【作者】 吴世军；

【导师】 徐建民；

【作者基本信息】 中国林业科学研究院 ， 林木遗传育种， 2012， 博士

【摘要】 本文以尾叶桉及其杂种无性系为研究对象，开展尾叶桉遗传改良及其杂种无性系多性状综合选育研究，分析尾叶桉无性系的遗传变异与选择增益，对尾叶桉全双列亲本及交配组合进行评价，估算一般配合力效应、特殊配合力效应、杂种优势和自交衰退；开展尾叶桉杂种无性系生长与材性、生长与干形的综合选育评价；分析无损检测方法在尾叶桉杂种无性系材性选育中的应用前景；分析尾叶桉杂种无性系年度相关及其变异研究，为制定杂交育种策略和桉树产业升级奠定理论基础。主要结论如下：（1）对21、52、71和96个月尾叶桉无性系的生长、材性、干形和树皮特性进行方差分析后表明：生长、材性和单株材重均在0.01和0.05水平达显著差异。不同指标的遗传变异差异较大，单株材重的遗传变异系数最大。生长指标的重复力为0.36到0.53，材性指标的重复力为0.35到0.51，干形指标的重复力为0.21到0.24，树皮特性的重复力为0.07，单株材重的重复力为0.31。胸径的年度间相关系数表明：21个月生时的胸径无法预测96月生胸径，而只能预测52个月和71个月的生长。71个月生时胸径的入选率在10%到30%时选择增益最高，52个月生时入选率在60%到90%时选择增益最高。遗传改良选择增益结果表明，各性状的增益值在-2.11%到8.10%之间，除分枝和树皮率外，其它指标均为正增益。（2）尾叶桉种内6×6全双列交配遗传分析表明：同一育种材料不同性状一般配合力和特殊配合力效应不同；具有较高生长性状一般配合力的亲本往往可以获得较高的特殊配合力，具有较高木材密度一般配合力的亲本往往可以获得较低的特殊配合力；同一亲本不同地点的衰退程度有所不同，即使是同一亲本同一地点，不同指标的自交衰退仍有所差异；不同交配组合间的杂种优势差异较大，树高和胸径在各组合间的杂种优势范围基本一致，不同杂交组合的杂种优势在不同地点间差异较大，相同亲本的正交与反交组合的杂种优势具有一致性。遗传增益分析表明：各性状的增益值在-13.19%到25.47%之间，除木材密度和树皮率外，其它指标均为正增益，生长性状的遗传增益要高于其它性状，全双列子代的总体增益要远远大于无性系的增益值。（3）对19个51月生尾叶桉杂种无性系的生长、材性和树皮率进行方差分析后，结果表明：除木材密度外，生长指标和材性指标在无性系、地点以及无性系与地点的互作间均存在极显著差异。生长指标的遗传变异系数为8.4%到27.9%之间，材性指标的遗传变异系数为2.7%到11.1%之间，树皮率的遗传变异系数为14.0%到23.3%之间。生长指标的重复力为0.73到0.96之间，材性指标的重复力为0.32到0.93之间，树皮率的重复力为0.77到0.88之间。同一性状不同地点间的遗传相关达极显著水平。生长性状与Pilodyn值之间呈0.28到0.65的正相关关系；生长性状与树皮率均呈现负相关关系；生长性状与木材密度的遗传相关系数在-0.67和0.43之间。不同杂种无性系的差异性表明：应加强对尾叶桉与巨桉组合的木材密度选育，加强对尾叶桉与细叶桉和赤桉的生长量选育。（4）通过分析建立在广西22个56月生尾叶桉杂种无性系的Pilodyn值与整株木材密度、边材密度、心材密度和弹性模量间的相互关系表明：Pilodyn值在不同处理、不同方向及不同参试无性系间均存在极显著差异。Pilodyn值与各材性指标间的相关系数在-0.433到-0.755之间，呈显著到极显著负相关，表明Pilodyn方法可以有效预测尾叶桉杂种无性系的木材密度和弹性模量。分析建立在广东的23个51月生尾叶桉杂种无性系各材性指标间的相互关系表明：Pilodyn值与木材密度间呈极显著负相关（r=-0.83）；木材密度与弹性模量的相关系数为0.74；应力波速与木材密度和弹性模量的相关系数分别为0.52和0.96，表明Pilodyn和微秒计均可有效预测尾叶桉杂种无性系的木材密度和弹性模量。（5）对20个44月生尾叶桉杂种无性系的生长性状和形质性状进行多重比较表明：共有10个无性系的蓄积量超过总体平均值，生长最快的是No.3（DH32-28)，生长最差的是No.17（U6）。树高、胸径和单株材积的重复力分别为0.86、0.80和0.80；冠幅、枝下高、干形和分枝的重复力分别为0.54、0.85、0.77和0.44。树高、胸径和单株材积的遗传变异系数分别为9.84%、9.91%和28.54%；冠幅、枝下高、干形和分枝的遗传变异系数分别为18.26%、11.73%、12.03%和17.28%。各性状相关性分析表明生长量较大的无性系往往具有较大冠幅、较好的干形和分枝。（6）对广东新会地区2年生到6年生尾巨桉无性系DH32-29的生长指标和材性指标进行方差分析表明：除木材密度外，不同年度间其它指标间均达到极显著差异。年度间生长指标和材性指标的生长趋势表明：无性系DH32-29的轮伐期应至少6年或更长。表型相关系数表明：同一年度不同生长指标间均达极显著相关，生长指标和木材密度间的相关系数随林龄增长而有所变化，2年生和5年生的相关系数在-0.03到-0.54间，3年生、4年生和6年生的相关系数在0.003到0.3之间。Pilodyn值与木材密度间的相关系数表明：Pilodyn可以用来分类不同基因型或不同地点的木材密度，但不能有效预测单株或单一无性系的木材密度。更多还原

【Abstract】 In this thesis, Eucalyptus urophylla families and hybrids clones with E.urophylla S.T.Blake were researched for genetic improvement and multiple-traits selection in order toanalyze genetic gain between generations, evaluate parents and cross combinations, estimategeneral combining ability, specific combining ability, heterosis and inbreeding depression,select best clones with fast growth, high wood properties and good stem-branch traits,investigate the effectiveness of nondestructive methods to predict wood properties standingtree traits in eucalypt hybrids clones, analyze age trends and correlations of growth and woodproperties in clone of Eucalyptus urophylla×E. grandis, and make a academic base foreucalypts breeding strategy and upgrade in industries. The major conclusions were to:(1) Growth traits, wood properties, stem-branch characteristics and bark percentage wereassessed for E. urophylla clones measured at age21,52,71and96months. Analysis ofvariance showed that