Genetic Evaluation of Rapid 

Forest Service Height Growth in Pot- and 

NortheasternForest Nurser~-GrOWn Scotch Pine 

Experiment Station w 

Research Paper 

N E-554 Maurice E. Demeritt, Jr. 

Henry D. Gerhold 
The Authors 

Maurice E. Demeritt, Jr. is a research geneticist with the Genetics Project, 

Northeastern Forest Experiment Station, Durham, New Hampshire. He has a 

B.S.F. and MS. from the University of New Hampshire and a Ph.D. in genetics 

from the Pennsylvania State University. He joined the Forest Service in 1972. 

Henry D. Gerhold is Professor of Forest Genetics at the Pennsylvania 

State University. He has a B.S. and M.F. from the Pennsylvania State University 

and a Ph.D. from Yale University. 

Abstract 

Genetic and environmental components of variance for 2-year heights of 

offspring from inter- and intra-provenance matings in Scotch pine (Pinus 

sylvestris L.) were studied to determine which provenances and selection 

methods should be used in a program to improve ornamental and Christmas 

trees. 

The study represents 11 experiments (parental groups), consisting of 

families from 7 diallel matings minus selfs in 5 different provenances, 3 

factorial matings between provenances, and 1 from open pollination. The 

seedlings for the 11 experiments were grown in pots and in a nursery for 2 

years. 

Heritability estimates of 2-year height from inter- and intra-provenance 

matings tended to be larger on a family basis than on an individual basis, 

with the larger estimates being from nursery evaluations. In general, additive 

genetic variance was larger than dominance variance, although dominance 

variance increased in provenance hybrids. Nursery evaluation was preferred 

to pot evaluation of 2-year height because heritability estimates were larger 

and error variances were smaller for the experiments evaluated. Individual 

selection in the nursery within the German provenance seems to be the best 

method for improvement of 2-year height of the provenances evaluated in this 

study, although the rate of improvement in the Spanish provenance may be 

greater. Simple recurrent selection would be a good method for improvement 

of traits important to the Christmas tree producing industry. 
Introduction Materials and Methods 

Scotch pine (Pinus sylvestris L.) 

is a major timber species in Europe 

and Asia. It is an important Christmas 

tree species in the United States and 

Canada. Large numbers are planted 

annually along highways and for other 

landscape and ornamental purposes. 

Breeding programs have been 

undertaken in the United States at 

the Pennsylvania State University and 

by the U.S. Forest Service at Lincoln, 

Nebraska, to improve the ornamental 

quality of the species. Both programs 

focus on improving traits important 

to Christmas tree and amenity uses. 

Evaluation of the genetic control of 

growth of different provenances and 

interprovenance crosses using estimates of components of variance 

would be very valuable in designing 

such programs. Evaluation of different 

provenances allows the breeder to 

select the most promising ones to 

work with. Interprovenance hybridization could reveal heterosis, combine 

desirable traits, and create greater 

variability for selection purposes. 

These evaluations and estimates allow the breeder to maximize genetic 

gain for a given input of resources. 

This study was designed to estimate mean heights and genetic and 

environmental components of variance of 2-year-old seedlings from 

inter- and intra-provenance matings. 

The specific objectives were: (1) to 

estimate additive and dominance 

genetic components of variance and 

environmental components of variance from inter- and intra-provenance 

matings, (2) to estimate heritability 

on an individual basis and on a family 

basis, (3) to compare nursery and pot 

propagation methods to determine 

the better method for genetic evaluation, and (4) to make recommendations concerning selection and 

breeding methods. 

Inter- and intra-provenance crosses 

made in 1969 and 1970 were grouped 

by parentage into 11 experiments. The 

parents were from five introduced 

provenances of Scotch pine: four 

provenances growing at the Kellogg 

Forest of Michigan State University 

and one provenance growing at the 

Pennsylvania State University (Table 1). 

The four provenances at the Kellogg 

Forest were derived from native European forests and are part of a geographic variation test in Scotch pine 

(Figure 1) reported by Wright and Bull 

(1963). The provenance at the Pennsylvania State University is from 

Sierra de Guadarrama, Valsain Forest, 

at 1000 meters in central Spain (near 

245 of Wright and Bull 1963) and is 

not part of a formal provenance study. 

The parents were selected for heavy 

flowering but not for other growth 

traits. 

