Suggested projects in the genetic improvement of Southern forest trees

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scientific knowledge, policies, or practices.

TATION PAPER NO. 20 DECEMBER 1952

TS SUGGESTED PROJECTS
, IN THE
GENETIC IMPROVEMENT
OF SOUTHERN |
FOREST TREES

BY

THE COMMITTEE ON SOUTHERN
FOREST TREE IMPROVEMENT

FORESI! SERVICE

U.S. Department of Agriculture

Southeastern Forest Experiment Station

Asheville, North Carolina

es ele Demmon,

This publication was prepared by the Committee on Southern
Forest Tree Improvement to assist those who might take part in forest
genetics research.

Previous publications and reports prepared by or for the com-

mittee are:

ile

Report of the first southern conference on forest tree im-
provement. Atlanta, Ga., January 9-10, 1951. Mimeographed.
U. S. Korest Service, Atlanta, Ga:

Proposal for a cooperative study of geographic sources of
southern pine seed. Subcommittee on Geographic Source of
Seed, Philip C. Wakeley, Chairman. Mimeographed. Southern
Forest Experiment Station, New Orleans, La. Oct. 25, 1951.

Standardized working pian for local tests of seed source.
Subcommittee on Geographic Source of Seed, Philip C. Wakeley,
Chairman. Mimeographed. Southern Forest Experiment Station,
New) Ombeans Wiaa sOGie 5k ore

Hereditary variation as the basis for selecting. superior
forest trees. Keith W. Dorman, Chairman, Subcommittee on
Tree Seiection and Breeding. Southeastern Forest Experiment
Station, Station Paper No. 15. March i952.

Directory of forest genetics activities in the South. Keith
W. Dorman, Chairman, Subcommittee on Seiection and Breeding.

Southeastern Forest Experiment Station, Station Paper No. i7.
March i952.

Working pian for cooperative study of geographic sources of
southern pine seed. Subcommittee on Geographic Source of
Seed, Phiiip C. Wakeley, Chairman. Processed. Southern
Forest Experiment Station, New Orleans, La. Sept. 12, 1952.

CONTENTS

HSTANCRGO CNC CHOI ra terc aloe) ail attain ede aa eo per eu) tate

Q

Suggested Projects in the Application of Genetics
TOnuneuComlechion OL SeCautoOrnrlanGane (75 c.. . s

Suggested Projects in eens Source of Seed for
Honestm mr Vamuime” yee ea os Ss erste eh a yews

Objectives in the Improvement of Southern Forest
Trees Through Selection and Breeding ......e-

Supporting Studies Needed in Techniques and Basic
USRerrerOlmmMoresc GEneCleS sj. lis 2) 1s «i 2. =

SySILSS AOA ose Ge. Siam ae iG) Bol Maken. con cr icuecr onthe hoowels te tc
POA COMUCH SiG USS) erie scent! |e) seh vot «es ve =
BGS C CMe Neh metalat ct evel Metmraneuiat ek he Lerten et, oe 26
Methods for Control of Flowering and Fruiting .
Methods of Vegetative Propagation .......

Equipment for Tree Improvement Work .....

SUGGESTED PROJECTS IN THE GENETIC IMPROVEMENT OF
SOUTHERN FOREST TREES

by

The Committee on Southern Forest Tree Improvement

INTRODUCTION

At the close of a South-wide conference on forest genetics held in
January 1951, a standing committee representing State, federal, industrial,
and educational forestry groups was appointed to foster and encourage tree
improvement work in the South. This Committee on Southern Forest Tree Im-
provement has set up the following purposes to guide its work:

(1) To advise and assist those interested in the improvement of
southern forest trees in arranging and conducting research and
development programs.

(2) To provide a clearing house for forest tree improvement infor-
mation.

(3) To provide for or assist in the coordination of a South-wide
program of tree improvement research and development.

(4) To foster and encourage the advancement of knowledge of southern
Eee, Genetics.

