Genetic control of fiber properties and growth in triploid hybrid clones of Populus tomentosa

To better understand the genetic control of fiber properties (fiber length [FL], fiber width [FW] and coarseness [C]) and growth traits (tree height [H], diameter at breast height [DBH] and stem volume [SV]) in triploid hybrid clones of Populus tomentosa carr., genetic relationships among selected fiber properties with growth traits were examined in five-year-old clonal field trials located in Yanzhou, Gaotang and Xiangfen, China. In total, 180 trees from 10 clones were sampled from the three sites. The site had a moderate effect on FW, C and tree growth, and a highly significant (P<0.001) effect on FL and fiber length/width (FL/W). Clonal effects were also significant (P<0.05) for all studied traits except for the DBH and SV. Clone×site interactions were significant for all studied traits (except for FL). The estimated repeatability of clonal mean for FL (0.91) was higher than for FW (0.88), C (0.77), FL/W (0.74), H (0.62), DBH (0.61) and SV (0.55). Intersite genetic correlation estimates indicated that fiber properties were more stable than growth traits. Positively insignificant genetic correlation estimates between FL and growth trait and negatively insignificant genetic correlation estimates between C and growth traits were observed. This suggests that in the triploid hybrid poplar, clones selection for growth traits will not result in a significant increase or reduction in the fiber properties.     

Genetic parameters of growth and stem forking for black spruce progeny tested in New Brunswick,Canada

We investigated genetic parameters for juvenile to mature growth and stem forking in black spruce [Picea mariana (Mill.) B.S.P.] in order to obtain reliable estimates for supporting eastern Canadian tree breeding strategies. The study was based on data collected from two series of progeny tests of black spruce in New Brunswick (NB) including 285 open-pollinated families and more than 57,000 individual trees. Height (HT), diameter at breast height (DBH), and stem forking (SF) were periodically measured between ages 5 and 35 years. Results showed that tree volume (V), HT and DBH were highly genetically controlled, with average individual narrow-sense heritability (\(h_{i}^{2}\)) estimates of 0.29, 0.29 and 0.21, and family mean heritability (\(h_{F}^{2}\)) estimates of 0.82, 0.85 and 0.77, respectively. SF had low \(h_{i}^{2}\) (= 0.06 on average) but had moderate \(h_{F}^{2}\) (= 0.56), indicating family selection might effectively reduce SF. Both \(h_{i}^{2}\) and \(h_{F}^{2}\) increased with age and then stabilized or declined, being the highest around ages 15–20 years for all traits. The type-B genetic correlation (\(r_{B}\)) estimates were moderate to high for all the traits, suggesting negligible genotype × environment interactions. Strong age–age genetic correlation estimates were found for growth traits, implying the potential for practicing early selection. Age–age genetic correlation estimates were moderate for SF (= 0.72). Trait–trait genetic correlation estimates were strong and positive among growth traits, but between growth traits and SF they were mostly negligible albeit positive. Overall, results suggest that genetic selection will be effective for growth traits but much less so for reducing stem forking in New Brunswick’s black spruce.     

Genetic correlations among juvenile wood quality and growth traits and implications for selection strategy in Pinus radiata D. Don

? Juvenile wood quality in Pinus radiata is affected by factors such as low density, stiffness, and high microfibril angle, spiral grain, and shrinkage. Adverse genetic correlations between growth and wood quality traits remain as one of the main constraints in radiata pine advanced generation selection breeding program.

? Juvenile wood property data for this study were available from two progeny tests aged 7 and 6 y. We estimated the genetic correlations between stiffness, density, microfibril angle, spiral grain, shrinkage in the juvenile core and DBH growth in radiata pine, and) to evaluated various selection scenarios to deal with multiple objective traits.

? Negative genetic correlations were found for modulus of elasticity (MoE) and density with microfibril angle, spiral grain, shrinkage, and DBH. We observed low to moderate unfavourable genetic correlations between all wood quality traits and DBH growth.

? These low to moderate genetic correlations suggest that there may be some genotypes which have high DBH growth performance while also having high wood stiffness and density, and that the adverse correlation between DBH and MoE may not entirely prohibit the improvement of both traits. Results indicate that, in the short term, the optimal strategy is index selection using economic weights for breeding objective traits (MAI and stiffness) in radiata pine.

? In the long-term, simultaneously purging of the adverse genetic correlation and optimizing index selection may be the best selection strategy in multiple-trait selection breeding programs with adverse genetic correlations.

