Age–age correlations and early selection for growth traits in 40 half-sib families of Larix principis-rupprechtii

Larix principis-rupprechtii Mayr is a dominant species in coniferous forests of North China. However,early selection of L. principis-rupprechtii for growth traits is poorly characterised. To explore the optimal selection age for this species, heights(HT) and diameters at breast(DBH) of 40 half-sib families were measured at ages 3, 12,22, and 28 years in a progeny test population established in the town of Kangjiahui, Shanxi Province. Age trends in heritability, age–age genetic correlations, and early selection efficiency for height and DBH were analysed. The individual heritability of these growth traits varied over time, and maximized at different ages(0.55 at age 12 for HT and 0.48 at age 28 for DBH). The age–age genetic correlations were always positive, and the majority were high(0.790–0.953) between the juvenile and mature ages for HT and DBH. For the same pairs of measurements, HT demonstrated higher age–age genetic correlations than DBH, and both age–age genetic correlation data sets were described well by the linear relationship with the logarithm of the age ratio(r~2[ 0.90). The regression slope for DBH was lower than that for HT. Based on the early selection efficiency estimates, the optimal selection age could be as early as age 6 for DBH and 8–9 years for HT. The results of this study provide information that can be used to assist early selection practices in L. principis-rupprechtii improvement programs in Shanxi Province.     

Selection of superior families of Pinus massoniana in southern China for large-diameter construction timber

This study addresses the increasing demand for large-diameter production timber,and considers the time and space variability of half-sib families of Pinus massoniana.Height,diameter at breast height(DBH)and timber volume of 440 open-pollinated half-sib progeny families were investigated in 14 progeny trials in different years and production regions.An evaluation of the genetic variation of all half-sib families was carried out during the sustainable rapid growth period and individual volumes were characterized as a major index.ANOVA analysis showed that there was considerable variance in the growth traits of most families in different years and on different sites.The variations caused by temporal and spatial changes of the mating system required three selection methods for analysis.The results show that there were differences among the heritabilities of different growth traits by different halfsib progenies.Average heritability values of height,DBH and volume were 0.33,0.34 and 0.36,respectively.Fortyfive superior families were selected in every progeny test,12 were selected in progeny trials by different years and five in different habitat progeny trials.Three superior families(Gui GC553A,Gui GC414A and Gui GC431A)were selected,although in different years and production regions.The genetic gains of timber volume of these selected r families ranged from 1.20 to 47.00%,which could provide a foundation for superior wood property selection and serve as material for seed improvement and extension in surrounding areas.     

Options for converting a clone trial of Eucalyptus camaldulensis into a clonal seed orchard considering gain,fertility and effective clone number

We evaluated a clone trial comprised of 20 ramets each of 40 Eucalyptus camaldulensis clones for growth and fertility at 4 years of age. The clones differed significantly in growth with 65–100 % survival in 38 clones while two clones had low survival(40 and 10 %).Fecundity was high and fertility variation low, as indicated by the sibling coefficient value(W = 1.4) with 55 % of clones contributing 80 % of the fruits. Thinning strategies were considered to convert the clone trial to a clonal seed orchard and enhance both gain and diversity in seed crop.When clones were selected based on growth without considering fertility, truncation selection(to retain clones with higher DBH than the trial mean value) would give 8 %gain, but 59 % reduction in effective population size(Ne).Gain and predicted diversity(Ne) was highest when ramets were selected in linear proportion to the breeding value of each clone. Mass selection with the same intercept(for DBH) as truncation selection would give a moderate 3 %gain, but over two times higher predicted Nethan truncation selection. When fertility of retained trees was considered after thinning, mass selection would yield 52 %effective contribution from the orchard trees compared to only 30 % contribution from truncation selection and linear thinning. Higher representation of superior clones in linear thinning and mass selection would lead to greater fertilityvariation and over 30 % reduction in effective clone number(Nc) from that predicted(Ne, assuming equal fertility among ramets) before thinning.     

