4_Conventional_Breeding

FUNCTIONAL GENOMICS OF CARBON ALLOCATION FOR GROWTH AND FITNESS IN POPULUS International poplar symposium Ⅳ Nanjing, China 2006 Session Ⅱ Advances In Conventional Poplar Breeding and Gene Conservation[.]

Session Ⅱ

Advances In Conventional Poplar Breeding and

Gene Conservation

A case study on the Genotype Environment interaction of poplar Growth

Huogen Li 1 , Huixin Pan 1 , Shunzhang Cai 2 , Xiangjin Yan 3 , Hefeng Xie 4

1) Nanjing Forestry University, Nanjing, 210037

2) Baoying Multiple management Bureau of Jiangsu Province, Baoying,

3) Siyang Multiple management Bureau of Jiangsu Province, Siyang,

4) Forest seed & seedling center, Shandong Forestry department, Jinan,

A significant difference was found existed among clones based on the analyses of variance

of growth traits such as DBH, height and volume of 80 11-year-old Eastern cottonwood clones.The broad-sense heritability of DBH, height and volume were 30.7%, 20.4% and 32%respectively The result indicated that it is possible to select excellent clones among the clonepopulation A elementary evaluation was made to each clone under the comprehensiveconsideration of growth, stem form, and then several superior clones such as clones I-69,S3412, S3239 and S3240 were picked out as the potential varieties

The genotype-environment interaction of the growth was analyzed based on theinvestigation of 12 cottonwood clones from 3 clone testing plantations situated at Xu Zhou andBao Ying in Jiang Su province, and Ning Yang, Shan Dong province The conclusion showedthat the genotype-environment interaction was extremely remarkable In order to guide theirextension in the future, the genetic stability and adaptation of 12 clones were also explored

Keywords: Eastern cottonwood, Genotype Environment interaction, Genetic stability,

Heritablity

A Mechanistic Framework for Characterizing the Genetic Architecture of Biomass Partitioning

Rongling Wu and Song Wu

Department of Statistics, University of Florida, Gainesville, FL 32611, USA

The shapes and sizes of living things can be explained in terms of biological, chemical andphysical processes Yet, the genetic mechanisms underlying patterns in the shapes and sizes ofplants and animals through these processes have been poorly understood In this talk, we willpresent a statistical framework for characterizing the genetic architecture of morphologicalvariation in allometrical shape with genetic linkage maps This framework is incorporated bymechanistic global allocation rules for patterns of biomass partitioning, allowing quantitativetests of the interplay between genetic actions and development shape The framework modelhas been validated through simulation studies and a real example for poplar trees The proposedmodel will have great implications for understanding the genetic regulation of morphologicalshape and development and, ultimately, providing scientific guidance for the selection ofideotypes that display optimal resource use efficiency in agriculture and forestry

AN OVERVIEW OF CURRENT ASPEN AND POPLAR BREEDING IN CANADA

Industrial participation and needs are driving much of the work in the prairies with someFederal Government collaboration, while the eastern program in Quebec is run primarily by theProvincial Government There is an increasing realization in these traditional tree breedingprograms and active work within the Poplar Council of Canada of the need to bring themolecular tools available through the sequencing of the poplar genome, to assist with rapidselection and screening in these operational end-user focused programs

As the need for a guaranteed fibre supply for pulp and plywood, and options for alternativeenergy and reclamation tools for phytoremediation expand, the traditional uses of hybridpoplars for shelterbelts around farm fields and riparian plantings along stream or pond edges,

no longer drives the primary focus in these programs Collaborations have developed thatsupport breeding programs where each partner may have a different end-use in mind, but withthe diversity of genetic stock that can be produced through hybrid breeding, many objectivescan be met within a single program Time-permitting, details of specific programs will also bediscussed

CONSERVING THE GENETIC RESOURCES OF POPULUS SSP IN PAIN

N Alba(1), H Sixto(1), C Maestro(2), J L Peñuelas(3), S C González-Martínez (1), R Alía(1)

(1) Dpt Resources and Systems Forestry CIFOR-INIA, alba@inia.es (2) Forest Resources Unit Centre for Research and Technology Agrarian (CITA-DGA) cmaestro@aragon.es (3) National Centre for improvement and genetic conservation of forest genetic resources.