The "how" and "what" of tree improvement work have been major con-
cerns of the committee since its inception. The "how" has been approached
by the preparation of guideline publications intended to summarize the best
current recommendations or methodology in seed-source testing, selection of
SUPERIOG trees, progeny testing, and the application of genetics to seed
collection. The guides published to date are listed inside the front cover.

The present publication attempts to tell the "what" of tree improve-
ment research. It is directed to those who can help in a South-wide advance
on the broad front of forest genetics and who want suggestions on what to do.
For this purpose, the committee has compiled an inventory of the many
studies that await attention.

The committee has not attempted to present a completely organized
program with priorities and time schedules. The work selected by any

particular group necessarily depends on the local forest problem, the
objective of the organization, and the money and skills available to it.

On the other hand, the committee does assist in coordination of
programs to the extent feasible. Particular attention is called to the
committee's "Directory of Forest Genetics Activities in the South," which
should be used in conjunction with this list of needed projects. The
directory telis who is doing what, and also lists the arboretum materials
available throughout the South. Those interested in a given field of
genetics research are encouraged to keep in touch with others who are
shown by the directory to be working on the same species or problem.

The committee also serves as a clearing house for information
through its semi-annual newsietter, its general meetings, its committee
meetings, and its four subject-matter subcommittees on the following
sub jects:

Geographic source of seed
Genetic control of seed
Selection and breeding
Progeny testing

The committee is also giad to offer advice to individuais or
groups as to the particular types of tree improvement work that will best
meet their needs.

The remainder of this report is devoted to a list of projects or
studies needed in the several major phases of southern forest tree im-
provement .

oye

F

SUGGESTED PROJECTS IN THE APPLICATION OF GENETICS TO

THE COLLECTION OF SEED FOR PLANTING

Definition of an acceptable tree suitable for seed production
HOGCNsoGemh sSOpeCues . and HOSS Digi TOm Specie WSES.

Relation of average annual seed yield to age, site, stand con-
GitGtOn spas COne bearing history, Ebe., Tor diftrerent species,

to show seed producing capacity of seed orchards.

Stimulation of seed production by means of fertilization, re-
lease, wounding, banding, and other treatments.

Research on the relation of drought, insects, and other factors
to pollen, cone, and seed losses in southern pines.

Research on causes of low germination of apparently viable
seed.

Seed-testing laboratory for service testing.

Techniques for mass storage of seed collected in abundant seed
Wears.

Development of equipment for large-scale seed collection from
standing trees.

Research on the inheritance of seed production.

oe

SUGGESTED PROJECTS IN GEOGRAPHIC SOURCE OF SEED FOR

FOREST PLANTING

Restricted tests of geographic source of seed within an agency's
seed collection territory ;for example, a State), as outlined

in the committee's publication "Standardized Working Plan for
Local Tests of Seed Source."

Participation in region-wide cooperative studies of seed source,
such as those initiated under the sponsorship of the committee
in 1951. See "Working Pian for Cooperative Study of Geographic
Sources of Southern Pine Seed," prepared under the committee's
sponsorship.

Basic studies of the phenological and physiological data asso-
ciated with geographic seed source. Exampies are dates of
pollination, onset of growth, termination of growth, frost re-
sistance, and response to day length of different geographic
strains, both in seed source plantations and in native strains.

Reiation of geographic seed source to disease resistance and to
wood properties.

Studies of the relative effect of environment (climate, soil,
ete.) and of heredity (local breeding populations, migration
paths) as determinants of seed collection areas.

OBJECTIVES IN THE IMPROVEMENT OF SOUTHERN FOREST TREES

THROUGH SELECTION AND BREEDING

Increased volume growth per acre in commercial species.