Table 1.-Description of plant materials in experiments, showing mating designs and the 

number of fam~lies planted in pots and in the nursery 

Experiment Year of 

N o. mating Mating design Provenance 

Number of families 

Pots Nursery 

1 1970 6 x 6 diallel Spanish 

minus selfs 

2 1970 6 x 6 diallel Spanish 

minus selfs 

3 1970 6 x 6 diallel Spanish 

minus selfs 

4 1969 6 x 6 diallel French (212)a 18 10 

minus selfs 

5 1969 5 x 5 diallel French (238) 11 8 

minus selfs 

6 1969 4 x 4 diallel French (316) 7 6 

minus selfs 

7 1969 6 x 6 diallel German (250) 24 13 

minus selfs 

8 1970 5 x 6 factorial French (212) Q x Spanish a 13 5 

9 1970 3 x 6 fadtorial French (212) Q x German (250)~ 18 13 

10 1970 6 x 4 factorial German (250) 9 x French (212)~ 22 12 

11 1969 open pollination Spanish 18 17 

aNumerical identification of provenances as reported by Wright and Bull (1963). 
In mid-May 1969 and 1970, female 

strobili were isolated on the trees, 

pollen was collected and extracted, 

and pollinations were made. The pollination procedure was identical to that 

reported by Gerhold (1968). Pollinated 

strobili were marked with colored 

plastic rings. 

Cones were protected from squirrels by window screening and were 

collected in September 1970 and 1971 

from matings made in the previous 

years. Cones that did not open readily 

were dissected, and all full seeds 

were extracted. 

In March 1972, seeds were sown 

in a greenhouse in Styroblock "2" 

containers filled with a 2:1 peatperlite mix and covered with 118 inch 

of sand. In early June 1972, seedlings 

were transplanted to 6-inch pots filled 

with 1:1:2 mix of peat, perlite, and 

loam soil. Each family was represented by four seedlings in a pot in 

each of six blocks. The seedlings 

were watered and fertilized when 

necessary. 

About 2 weeks later, additional 

seedlings were transplanted to standard nursery beds at the Penn Nursery, Potters Mills, Pennsylvania. Each 

experiment consisted of families 

randomized within six replications 

in 10-tree row plots. The seedlings 

received standard nursery care. 

In October 1973, 2-year heights 

were measured and recorded to the 

nearest centimeter for seedlings in 

pots and in the nursery. 

Figure 1.-Natural distribution of Scotch pine in eastern Europe (shaded) 

(Critchfield and Little, 1966) and provenances included in this study (large 

dots). 
Analyses of variance of Byear 

height data were performed for each 

experiment using plot means for 

trees in pots and those in the nursery. 

Analyses of variance were also performed by combining the three 6 x 6 

Spanish diallel experiments into an 

18-parent disconnected diallel using 

plot means for pots and for the nursery. Also, analyses of variance were 

performed on the combined pot and 

nursery data, treating the two different 

environments as location effects. A 

general least-squares program for 

diallel data was used to analyze the 

seven diallel experiments (Schaffer 

and Usanis 1969). A least-squares 

program using unequal subclass 

numbers was used to analyze the 

other four experiments. The program 

follows the outline of the methods 

published by W. R. Harvey (1960). 

Heritability estimates using only 

intrapopulation methods were calculated for each experiment at each 

location (pots and nursery) on an 

individual basis and on afamily basis, 

using standard formulas (Table 2). 

Heritability estimates on an individual 

basis are commonly used for estimating the ratio of additive genetic to 

total variance and are appropriate 

for estimating gain from mass selection among randomly placed seedlings 

in either environment (pots or nursery). 

Heritability estimates on a family 

basis are appropriate for estimating 

gain from selection among half-sib 

families. For this study, 4 seedlings 

per plot in pots with replication or 8 

of the 10 seedlings per nursery row 

with replication were assumed for 

estimates of heritability on a family 

basis. If all seedlings in nursery rows 

were present, the border or outside 

trees were not measured. 

Table 2.-Formulas for estimating heritability on an individual basis and a family basis. 

Mating Heritability 

design Individual basis Family basis 

4 &a 

diallel 

26ca + &a + $mat + #ec + "2p 6 

factorial 4 aZ (male or female) aZ (male or female) 

amale + dema~e + $,f + 4 + 6 Wdmale+Wd+male +L $mf +1 4 +L 6 

rn rn rn r rn 

O.P. 4 dam 

%m+4+6 

gCa = general combining ability 

= specific combining ability $,,, = maternal effects 

$,ale = male variance 

demale = female variance 

df = male x female variance 

#ec = reciprocal effects dam = family variance 

4 = among-plot variance r = number of replications 

= within-plot variance n = numbers of treeslplot 
Results 

A. Mean Height. Large differences in Byear mean height were 

found among the Scotch pine seedlings of the five original provenances 

and also between those provenances 

grown in pots and in the nursery 

(Table 3). Seedlings from every experiment were shorter in the nursery than 

those grown in pots. There were no 

significant changes in ranking of 

provenances between the two environments. Spanish seedlings were the 

shortest and German seedlings were 

the tallest. The three French provenances were intermediate in height 

between the Spanish and German 

provenances with French (212) seedlings being the tallest, next French 

(316) seedlings, and finally French 

(238) seedlings, the shortest of the 

French provenances. 