     

马尾松产脂力与生长性状的家系变异及优良家系早期选择

利用设置在福建南平国有来舟林业试验场马尾松高产脂半同胞家系测定林,研究其产脂力与生长、树冠性状在家系间的遗传变异以及它们之间的遗传相关性,并进行脂用马尾松优良家系及优良单株选择。结果表明,马尾松产脂力与生长、树冠性状皆存在显著的家系差异,相对于生长、树冠性状,产脂力变异较大,变异系数高达61.91%,具有丰富的选择基础。产脂力受中度遗传控制,家系遗传力和单株遗传力分别为0.42和0.31,表明对马尾松产脂力通过家系和单株选择可取得较好的改良效果。性状遗传相关分析结果显示,马尾松家系产脂力与胸径、树高和材积呈较高的正遗传相关,表明在遗传育种进程中可同时对生长性状和产脂力进行改良。此外,产脂力与冠幅、冠高、轮盘数、活枝数也呈较高的正遗传相关。综合生长、树冠性状的遗传力以及与产脂力相关程度,认为胸径是高产脂优树间接选择的最佳指标。以单株产脂量和单株材积生长作为综合选择指标,共选出20个优良家系和16株优良单株,选出的优良单株产脂力遗传增益在52.54% 154.40%,单株材积遗传增益在0.22% 31.85%。     

乐昌含笑优树子代测定及选择*

对九曲水林场乐昌含笑家系试验林6年生观测数据进行分析,方差分析结果表明树高、胸径和材积3个生长性状家系间差异达极显著水平,形质性状的冠幅也达极显著水平;相关分析表明生长与形质性状存在正相关关系;遗传参数估计结果生长性状的家系遗传力处于中等偏上水平,而大部分形质性状处于中等偏下水平;根据多重比较结果,以材积为选择目标,选出9个生长量大于群体均值10%的速生家系,现实增益介于14.85%～45.29%之间。     

Inheritance of growth and survival in two 9-year-old,open-pollinated progenies of an advanced breeding population of Chinese firs in southeastern China

Tree growth traits (tree height, DBH and stem volume) and survival from two 9-year-old, open-pollinated progeny tests of Chinese fir were investigated for heritability, genotype × environment interaction, age-age genetic correlation and selection efficiency. The 97 and 79 families planted at two sites were collected from the third-cycle seed orchard. Individual heritability was estimated between 0.05 and 0.21 for tree height, DBH, and volume and between 0.45 and 1.0 for survival. Family heritability was between 0.20 and 1.14. Significant genotype × environment interaction was observed for the three growth traits. Type B genetic correlation was between 0.41 and 0.67 with an increasing trend as tree grows. High age-age genetic correlation was observed with correlation reaching 0.9 after age 4 for height, DBH, and volume. The genetic gains were estimated at 3.26, 3.39 and 5.98 % for tree height, DBH, and volume with 10 % selection intensity. The implication for advanced tree breeding in Chinese fir is discussed.     

尾叶桉第1代与第2代群体间生长性状和木材材性的遗传控制对比研究

利用4个尾叶桉（Eucalyptus urophylla）自由授粉子代试验（其中D46、D54 2个试验为第1代子代试验,D135、SE35 2个试验为第2代子代试验）作为研究对象,对其生长性状和木材材性进行遗传参数估算.研究结果表明,生长性状和树皮性状受到较低的遗传控制,其狭义遗传力(h2):胸径(DBH) 0.0...     

Genetic variation in wood stiffness and strength properties of hybrid larch (Larix gmelinii var. japonica × L. kaempferi)

Genetic parameters for wood stiffness and strength properties were estimated in a 29-year-old hybrid larch stand (Larix gmelinii var. japonica × Larix kaempferi). The study included 19 full-sib larch families from Hokkaido, northern Japan. Implications of these genetic parameters in wood quality improvement are subsequently discussed. Traits included in the analyses were the dynamic modulus of elasticity of green logs (E _log), the modulus of elasticity (MOE), the modulus of rupture (MOR), compression strength parallel to the grain (CS) in small clear specimens, wood density (DEN), and diameter at breast height (DBH). DEN had the lowest coefficients of variation and MOE the highest. The narrow-sense heritability estimates of E _log, MOE, MOR, and CS were 0.61, 0.44, 0.60, and 0.43, respectively, and those of DEN and all mechanical properties increased from an inner to outer position within the stem. E _log and DEN had high positive phenotypic (0.52–0.83) and genetic (0.70–0.92) correlations with MOE, MOR, and CS. The mechanical properties of the inner position of the stem had rather high phenotypic and genetic correlations with those of the outer position and overall mean. The predicted gains in wood stiffness (E _log and MOE) were higher than those of the strength properties (MOR and CS). The predicted correlated responses in MOE, MOR, and CS when selecting for E _log and DEN were 72.6%–97.8% of a gain achievable from direct selection of these traits. DBH showed an insignificant correlation with all mechanical properties, although selection of this trait had a slightly negative effect on the mechanical properties.     