Cost-effectiveness analysis of subsidy schemes for industrial timber development and carbon sequestration in Japanese forest plantations

This study uses simulations to investigate the effects of implementing two different Japanese forestry subsidy systems on timber production and carbon stock, and examines the consequences for harvesting strategies. An existing Local Yield Table Construction System (LYCS), a wood conversion algorithm, and a harvesting cost model were used in the simulations to test the applicability of different subsidies to the thinning of stands. Using forest inventory data collected by local government staff, simulation output was used to calculate forestry profits, carbon stocks, subsidies, the amount of labor required, and the cost effectiveness of investing in subsidies. By comparing the output of simulations based on two scenarios, we found that both the clear-cutting area and the amount of harvested timber were larger under Scenario 2, in which the rules governing subsidy allocations are more relaxed, than under Scenario 1, in which the rules are more restrictive. Because the harvested timber under Scenario 1 was mainly produced by clear-cutting, the forestry profits and the subsidy predicted in the early period of the simulation, were larger under Scenario 1 than under Scenario 2. In contrast, the carbon stock was larger under Scenario 2 than under Scenario 1. The simulation model is likely to be useful for improving Plan-Do-Check-Act cyclesimplemented in Japanese forest management systems.     

Clonal variations in nutritional components of Pinus koreansis seeds collected from seed orchards in Northeastern China

From four Korean pine(Pinus koraiensis)orchards, 60 clones were selected and analyzed for the fatty acid and amino acid components of the seeds to reveal the variations and correlations of the seed characteristics among the clonal source orchards and clones. The nutritional components of the seeds of the P. koraiensis trees exhibited rich genetic variation; the variation coefficient of the fatty acids was 2.24–66.83 %, while the variation coefficient of the amino acids was 14.70–38.88 %. Relatively high genetic-improvement potential exists for the nutritional components of the seeds. The phenotypic differentiation of the fatty acid and amino acid components reveals that variation within the population(85.18 %) was the primary source for the variation of the fatty acid components; variation among the orchards(63.08 %) was the primary source of the variation of the amino acid components. Data drawn from various clonal source orchards all showed that the seed characteristics were highly controlled by heritability(h2[ 80 %), and the seed characteristics of the P. koraiensis trees exhibited a similar genetic gain trend. The principal components were analyzed to obtain the comprehensive principal component value for each clonal seed orchard. Twelve clones were selected based on a clonal selection rate of 20 %. Correlation and multiple stepwise-regression analyses were conducted, considering different location conditions, to reveal the stable correlations between the seed characteristics to facilitate improvements of the seed yield of P.koraiensis trees and the clonal selection. Species of real characteristics in P. koraiensis were controlled by higher heritability. Genetic gain was obtained by selecting of superior clones.     

Spatial analysis increases efficiency of progeny testing of Chinese fir

We used spatial, global trend and post-blocking analysis to examine the effectiveness of a progeny trial in a tree breeding program for Chinese fir(Cunninghamia lanceolata(Lamb.) Hook) on a hilly site with an environmental gradient from hill top to bottom. Diameter at breast height(DBH) and tree height data had significant spatial auto-correlations among rows and columns. Adding a firstorder separable autoregressive term more effectively modelled the spatial variation than did the incomplete block(IB)model used for the experimental design. The spatial model also accounted for effects of experimental design factors and greatly reduced residual variances. The spatial analysis relative to the IB analysis improved estimation of genetic parameters with the residual variance reduced 13 and 19%for DBH and tree height, respectively; heritability increased35 and 51% for DBH and tree height, respectively; and genetic gain improved 3–5%. Fitting global trend and postblocking did not improve the analyses under IB model. The use of a spatial model or combined with a design model is recommended for forest genetic trials, particularly with global trend and local spatial variation of hilly sites.     