Mean 2-year heights of interprovenance seedlings were intermediate between those of their two 

parental provenances (Table 3). There 

was a slight tendency for the hybrid 

seedlings to be closer to the height 

of the female parent's provenance. 

There was a slight heterotic response for 2-year height for the French 

x Spanish seedlings grown in pots. 

French x Spanish hybrid families 

averaged 107 percent of the average 

provenance mid-parent value. Individual hybrid families grown in pots 

ranged from 83 to 136 percent of their 

respective mid-parent values. There 

seems to be no clear heterotic response in the German x French hybrid seedlings grown in pots and in 

the nursery. The German female x 

French male hybrid families averaged 

106 and 98 percent of their average 

provenance mid-parent values in pots 

and in the nursery, respectively. Individual German female x French male 

families ranged from 87 to 114 percent and 81 to 103 percent of their 

respective mid-parent values in pots 

and in the nursery, respectively. The 

French female x German male hybrid 

families averaged 99 and 95 percent of 

their average provenance mid-parent 

values in pots and in the nursery, 

respectively. Individual French female x German male families ranged 

from 83 to 109 percent and 78 to 102 

percent of their respective mid-parent 

values in pots and in the nursery, 

respectively. 

Table 3.-Two-year heights and error variances for Scotch pine 

seedlings grown in pots and in the nursery 

Pots Nursery 

Experiment 

Mean (cm) $, , Mean (cm) $, 

Spanish diallel #I 

Spanish diallel #2 

Spanish diallel #3 

Spanish open pollination 

French (212) Q x Spanish a 

French (212) diallel 

French (212)~ x German (250)~ 

German (250) Q x French (212)a 

German (250) diallel 

French (316) diallel 

French (238) diallel 

aNo analysis of variance was conducted on these data because of the large number 

of missing cells. 

B. Estimates of Components of 

Variance. Within experiments and locations, within-plot variances (&) 

generally were less than among-plot 

variances ($,), although in most instances these variances were quite 

similar in magnitude (Table 4). In only 

one instance, the German (250) nursery diallel, was among-plot variance 

more than twice the within-plot variance. Across all experiments, the 

among-plot variances were from 8 to 

58 percent of their respective total 

variances. Also, within-plot variances 

ranged from 9 to 42 percent of their 

respective total variances. There was 

quite a range in magnitude of components of variance between locations and among experiments. This is 

a reflection of differences in the error 

terms of each experiment. The ratios 

of among-plot and within-plot components of variance to their respective 

error components of variance were 

quite consistent. 

Table 4.-Within-plot and among-plot components of 

variance for experiments as a percentage of total variance. 

Experiment 

Pots Nursery 

444 4 

Spanish diallel #I 35 37 23 34 

Spanish diallel #2 40 45 22 2 1 

Spanish diallel #3 41 45 30 36 

Spanish diallels Combined 39 43 24 39 

Spanish open pollination 42 37 26 44 

French (212)Q x Spanish D 34 22 

French (212) diallel 32 48 26 35 

French (212) Q x German (250)~ 30 27 9 8 

German(250)~ xFrench(212)a 35 35 18 18 

German (250) diallel 33 52 24 57 

French (316) diallel 37 58 -a -a 

French (238) diallel 30 34 41 48 

aNo components of variance were estimated because no analyses of 

variance were conducted on these data. 
When plot and nursery data were 

combined, general combining ability 

(GCA) was the largest component of 

variance in the Spanish diallels and in 

the German (250) diallel experiments 

(Table 5). Specific combining ability 

(SCA) was the largest component of 

variance in the French (212) diallel experiment. Reciprocal effects were the 

largest component of variance in the 

French (238) diallel experiment. Components of variance were quite consistent among the three Spanish diallel 

experiments, with few exceptions. 

GCA by location components of variance were small for all provenances. 

In pot analyses, GCA was the 

largest component of variance in the 

Spanish #2, #3, and combined Spanish diallel experiments and in the 

French (316) experiment (Table 5). 

SCA was the largest component of 

variance in the Spanish #1 diallel and 

the French (212) diallel experiments. 

Reciprocal effects were the largest 

component of variance in the French 

(238) diallel experiment. 

In nursery analyses, GCA was 

the largest component of variance in 

the Spanish #1, #2, and combined 

Spanish diallel, the French (212) 

diallel, and the German (250) diallel 

experiments (Table 5). SCA was the 

largest component of variance in the 

Spanish #3 diallel experiment. Maternal effects were the largest component of variance in the French (238) 

diallel experiment. 

