ORIGINAL ARTICLE

Seed quality of Siberian larch (Larix sibirica Ldb.) fromgeographically diverse seed sources in Mongolia

NYAM-OSOR BATKHUU1, DON KOO LEE2, JAMSRAN TSOGTBAATAR3 &

YEONG DAE PARK2

1Department of Forestry, Faculty of Biology, National University of Mongolia, Ikh surguuliin gudamj 2, 210-646,

Ulaanbaatar, Mongolia, 2Department of Forest Sciences, Seoul National University, 151-921, Seoul, Korea, and3Institute of Geoecology, Mongolian Academy of Sciences, 211-238, Ulaanbaatar, Mongolia

AbstractThe rehabilitation of degraded forests in Mongolia has had very low success and the total successfully reforested arearepresents only 5% of the total degraded forests. Such poor results may be partly attributed to the low quality of plantingstock owing to the poor quality of seeds. The objective of this study was to determine the geographical variation in seedquality of Siberian larch (Larix sibirica Ldb.) from eight different locations in Mongolia. A significant seed source variationwas observed in seed quality traits, such as seed weight, viability, germination capacity, germination energy and seedlingemergence. In the present study, some of the characters were correlated with geographical and climatic factors includinglongitude, latitude, altitude, temperature and precipitation of the location of seed origin or collection sites. On the basis ofthese results, it may be concluded that source 5 (Binder) and source 6 (Huvsgul) were superior among the seed sourcesstudied in terms of seed quality. Therefore, it is advisable that these seed sources be used for collection of the bulk quantityof seeds to achieve better productivity and more vigorous seedlings.

Keywords: geographical variation, Mongolia, seed quality, seed source, Siberian larch.

Introduction

Forest resources in Mongolia have been continu-

ously degrading over the past few years owing to

improper exploitation and inadequate management,

which negatively affect environmental conditions

causing severe deforestation, desertification and

ecological stress in some regions. In recent decades,

Mongolia has lost approximately 4 million ha of

forests, averaging 40,000 ha year�1, but between

1990 and 2000, the rate of deforestation increased

to 60,000 ha year�1. As a result of ongoing loss and

degradation, only 13 million ha of forests can be

considered as relatively remote, closed canopy for-

ests. Much of the other 5.3 million ha of forests is

fragmented and degraded (World Bank, 2002).

According to another report on forest status of

Mongolia, some 1.6 million ha of forest area was

completely destroyed between 1974 and 2000 by

fire, improper and illegal logging, overgrazing,

mining activities, pests and diseases, causing severe

ecological stress (UNEP, 2002).

The success of plantation and reforestation

depends on many factors, including seed and

seedling quality, matching species to the appropri-

ate site, and the silvicultural practices employed.

Given the tremendous genetic variation in forest

tree species, the origin of plant material is one of

the most important factors in successful establish-

ment of plantations and reforestation. The use of

seeds geographically adapted to a specific region

can increase resistance to pests, pathogen damage

and unfavourable growth conditions, and yield

higher seedling survival and better performance.

Extensive guidelines for the transfer of conifer seed

and seedlings exist worldwide, and were developed

based on climatic data, as well as geographical and

genetic information. However, only a few studies

Correspondence: N.-O. Batkhuu, Department of Forestry, Faculty of Biology, National University of Mongolia, Ikh surguuliin gudamj 2, 210-646,

Ulaanbaatar, Mongolia. E-mail: nbatkhuu@biology.num.edu.mn

Scandinavian Journal of Forest Research, 2010; 25(Suppl 8): 101�108

ISSN 0282-7581 print/ISSN 1651-1891 online # 2010 Taylor & Francis

DOI: 10.1080/02827581.2010.485815

have been conducted in Mongolia (Milyutin et al.,

1988; Bat-Erdene & Dashzeveg, 1995; Batkhuu

et al., 1998; Jamiyansuren, 1989), and information

on seed source control, regulation, seed transfer

and seed zoning was lacking in these studies.

Siberian larch (Larix sibirica Ldb.) is the most

important and widely distributed timber species in

Mongolia. This can be explained by its broad

tolerance in moisture, temperature and soil require-

ments. Pure natural stands and open woodlands of

L. sibirica occupy almost 60% of the total closed

forest area in Mongolia. It is a single tree species that

appears in most favourable habitats in both steppe

and mountain tundra (Savin et al., 1978; Milyutin &

Vishnevetskaia, 1995).