there were significant differences on growth traits, wood properties andindividual tree wood weight at0.01and0.05levels among clones. Different traits had differentcoefficients of variation, while individual tree wood weight had biggest variation value.Repeatability ranged from0.36to0.53for growth traits,0.35to0.51for wood properties,0.21to0.24for stem-branch characteristics,0.07for bark percentage and0.31for individual treewood weight. The strongly negative genotypic correlations suggesting that selection ondiameter at breast height at21months can not be effective to predict diameter at breast heightat96months whereas it could be used to predict diameter at breast height at52and71months.The selection gain on diameter at breast height over bark by different selection proportions at21,52,71and96months old expressed that selection gain at71months was some what higherthan that at other ages during10%to30%selection proportion, while selection gain at52months was some what higher than that at other ages during60%to90%selection proportion.Genetic gain ranged from-2.11%to8.10%, and this value of branch and bark percentage werenegative. (2) Genetic analysis of6×6full diallel mating showed that different traits showeddifferent general combining ability and specific combining ability even for same parents. Crosscombinations with high general combining ability for growth traits always had high specificcombining ability. Cross combinations with high general combining ability for wood basicdensity always showed low specific combining ability. Inbreeding depression rangeddifferently for different parents with different traits in different sites. Different crosscombinations at different sites showed different heterosis. The heterosis of tree height hadsimilar value range of diameter at breast height. Same parents always had similar original andreciprocal heterosis. Genetic gain ranged from-13.19%to25.47%and this value of studiedtraits were positive except for wood basic density and bark percentage. The genetic gains ofgrowth traits were higher than other traits. The genetic gain of full diallel families wasgenerally higher than clones.(3) Growth traits, wood properties and bark percentage were assessed for19hybrideucalypt clones sampled at age51months. Analysis of variance showed that there weresignificant differences in growth traits and wood properties between clones and sites, and thatthe clone×site interactions were also significant except for basic density. Coefficients ofvariation ranged from8.4%to27.9%for growth traits,2.7%to11.1%for wood properties and14.0%to23.3%for bark percentage. Repeatability ranged from0.73to0.96for growth traits,0.32to0.93for wood properties and0.77to0.88for bark percentage. Strong genotypiccorrelations between the same traits in clones at pairs of sites indicated that the traits wererather stable across sites. The correlations between growth traits and Pilodyn pin penetrationwere positive, ranging from0.28to0.65and therefore unfavorable as lower wood density willbe associated with higher values of Pilodyn pin penetration and improved growth rate. Thegenotypic correlations between growth traits and basic density ranged from-0.67to0.43, andgenerally favorable negative genotypic correlations between growth traits