photos:white callus formed at the base of cuttage after 21days and adventitious roots appeared after 35 days.The rooting type of cuttings was mixed rooting type,it is mainly rooted in the skin,the callus produced a few adventitious roots.The roots anatomical structure was observed by microscope,which were divided into four stages:induce differentiation of root primordial cells,root primordial cells to form root primordium,root primordium development to form adventitious roots and elongation of adventitious roots.The callus rate was significantly positively correlated with the ABA content of the 21-day cutting,and was significantly negatively correlated with the activities of SOD and POD.The rooting rate was significantly positively correlated with the IAA and ZR content of the 63-day cutting（P<0.05）.Endogenous hormones and oxidation Enzymes have different effects on callus and rooting through synergy.（3）The orthogonal experiment design of L₉（3⁴）with three factors and three levels was used to explore the influence of mother tree age,leaf retention methods and substrate on rooting.The results showed that the age of the mother tree and the way of leaf retention had a significant effect on rooting（P<0.05）.The older the mother tree,the harder it is to root.The rooting effect of retaining apical bud and 1 leaf（L₁）was better than that of retaining only apical bud（L₂）or lateral bud（L₃）.The rooting rate of P₁ treatment combination was 45.31%,which was the best treatment combination.（4）After treatments with different leaves retention methods,the cuttings rooting process was observed by photograph and microscope,and the contents of endogenous hormones and nutrients in apical buds,lateral buds and leaves were measured.The rate of callus formation and differentiation of root primordial cells in L₁ were significantly faster than that in L₂ and L₃.The contents of IAA and ZR decreased rapidly in the early stage and increased slowly after rooting.The content of GA₃ was on the rise,but ABA content increased rapidly in the early stage and decreased slowly in the middle and late stage.The callus rate was significantly positively correlated with the ZR content of 21-day cuttings,and was positively correlated with soluble protein and soluble sugar content,but not significantly（P<0.05）;the rooting rate was significantly positively correlated with soluble protein content,which was associated with IAA,ZR content showed a very significant positive correlation（P<0.01）.（5）Studies have shown that the sterile seedlings obtained from seed embryos have low pollution rate during tissue culture and simple operation,but the induced adventitious buds grow weakly,which is not conducive to subsequent propagation and culture.It is difficult to sterilize the new stems of the V.Montana eucalyptus outdoor,and it is very easy to brown and contaminate,and only a small number of adventitious buds can be obtained for subsequent propagation and culture.The cutting seedlings in the greenhouse are pre-disinfected,it is easy to obtain more sterile adventitious buds,and the adventitious buds grow vigorously,which is conducive to the multiplication and culture.The cultivation of outdoor superior trees by grafting,cutting and other methods can increase the success rate of tissue culture.（6）Phytohormones 6-BA and IBA are more conducive to the regeneration of V.Montana tissue culture,6-BA concentration is lower,axillary buds are less branched,and explants germinate more slowly.Too high concentrations of IBA and 6-BA can easily cause vitrification of explants and obtain abnormal buds.When the concentration of IBA is kept constant,with the increase of 6-BA concentration,the proliferation coefficient of adventitious buds shows a downward trend,and the low concentration of 6-BA is more conducive to the proliferation of adventitious buds.Comprehensive comparison of the growth of adventitious buds in each medium,it was found that MS+2.0 mg/L 6-BA+0.01 mg/L IBA medium had better induction effect.When advancing with adventitious buds obtained from sterile seedlings,it was found that MS+2.0 mg/L 6-BA+0.01 mg/L IBA+1.0 mg/L GA₃ medium had better proliferation effects.When advancing with adventitious buds obtained from cuttings,it was found that MS+2.0 mg/L 6-BA+0.05 mg/L IBA+1.0 mg/L GA₃ medium had better proliferation effects.Sprouts produced a small amount of adventitious roots in the medium containing 1.0 mg/L IBA,and rooting points were generated in the medium containing 0.5 mg/L IBA and 1.0 mg/L ABT-1,but no adventitious roots were formed.