Larix sibirica has been widely used for reforesta-

tion and rehabilitation activities in Mongolia be-

cause they are native and the best growing tree

species. However, reforestation success has been

very low and the survival rate of planted seedlings

is 30�60%, seldom reaching 50%. Consequently,

the total area that has been successfully replanted

represents only 5% of the total forest lost (World

Bank, 2002). A target of 150,000 ha of forests

needs to be rehabilitated, but an average of only

5000 ha is being planted each year (Tsogtbaatar,

2004). The main reasons for the poor results of

the plantations are the lack of compatibility

between sites and species, poorly equipped nursery

systems with outdated techniques, poor site pre-

paration, poor quality of planting stock due to

poor seed and nursery techniques, seed orchard

unavailability and forest plantations on grazing

land often being resented by herders (JICA et al.,

1998).

The objectives of this study were to determine

geographical variation in seed quality of the Siberian

larch, to develop strategies for genetic conservation

and seed zoning, and to select the most promising

seed sources for reforestation of degraded forest

lands of Mongolia.

Materials and methods

Seed materials

Seeds of the Siberian larch (Larix sibirica Ldb.) were

collected from the natural stands of eight different

geographical locations in Mongolia between 2003

and 2004 (Table I, Figure 1). Laboratory tests for

seed quality were conducted according to the inter-

national rules for seed testing (International Seed

Testing Association, 1999) at the Division of Forest

Genetics and Forest Seed Research Center of Korea

Forest Research Institute (KFRI). Seeds were ex-

amined for its quality by the purity test, weight of

1000 seeds and germination test, seed viability was

assessed by soft X-ray photography and the tetra-

zolium test.

Germination test in the laboratory

The germination capacity (GC) in a germination

cabinet was considered as the standard method in

this study. One-hundred seeds with four replica-

tions from each seed sources were soaked in

distilled water and then germinated on filter paper

in a Petri dish under light conditions for 21 days.

The temperature was maintained at 208C. Germi-

nation was checked every day and seeds were

considered germinated when the length of root

radicle was twice as large as seed size. Seed

germination values were recorded and quantified

as GC and germination energy (GE). GC is the

proportion of total germinated seeds to total sown

seeds, expressed as a percentage. GE, also ex-

pressed as a percentage and one of the commonly

employed indices of speed of germination (ISTA,

1999), is computed as the proportion of total

Table I. Description of seed sources used in this study.

No.

Seed

source

Collection

date

Forest

vegetation

region

Lat.

(N)

Long.

(E)

Alt.

(m)

Mean annual

temperature a

(8C)

Mean annual

precipitation a

(mm)

1 Ovorkhangai Sept. 2003 SW Khangai 46.5 102.2 1700 �1.8 296.2

2 Zavkhan Aug. 2003 West Khangai 47.5 96.3 1658 �6.3 225.7

3 Tuul River Sept. 2003 Eastern Khentii 47.6 108.0 1843 �3.3 250.7

4 Mongon Sept. 2003 Eastern Khentii 48.1 108.3 1450 �2.73 281.5

5 Binder Sept. 2004 Eastern Khentii 48.4 110.3 1100 �1.26 327.1

6 Huvsgul Sept. 2003 Jidiin 49.4 100.1 1275 �1.3 235.5

7 Uvs Sept. 2003 West Khangai 49.4 94.2 1200 �3.36 146.5

8 Turag Sept. 2003 Jidiin 51.2 100.5 1700 �1.3 231.5

Notes: aSource�long-term mean annual temperature and precipitation data obtained from Institute of Meteorology, Mongolian Academy

of Sciences (2005).

102 N.-O. Batkhuu et al.

germinated seeds after 1 week (7 days) to the total

germinated seeds after 21 days.

X-ray contrast method

In order to investigate the internal structure of seeds,

100 seeds randomly sampled with four replications

were placed in a Petri dish and radiographed under

24 kV and 68 mA for 20 s. X-ray photography (Work-

Leader-90; Softex Co., Japan) was saved both as a

printed image and as a JPEG image file on the

computer. A seed was considered viable if its embryo

was free from impregnation and the endosperm was

not impregnated by more than 25% from the

projected X-ray pictures.

