Study On Key Techniques And Rooting Mechanism Of Softwood Cuttings Of Quercus Variabilis

Quercus variabilis is an important afforestation tree species unique to China.In recent years,a number of excellent types have been widely used in urban landscaping.In the traditional seed propagation,the traits of the offspring tend to be differentiated,but the asexual reproduction is just enough to overcome this,and the stable inheritance of the trait can be ensured.In addition,cutting propagation is widely used as the most widely used technique in asexual reproduction.For Q.variabilis with root hard,the general asexual reproduction method are difficult to take root.Little attention has been paid on the selection of plant growth regulators and the rooting mechanism in the cutting propagation of Q.variabilis.In the current study,semi lignified branches of Q.variabilis were subjected to study cutting propagation.The characteristics of cuttings,age of mother tree,type of substrate,type and concentration of plant growth regulators were explored.Through analysis of the differences of root development,nutrient content,enzyme activity and endogenous hormone content during rooting of different ages parent trees to explore the relationship between the change of physiological activity and the formation of root system and the key to rooting.The main results of this paper as follows:Plant growth regulator types significantly affected adventitious root initiation and development of Q.variabilis.The optimum concentrations of IBA,ABT and NAA were 1000 mg·L-1,1500 mg·L-1 and 1500 mg·L-1,respectively,depending on the type of plant growth regulator.And IBA yielded the most ideal effect for the rooting of cuttings.The combination of IBA with 1000 mg·L-1 had the most advantageous to adventitious root formation and root development of cuttings.The rooting index of cuttings in the mixed matrix of perlite and vermiculite was better,and the average rooting rate was 23.6%.June 25 or July 5 is the ideal picking time,at this time the rooting rate is higher,and July 5 harvest cutting rooting index up to 7.4cm;the rooting index of the middle or upper past of shoots is significantly better than that of the base;cuttings to retain two half leves significantly higher than a whole leaf and a half leaf,and the rooting index reached 5.7 cm.Cuttings severely affected by the age of the parent tree,the rooting rate of 2-year-old parent tree cutting tree reached 86.2%,while that of 7-year-old parent tree fell to 34.7%.According to the comprehensive analysis,it was found that the middle or upper part of the shoots was collected in the late June or early July,two haves leaves to keep,treated with IBA1000mg·L-1 under the mixed matrix of perlite and vermiculite,which have a better rooting index.Three kinds of plant growth regulators could promote the development of root system,and the effect of IBA was the best,which was more significant than ABT and NAA.In addition,the distribution of root diameter was mainly affected by parent tree age.2-year-old parent tree cuttings compared to 7-year-old tree can be about 20d rooting,and the adventitious roots distributed in most of the basal part of the cuttings,which were skin rooting and 72%-89%are composed of roots with diameter D<1.0mm.7-year-old parent tree cuttings were more difficult to take root,mainly to the root of the skin,both a small amount of callus rooting,and the roots were more concentrated in the base incision 1.0cm range of cuttings.The root structure is intact and distributed evenly at each diameter,which includes fewer first order adventitious roots.It was shown that the age of mother plants and plant regulators were the main factors affecting the adventitious root morphology.The formation of adventitious roots in the cuttings of Q.variabilis was influenced by nutrients,oxidases and endogenous hormones.However,these physiological indexes were slightly different in the process of rooting.The results showed that the effects of interaction between parent tree age and plant growth regulators on the content of soluble sugar,total nitrogen,the activity of POD,IAAO and he content of IAA,ABA,ZR,IAA/ABA were significantly.In the main effect,the C/N was significantly increased by IBA treatment,while C/N value were significantly decreased with parent tree age increased.The correlation between C/N,IAA/ABA ratio,POD activity and IAA,ZR content was negatively correlated with rooting rate.