For particular purposes, develop strains of pine or hardwoods
having wood characteristics desired, such as:

a. High density and strength

b. Low density and ease of working

ec. Desirable texture

div “hons, fibers

e. ptraight grain and low fibril angle

f. Small knots

g. Desirable sapwood-heartwood ratio

h. Desirable content of extractives in the wood

Resistance to important diseases:

a. Fusiform rust canker in slash and loblolly pine
b. Brown-spot in longleaf pine

ec. Littleleaf in shortleaf and loblolly pine

d. Fomes annosus root rot in redcedar, etc.

e. Biister rust in white pine

££.) Oak wilt, heartrot, ete., in hardwoods

Resistance to insect pests:

a. Bark beeties in ail southern pines
b. Nantucket pine tip moth in loblolly pine and shortleaf pine
c. White pine weevil in white pine

Increased yields of high-quality naval stores products from
slash and iongleaf pine.

Tree varieties with high resistance to drought for planting on
dry sites, especially longleaf pine and other species that grow
naturally on such sites.

Strains of longleaf pine that make rapid initial height growth
in the seedling stage.

Strains of forest trees that permit greater utilization of the
stem. These strains in all important species may have shorter
crowns, shorter branches, less stem taper, and accelerated
natural pruning.

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Hardwoods, such as yellow-poplar and white oak that do not
have epicormic sprouts.

Varieties of yeilow-poplar, maple, black cherry, walnut, sweet-
gum, etc., that have figured wood.

Black walnut that produces nuts of superior quality and at the
same time high-quality wood in planted stands.

Sweetgum that has straight grain rather than interlocked grain,
for ease in drying and working.

Redcedar that has high vigor, desirable characteristics for use
as Christmas trees and other products.

Black locust with good form, high heartwood percent, and fast
growth.

Virginia pine with straight stems, small stem taper, and better
natural pruning ability.

White oak, red oak, ash, hickory, yellow-poplar, and other hard-
woods that have high growth rate yet produce wood suitable for
various products. This may require higher density, lower den-
sity, greater strength or other characteristics, depending upon
use for products such as veneer, jumber, handiles, etc.

Dense-crowned, rapid-growing firs, cedars, or other species that
have attractive foliage, color, and other desirable character-
istics for Christmas trees.

Polypioid or mutant forms of important hardwoods species that
may have the optimum chromosomal complement for vigor, wood
quality, and resistance to pests.

White pine that prunes itself well naturally.

Chestnut that is blight-resistant and that is a timber-type tree,
Suitable for forest planting sites.

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SUPPORTING STUDIES NEEDED IN TECHNIQUES AND BASIC

ASPECTS OF FOREST GENETICS

Selection

Develop techniques of sellection:

as

Determine the range of inherent variation within species
with regard to tree quality for timber products (logs, poles,
piling, ties, lumber, veneer, etc.), derived products (pulp,
cellulose, lignin, essential oils, etc.), oleoresin, and
edible fruit; also with regard to resistance to drought, in-
sects, fungi, viruses, extremes of heat or cold, and mechan-
icai damage from ice or snow. Determine standard deviation
for each trait and the correlation between pairs of the more
economicaily important traits.

Conduct surveys for phenotypically superior trees and pre-
pare catalogues to make them available to foresters and
tree breeders.

Determine intraspecific taxonomic variation in important
species. This wiil require cooperation of taxonomists to
no=atalyZe Lae SGauus Ol Speeles, Varieties, Lorms, (races,
and strains.

Incorporate knowledge obtained fram studies in mode of in-
heritance into pians for selecting superior phenotypes in
wild populations. This will require knowledge of the eco-
nomic value of important characters and the degree of gene-
tie control. The data will be used in writing specifications
for phenotypically superior trees in surveys for breeding
stock.

Determine which methods of selection, such as the total score
method, tandem method, or others used by plant and animal
brecders, ace Suatable) for use an breeding plans for forest
ne SSSc

Determine correiation between juvenile and adult characters or
those of intermediate ages as a basis for seiection in nursery
beds or evaluation of hybrids at a very young age.

hk

Determine the place of mass selection in silvicultural prac-
tices for major species. Results of these studies should
guide selection of crop trees and seed trees when intermediate
and final cuts are made. Criteria for judging the inherent
value of standing trees will be needed.