Tetrazolium staining test

For the tetrazolium staining test a P-buffered solu-

tion of 2,3,5-triphenyl tetrazolium chloride, pH 7.4,

was used according to ISTA prescriptions. Incuba-

tion in the staining solution was performed at 308C in

the dark for 24 h. Before staining, seeds were

hydrated in distilled water for 24 h at room tempera-

ture. Four replications of 100 seeds from each seed

source were tested. Seed tips towards the radicle end

were longitudinally cut off by 2 or 3 mm. The cut

seeds were transferred on filter paper in a Petri dish

which was moistened with tetrazolium chloride

solution and stained in an incubator. Seeds with

completely stained embryo and endosperm were

considered viable.

Data analysis

The differences in seed quality between seed sources

were determined by analysis of variance (ANOVA) and

Duncan’s multiple range test (DMRT) was used for

multiple comparisons. Pearson’s simple correlation

and regression equation were used to examine the

relationship between geographical characteristics

and seed quality variables. Cluster analysis was

carried out on seed quality traits. Dissimilarity

matrices were constructed using the Euclidean

distance method on standardized variables and

Ward’s clustering algorithm was used (Quinn &

Keough, 2002).

Results

Considerable variation in seed quality traits was

observed among seed sources. Seed quality traits

Figure 1. Location of seed sources of Larix sibirica Ldb.

Seed quality of larch in Mongolia 103

such as GC, GE, weight of 1000 seeds, viability and

seedling emergence varied significantly among seed

sources (Tables II and III).

Overall mean GC and GE were 51% (2.6�83) and

34% (1.6�59), respectively. The highest GC (83.39

7.02) and GE (59.097.81) were found in source 5

(Binder), whereas the lowest values were found in

source 3 (Tuul River) (Table III, Figure 2). A cutting

test after the standard germination test showed that

source 3 (Tuul River) had a high number of empty

seeds (75.2%) compared with other low-performing

seed sources.

The correlation analysis shows that seed viability

has a significant effect on seed germination char-

acteristics, such as GC, GE and seedling emergence

(r�0.98, 0.91 and 0.88, respectively).

Figure 3 shows the mean viability of studied seed

sources and the overall mean viability (59%) of the

studied seed sources. This varied from 15% for

source 3 (Tuul River) to 77% for source 5 (Binder).

The mean weight of 1000 seeds of the studied

Siberian larch seed sources was 6.65 g (Figure 4).

The heaviest seed (7.290.06 g) was recorded from

source 3 (Tuul River) and the lightest (5.9690.11 g)

from source 8 (Huvsgul) (Table II).

The mean period of seedling emergence (nursery

germination) was between 22 and 45 days after

sowing, and varied from 26% (2�43) to 33% (2�55)

in the greenhouse and open nursery, respectively

(Table II, Figure 5).

In this study, some of the seed quality character-

istics were correlated with geographical and climatic

factors such as longitude, latitude, altitude, tempera-

ture and precipitation of the seed origin or collection

sites. Weight of seeds was negatively correlated (r��0.72) with latitude and positively correlated

(r�0.72) with longitude. There was a decline in the

values of traits (Table IV).

The results of cluster analysis on all measured seed

quality variables are summarized in a dendrogram

(Figure 6). Three distinctive cluster groups were

identified with respect to their similarity in seed

quality variables, including GE, GC, seed weight,

viability and seedling emergence under different

nursery conditions. Source 3 (Tuul river) alone

formed one group with the lowest seed quality

among studied seed sources of L. sibirica. One group

was comprised of sources 1 (Ovorhkangai), 2 (Zav-

khan) and 7 (Uvs), and another group consisted of

seed sources 3 (Tuul River), 4 (Mongon), 5 (Bin-

der), 6 (Huvsgul) and 8 (Turag).

The overall ranking of seed quality traits for

L. sibirica is as follows: source 5 (Binder), source 6

(Huvsgul), source 4 (Mongon), source 7 (Uvs),

source 8 (Turag), source 2 (Zavkhan), source 1

(Ovorkhangai) and source 3 (Tuul River) (Table III).

Discussion

Seed quality plays a major role in the production of

high-quality plants. Many factors, both biological

and environmental, influence the quality of seed

produced by a given tree under natural conditions.