Table 5.-General and specific combining ability, maternal, reciprocal, and 

general combining ability by location components of variance for 

2-year height in diallel experiments as a percentage of total variance. - -- 

Component Spanish French German 

Location of 

Variance #1 #2 #3 Combined 212 238 316 250 

&a 

Pots dca 

amat 

4ec 

&a 

Nursery dca 

$mat 

4ec 

&a 

Pots dca 

and dmat 

nursery 4ec 

$gca by 

LOC. 

Wariance components due to reciprocal effects were not estimated because the matrices of coefficients of the expected mean squares were singular and could not be inverted. 
Family components of variance 

for the Spanish open pollination experiments from pots, nursery, and 

combined analyses were 21, 28, and 

25 percent of their total variances, 

respectively (Table 6). The family 

component of variance from the nursery analysis accounted for a larger 

percentage of the total variance than 

did the same component in the pots 

or combined analyses. 

Female components of variance 

were larger than either male or male x 

female components of variance in all 

French (212) female x German (250) 

male hybrid analyses and the German 

(250) female x French (212) male hybrids in pots and combined analyses 

(Table 6). In the two other analyses, 

the male x female components of 

variance were small. 

C. Estimates of Heritability. In 

the diallel experiments, most estimates of .heritability of 2-year height 

in pots were smaller than heritability 

estimates of height in the nursery 

(Table 7). Heritability estimates on an 

individual basis ranged from 0 to 0.45 

in pots and from 0 to 1.25 in the nursery. Heritability estimates on a family 

basis ranged from 0 to 0.55 in pots 

Table 6.-Male, female, and male x female components of variance for 2-year height in provenance hybrids and open pollination experiments 

as a percentage of total variance. 

Component Spanish French (212) Q French (212) 9 German (250) Q 

Location of open x x x 

variance pollination Spanish cr German (250)cr French (212)~ 

hales 

Pots deemales 

4 x f 

$males 

Nursery dema~es 

4, x f 

Pots $males 

and dema~es 

nursery dm x r 

acomponent of variance due to open pollination families. 

Table 7.-Estimates of heritability of 2.year height on an individual 

and family basis in diallel experiments 

Spanish Diallels French Diallels German Diallel 

Location 

#1 #2 #3 Combined 212 238 316 250 

Individual 0.27 0.45 0.43 0.29 0 0.26 0.19 0.25 

Pots Family 0.32 0.52 0.55 0.40 0 0.46 0.31 0.37 

Individual 0.97 1.25 0 0.82 1.11 0 - 0.51 

Nursery Family 0.81 0.90 0 0.77 0.84 0 - 0.58 
Discussion 

and from 0 to 0.90 in the nursery. 

Estimates of heritability were different 

among the provenances studied. The 

six heritability estimates of zero seem 

inconsistent with observed patterns, 

especially those for the nursery, but 

may be due in part to small sample 

sizes. 

Heritability estimates from the 

Spanish open pollination experiment 

were slightly larger when estimated 

in the nursery compared to pot estimates (Table 8). Heritability estimates 

on an individual basis were 0.84 and 

1.19 from pot and nursery evaluations, respectively. Heritability estimates on a family basis were 0.70 and 

0.79 for pot and nursery evaluations, 

respectively. 

Most heritability estimates for 

the interprovenance experiments were 

moderately high for 2-year height, 

regardless of whether they were calculated on an individual or family 

basis or from pot or nursery data. 

Heritability estimates were higher 

when female components of variance 

were used to estimate additive variance than when male components 

were used. Heritability estimates for 

provenance hybrids were quite variable, but similar to estimates from 

the diallel analyses for pots and 

generally less than estimates for the 

nursery. 

Heritability estimates on an individual basis for provenance hybrids 

based on males ranged from 0 to 0.35 

and from 0.17 to 0.93 for pots and 

nursery data, respectively (Table 8). 

Family heritability estimates of males 

derived from pots and the nursery 

ranged from 0 to 0.29 and from 0.26 to 

0.30, respectively. Heritability estimates on an individual basis based 

on females ranged from 0.52 to 1.06 

and from 0.28 to 1.99 for pots and 

nursery data, respectively. Family 

heritability estimates based on females ranged from 0.43 to 0.71 and 

from 0.44 to 0.65 for pots and nursery 

data, respectively. 

Statistical developments and 

analyses in this study included populations generated by crossing presumed random individuals within 

provenances and by crossing presumed random individuals from twoparent provenances. lntraprovenance 

estimates of genetic parameters can 

be related to the provenances from 

which the parents are a random sample. For interprovenance estimates of 

genetic parameters, the reference 

provenance is a theoretical population 

formed from the union of all possible 

gametes from one population with 

those of a second population. Intrapopulation theory is quite satisfactory 

for interpopulation studies if the 

same alleles are present in the twoparent populations and if the gene 

frequencies do not differ greatly. If 

the gene frequencies in the two-parent 

populations are different, frequencies 

at linked loci in the interpopulation 

will not reach Hardy-Weinberg equilibrium in one generation. The genetic 

interpretation of the covariances 

Table 8.-Estimates of heritability of %year height on an individual and family basis in 

open pollination and provenance hybrid experiments. 