The need to conserve the genetic resources of our native poplars is reflected in thedifferent initiatives being developed by both central and local government The Europeanprogram for the conservation of forest genetic resources (EUFORGEN) aims to implement both

in situ and ex situ conservation strategies.

Until now, the ex situ initiatives in Spain have involved the installation and maintenance of collections of P alba, P nigra and P tremula.

The P alba collection is located in the National Centre for Forest Genetic Improvement

"El Serranillo” (Guadalajara) belongs to DGB (Environment Ministry) It is made up of 24families and more than 400 clones which are kept as stool beds, and an arboretum with about

300 clones The P alba accessions from Ebro Basin are duplicated in CITA (Saragossa) The

work undertaken focuses on the study of genetic variation through isoenzymes, morphology,

and growth habit Some studies focused on in situ conservation strategies aim at genetic flow,

species’ regenaration strategies, adaptive differentiation between sex morhs and ISPsestablishment

The P tremula collection, installed in the DGB nurseries is the result of an agreement between INIA and DGB It comprises more than 50 clones, propagated using ‘in vitro’

techniques This collection is currently kept in an arboretum that was located at “Valsaín”(Segovia)

The Spanish collection of P nigra is located at the CITA-DGA (Saragossa) and at

CIFOR-INIA (Madrid) Bothd sites comprised more than 325 accessions, from Ebro Basin populationsmainly, where the specie presence is more frequent Clones from Tajo and Duero Basins (where

the species’ area is smaller) are also present The P nigra Spanish collection is kept (totally or

partially) in arboretums and stood beds Ebro clones from installed in DGA (Saragossa)andthose from Duero and Tajo were installed in INIA and DGB (Madrid, Guadalajara andSegovia) Studies using different molecular markers (Isoenzymes, Microsatellites and AFLP´s)

and morphological characterization show that Spanish P nigra populations maintain a high

level of genetic diversity

•The establishment of an in situ and ex situ conservation strategy requires an in-depthstudy into the diversity of the species in question The use of molecular markers is one of thetools available for this purpose, jointly with adaptive and morphological studies

•The conservation methods established within the EUFORGEN workgroups had facilitatethe development of this task in our country as well as promoting the exchange of both know-how and resources

•Although ex situ conservation work is to some extent under way, with the establishment

of collections and the initiation of evaluation and characterisation studies, the same cannot besaid for in situ conservation for which stand characterisation, selection and management arenecessary to further this objective Managing the riverside is fundamental to the in situconservation of resources of these species Therefore managers must be provided with thenecessary tools and guidelines.

Directive selection ， development and popularization of new

Populus varieties for industrial wood plantation in northern China

Zhang Qi-wen Li Jin-hua

Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, P R China

Email: zhangqw @forestry.ac.cn Fax:+86-10-62872015

In China, there are large area of poplar plantation with low commercial value of cultivars

In order to meet the increasing need for industrial wood, we undertook the key project of poplar

genetic and improvement which mainly focus on clones of Section Aigeiros After

hybridization, introduction and selection of poplar breeding for more than fifteen years, we

finally got most super cultivars for the plain area in Northern China, No.107 (P euramericana

cv ‘Neva’), No.108 (P euramericana cv ‘Guariento’), No.111 (P euramericana cv ‘Bellotto’), No.110 (P deltoides ×P maximowiczii cv ‘Eridano’) These cultivars perform well with fast

growing rate, high quality wood, straight trunk, narrow crown and have strong resistance Woodgrowing rate of ‘Neva’ and ‘Guariento’ increase 60 percent than the comparison cultivar, I-214

(P euramericana cv ‘I-214’) After the certification of national register authority as poplar

cultivars, ‘Neva’ and ‘Guariento’ were planted spreading in 14 provinces and regions mainly onmedium plain of Northern China The size of total area was 18.37 million hectare On condition

of intensive management, wood yield of plantation with two cultivars was between 25.5 and46.5 cubic meter per hectare each year and increased between 13.5 and 21 cubic meter perhectare each year than that of I-214 Wood increase of all plantation was between 1653 and