Selection of phenotypes for specific purposes. It is probable
that many aberrant forms of forest trees will be noted in sur-
veys for phenotypicaliy elite trees for forestry purposes.
Some of the aberrant forms may have value as specimen trees or
for landscaping. Others, especialiy mutants, may have value
in cytological studies.

Anatomical Studies

Determine effect of variations in structural features (width
of rings, proportions of springwood to summerwood, fiber
length, and fibril angle in cell walls) on important properties
of density, strength, shrinkage, and pulping properties of
wood.

Develop practical methods for selecting trees with superior
wood properties on the basis of the related anatomical fea-
tures. This involves sorting out the purely environmental from
the genetic influences on the above-named anatomical characters,
so that inherently superior trees can be identified in the

IP ILS ILCL

Breeding

Learn mode of inheritance of various characters:

a. ‘Determine compatibilities for crossing within species of
softwoods and hardwoods.

b. Determine relative importance of chromosomal and cytoplasmic
inheritance of morphological and physiological characters
of economic importance.

ec, Determine Mendeiian ratios for inheritance of vegetative
vigor, tree form, crown width, pruning ability, resistance
to pests, and other characters of economic importance. This

includes studies of dominance or recessiveness of impor-
tant characters and studies of number of genes involved in
inheritance of characters. The genetic correlation between
pairs of traits shouid be determined. Breeding material
for such studies may be obtained from studies of natural
variation and surveys for phenotypically superior trees.

Determine incidence of hybrid vigor in crosses within and
between important species.

For major species determine fertility of the seed and vigor
of offspring after selfing. Self-incompatible species will
require cross pollination; self~compatible species may be
selfed or inbred. Seifing is a valuable technique for in-
creasing genetic uniformity.

Develop methods for obtaining combinations of desirable char-
acters in hybrids:

a.

From the studies of mode of inheritance of characters de-
termine effectiveness of cross-pollination and inbreeding
to obtain combinations of valuable characters in the first
generation.

Develop breeding plans for a series of crosses and back
crosses suitable for use with forest trees. This will re-
quire modification of conventional methods used in breeding
annual crops, fruit trees, and farm animals. With a know-
tedzevot ankeritance of characters ian brees, it should be
possible to plan’ a series of controlled crosses to combine
valuable genes into superior gene complexes.

Cytological studies:

Determine chromosome number of tree species.

Determine incidence of naturally occurring polyploid in-
dividuals or races; also other types of mutants, such as
amphidiploids and aneuploids. This can be done in con-
Junction with studies of intraspecific taxonomic variations.

Determine if chromosome pairing is normal in hybrids. This
has a bearing on some types of sterility and is therefore
important in breeding programs.

Determine optimum number of chromosomal sets for maximum
vegetative vigor, particuiarly in hardwoods where some poly-
ploids are more vigorous than are diploids. This also has

importance in breeding softwoods, where polyploids may be
less vigorous than diploids and would have negative selec-
tion value.

e. Develop methods for inducing mutations, particularly poly-
ploids, to develop new tree types and permit cross-breeding
of plants that have different numbers of chromosomes so
that they will produce fertile offspring.

Explore genus Pinus and genera of important hardwoods for
breeding material;

a. Determine species mostly likely to be adapted to climatic
conditions in the South.

b. Establish observation plots of selected introduced species
to determine vigor, tree form, and resistance to pests
under typical growing conditions in the South. These tests
should be made in each climatic zone and physiographic
region.

ec. Analyze characteristics of important species of softwoods
and hardwoods with the purpose of preparing breeding plans
to obtain in hybrids superior combinations of traits such
as vigor, tree form, and resistance to pests.

