Study On Graft Affinity Of Michelia Platypetala 'Fenyun' At Seedling Stage

In this paper,taking Mchelia platypetala 'Fenyun' as scion,two-year seedlings of Magnolia denudate,M.liliflora,M.chapensis and M.maudiae as rootstock,We conducted the graft.We judged the grafting affinity between 'Fenyun' and 4 kinds of rootstock from three aspects.One is the survival rate of graft seedlings,anothor one is differences of physiological indexes in leaves between scion and rootstock,and the last one is growth and physiological dynamics of grafted seedling.Through the determination of survival rate,growth indexes and physiological indexes,combined with correlation analysis,principal component analysis and membership function method,we studied the grafting affinity of seedlings under greenhouse and outdoor in the seedling stage,the following conclusions were drawn:1.The order of survival rate of 4 kinds of grafted seedlings is as follow,M.maudiae and M.liliflora are the highest,which is 88.33%and 83.33%respectively;the second one was M.denudata with 75%,M.chapensis are the lowest one with 63.33%.2.The difference of physiological level of leaves between rootstock and scion can predict the graft affinity.The absolute difference which of soluble sugar,soluble protein and POD activity in the leaves between rootstock and scion have significantly negatively correlated with the survival rate.The smaller absolute difference is,the higher survival rate.That 3 indexes can be used as early determination index of grafting affinity.3.The indexes to evaluate dynamic changes of the grafted seedlings of different rootstocks including the length of new shoots,the number of leaves,the diameter of the stock and the diameter of the scion.The new length increased slowly after grafting,and then they are entered the rapid growth stage from July to October,after October,the growth speed slowed down.The number of leaves,the diameter of the rootstock and scionr showed a continuous growth trend after grafting,and grow slowly after October.4.The characteristics of physiological indexes of different rootstock seedling in early stage is as follow,the chlorophyll content were changed by trend of two-peaks.In the whole growth period,carotenoid content,soluble protein content,POD and SOD activity were first increased and then decreased,while the soluble sugar content was decreased first and then increased.Except for soluble sugar reached the minimum value in July,other physiological indexes reached peak value in July and April which is consistent with the growth peak period.5.The 10 seedlings growth and physiological indexes were measured by principal component analysis,the result showed that,the most important index for the affinity of seedling stage is soluble sugar content,shoot length,leaf number,diameter of stock,diameter of scion.that 5 indexes above can be used as indicators of determination grafting affinity.6.Using the method of membership function to calculate the affinity indexes of 4 kinds of Rootstocks,the result showed that the affinity index was ordered as follows,M.maudiae>M.liliflora>M.denudata>M.chapensis,consistent with the order of survival rate.7.The environment of greenhouse and outdoor had little effect on the grafted seedling growth.But from the affinity index,the grafting affinity of different rootstocks showed great difference between 4 kinds of rootstocks in outdoor,while the difference was smaller in greenhouse.