2572 cubic meter, showing considerable commercial benefit

On aspect of selection and development of new poplar cultivars for industrial wood, therewere methods and results as these as following Firstly, twice silviculture and strictly screeningwith several steps from Italy poplar selection procedure improved coefficient of clonalselection Secondly, multitraits selection with growth, wood quality, trunk and crown ensureddirectional selection of poplar cultivars for industrial wood Thirdly, appropriate time ofselection age would be between 4- and 7-year-old for paper pulp wood, which have fastergrowth rate, more wood density, longer fiber and fewer extracts of 1% NaOH Fourthly, clonal

fingerprinting of two cultivars of Section Ageiros were established by AFLP DNA marker,

which could be useful in identification, registration of cultivars Lastly, APMP puly assay withwood of ‘Neva’ showed it was qulity wood for pulp, which laid a foundation for integrativepoplar plantation-paper industry

Key words: poplar, Populus, new cultivars, fast-growing and high-yield plantation, genetic

improvement, popularization

Field test of introduced new poplar clones

QIN Guang-hua 1 , JIANG Yue-zhong 1 , QIAO Yu-ling 1 , B Nottola 2

1 Shandong Academy of Forestry, Jinan 250014, P R China

2 Societa Agricola E Forestale per Le Plante (S P A), Roma 00153, Italy

Poplar is one of the dominant tree species for the establishment of fast growing plantations

in Shandong Province Eighteen poplar clones belonging to Populus aigeiros Section were introduced from Italy, Turkey and domestic regions Populus deltoides cv ‘Lux’ I-69/55 (I-69),

which was widely used in Shandong Province, China, was taken as control clone Following arandomized complete block design, seedling test and controlled afforestation trials were carried

out at Juxian County, Caoxian County and Laiyang city The results showed that the poplar clone (Populus × euramericana cv ‘102/74’), namely 102/74, performed well both in terms of

adaptability and growth rate The mean height (H) (13.9 m), diameter at breast height (DBH)(18.0 cm) and volume growth (V) (0.1445 m3 ) were, were 2.2 %, 21.6% and 52.9 % higherthan those of I-69 (CK), respectively, at the age of 5 years at three experimental sites.Moreover, the clone can be propagated easily and showed high resistance to poplar disease, pest

as well as salinity and had longer growing period Furthermore, wood basic density and fiberlength of new poplar clone (102/74) were as same as I-69 (CK) It was concluded that theselected clone (102/74) was ideal for the establishment of fast-growing poplar plantations,especially for the pulpwood plantations in Shandong Province

Keywords: Poplar, Clones; Introduction; Selection

Genetic Analysis on Growth and Wood Properties and

Comprehensive Selection of Populus deltoides Clones

Tang Yuxi 1，2 Wu Lixun 2 Wu Min 2 Xu Shifeng 2 Tang Jie 2

1 Central South Forestry University Changsha 410004 2 Hunan Academy of Forestry Changsha 410004

According to the 6-year-old data of 18 populus deltoides clones，the genetic variation and

correlations between growth and wood properties were studied Besides fiber content and fiberlength，the clone effect was highly significant for other 6 traits such as DBH，height，individualstem volume， fiber width， ratio of fiber length to width，wood basic density The broad-senseheritabilities ranged from 0.6109 to 0.9053， it indicated that the variations of 6 traits weremoderately or intensively inherited The inheritances of growth characters and wood propertieswere independent，as pulp-making material，the improvement of growth traits should regarded

as the premise By using Gray Related Analysis，5 new hybrid P deltoides clones with excellentcomprehensive traits were selected， especially ， P deltoides cl.‘xianglin 90’ and P deltoids

cl.‘xianglin 77’ were outstanding among them Compared with P deltoids cv.‘I-69/55’ ， the

individual stem volume respectively improved 60.71%， 46.45% ， and the individual fiberproduction respectively improved 51.43%，44.13%

Key words: Genetic variation， Gray Related Analysis ， Comprehensive selection ， Populus

deltoides Clones

Genetic differentiation of Black Cottonwood, P trichocarpa Torrey

& Gray in British Columbia

Ying, Cheng C., Xie, Chang-Yi, Holowachuk, Diane, and Yanchuk, Alvin

RESEARCH BRANCH, BRITISH COLUMBIA MINISTRY OF FORESTS AND RANGE, 1 ST FLOOR, 722 JOHNSON ST., VICTORIA, B C 9519 STN PROV GOVT VICTORIA BC V8W 9C2 BRITISH COLUMBIA, CANADA.