Index selection for growth and construction wood properties in Pinus elliottii open-pollinated families in southern China

The initial introduction of Pinus elliottii (PEE) to China occurred in the 1930s, and the planting of this conifer species has now attained close to 3 million ha in the subtropical zone of southern China. A large-scale genetic improvement program for PEE was implemented in southern China to produce fast-growing trees with high wood quality to address the severe shortage of timber production over the last two decades. In this paper, selection for stem volume, basic wood density (DEN) and modulus of elasticity (MOE) was based on the Smith–Hazel index, and a total of approximately 2 000 individual trees from 158 PEE open-pollinated families were selected at 22 years of age. The DEN and MOE for each tree were determined by non-destructive evaluation techniques using the Pilodyn and Hitman Director ST300® acoustic velocity device. The heritabilities and genetic and phenotypic correlations for the traits that were measured were estimated using the residual maximum likelihood approach in the flexible mixed modelling program ASReml-R. The results showed that the heritability estimates for the wood properties were between 0.292 and 0.309, and the heritabilities of the growth traits ranged from 0.129 to 0.216. The genetic correlation between the DEN_P and acoustic velocity (V?) with MOE_P was 0.45 and 0.95, respectively. An indirect selection based on V was observed to be highly effective for determination of MOE. It indicated that V can be integrated into tree improvement programs as a useful index of MOE by ranking candidate families or individuals within the selection population. The genetic correlations between the growth traits and wood properties were not significant. By contrast, the phenotypic correlations between them were significantly positive, but the correlation coefficients were very low. The appropriate selection index (I₄), which placed 10 times as much weight on DEN and MOE as the equal emphsis method, was determined as the appropriate selection index.     

Selection of Corymbia citriodora for pulp productivity

Evaluation of a series of spotted gum (Corymbia citirodora) progeny trials, established in the subtropical region of Queensland, Australia, was undertaken to provide information for the development of advanced-generation breeding populations suitable for pulp production. Measurements of growth at two ages were combined with assessments of wood density and pulp yield from a selected sample of provenances to provide comparisons between provenances, to generate genetic parameter estimates and to predict genetic gain potential. Although growth at this age was moderate relative to other eucalypts, the near-infrared predictions of average wood density of 756 kg m^?3 and pulp yield of 55% indicate the species has considerable potential as a pulpwood crop. A pulp productivity breeding objective was used to identify production populations using a range of selection trait weightings to determine potential genetic gain for pulp productivity. Genetic parameters indicated (1) levels of genetic control were moderate for all traits and higher for wood property traits, (2) genetic improvements could be achieved by selection among and within provenances with greater levels of improvement available from selection within populations, (3) genotype by environment interactions were negligible, (4) genetic correlations between traits were favourable, and (5) selection of volume production alone would maximise improvements in pulp productivity.     

尾叶桉×细叶桉木材密度与生长的联合选择

[目的]评估Resistograph钻刺法间接测定尾叶桉×细叶桉木材密度的可靠性,检测杂交亲本对子代表型的效应以及生长与木材密度的相关,评选速生、优质的尾细桉杂种。[方法]基于10株尾叶桉与10株细叶桉不完全析因交配产生的56个杂交组合的7.5年生试验林,利用79株分析容积法与Resistograph钻刺法测定的木材密度的相关,通过方差分析检测亲本对杂种生长和木材密度的效应,结合多重比较和独立淘汰法进行材积和木材密度的联合选择。[结果]容积法与Resistograph钻刺法测定的木材密度的表型相关系数为0.52(P0.001),遗传相关系数为0.55(P0.05);树高、胸径及材积的母本间和父本间均呈极显著差异(P0.001或0.01),但母本×父本互作的效应不显著;对钻刺木材密度,父本间呈极显著差异(P0.001),母本×父本互作显著(P0.05),但母本间差异不显著;树高、胸径和材积间的表型相关和遗传相关均极显著(P0.001),其与钻刺木材密度的表型相关极显著(P0.001),但遗传相关不显著;评选出速生、木材密度较高的杂交组合14个、单株17株。[结论]Resistograph钻刺法是一种间接测定尾细桉木材密度的简便、经济和可靠的方法;母本和父本选择以及母本与父本的组配对培育速生、材质优良的尾细桉杂种均较重要;尾细桉生长与木材密度的遗传相关不显著,需要对这两类性状分别进行选择;评选的尾细桉杂交组合和单株为培育速生、优质的桉树良种提供了有用的材料。     