STUDY ON THE PROVENANCE TEST OF DAHURIAN LARCH SELECTION OF BEST PROVENANCE

In this paper,it is studied that the growth characters of the progeny of 16provenance of larix gmelinii within the all 13 experimental sites by means of the analysis of va-riance,provenance stability,productivity index,rank correlation,synthetic index selection andPCA.The provenances were divided into three patterns:The first type have low and steady prod-uctivity;The second type have high but unsteady productivity;The third type is between theproductivity of the first and second type.Through the analysis on the feasibility and the reliabili-ty of the provenance early selection,the best provenances which lie in the southeast of theXiaoxingan Mt.are regarded as the best and suitable for a large afforestation areas of Larixgmelinii.Then in the north of Xingan Mt.,the local or the northwest provenances of theXiaoxingan Mt.should be used.The genetic gain was calculated on the basis of the provenanceheritability and the utilization of the best provenance were evaluated in this paper.     

Variation,inheritance and correlation of growth characteristics of <Emphasis Type="Italic">Populus deltoides</Emphasis> Bartr. at various ages in the central-plain region of Punjab,India

The growth performance of twenty poplar(Populus deltoides Bartr.) clones,planted in the central-plain region of Punjab in north-western India,was evaluated using a randomized block design with three replications and plot size of four plants.Significant differences among clones were observed for diameter at breast height(DBH),height and volume per tree at age five,six and eight years.Clone L-48/89 recorded significantly superior volume than the control(G-48) at all ages,with superiority of 51.4,43.9 and 48.5 per cent at age five,six and eight years,respectively.The phenotypic and genotypic coefficients of variation were the highest for volume(26.55-34.66% and 15.84-26.00%) and the minimum for tree height(8.43-12.13% and 4.71-7.59%).The broad sense heritability was relatively higher for DBH(0.42-0.55) and genetic advance as per cent of mean was highest for volume(19.48-40.18).All genetic parameters increased with age.All traits showed significant positive correlation with each other.     

Effect of selective cutting type on the chainsaw productivity in Caspian Forests

Time and motion studies were conducted to evaluate the impact of selective cutting type on Chainsaw productivity in Caspian forests,the selective cutting performed as single and group selection cutting in the region.The selective cutting was performed on a 42-ha tract with an average slope of 30%.The results indicate that felling time for per tree is most affected by diameter at breast height,the distance among harvested trees in single-tree selection method and diameter at breast height in group selection method.The production rate in single and group selection cutting were 21.2 m 3 h-1 and 28.4 m 3 h-1 for one person,respectively.Considering the gross and net production rate in single and group selection cutting,the unit cost was 1.11 USD m-3 and 0.88 USD m-3,respectively.The results indicate that group selection cutting can be more profitable than single-tree selection method.     

Early evaluation of growth traits of Larix kaempferi clones

Early selection is an important method to shorten the breeding cycle for tree species, which may differ in the time for early selection.To evaluate the early selected time for Larix kaempferi, tree height and diameter at breast height of 57 L.kaempferi clones were measured over many different growth years.The results indicated that, except for age × clone interaction for diameter at breast height(P = 0.741), there were significant differences among all variation sources(P 0.01).The coefficient of phenotypic variation ranged from 14.89 to 35.65%for height and from 19.17 to 23.86% for diameter at breast height in different growth years.The repeatability of height and of diameter at breast height among clones was high,ranging from 0.6181 to 0.8531(height) and from 0.8443 to0.8497(diameter at breast height), in different growth years.There were significant positive correlations between all pairs of growth traits except between height in the 2 nd growth year and height in the 30 th growth year; and between height in the 2 nd growth year × diameter at breast height in the 30 th growth year.With a comprehensive evaluation method and a selection ratio of 10%, L65,L1, L62, L9, L15, and L78 were selected as excellent clones in the 30 th growth year.Their average values of height and diameter at breast height were 9.81 and 16.57%higher than the overall average, representing genetic gains of 6.46 and 13.99%, respectively.This study provides a theoretical foundation for the genetic improvement of L.kaempferi.     