In this study, considerable variation in seed

quality traits was observed among seed sources of

L. sibirica from geographically distinct regions of

Mongolia (Tables II and III). The results obtained

in this study for GC and GE were lower (Table III,

Figure 2) than those found by Iroshnikov and

Fedorova (1974). GE was 60% and 90%, GC was

Table III. Means of seed characteristics of Larix sibirica seed sources used in this study (n�400).

Seedling emergence (%)

No.

Seed

source

Germination

capacity (%)

Germination

energy (%)

1000 seed

weight g

Viability

(%)

Open

nursery

Greenhouse

nursery

1 Ovorkhangai 38.66d 27.33c 6.61c 51.33b 20.8 16.6

2 Zavkhan 47.01cd 24.0c 6.73bc 65.33ab 33.2 �3 Tuul River 2.66e 1.66d 7.18a 15.33c 2.99 2.16

4 Mongon 46.66cd 26.33c 6.96ab 68.0a 44.4 19.2

5 Binder 83.33a 59.0a 6.96ab 77.33a 54.2 37.5

6 Huvsgul 62.66bcd 51.33ab 6.51c 72.0a 55.5 43.9

7 Uvs 64.01bc 44.33b 6.18d 66.0ab 27.7 36.7

8 Turag 66.20b 41.83b 5.96d 63.3ab 27.5 20.3

Mean 51.40 34.8 6.65 59.83 33.28 25.18

Notes: Means with different letters are significantly different according to Duncan’s multiple range test at the 5% level.

Table II. Anova for seed characteristics of Larix sibirica seed

sources (n�400).

Variables df F value

Weight of 1000 seeds 7 29.95***

Seed viability 7 15.57***

Germination capacity 7 20.47***

Germination energy 7 16.25***

Notes: ***Significantly different at 0.001.

104 N.-O. Batkhuu et al.

0

20

40

60

80

100

No.1 No.2 No.3 No.4 No.5 No.6 No.7 No.8

Seed sources

Ger

min

atio

n ch

arac

teri

stic

s (%

)

Germination capacity

Germination energy

Figure 2. Seed germination characteristics of Larix sibirica seed sources. Bars indicate standard error.

No.1 No.2 No.3 No.4 No.5 No.6 No.7 No.8

Seed sources

0

20

40

60

80

100

Seed

via

bilit

y (%

)

Figure 3. Seed viability of Larix sibirica seed sources. Bars indicate standard error.

No.1 No.2 No.3 No.4 No.5 No.6 No.7 No.8

Seed sources

0

2

4

6

8

Seed

wei

ght (

g)

Figure 4. Seed weight of Larix sibirica seed sources. Bars indicate standard error.

Seed quality of larch in Mongolia 105

65% and 93%, percentages of full seeds were 30%

and 39%, in East Siberia and East Khentii of

Mongolia, respectively (Iroshnikov & Fedorova,

1974). Lower germinability and viability were re-

corded for source 3, which originated from the

upper stream of Tuul River, where forests have

been extensively logged since the 1960s, and the

impacts of forest fires and pest impacts are high.

These factors may have negatively affected forest

stand structure while reducing seed quality. Under

conditions of limited resources, plant may allocate

the available resources to the production of fewer

larger seeds or many smaller ones (Harper et al.,

1970). Source 3 (Tuul River) had the highest seed

weight among the studied seed sources. Stressful

environmental conditions (e.g. shade, drought and

herbivory) favour the selection of larger seeds as

they provide more reserves for the successful estab-

lishment of seedlings (Moles & Westoby, 2004).

In the present study, no particular correlation was

found between seed weight and seed germination

variables among seed sources (Table IV). The seed

weight of studied seed sources L. sibirica showed

lower variation (Table III, Figure 4) than results

obtained by Abaimov et al. (1998). The average

weight of 1000 filled seeds varied from 4 g to 10 g in

natural populations of L. sibirica in Russian Siberia,

adjacent territory to Mongolia. The highest seed

weight in L. sibirica (8.9 g) was observed in the

southern taiga zone in the Lena-Angara and Prian-

garie Plateaux, Eastern Sayan Mountains. The low-

est seed weight in L. sibirica (3.8 g) was found in the

Khantayka river basin at 688N latitude (Abaimov

et al., 1998).