Location Spanish French (212) Q French (212) Q German (250) Q 

open pollination X X X 

Spanish a German (250)a French (212)a 

malesa 0.00 0.22 

Individual 0.83 femalesb 0.68 1.06 

Pots combinedC 0.34 0.64 

males 0.00 0.14 

Family 0.70 females 0.71 0.67 

combined 0.36 0.41 

males - 0.93 0.17 

Individual 1.19 females - 1.99 0.28 

Nursery combined - 1.46 0.23 

males - 0.30 0.76 

Family 0.79 females - 0.65 0.44 

combined - 0.47 0.35 
among relatives for the interpopulation will differ from the intrapopulation 

interpretations (Stuber and Cockerham 

1966). We used intrapopulation theory 

to study interpopulation crosses because we had no objective evidence 

that our interprovenance crosses 

violated intrapopulation genetic theory. 

Estimates of interprovenance 

parameters can be very useful. Reciprocal recurrent selection (RRS) 

used performance of test cross progeny as a basis for selection and has 

been successful in maize breeding 

programs (Stuber 1970). 

Shelbourne (1969) reviewed tree 

breeding strategies including RRS 

with quantitative genetic expectations 

of gain. He predicted gain in Pinus 

radiata for stem straightness and 

diameter using various strategies. 

The greatest gains for both traits 

were predicted for a second stage 

clonal orchard; slightly smaller gains 

were predicted for clonal propagation 

and testing. 

There seemed to be little heterotic response for 2-year height in the 

interprovenance crosses of Scotch 

pine when all families are considered. 

Heterosis was measured as the difference between the provenance hybrid family and the average of the 

two parents (mid-parent) calculated 

from intraprovenance full-sib families 

in diallels. All interprovenance mean 

heights were intermediate between 

the mean heights of the parent provenances (Table 3). There were a few 

differences between the average 

height of seedlings of hybrid families 

and the calculated mid-parent values 

for those families, but the number of 

families was not greater than one 

might expect purely by chance. Zeaser 

(1976) found no real differences between the average of 13 haguenensis x iberica hybrid families and 

calculated mid-parent values for 8-year 

height. This is further evidence that 

there is little chance of finding heterotic responses in early height growth 

among the interprovenance crosses 

of Scotch pine from this area of its 

natural range. 

In the Spanish open pollination 

experiment, the contribution of male 

parents by wind pollination may not 

have been a random process. A considerable proportion of the progeny 

within families may, in fact, be fullsibs. As the proportion of full-sibs 

increased, the component of variance 

due to families would approach half 

the additive variance plus one-quarter 

the dominance variance rather than 

one-quarter the additive variance. 

This would result in overestimation 

of true additive variance and of heritability. Heritability estimates from 

open pollination progeny in pots were 

considerably larger than estimates 

from controlled matings in pots. 

Heritability estimates from open pollination and controlled matings were 

similar in the nursery. Comparison of 

genetic parameters generated from 

the 18 parent Spanish disconnected 

diallel analyses and the same 18 

parents in the Spanish open pollination analyses provided similar heritability estimates for Byear height only 

in the nursery evaluation. These 

limited evaluations seem to indicate 

that genetic estimates from open pollination experiments probably do not 

greatly overestimate true genetic 

parameters when evaluations are 

made in the nursery. 

lntrapopulation genetic theory 

may not be satisfactory for estimation of genetic snd environmental 

components of variance for interpopulation studies. Genes and gene frequencies which determine height 

appear to be different among the 

provenances because of the differences in mean heights among provenances. Heritability estimates for 

2-year height from interprovenance 

studies using intrapopulation genetic 

theory were more variable than estimates from intraprovenance studies. 

Heritability estimates from nursery 

data tended to be less variable for 

provenance diallel experiments than 

for interprovenance experiments. 

Dominance variance may increase in 

importance compared to additive 

genetic variance in interprovenance 

crosses if the populations are different in genetic structure. Interprovenance crosses may not be in 

Hardy-Weinberg equilibrium and therefore no predictions for F, performance 

can be made. 

Estimates of the relative magnitude of genetic components of variance in seedling height of Scotch 

pine can probably be obtained by 

evaluating at least 30 families at 

two locations. However, reliable estimates of genetic components of variance can probably be obtained by 

evaluating 90 families at two locations. Estimates of components of 

variance were quite consistent for 

combined analyses for the three 

Spanish population 6 x 6 diallel 

experiments (Table 5). Pederson (1971) 

stated that an 8- to 10-parent diallel 

mating design is probably the minimum size to obtain good estimates of 

genetic components of variance. 