Methods for Control of Flowering and Fruiting

Develop methods for inducing flowering in very young trees to
reduce the time required for controlled breeding several genera-
tions of trees. Techniques. such as freezing, top grafting, arti-
ficial illumination, ringing, and strangulation may be tried.
Also, selection of early flowering strains may be possible.

Perfect methods of stimulating flowering or fruiting in large
trees, to aid in controlled breeding or in mass production of
seed of selected trees and strains.

» Develop methods of pruning and culture for mass production of seed

in planted seed orchards. This might require methods of crown
pruning to keep the trees smail in size but capable of producing
a large number of flowers. Such techniques would be useful in
large-scale controlled breeding or in production of seed of
superior strain.

2 MNOrrs

Develop methods for controlled mass pollination in production
of seed of superior strains. New techniques may be needed in
seed orchard management to insure cross-pollination of certain
strains to avoid possible undesirable effects of inbreeding.
Control of pollen production would be an important aid in
breeding monoecious plants because it would make emasculation
unnecessary.

Methods of Vegetative Propagation

Develop methods of propagating--by grafts or cuttings--the
important tree species. This includes grafting material from
mature trees to seedling stocks and material from seedlings or
young trees to branches of mature trees.

Investigate stock-scion relationships in forest trees to permit
use Of dwarfing or stimulating effects for special purposes in
produetion of breeding stock, development of seed orchards, or
for field planting. Field planting of grafted stock or cuttings
may be feasible with figured strains of walnut, poplar, maple,
and other species.

Determine to what extent ability of cuttings to root is geneti-
cally determined. If strongly controlled in certain species,
EOouine, ability should be a character to consider in selection.

Perfect techniques for using vegetatively propagated material
to estimate the genotype of selected phenotypes.

Equipment for Tree Improvement Work

Controlled breeding;

to herhecemMmOrLe Chnucr1en CQuapmens Om .collceting pollen,
extracting pollen, bagging flowers, pollinating flowers,
protecting cones from pests, and marking the flowers that
have been pollinated.

bd. Develop new equipment or adapt existing equipment for climb-
ing mature trees.

c. Develop methods and equipment for storing and transporting
pollen of all important genera.

2. Seed collection:
a. Develop equipment for collecting cones from mature trees.

b. Develop methods of seed extraction and seed cleaning suit-
able for small amounts of fruit.

The Committee on Southern Forest Tree
Improvement

D. A. Anderson

T. EE. Bercaw
Fioyd M. Cossitt
Keith W. Dorman
G. I. Garin
George H. Hepting
C. M. Kaufman

Io dk ilihatania= dire.
ING. [Big JeteaveS
Philip C. Wakeley
E. G. Wiesehuegei
Carl E. Ostrom (Chairman)

Agriculture-Asheville

Seen &

iii

Membership of Subcommittees of the Committee on Southern

Forest Tree Improvement

Geographic Source of Seed

P. C. Wakeley, chairman J. Re Hamilton
D. A. Anderson R. M. Lindgren
ete bereaw N. W. Sentell
Fie bane aee

Genetic Control of Seed

F. M. Cossitt, chairman R. A. Bonninghausen
Se 15 (Cfeteakial EK. Hinson

Pala haanan T. E. Maki

ha 154 dehealOre WeoNe Palmer der.

Selection and Breeding

Keith W. Dorman, chairman B. Zak

D. A. Anderson Bruce Zobel

C. M. Kaufman IA) feeu lekehangrsne
W. B. Baker Pe He Harvey:
Siesochase Dooeerauley,
CraaGes Doak Meee elo
feels eRaehiGcers EB. Jo Schreiner

Progeny Testing

E. G. Wiesehuegel, chairman e Burton

°

G. W
G. H. Hepting W. H. Cummings
Keith Leasure F. X. Schumacher
Gu Lk. Sichnur =. B. Chase
L. T. Easley PP. Hs Harvey,

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