Among the studied seed quality variables, except

for seed weight, a strong negative correlation was

found with altitude, which is similar to the results

obtained previously by Jamiyansuren (1989, 1992).

However, some studies reported that the weight of

1000 seeds to be related to altitude and forest types

(Deryuzhkin, 1970). In this study no latitudinal or

geographical similarities in seed quality traits were

observed, but altitude had a significant effect on the

seed quality of L. sibirica seed sources (Table IV).

However, cluster grouping resembled the natural

distribution of L. sibirica by the classification of

forest-vegetation zones of Mongolia.

One group was comprised of sources 1 (Ovorh-

kangai), 2 (Zavkhan) and 7 (Uvs), all from Khangai

mountain forest-vegetation zone, which has poor

growing conditions with low precipitation, long and

cold winters, and high elevation. Another group

consisted of seeds from sources 3 (Tuul River),Figure 6. Dendrogram of cluster groupings of Larix sibirica seed

sources based on similarity of their seed quality variables.

No.1 No.2 No.3 No.4 No.5 No.6 No.7 No.8

Seed sources

0

10

20

30

40

50

60

Seed

ling

emer

genc

e (%

)

Open nursery

Greenhouse nursery

Figure 5. Seedling emergence at different nursery conditions of Larix sibirica seed sources. Bars indicate standard error.

106 N.-O. Batkhuu et al.

4 (Mongon), 5 (Binder), 6 (Huvsgul) and 8 (Turag),

originating from the Trans-Baikal forest-vegetation

zone, which is milder than Khangai mountain

forest-vegetation zone with lower elevation, high

temperature sum and longer growing season. The

geographical distribution and climatic characteristics

of the studied seed sources are shown in Figure 1

and Table I. Germination emergence and seedling

emergence accounted for most of the variation in the

seed viability among L. sibirica seed sources.

In conclusion, seed quality traits of diverse seed

sources of L. sibirica revealed the existence of

considerable geographical variation in seed quality

traits (GC, GE, seed viability, weight of 1000 seeds

and seedling emergence). During bulk seed collec-

tion, either for ex situ conservation in seed banks or

for seedling production for plantation establishment

or reforestation, collection should be made from

several sources to ensure sufficient genetic variability

in future plants and to obtain good germination

performances.

Among the studied seed quality variables, except

for seed weight, strong negative correlation was

found with altitude of the seed source origin in

L. sibirica. Germination emergence and seedling

emergence contributed to the total variation in the

seed viability of L. sibirica seed sources.

Overall, sources 5 (Binder) and 6 (Huvsgul)

showed excellent performance in seed quality traits

among the studied seed sources, whereas source 3

(Tuul River) had the worst results.

Seed quality traits GC, GE, seed weight and seed

size may vary owing to both internal (maternal and

heredity) and external (environmental) conditions

operating at the time of seed development. As this

study is the first attempt in Mongolia, further study is

recommended to quantify seed source or population

variations and to conduct progeny trials in order to

select genotypes suitable for different geographical

conditions with respect to time of seed collection.

Consideration of ecologically important genetic var-

iation within species is important, and this informa-

tion should be integrated into seed collection and

seed certification strategies for successful ecological

restoration. Increased attention on incorporating tree

improvement into operational seedling production is

needed as the present levels of nursery improvement

appear to be insufficient to meet future demands for

vigorous seedlings in the reforestation of degraded

forests in Mongolia.

Acknowledgements

This study was carried out with the support of

‘‘Cooperative Research for Restoration of Degraded

Ecosystems in Northeast Asia’’, Korea Science and

Engineering Foundation; and ‘‘Forest Science &

Technology Projects (No. S210707L1010)’’, Korea

Forest Service. We also gratefully acknowledge

Marilyn D. Sabalvaro for helpful reviews of an earlier

version of this manuscript.

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Variable Latitude Longitude Altitude Temperature Precipitation

Germination capacity 0.54* �0.18 �0.77* 0.37 0.01

Germination energy 0.53* �0.14 �.083* 0.52* 0.02

Weight of 1000 seeds �0.72* 0.72* 0.10 �0.21 0.59*

Viability 0.36 �0.22 �0.73* 0.18 0.02

Seedling emergence at open nursery 0.25 0.09 �0.78* 0.30 0.22

Seedling emergence at greenhouse nursery 0.39 �0.38 �0.90** 0.42 �0.20

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