Work at North Carolina State University with yield of corn suggests 

that at least 256 full-sib families are 

necessary to obtain reliable estimates 

of additive and dominance variance 

and that these families need to be 

tested in at least 2 years and two 

locations (Dudley and Moll 1969). 

Inconsistencies in estimates of components of variance among Spanish 

diallel experiments within locations 

may be the result of using too few 

parents to produce too few families. 

Namkoong (1979) states that "the 

geneticist may want to estimate 

means and several components for 

several traits from a reasonable population sample. Thus, given the capability for estimating variances and 

means, but with multiple demands for 

estimates, either some compromises 

on efficiency or several different 

experiments will have to be run". 

Differences in the relative importance of the genetic components 

of variance for combined analyses 

among populations suggest that the 

provenances evaluated in this study 

differed in genetic makeup. 

The similarity of genetic components of variance among the three 

Spanish diallel experiments and the 

combined Spanish diallel experiment 

combined over locations strengthened 

the evidence that the five provenances 

were different. 
There is little reason to doubt the 

validity of the assumptions that are 

required for the estimates of additive 

genetic variance in the diallel mating 

designs used in this study. However, 

additive genetic variance estimated 

from open pollinated families probably 

is inflated somewhat by full-sibs and 

maternal effects. Also, estimates of 

additive genetic variance using the 

female component of variance from 

factorial mating designs may be inflated by maternal effects. The parent 

trees are most likely random members 

of some non-inbred population, although the parents were not chosen 

randomly. Parents were selected only 

for adequate flowering to make the 

necessary pollinations for the particular mating design being used. However, some might argue that selecting 

trees with adequate flowering increases the chances that their parents 

are related. It is assumed for this 

study that there was no correlation 

between the flower production of the 

parents and 2-year height of the resulting progeny. In many applications, it is difficult to conceptualize a 

population from which a given set of 

parents could be chosen at random 

(Baker 1978). Any inbrbeding that 

occurred would not be abnormal, 

moreover. Each provenance or stand 

collection consisted originally of 

seed from 10 or more average trees 

from an area of several acres (Wright 

and Bull 1963). It is difficult to estimate just what the relatedness of the 

parent trees might be and what effect 

it had, if any, on provenance variances 

estimated from their progeny. 

Maternal effects probably inflated the estimates of additive genetic variance of 2-year height in the 

open pollination experiment and also 

in interprovenance experiments where 

the female component of variance 

was used to estimate additive genetic 

variances. Maternal effects were 

positive in many of the diallel analyses. It is not known to what extent 

maternal effects may inflate estimates of additive genetic variance. 

Estimates of maternal effects from 

diallel analyses indicated that they 

could greatly influence estimates of 

additive genetic variance. 

GCA was larger than SCA in some 

diallel experiments. This same relationship was found for 2-year height 

in eastern white pine (Kriebel et al. 

1972) and black spruce (Morgenstern 

1974). 

Nilsson (1970) found for 2-year 

height of Scotch pine that additive effects were significantly greater than 

specific combining effects mainly 

within provenances, and the same 

trend held to a lesser extent within a 

geographical range of 2% " latitude 

and 400 meters in altitude. He also 

found no case where female effects 

were greater than male effects, which 

indicated that maternal effects for 

his study were fairly'small. This study, 

however, showed that female effects 

were greater than male effects, which 

indicated that maternal effects were 

important. 

Dominance variance was much 

larger in interprovenance matings 

than in intraprovenance matings of 

Scotch pine. In a western white pine 

experiment where the pollen parents 

were from a stand 65 miles from the 

female parents, estimates of dominance variance from the interaction 

of males x females for 1-year height 

was larger than either the male or female components of variance (Hanover 

and Barnes 1963). 

Narrow-sense heritability estimates for Byear heights were variable 

among the five provenances used in 

this study. There is, however, enough 

consistency in the estimates when 

comparisons are made within locations and method of estimation to 

make reasonable estimates of the 

range of genetic control of 2-year 

height. Two-year height is under 

strong genetic control in some Scotch 

pine provenances, especially when 

the seedlings are grown in the nursery. Heritability estimates on an 

individual basis for pot and nursery 

evaluations of Spanish open pollination progeny are similar to the estimate of 0.94 previously reported for a 

similar experiment in the same provenance (Demeritt et al. 1975). Heritability estimates of 2-year height from 

pot evaluation of diallel matings are 

similar to estimates on an individual 

basis of 0.24 and 0.30 reported for 

2-year height from diallel matings in 

eastern white pine (Kriebel et al. 1972). 

Also, family heritability estimates 

from nursery evaluations are slightly 

larger than the heritability estimate 

of 0.59 reported for black spruce from 

7 x 7 nursery diallel experiment 

(Morgenstern 1974). 