25年生马尾松生长和木材基本密度家系变异与选择

以福建省华安县西陂林场的25年生来自省内不同产地的46个马尾松自由授粉家系试验林为试材,研究了达主伐年龄时马尾松生长、干形和木材基本密度的家系差异以及性状间的相关性,并依据不同培育目标选择优良家系。结果表明,马尾松生长、树干圆满度和木材基本密度皆存在显著的家系差异,其中生长和树干通直度变异相对较大,而树干圆满度和木材基本密度变异较小,变异系数在10%以下。生长和干形性状受到弱至中度的家系遗传控制,家系遗传力为0.23 0.46;木材密度受到的遗传控制相对较强,家系遗传力为0.46。性状遗传相关分析结果显示,选择速生种源可同时改良树干圆满度,但对树干通直度和木材基本密度影响不大。根据不同用材对材质材性要求,选出24个纸浆纤维材优良家系和6个锯材优良家系,平均木材干物质量和胸径生长皆为对照的1.16倍。     

Estimation of genetic parameters using spatial analysis of Pinus elliottii Engelm. var. elliottii second-generation progeny trials in Argentina

Non-spatial and spatial analyses were carried out to estimate genetic parameters for growth and stem straightness traits between ages 4 and 7 in two series of eight progeny trials of Pinus elliottii Engelm. var. elliottii (PEE) established in 2004 and 2008, comprising 429 open-pollinated families from Instituto Nacional de Tecnología Agropecuaria (INTA) tree breeding population in Argentina. A first-order autoregressive spatial mixed model was found to significantly improve the fit of the model, compared with the standard non-spatial mixed model approach, due to substantial spatial heterogeneity within sites. The average individual-tree narrow-sense heritability estimates based on this spatial analysis were 0.49 for diameter at breast height, 0.36 for total height, and 0.48 for volume, with stem straightness being low to moderate (average?=?0.11). The additive genetic correlation estimates between growth traits were positive (0.51?≤?\(\hat{r}_{a}\)?≤?0.99) and statistically significant from zero. In contrast, the genetic correlations between growth traits and stem straightness although in general also positive were not significantly different from zero (??0.22?≤?\(\hat{r}_{a}\)?≤?0.59). Age-to-age genetic correlations were consistently higher for growth traits (\(\hat{r}_{a}\)?≥?0.81) than for stem straightness (\(\hat{r}_{a}\)?≥?0.33). The average additive genetic correlation estimated between sites within test series was high for all traits evaluated (average?>?0.72). In contrast, average additive genetic correlation estimated between sites across series was slightly lower (average?<?0.63). Implications of all these parameter estimates for genetic improvement of PEE in Argentina are discussed.

     

湖北省马尾松优树半同胞子代测定研究

1991～1992年从湖北省马尾松主要分布区选出116株优良单株,1994年建立了相应的半同胞子代测定林。2011年对子代测定林生长性状、通直度、树皮厚度指数、弹性模量等进行了调查和分析。结果表明:树高、胸径、材积和弹性模量等4个性状在家系间都存在极显著的差异,也表明各优树之间存在广泛变异。树高、胸径和材积的家系遗传力分别为0.689、0.729和0.791,均大于单株遗传力,表明:各家系的主要生长性状受到较强的遗传控制,对参试家系进行选择,能取得比较理想的结果。弹性模量家系遗传力为0.507,属于中等程度的遗传,而树皮厚度指数这一指标家系遗传力较低。按照大于整体平均值加1倍标准差进行选择,树高、胸径、材积和弹性模量4个性状分别有14、14、15和14个家系入选,遗传增益分别为6.4%、11.1%、28.1%和6.6%。     

大径材杂种落叶松优良家系选择

为选择适宜大径材培育的杂种落叶松优良家系,以40年生全同胞子代测定林31个家系为研究对象,对其生长性状、干形性状、遗传力及遗传增益进行了测定.结果 表明:生长性状单株遗传力整体高于干形性状,树高单株遗传力平均值超过0.5,胸径平均值超过0.4,中央直径平均值超过0.3,材积的平均值超过0.5.胸径和材积的相关系数为0....     

