| Melia azedarach Linn.is the model plant of Melia,Meliaceae.It is a fast-growing with high quality timber mult i-purpose tree species and rich in wild resources on the widely distribution.According to the observation on the growth traits of different provenances and families of M.azedarachat three years old at three sites in Guangdong Province,this study analyzed the geographic variation trend of growth traits and preserving rate,evaluated the tested provenances and families on growth,and selected out some superior provenances and families preliminarily.The main conclusions were obtained as follows.1.Tree height(Ht),diameter at breast height(DBH),under branch height(Hb),stem form,crown diameter and preserving rate of M.azedarach showed relatively abundant phenotypic variation at three sites in Guangdong Province.The variation among provenances on each trait was extremely significant at three sites,so there was biggish selection potential on the provenance level.The provenance repeatability of growth traits(2=0.42~0.98)was in the middle or high level.O n these traits,the variation among sites,among blocks within site,among provenances,provenance and site interaction term,and provenance and block within site interaction term all reached extremely significant level;In addition to the random error,the percentage of variance components of sites or blocks within site was always higher than other effect terms,which meant that the environment influenced the growth greatly.2.The geographic variation trend of growth traits showed main variation along with latitude,and complementary variation along with longitude.Ht,DBH,Hb,stem formand crown diameter of M.azedarach showed significant or extremely significant negative correlation with latitude,and preserving rate showed significant negative correlation with altitude.This geographic variation had obvious climate ecology basis.The provenances which came from areas with lower air pressure,higher temperature,and more abundant rain usually had better adaptability and advantages on growth.3.O n the sites III,among the growth traits,the preserving rate and DBH were the main contribution traits,the second was the Ht and crown diameter.And the tested 14 provenances were clustered to two categories: group I(including NO.0102,NO.0524,NO.0415,NO.0205,NO.0631,NO.0309,NO.1604,NO.0739 and NO.0842 provenance)was mainly from south C hina,which grew quickly,straightly and preserved well;group II(including NO.1101,NO.1501,NO.1154,NO.1501 and NO.1603 provenance)was from north C hina,which grew slowly and crookedly.4.The variation among families on each trait was extremely significant at three sites,so there was biggish selection potential on the family level.The heritability on different traits was obviously different.DBH(2=0.40~0.84),Ht(2=0.28~0.70),and crown diameter(2=0.27~0.75)were highly controlled by genetic factor,stem form(2=0.00~0.42)and Hb(2=0.17~0.29)were weakly controlled by genetic factor,while the heritability of preserving rate at different sites varied greatly.The ranking of phenotypic mean of tested families on different traits had much difference,and undulated among years,so that only a handful of families grew well on all the main traits.O n these traits,the variation among sites,among blocks within site,among families,family and site interaction term,and family and block within site interaction term all reached extremely significant level;In addition to the random error,the percentage of variance components of sites or blocks within site or family and block within site interaction term was always higher than other effect terms,which meant that the environment influenced the growth greatly.5.Ht,DBH,Hb,stem form,and crown diameter mostly presented significant or extremely significant positive correlation with each other.The correlation coefficients between Ht and DBH(r =0.35~0.71),between DBH and crown diameter(r =0.53~0.60)were generally high.In addition,Ht,DBH,stem form and crown diameter had high positive Juvenil-mature correlation.O n the provenance level,the Juvenil-mature correlation coefficients of Ht(=0.70~1.05)and stem form(=0.65~1.09)were higher than other traits;while on the family level,the Juvenil-mature correlation coefficients of DBH(=0.73~0.81)were higher than other traits.6.At site I,5 superior provenances were selected out,included NO.0413,NO.0753,NO.0523,NO.0412,and NO.0527 provenance,mainly came from Guangdong,Hainan,and Yunnan Province,and the geneticgain of growth traits varied from 0.38% to 8.60%.At site II,3 superior provenances were selected out,included NO.0739,NO.0631,and NO.0205 provenance,mainly came from Yunnan,Guangxi,and Jiangxi Province,and the geneticgain of growth traits varied from 0.44%~2.59%.At site III,3 superior provenances were selected out,included NO.0415,NO.0205,and NO.0631 provenance,mainly came from Guangdong,Jiangxi,and Guangxi Province,and the geneticgain of growth traits varied from-0.25% to 9.02%.7.The breeding value(BV)and its ranking of the tested families on different traits presented great difference,and only a handful of families' BV ranked into the top 20%.At the same time,the BV ranking of tested families in different years also presented difference on various degrees.8.At site I,23 superior families were selected out,included NO.041,NO.042,NO.072,NO.035,NO.239,NO.223,NO.033,NO.040,NO.121,NO.034,NO.075,NO.243,NO.077,NO.036,NO.066,NO.224,NO.060,NO.076,NO.061,NO.102,NO.068,NO.230,and NO.200 family,and the geneticgain of growth traits varied from 0.00% to 15.36%.At site II,16 superior families were selected out,included NO.121,NO.325,NO.302,NO.296,NO.319,NO.135,NO.194,NO.311,NO.196,NO.120,NO.018,NO.304,NO.224,NO.290,NO.066,and NO.303 family,and the geneticgain of growth traits varied from 0.77% to 5.06%.At site III,9 superior families were selected out,included NO.293,NO.305,NO.053,NO.286,NO.065,NO.300,NO.064,NO.303,and NO.260 family,and the geneticgain of growth traits varied from 1.05% to 14.22%.Among the 3 sites,the NO.047,NO.054,NO.147,and NO.225 family had the average genetic stability(bi=1,(94)2= 0),the NO.143,NO.145,NO.155,NO.209,NO.211,NO.224,NO.322,NO.323,NO.325,NO.328,NO.329,NO.330,and NO.331 family had higher genetic stability(bi<1),and the NO.053,NO.055,NO.056,NO.064,NO.065,NO.066,NO.142,NO.205,NO.214,and NO.217 family had lower genetic stability(bi>1).At site I,among three years(2014~2016),the NO.034 and NO.333 family had the average genetic stability,the NO.031,NO.075,and NO.239 family had approximately average genetic stability,and the NO.105,NO.142,NO.159,NO.161,NO.223,and NO.247 family had higher genetic stability. |
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