Genetic differentiation of black cottonwood in British Columbia was studied in a garden environment A total of 835 clones from 181 provenances along 36 drainages weretested for three years and the assessed traits include height growth, abnormal leaf flushing, and

common-leaf disease (Salsa sordida and Melampsora occidentalis ) infection Results revealed a sharp

north-south regional differentiation in all the assessed traits Northern populations demonstratedsevere mal-adaptation in the southern environment at the test site Besides natural selection,restricted gene flow along a “no-cottonwood” belt may also have played a significant role inshaping the observed pattern of geographic differentiation Trees from Lower Fraser River andNechako River – Upper Fraser River drainages not only demonstrated outstanding growth butalso were relatively free of diseases or abnormal flushing, suggesting those areas may have thebest source of materials for selection and breeding

Genetic Variation of Three Populus euramericana Clones

Anatomical, Physiological and Growth Traits

Zhengtian Niu， Qiwen Zhang*， Jinhua Li，Zhenyuan Sun

Institute of Forestry, Chinese Academy of forestry， Beijing 100091

Phone : 010-62889600 Email，sxnzt@126.com

Anatomical and physiological characteristics related with biomass of rooted cuttings of 3

Populus canadensis genotypes were evaluated in a controlled pot test in the field experiment.

Measurements were taken on the net photosynthesis rate, intercellular CO2 Concentration,transpiration rate, Stomatal conductance, Stomatal length,stomatal density on both side of theblade, the thickness of palisade tissue and spongy mesophy(II), leaf area, leaf length, leaf freshmass and specific dry mass Total height, basal diameter, and above-ground biomass weremeasured after 8 months The results showed that the three clones growth exhibit significantinter-clonal variability, which are mainly from clones different genotype Stomatal length,stomatal density on abaxial side of the blade, the thickness of palisade tissue, leaf area and leaflength characteristics exhibited a high degree of statistically significant inter-clonal variability,indicative strong genetic control Strong correlations were observed between: 1) Height, basaldiameter and biomass with each other 2)The number of stomata on abaxial leaf surface andstomatal length with height, basal diameter and biomass, 3) The thickness of the palisade leaflayer with height, basal diameter and biomass, 4) Leaf area, leaf length with height basaldiameter and biomass The results indicate that abaxial stomata number, thickness of thepalisade tissue, leaf area and leaf length may be useful selection criteria in the identification

of genotypes with economic traits The results may be useful for marker-assisted breeding.Construction of high yielding hybrid ideotype with desirable anatomical features wasconsidered to be feasible

Key words: Populus canadensis Clone, Anatomy, Physiology, Variance, Correlation, Selection,

Induction of Triploids in White Poplar

Kang Xiang-yang(1) Zhang Jin-feng(1) Zhang Ping-dong(1) Li Yan-hua(1)

(1) Institute for Chinese White Poplar, Beijing Forestry University, P R China, kangxy@bjfu.edu.cn/Fax: 0086-10-62338013

Trees with polyploidy general display characteristics of heterosis over normal diploids.For example, triploid poplar trees not only grow fast but also have low lignin and high cellulosecontent because of the giant cellulose cell minus the cell number and surface within a certainvolume timber Thus selection and production of triploid poplar trees can produce more paperand other fiber products that benefit the forest industry In recent years, using white poplar

Populus tomentosa, ，P tomentosa×P.bolleana，and (P alba×P glandulosa) as material, we