For evaluating progeny, the 

nursery is preferred to pots because 

error variances were smaller and 

heritability estimates for 2-year height 

were larger. Genotype by environment 

interaction was of relatively minor 

importance because GCA by location 

components of variance were small. 

Larger nursery than pot heritability 

estimates mean that a seedling's 

phenotypic value is probably a more 

reliable indication of its breeding 

value if it is grown in the nursery than 

if it is grown in a pot. There is no 

conclusive evidence that this is the 

situation. It may be that we are evaluating a different sort of genotype 

and environment interaction and 

nursery is just another environment; 

i.e., no better or no worse than pots. 

The best selection method for 

improving 2-year height among the 

provenances evaluated in this study 

is by individual selection of superior 

phenotypes from nursery evaluation 

of German (250) provenance seedlings. The German provenance (250) 

height in the nursery was 114 percent 

of the next tallest provenance, the 

hybrid provenance German (250) female.and French (212) male. Narrowsense heritability of 0.51 for the German (250) nursery diallel experiment 

means that a seedling's phenotypic 

value will be a reliable indication of 

its breeding value for that age. High 

heritability estimates in the Spanish 

provenance indicate promising possibilities for improving height in that 

provenance, even faster than in the 

German (250) provenance. 

No appreciable parent-progeny 

correlations were found in studies of 

2- to 8-year Scotch pine progeny 

heights in the Netherlands (Squillace 

et al. 1975). However, the parents 
Conclusions 

were growing some distance from the 

progeny and probably in different 

environments. They indicated that 

progeny testing of many selections 

would be required to make any appreciable genetic gain. Progeny testing 

of selections may be necessary in 

this program if parent-progeny correlations of heights at different locations 

are low. Juvenile-mature correlations 

would be an important consideration 

if selection on the basis of 2-year data 

were used for predicting performance 

later in life. 

Squillace and Gansel (1974) reported 3- versus 25-year correlations 

computed between families, within 

families, and for all trees regardless 

of families for wind-pollinated and 

control-pollinated progeny slash pine. 

Between-family, within-family, and alltree correlations for wind-pollinated 

progeny were 0.00, 0.14, and 0.10, 

respectively. Between-family, withinfamily, and all-tree correlations for 

control-pollinated progeny were 0.53, 

0.14, and 0.10, respectively. Betweenfamily correlations indicate the reliability of early selection of families; 

within-family correlations relate to 

early selection of individuals within 

families; and all-tree correlations indicate the reliability of early mass 

selection. 

Wright and Baldwin (1957) reported a correlation of 0.861 for 4- 

versus 17-year height of 50 Scotch 

pine provenances computed from plot 

averages. They concluded that 17-year 

heights could be forecast with accuracy from nursery measurements. 

Reliable between-family, within-family, 

and all-tree correlations are needed 

for 2- versus 8- to 12-year heights in 

Scotch pine to judge the reliability of 

early nursery selection for Christmas 

tree and ornamental uses. 

For Christmas tree or ornamental 

use, provenance hybridization may be 

a useful method for combining desirable traits from different provenances. Zeaser (1976) found that 

haguenensis x iberica Scotch pine 

varietal hybrids were better suited 

for Christmas or ornamental use than 

either parental variety because of 

their combination of desired height, 

foliage color, and trunk form. Provenance hybridization would be especially useful in programs where certain 

desired traits were absent from promising provenances, such as resistance 

to a disease. 

Once superior-provenance hybrid 

families or trees are selected, they 

could be mated to produce F, progeny 

for further evaluation. Also, selected 

F, hybrids with desired traits could 

be backcrossed with selected trees 

in one of the parental varieties. Higher 

order filial generations could be produced and then a recurrent selection 

program could be conducted in the 

composite population which might 

be a useful alternative for combining 

useful traits in different populations. 

The best possibility for improvement of early height growth for Christmas tree or ornamental uses would 

be in the Spanish provenance. This 

study indicated that 2-year height 

growth was under strong genetic 

control, especially in the nursery 

evaluation. Spanish Scotch pine already has desirable needle color for 

ornamental purposes. Large numbers 

are planted each year to be harvested 

in 8 to 12 years for Christmas trees. 

Simple recurrent selection with 

or without progeny testing would be 

a good method of improving height 

growth, needle color and density, 

and trunk form for Christmas tree or 

ornamental uses. Superior quality 

Christmas trees could be identified in 

plantations and saved for seed production after the remainder of the 

trees have been removed. Plantationgrown Scotch pines flower and produce seed at approximately the same 

age as they are harvested for Christmas trees. Seedlings produced from 

this improved seed would serve as 

planting stock for the next Christmas 

tree plantation. 

From the analysis of Byear height 

of Scotch pine provenances and provenance hybrids studied in pots and in 

the nursery, the following conclusions 

can be supported: 

1. Heritability estimates from 

inter- and intraprovenance matings 

tend to be larger on a family basis 

than on an individual basis, the higher 

estimates being from the nursery 

evaluation. 

