Studies On Selection And Grafting Propagation Of Fine Germplasm Of Millennium Paulownia In Southern Hunan

Aleurites montana is an Euphorbiaceae Aleurite plant.In recent years,the planting area of Aleurites montana increasingly expands,and the planting area of Aleurites montana in southern Hunan has exceeded 1333 hm2.At present,the excellent seeds of the Aleurites montana are few.Guangxi has bred out four clones of'Guizhou' series,and Zhejiang has bred out three clones of 'Zhegui' series.These above clones are characterized by fast-growing,early fruit,high yield and high quality,which can make the yield per square area multiplied.However,Aleurites montana is a strong regional tree species.The clones bred out in Guangxi and Zhejiang cannot be well adapted to the surroundings in Hunan.Currently,there are no excellent clones of Aleurites montana bred out in Hunan,and the cultivation of Aleurites montana is still through seedling afforestation.Although the seeds have been selected,for the trees with the seed propagation,the serious differentiation phenomenon appears in the aspects of the fruit quantity,fruit size and fruit insertion pattern due to the dioecism and genetic segregation.About 30%of the male plant do not bear fruit,which results in low yield per unit area.In this paper,in order to cultivate the excellent clones of Aleurites montana suitable for planting in Hunan,the Aleurites montana in Hunan was selected as the research object.The fruit bearing per plant,fruit yield per plant,the resistance capability to pests and diseases,fruit accumulation degree and fruit ripening consistency were considered as the phenotypic traits selection indices of Aleurites montana.The weight per fresh fruit,seed yield ratio of the fresh fruit and oil yield of the dried nut were considered as the evaluation indices of the fruit quality.The evaluation system was constructed by comprehensive evaluation method.At the same time,the cultivated excellent plant was considered as the scion-seed tree,and the comparative experiments regarding the grafting method,grafting season and grafting lignification degree were conducted.The main findings are as follows:(1)Thirty strains of excellent trees were primarily selected from the 67 selected excellent trees through the phenotypic traits evaluation.There are 4 strains of grade I among them.Their mean values of fruit bearing per strain and fruit yield per strain are 887.50 and 16.63 kg,respectively,which are 244.49%and 177.48%of that of the 67 selected excellent trees.The scores of the resistance capability to pests and diseases,fruit accumulation degree and fruit ripening consistency of the four excellent trees are four.There are 10 strains of grade ?.Their mean values of fruit bearing per strain and fruit yield per strain are 585.10 and 14.75 kg,respectively,which are 161.18%and 157.42%of that of the 67 selected excellent trees.There are 16 strains of grade ?.Their mean values of fruit bearing per strain and fruit yield per strain are 423.00 and 11.31 kg,respectively,which are 116.53%and 120.70%of that of the 67 selected excellent trees.(2)According to the evaluation index of fruit quality,19 strains of excellent trees were selected from 30 primary selected trees.There are 4 strains of grade I.The mean values of the four indices are 58.61g,29.37%,60.29%and 61.18%,respectively,which are 109.51%,100.86%,118.56%and 127.64%of that of the 30 primary selected trees.There are 9 strains of grade 2.The mean values of the four indices are 54.88g,29.80%,54.69%and 51.39%,respectively,which are 102.35%,102.34%,107.55%and 107.22%of that of the 30 primary selected trees.There are 6 strains of grade ?.The mean values of the four indices are 58.88g,28.05%,49.23%and 47.12%,respectively,which are 109.81%,96.33%,96.81%and 98.31%of that of the 30 primary selected trees.(3)From the perspective of the different grafting seasons,methods and scion maturity,the good effect of the grafting of the Aleurites montana can be achieved by cutting in spring and cutting in autumn.The grafting survival rate is 50%-55%,which followed by spring budding with the survival rate of 45%-50%.Moreover,grafted in the autumn,the semi-wood green branches should be used for cutting,which can achieve the best effect.The grafting survival rate can reach about 75%.