have studied the mechanism and developed the technique for inducing triploid trees Severalsteps were involved in the induction of triploid poplar trees First, the best treatment stages forobtaining 2n white poplar pollen were in the pachynema or diakinesis of meiosis when budswere treated with colchicines solution or high temperature The 2n pollen rate can be more than80% if white poplar male buds were treated on right stage The 2n pollen vitality and itsgermination process were observed and counted by live fertilization test The 1n pollen in thepollen mix was used as a check because it was much smaller than the 2n pollen and easy toobserve The 2n pollen germinated slowly than the 1n pollen, which was the main reason forobtaining low success rate of triploid plants because of the poor competition of 2n pollen in theprocess of fertilization However, the germination of 2n pollen can be greatly increased andthus produce much higher percent triploid plants (30 times) compared to the normal hybridfilial population when the mixed pollen was treated with 60Co radial The 1n pollen was moresensitive than the 2n pollen when the mixed pollen powder was exposed to the radiation Themeiosis process of megaspore was difficult to observe The microspore was exploited as acheck according to the development time relative to each other A method was used forcomparatively judgment the effective treatment stage of the chromosome doubling of the

megaspore The megaspore of P.tomentosa×P.bolleana and Populus alba×P.glandulosa was in

pachynema or diakinesis of meiosis while its microspore was in the stage of pollen cell with asingle nuclear in the side of cell wall when those two flower branches began to water cultured

at same time The percent triploid plant can reach 16.7% when the female flower buds weretreated with colchicines solution at the time of male flower buds in the stage of pollen cell with

a single nuclear in the side of cell wall A new triploid white poplar inducing technique wasdiscovered That is the female flowers were treated with colchicines solution after pollination.The success rate for triploid plant could reach 57.1% when the female flowers of

P.tomentosa×P.bolleana and Populus alba×P.glandulosa were treated with colchicines solution

after pollinated 24h to 36h These studies of poplar chromosome doubling and triploidinducing will have important reference value for enlarging the triploid parents resources andincreasing the population number of triploid plants and other similar tree specie polyploidbreeding

Key words: poplar, chromosome double, colchicines, effective treatment stage, triploid

Induction of triploid white poplars by chromosome doubling of the

female gamete of Populous alba × P glandulosa

Y H Li(1), X Y Kang (1), Z H Zhang (1), H G Chen (1)

1), Key Laboratory for Genetics and Breeding of Forest Trees and Ornamental Plants, Ministry of Education, Beijing Forestry University, Beijing 100083, China kangxy@bjfu.edu.cn

In triploid poplar breeding, an improved technology was suggested that triploids wasinduced by chromosome doubling of female gamete 2n female gametes has competitiveadvantage over 2n 2npollen in fertilization Triploid plants could be obtained immediately afterfertilization events However, meiosis of the megaspore mother cells is difficult to observequickly Cytological studies found that the meiosis stages of megaspores and microspores of

Populous alba × P glandulosa were closely correlated in their development So meiosis of the

megaspore mother cells could be judgment timely by observing meiosis of microspores.Chromosome doubling could be achieved in an effective colchicines-induced stage Thefrequency of triploids has been increased Microscopic examination was employed to found that

meiosis of microspore mother cells of P alba × P glandulosa developed into monokaryotic

pollen at mitosis metaphase and into the stage of pollen cell with a single nuclear in the side ofcell wall, meiosis of megaspore mother cells was in the bouquet stage and pachytene,Temporality , the female buds were dipped in the bottle of a 0.5% solution of colchicine Then

hand pollination with the n pollen of P tomentosa The highest percentage of triploids was

16.7% It is helpful to tree ployploid breeding

Meiosis and Chromosome Behaviours of Pollen Mother Cells in

Populus simonii Carr × P nigra L ‘Tongliao’

H Zhang, P D Zhang

Key Laboratory for Genetics and Breeding of Forest Trees and Ornamental Plants, Ministry of Education Beijing Forestry University, 100083, P R China.

The meiotic process and chromosome behaviours of pollen mother cells are studied in

Populus simonii Carr × P nigra L ‘Tongliao’ cultured in greenhouse The meiotic stages have

close relation to the observing features of the male flower buds and the color of anthers.Prophase occupies about 90Ⅰ ， time for the whole meiotic process There are several univalents

in metaphase , lagging chromosomes in anaphase and natural large pollens in Ⅰ Ⅰ P simonii × P nigra ‘Tongliao’, due to its high heterozygosity of genetics Two nucleoli in prophase andⅠeight nucleoli in one daughter nucleus of telophase and are observed, and the multi-nucleoliⅠ Ⅱ

may be relative to the paleopolyploid origin of the genus Populus L After late leptotene, five

to nine different phases can be observed usually in the same flower bud or the same flower even

in the same anther The asynchronism of meiotic process may be an evolutionary compromiseadapting the local conditions, and important for propagation of populations