2. In general, additive genetic 

variance was larger than dominance 

variance, although dominance variance increased in interprovenance 

crosses. 

3. Individual nursery selection 

within the German (250) provenance 

seems to be the best method of improving Byear height because it was 

the tallest and most variable of the 

provenances evaluated in this study. 

The rate of improvement in the Spanish provenance could be greater, 

however, because heritability estimates were generally higher. 

4. Provenance hybridization may 

be especially useful in programs 

where desired traits are absent from 

promising provenances. 

5. Simple recurrent selection 

with or without progeny testing within 

the Spanish provenance seems to be 

the best method for improving provenances used for Christmas tree or 

ornamental purposes. 
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of 2-year height of Scotch pine 

seedlings. In: Proceedings, Northeastern Forest Tree lmprovement 

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breeding. Silvae Genetica. 17:31-32; 

1968. 

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of data with unequal subclass 

numbers. ARS Rep. No. 20-8. Washington, DC: U.S. Department of 

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R. A. Analysis of genetic variation 

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21 :44-48: 1972. 

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black spruce, Picea mariana (Mill.) 

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1974. 

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quantitative genetics in forestry. 

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DC: U.S. Department of Agriculture, 

Forest Service; 1979. 342 p. 

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partial diallel cross design. Res. 

Note No. 8. Stockholm, Sweden: 

Department of Forest Genetics, 

Royal College of Forestry; 1970. 

11 p. 

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heritability and degree of dominance from a diallel cross. Heredity 

27:247-264; 1971. 

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least squares analysis of diallel 

experiments: A computer program 

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NC: Genetics Department, North 

Carolina State University; 1969. 

61 p. 

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methods. Tech. Pap. No. 55. Wellington, N.Z.: Forest Research Institute, New Zealand Forest Service; 

1969. 43 p. 

Squillace, A. E.; Gansel, C. R. Juvenile: 

mature correlations in slash pine. 

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Squillace, A. E.; LaBastide, J. G. A.; 

Van Vredenburch, C. L. H. Genetic 

variation and breeding of Scots 

pine in the Netherlands. Forest 

Science, 21(4):341-352; 1975. 

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population statistics. In: Proceedings, Second Meeting of the Working Group on Quantitative Genetics, 

Section 22; 1969 August 18-19; 

Raleigh, NC: IUFRO; 1970:lOO-122. 

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effects and variance in hybrid pop. 

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1966. 

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Acknowledgements 

The authors wish to thank Dr. J. W. 

Wright, Michigan State University, for 

making available the plantation at 

Kellogg Forest for breeding, and the 

superintendents of Penn Nursery, 

Potters Mills, Pennsylvania, for making the nursery beds available and 

for giving the planted seedlings standard nursery care. 

This study was supported by 

grant AP00701, Office of Air Programs, 

Environmental Protection Agency and 

USDA Forest Service, Pinchot Institute for Environmental Forestry Research Project FS-NE-1851. This is 

Center for Air Environment Studies 

Publication No. 510-78. Authorized 

June 22, 1978, as Paper No. 5541 in 

the Journal series of the Pennsylvania 

Agricultural Experiment Station. 
Demeritt, Maurice E., Jr.; Gerhold, Henry D. Genetic evaluation 

of rapid height growth in pot- and nurserygrown Scotch pine. 

Research Paper NE-554. Broomall, PA: U.S. Department of 

Agriculture, Forest Service, Northeastern Forest Experiment 

Station; 1985. 11 p. 

Genetic and environmental components of variance for 2-year 

pot and nursery heights of offspring from inter- and intraprovenance matings in Scotch pine were studied to determine 

which provenances and selection methods should be used in an 

ornamental and Christmas tree improvement program. Nursery 

evaluation was preferred to pot evaluation because heritability 

estimates were larger and error variances were smaller for the 

experiments evaluated. Simple recurrent selection would be a 

good method for improving traits important to the Christmas 

tree industry. 

ODC 165.3; 165.62; 232.12; 232.1 3; 892.51 

Keywords: Scotch pine; hybrids; provenance; breeding; selection; 

Christmas tree 

a US. GOVERNMENT PRINTING OFFICE: 1985-505-0281539 I 

I 
Headquarters of the Northeastern Forest Experiment Station are in 

Broomall, Pa. Field laboratories are maintained at: 

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Morgantown, West Virginia, in sooperation with West Virginia 

University, Morgantown. 

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Orono. 

Parsons, West Virginia. 

Princeton, West Virginia. 

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New York College of Environmental Sciences and Forestry at 

Syracuse University, Syracuse. 

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Pennsylvania State University. 

Warren, Pennsylvania.