Estimation of genetic parameters on growth characteristics of a 35-year-old Pinus koraiensis progeny trial in South Korea

The effects of genetic and environmental factors on Pinus koraiensis growth were studied based on a35 year-old progeny trial composed of open-pollinated offspring of twenty-one plus trees.Height,DBH and volume of the offspring was analyzed using restricted maximum likelihood/best linear unbiased prediction in mixed model analysis.Significant site and family effects on the three traits were observed.The distinct growth of offspring by site with disparate climates corroborated the importance of planting species in suitable conditions.Growth differences by family was significant,emphasizing the importance of identifying families with either superior or inferior performance.The parental ranking was assigned in the sites,inferring the breeding value of each plus tree.The estimates of individual heritability(h_i~2) of height,DBH and volume growth were0.169-0.645,0.108-0.331 and 0.129-0.343 respectively,with higher h_i~2 of the height than DBH on each site.Coefficient of variance of genetic effect was higher with DBH in some cases,indicating the scope for selection is larger for this trait despite the lower heritability compared to height.For the variation between families in terms of the performance stability across sites,consideration of the genotype by environment interaction is required in selecting materials to be used in reforestation with Korean pine.A few families with either superior or inferior performance retained their parental ranking for at least a decade.Other families with increased growth on a particular site were identified,indicating their high breeding value and low stability.Differences in the genetic performance of the families by site requires delineation of the breeding region of the species.     

5年生木荷生长和形质性状的家系变异和选择

利用2008年营建于福建建瓯和江西永丰两地点近140个木荷优树家系的遗传测定林,研究5年生木荷生长和形质性状的家系遗传变异规律及家系与地点的互作,并初选出一批速生优质家系。方差分析结果显示,5年生木荷生长和形质性状在家系间的遗传差异均达到极显著水平;除第3组的最大分枝角性状外,木荷生长和形质性状也存在显著的家系×地点互作效应。性状遗传力估算值显示,树高、胸径和冠幅在两地点的家系遗传力估算值均较高,其变化在0.36 0.87间,受中等偏强的遗传控制,而树干通直度和分枝性状的家系遗传力估算值相对略低,受中等偏弱的遗传控制。性状相关分析显示,木荷家系树高、胸径和冠幅间呈极显著的遗传正相关,遗传相关系数在0.572 0.928间。最大分枝粗与树高和胸径也呈极显著遗传正相关,说明对速生的木荷家系须加强早期修枝,以培育优质的干材。以树高为选择标准,在福建建瓯和江西永丰两地点分别初选出24个和17个早期速生优良家系。     

枫香地理种源变异与选择

对我国15个枫香地理种源的4.5 a生幼林树高、胸径和冠幅等生长性状进行测定。通过方差分析、相关分析和遗传力参数等的估算结果表明:各地理种源间树高、胸径和冠幅差异极为显著,且树高和胸径有较高的广义遗传力,受中等强度遗传控制。树高、胸径与各种源的地理位置不相关,冠幅与纬度呈显著正相关。采用聚类分析,可以划分为4个种源区。根据枫香幼林生长表现,南部种源区表现最差,以中部种源区的湖南桑梓和东部种源区的江西湖城表现最好。     

枫香子代性状的遗传变异分析

自 2 0世纪 40年代以来 ,世界上许多国家注重短周期工业原料林的培育 (方乐金 ,2 0 0 0 )。由于阔叶树的生产效益及产量不及针叶树 ,故许多国家在人工林发展初期 ,均把针叶树作为发展重点 ,中国亦不例外 ,如南方杉木、马尾松等一些针叶树种占总造林面积的 80 %以上 (方乐金 ,2 0 0 0 )。大规模的针叶树替代了物种丰富的天然林群落 ,导致森林生态系统失衡 ,物种多样性降低 ,森林病虫害频频发生 ,人工更新难度加大等问题日益显露。同时 ,针叶树林产品相对过剩与阔叶树林产品不足 ,严重制约了林业自身的经济效益 (方乐金 ,2 0 0 0 ;施季森等 ,1…     

杉木2代种子园子代主要经济性状遗传变异及单株选择

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