and bark percentagewere also found. Differences among hybrid eucalypt clones indicated that more care should betaken regarding selection for wood basic density in cross of E. urophylla×E. grandis andgrowth in crosses of E. urophylla with E. tereticornis and E. camaldulensis. (4) Wood basic density, outer wood density, heartwood density, modulus of elasticityand pilodyn penetration were analyzed at22eucalyptus clones in Guangxi, at which time thetrial was aged56months. The results indicated that there were significant differences (1%level)in pilodyn penetration between different treatments, different directions and among the clones.Generally strongly negative correlations were found between pilodyn penetration and woodproperties, and the coefficients ranged from-0.433to-0.755, suggesting that the use of pilodynfor assessing wood density and modulus of elasticity was confirmed as a possibility. Woodproperties and nondestructive methods were assessed for23eucalypt clones in Guangdongsampled at age51months. Correlations between three traits assessed using nondestructivemethods and basic density measured on increment cores showed that genotypic correlationbetween Pilodyn penetration and basic density was significantly and negative (r=-0.83). Thecorrelation between basic density and modulus of elasticity was significantly positive (r=0.74).Stress wave velocity was found to be relatively strongly correlated with basic density (r=0.52)and modulus of elasticity (r=0.96). Results indicated that the average basic density andmodulus of elasticity can be predicted by using Pilodyn and Fakopp microsecond timer.(5) Growth traits and stem-branch traits were assessed for20hybrid eucalypt clonessampled at age44months. Analysis of results showed that there were10clones with highergrowth than general mean. The growth of No.3(DH32-28) was fastest, whereas the growth ofNo.17(U6) was lowest. Repeatability of growth traits, crown range, branch height, stem andbranch were0.86,0.80,0.80,0.54,0.85,0.77and0.44respectively. Coefficients of variation ofgrowth traits, crown range, branch height, stem and branch were9.84%,9.91%,28.54%,18.26%,11.73%,12.03%and17.28%respectively. Correlations results showed that cloneswith higher growth generally had bigger crown range, better stem and smaller branch.(6) Growth traits and wood properties were assessed for DH32-29, a clone of E. urophylla×E. grandis, at age of two to six years in Guangdong Xinhui. Analysis of variance of studiedtraits showed that there were significant differences (1%level) on all studied traits among agesexcept for wood basic density. Analysis of age trends of growth traits and wood propertiesrevealed that rotation length of DH32-29should be more than six years or longer. Phenotypic correlations among traits at individual ages indicated that correlations among growth traitswere strongly positive. There was significant change in relationship between growth and woodbasic density with increasing age, ranging from-0.03to-0.54at2and5year and0.003to0.3at3,4and6year. Correlations between Pilodyn pin penetration and basic density measured onincrement cores showed that Pilodyn could rank or group genotypes or sites into densityclasses, but failure to predict individual tree and individual clone.更多还原