Study On Progeny Test And Selection Of Half-sib Families Of Melia Azedarach L.

Melia azedarach is one of the wild distributed and fast growing native tree species in China.It is also of many good characters such as lower toxic, higher efficient and broad spectrtan botanical pesticides.Most of its resources are continuously and sparsely distributed.However,some of the resources had been damaged badly.It is urgent to collect,conserve and evaluate the genetic diversity of M.azedarach for scientifical and rational protection for germplasm resources,genetic improvement and the screening of superior germplasms.Genetic variation of growth and form traits,heritability and genetic correlation were studied systematically on 24 progenies of half-sib families of Melia Azedarach L.Eight superior families and twenty superior individual trees on growth and form traits were selected by index selection.The main results were as follows:1.The significant or strong significant differences not only were existed among families but also in families.The seedling trait diversity was rich in Melia azedarach L.The CV of seedling height and ground diameter were 5.581%and 8.147%.The phenotypie CV of ground diameter is higher than that of height,and the phenotypic CV among families is higher than that of individual trees.The heritability of seedling height among families(0.9819) and individual trees (0.8421) are higher than that of ground diameter(0.5629,0.4355) obviously.2.There is diversity variation among family's growth and tree form traits of four-year-old half-sib families of Melia azedarach L.The CV of height and the height under branch arc similar and lower.The CV of DBH,crown width and the height of divided branch are similar.The volume,the branch number and the diameter of main branch have big CV.The sequence of CV among trec form traits is straightness＞ratio of height and DBH＞ratio of crown width and DBH.There arc significant or strong significant differences among height,DBH,volume,the trunk height under branch,the height of divided branch,straightness and ratio of height and DBH;but among crown width,the branch number,the diameter of main branch and ratio of crown width and DBH are not significant.The heritability of volume is the highest of all traits.The sequence of others are diameter(0.8551),ratio of height and DBH(0.826),height (0.7870),the height of divided branch(0.6232),the trunk height under branch(0.5303),straightness(0.429),crown width(0.3923),the diameter of main branch(0.2650),the branch number(0.2531).3.There are significant or strong significant differences of height and diameter growth among different families in one year.The growth and CV are increasing with the time extending.The growth of 2004～2005 is lower than other years because transplantation.The growth CV of 2006～2007 is the highest,height and diameter growth are 36.59%and 53.32%leave each other.4.The correlation between growth traits with straightness is positive,with ratio of height and DBH and ratio of crown width and DBH is negative.The genetic relationship among growth traits is significantly positive.The correlation coefficients between volume with height and diameter are the highest,and the correlation is higher with diameter than that of height.The correlation coefficients between volume with diameter is high up to 0.917.The genetic relationship between straightness and ratio of crown width and DBH is negative.Selecting families and individual trees with low ratio of height and DBH and ratio of crown width and DBH,specially the low ratio of height and DBH families and individual trees,are beneficial to improve growth traits,and to carry out intention of indirect selection. 5.Dividing twenty four half-sib families with the application of principal component and clustering analysis into 7 clusters such as:Ⅰ:2,27,29,32 family,Ⅱ:4,5,10,22,28,18,33,6 family,Ⅲ:7,30,11,13,17 family,Ⅳ:8 family,Ⅴ:19,21,26 family,Ⅵ:20,25 family,Ⅶ: 23family.It seems that the half-sib families from the same provenance have the trend to show same genetic variation in growth and tree form traits.6.According the volume breeding values and comprehensive sorting of mixed index sorting of families and individual trees from 4-year old Melia azedarach L.,several superior families and individual trees were selected.The eight superior half-sib families are 23,6,5,7,10,28,4 and 2 family.The twenty superior individual trees are 28(1),20(3),6(1),25(2),23(4),5(4),23(1),4(1),22(1),7(1),27(2),17(2),5 (3),23(3),22(3),32(1),29(4),18(4),10(3),2(1).