Key words: Populus simonii Carr × P nigra L ‘Tongliao’, pollen mother cell, meiotic stage,

heterozygosity, multi-nucleoli, large pollen

Morphological diversity of black hairy poplar (Populus nigra

subsp caudina) in Bosnia and Herzegovina

Ballian D 1 ,Kajba D 2 , Idzojtic M 2

1 University of Sarajevo, Bosnia and Herzegovina

2 University of Zagreb, Croatia

Hairy type of black poplar is typical for Sub-Mediterranean area of Bosnia andHerzegovina, the Valley of Neretva River in particular, where this species is mainly distributed

in its lower flow, the population of Čapljina, and a smaller population at the mouth of theTrešanička River to Neretva River in its middle flow The population of Konjic, as well as thebasin of the Vrbas River, which is separated by a mountain chain of Makljen from the Nertevapopulation, belongs to the population of Bugojno

This species may, in the future, play a significant role, particularly within the processes ofglobal heating, because in its natural habitat it can stand well high temperatures

The target of this study is to determine the level of variability and to try to determine thecorrelation between these three populations by usage of morphologic markers and statisticalanalysis The herbarium material, from the three listed populations, has been collected for thisstudy, that is, 50 leaves from the trees, taken from the southern orientation of the tree crown,and its central part, only from the short fertile shoots We analyzed five characteristics: the leafblade length, the leaf blade width, the petiole length, the angle between the first lower lateralvein and the midrib, and the distance between the widest part of the leaf and the leaf base.The obtained results showed that the analyzed sizes point at presence of differences amongthe populations Thus, with the descriptive analysis there were demonstrated differencesbetween the populations of Čapljina, on one side, and the populations of Konjic and Bugojno

on the other Apart from the descriptive analysis that has been carried out, we have also done acluster analysis that showed grouping to two bigger clusters, Čapljina on one side, and Konjicand Bugojno on the other Between them there is however a relationship, thus the trees number

9, from the Čapljina and Konjic population, showed closeness by cluster analysis Thiscloseness points at previous relationship of the analyzed populations, and that this is a matter oftheir historical separation, along with specific paths of further development, under possiblyvery strong anthropogenic influence within the period of last 2000 years

Key words: Populus nigra subsp caudina, Hairy black poplar, morfological

ornamental city

Zhu Yanlin

Henan Academy of Forestry, Zhengzhou 450008, Henan Province, P R China

Populus deltoides CV.“zhonghong”， as a bud mutant of Poplar deltoids ， was found byscientific workers of the Forestry Academy of Henan in 2000 in Shangqiu Henan It had beenapproved by the Henan Inspection Committee of Superior Tree Species in March 2006

The stem form of Populus deltoides CV.“zhonghong” is perfectly straight and orbicular,

which is male and doesn’t fly garrulous The internode length is 3-5cm The leaf width is 23cm, and length is 12-25cm and the leaf area is smaller than Poplar 2025 obviously The bud

12-is ovoid which surface cling to v12-iscosity The top of the bud 12-is very red The angle between thebuds of the top stem and stem is less than 15°,but the lower buds are small which cling to stemclosely The figure of the leaves that have blunt sawtoothed edges is equilateral triangle ortriangle The petiole which is flat and costate are mauve.The branch or stem which don’t lignifytotally are mauve in growing season The lower part of the annual stem is ashen after which leaffall, but the top 50-70cm is brown The lenticel is white, long cylindrical and round, whichdistribut evenly The raised angle of bud is more obvious The middle arris of the middle orlower bud of annual stem extend generally to internode and link up with the mark amonginternodes

In Shangqiu Henan, Populus deltoides CV.“zhonghong” sprout during March 30 to April

3,which is earlier 6-9days than Poplar Zhonglin-46, earlier 3-5days than Poplar Zhonglin-69and later 3-4days than Poplar 2025 The top is closured between Sep18-24 The leaf falling isdone between Oct28 to Nov5, which is later about 15days than Poplar Zhonglin-69 and isn’t toodifference with Poplar2025