Efficiency of breeding strategy where grandparents — but not parents — contribute equally to the breeding population

? The objective was to optimise the strategy for maintaining the genetic balance in long-term breeding where the grandparents contribute equally to the breeding population, but the parents do not.

? The annual genetic progress under a budget constraint was compared for a number of scenarios. The factors considered were: genetic parameters, recruitment population size, mating number per grandparent, cost of plants and parents, selection age and time components. Phenotypic selection forward was assumed. Using more parents than grandparents affects the testing population only, thus, gene diversity loss and breeding population size remain constant.

? Using larger number of parents than grandparents was a superior strategy at all scenarios tested. The strategy with 6 parents per grandparent and 1% of the tested plants selected on their phenotype at age 15 for further mating is recommendable. The strategy to choose 6 parents per grandparent was robust over a heritability range 0.05 to 0.2. At a higher heritability, the optimum number of parents per grandparent was 2 to 4.

? Using larger number of parents than grandparents has the potential to improve annual genetic gain in the magnitude of 50% compared to the strategies currently used for Scots pine in Sweden.

     

Optimization of breeding population size for long-term breeding

A model for optimization of the long-term breeding population size by considering genetic gain, relatedness, time and cost components was developed for the optimum allocation of resources between the breeding and testing populations. The group coancestry and the average breeding value for the breeding population were merged into a joint index, known as group merit. The size of the breeding population was regarded optimal when the annual increase in group merit was maximized at a budget constraint. A study scenario with a balanced selection and parameters suitable to northerly conifers bred in a multipopulation design was applied. The optimum breeding population size ranged between 30 and 70. High heritability, more efficient breeding strategy, high additive variance at mature age, low annual budget, expensive testing method and a low value assigned to gene diversity favoured a small breeding population size.     

日本落叶松全双列交配生长性状的遗传分析

目的 通过全双列交配设计开展配合力分析,研究SCA（特殊配合力）对重要性状的相对贡献,旨在为日本落叶松的育种策略制定和育种群体管理提供重要遗传参数信息。 方法 本研究以13个母本和23个父本获得的6×6和4×4两组全双列交配设计的日本落叶松子代测定林为对象,利用空间模型对16年生和26年生的生长表型数据进行校正,采用单株模型对其配合力和正反交效应分析,研究加性效应、SCA效应的相对重要性及其在落叶松育种中的应用。 结果 自交子代在保存率性状上未表现出明显的自交衰退,生长性状在一些亲本中甚至优于相应异交后代;生长性状的正反交效应不明显,暗示在今后的育种中无需考虑交配方向。16年生时胸径和材积加性效应和显性效应显著,且显性效应大于加性效应,显性和加性效应方差比值分别为1.34和1.33。此时按亲本育种值排名选择前10个家系,当联合育种值和SCA进行选择时遗传增益分别为3.21%和8.04%,比单纯育种值选择的遗传增益（分别为2.76%和7.12%）分别提高16.30%和12.92%;26年生时胸径和材积的加性效应显著而显性效应消失。16年生时胸径和材积的单株狭义遗传力、单株广义遗传力和平均家系广义遗传力的变幅分别为0.070~0.074、0.164~0.173和0.546~0.572;26年生时胸径和材积的单株狭义遗传力分别增至0.13和0.10。 结论 胸径和材积在早期的显性效应显著,通过对SCA的利用可获得更高的遗传增益,即选择一般配合力高的亲本通过控制授粉配制高特殊配合力组合的种子,并从子代中选择优良单株进行无性扩繁,可获得最大化的遗传增益。     

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...     