The leaf colour of Populus deltoides CV.“zhonghong” is inimitable, which obviously

changes along with reasons and display extremely steady The all leaves and newly tenderleaves are rose from sprouting to early summer Henceforth, the tender leaves and branchs arevividly mauve till the middle ten days of October, but mature leaves on middle and lower stemchange red-green to green The whole blade turns into apricot pink gradually after mid-October,until falling leaves

The stem of Populus deltoides CV.“zhonghong” , as a high arbor, is tall and straight, which

grow rapidly and the crown is fleshy At the same time, it is a good ornamental, breed easilyand spread widely Furthermore， it more resists Poplar borer, aphid, acarus and rust thanPoplar2025 So it has filled in the blanks of the colored leaf varieties of trees and has aenormous development potentiality

Populus deltoides CV.“zhonghong” , as male tree, doesn’t pollute environment for fling

garrulous Accordingly, it is applied to city virescence, fast-growing and high-yield plantation,which is a rare varieties afforested in the passway , the joint department, urban and rural areas

or big environmental In other words, it has enormous economic, society and ecological benefit

Grafting and cutting are primary reproductive mode of Populus deltoides CV.“zhonghong”

The survival rate is highest with maternal variety, and the growth is the most rapid.

In a word, Populus deltoides CV.“zhonghong” ,as colored leaf and growing varieties of

trees rapidly, has enormous development potentiality and broad market prospects, which is anew variety demanding urgently to be developed

POPULUS X GENEROSA HYBRIDIZATION IN THE PACIFIC

NORTHWEST: A CASE STUDY OF A STRATEGIC NON-RECURRENT IMPROVEMENT PROGRAM

Stanton, Brian J and Shuren, Richard, A.

GreenWood Resources, Portland, Oregon, USA, bstanton@greenwoodresources.com

Genetic gains in poplar productivity in the Pacific Northwest over the last 25 years havebeen brought about largely through an empirical approach to tree breeding This has taken theform of non-recurrent F1 hybridization involving the indigenous P trichocarpa and P deltoides

from eastern North America Non-recurrent hybridization was chosen as the preferred strategy

as regionally adapted, elite varieties were very limited in number at the time commercialplantations were first established This situation created an imperative to rapidly produce asizable pool of new selections equal in productivity to the best commercial standards andrecruited from a diversity of pedigrees that collectively would minimize the risk of plantationfailure posed by evolving pest and unforeseen weather events realized through the continuousdeployment of a restricted number of hybrid varieties Although it was recognized that thisstrategy would not improve the mean performance of the F1 generation through theaccumulation of positive alleles via recurrent breeding of the constitutive parental species, thebelief was that the overall performance of the operational clone pool could be improved overtime through substitutions for the least productive standard clones using extreme genotypesselected from test populations bred from parental stock of unknown breeding value

The non-recurrent program was designed to annually recover superior genotypes selected

for Melampsora leaf rust resistance and stem volume from 12 F1 populations created from1990-2001 Each population was evaluated as a discrete set using a multiple-stage process toidentify individuals capable of meeting production yield targets Rust resistance was rapidlydeveloped by phenotypic selection at the outset of the process using two selection thresholds inseedling nurseries Population variation in the underlying determinants of resistance (e g.number of uredinia, length of latent period, sporulation rate) was reduced from 0.84 thresholdunits (t.u.) at the seedling stage to 0.56 t.u at the first stage of clonal evaluation when averagedover the 12 years At the same time, the mean rust liability of the test populations increased onaverage from –0.10 t.u in unselected seedling populations to 0.44 t.u in selected clonalpopulations Following truncation for rust resistance, populations were subjected to two cycles

of clonal evaluation for several components of individual stem weight to identify selections forrotation-age yield tests Those entering this final test stage exceeded first and second stageclone test means for stem diameter by 1.58 and 1.23 phenotypic standard deviations on average,respectively To date, the merchantable tonnage of those top selections that completed a fulleight-year rotation of yield testing have matched the productivity of the top standardoperational varieties (96 dry MT/ha) with individual clones producing up to 105 MT/ha.Additional gains in plantation yields have been possible by exploiting clone-by-environmentinteractions

The continuity of the non-recurrent hybridization program has benefited from its