油松自由授粉家系分阶段测定与选择的差异分析

为了分阶段测定油松自由授粉家系间差异和选择油松优良家系,对82个油松家系(22年生)进行生长性状的遗传变异分析,分析树高和胸径的年-年遗传相关、表型相关及历年的遗传方差和环境方差、遗传及表型变异系数、遗传力的同时,研究不同林龄树高和胸径与22年生时材积的相关关系。结果表明:油松家系间树高、材积等生长存在极显著差异。结合早期选择效率和选择正确率及去劣错误率,认为油松优良家系选择是可以在早期进行的,其初选年龄应是9年生时。此外,在22年生时以材积育种值为选择指标,筛选出24个油松优良家系,其单株材积实际增益分别较对照28、95和106增加了36.54%、8.92%和18.63%。最终选出速生优良家系和二代优树 61株,子代测定林入选二代优树的材积遗传增益分别较对照28、95和106增加了57.74%、25.81%和37.03%。所选出的优良家系和优良单株可作为油松育种材料在生产上推广应用。     

油松半同胞家系育苗试验

通过对桥山种子园半同胞家系和双龙子代测定林中的113个家系进行苗期试验,结果表明苗高生长方差分析差异呈极显著水平。遗传分析表明,油松家系苗期遗传力较大,呈强度遗传。以20%的入选率进行选择,桥山入选优良家系16个,黄龙入选优良家系4个,双龙子代林入选家系3个,遗传增益分别达到22.77%、21.16%和22.48%,选择效果十分显著。     

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.     

Realised genetic gains and estimated genetic parameters of two Eucalyptus grandis × E. urophylla hybrid breeding strategies

Conventionally, Eucalyptus grandis × E. urophylla (GU) hybrid material is first tested as seedlings in progeny trials for at least four years before ortets are selected and ramets of the selected ortets are propagated to test in clonal trials. The primary constraint with this ‘conventional hybrid breeding strategy’ (CHBS) is the time required to first test the hybrid material as seedlings. In order to address this, an ‘accelerated hybrid breeding strategy’ (AHBS) was investigated to reduce the time spent on testing GU hybrid material as seedlings. However, it is of utmost importance to quantify the impact the AHBS might have on genetic gains and genetic information. With this in mind, two clonal populations have been established with genetic material that derived from the CHBS and the AHBS. The main purpose of this study was to do a comparative study between the CHBS and AHBS, firstly to quantify the genetic gains per unit time for GU hybrid clonal populations that have been derived from the CHBS and AHBS respectively, and secondly to obtain genetic parameters such as heritabilities, the ratio of dominance, clonal within family variance, and the proportion of additive and non-additive genetic variance. The results indicated that the percentage realised volume gains per year was higher for the AHBS (3.7%) than for the CHBS (1.9%) when compared with the GU commercial clone. Thus, shortening the testing time of GU seedlings had a positive impact on volume gains per year. With regard to genetic parameters, both the AHBS and CHBS clonal populations indicated that non-additive genetic variation explained the majority (88% and 71%, respectively) of the genetic variation. Due to the pre-eminence of non-additive genetic variation, the narrow-sense heritabilties for the female and male effects were negligible for both clonal populations. Overall, the majority of the non-additive genetic variation was explained by the proportion of dominance variance, and less by the clone within family effect. These results suggest that, firstly, the time spent on testing GU hybrid material as seedlings should be minimised and, secondly, a hybrid breeding strategy to capture non-additive genetic variation should be adopted.     

俄罗斯沙棘育种概况与我国沙棘育种现状和展望

俄罗斯沙棘育种迄今已有60余年,前后分两个阶段,即选择育种阶段和杂交育种阶段。共育出50多个新品种。其特点是果粒大、无刺或少刺、产量高。我国沙棘育种工作起步晚,但进展快。经过10年的努力,在沙棘群体遗传改良、个体遗传改良、引进国外良种资源、杂交育种基础性研究等方面取得了重大进展,为生产单位提供了第一代良种,并为下一步杂交育种工作打下了坚实的基础。     

法国杨树良种选育与短轮伐期林培育及其研究方向

杨树在法国林业中占有重要地位。法国的杨树良种选育及短轮伐期林培育研究都处于世界先进水平。本文概述了法国杨树无性系登记、杂交育种、种源试验和用于短轮伐期林培育的优良无性系、营林抚育技术及经济效益, 并介绍了法国杨树良种选育与短轮伐期林培育的发展进程及研究方向。