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JOURNAL
OF FOREST
SCIENCE
VOLUME 66
ISSUE 6
(On–line) ISSN 1805-935X
Prague 2020 (Print) ISSN 1212-4834
Journal of Forest Science
continuation of the journal Lesnictví-Forestry
An international peer-reviewed journal published by the Czech Academy of Agricultural Sciences and supported
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© 2020 Czech Academy of Agricultural Sciences MK ČR E 1329
Journal of Forest Science
Volume 66, No. 6 2020
CONTENT
ORIGINAL PAPER
Gallo J., Vacek Z., Baláš M., Vacek S.: Germinative capacity and energy of critically
endangered Ojców birch (Betula oycoviensis Besser) in the Czech Republic ................................................... 227
Ju S., Xu D., Zhang C., Lu J., Jiang X., Ji L.: Induction of tolerance by chlorocholine chloride
in Sequoia sempervirens seedlings under natural cooling and drought.............................................................. 236
Yousefshahi B., Bazgir M., Jamali S., Kakhki F.V.: Morphological and molecular identification
of ectomycorrhizal fungi associated with Persian oak (Quercus brantii Lindl.) tree ..................................... 244
Yukhnovskyi V., Zibtseva O.: Green space trends in small towns of Kyiv region according
to EOS Land Viewer – a case study ................................................................................................................................ 252
Go to the website for information about Journal of Forest Science:
https://www.agriculturejournals.cz/web/jfs/
Journal of Forest Science
Volume 66, No. 6 2020
Editor-in-Chief
Vilém V. Podrázský
Prague, Czech Republic
Co-editors
Peter Surový Radek Pokorný
Prague, Czech Republic Brno, Czech Republic
Executive Editor
Jana Janovcová
Prague, Czech Republic
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Ignacio J. Diaz-Maroto Emanuel Kula Luděk Šišák
Santiago de Compostela, Spain Brno, Czech Republic Prague, Czech Republic
Roger-Dirk Eisenhauer Carsten Lorz Vít Šrámek
Pirna, Germany Freising, Germany Prague, Czech Republic
Michael Englisch Martin Moog Marek Turčáni
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Vladimír Gryc Sasa Orlovic Klaus-Hermann von Wilpert
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Petr Horáček Aleš Zeidler
Brno, Czech Republic Prague, Czech Republic
Journal of Forest Science, 66, 2020 (6): 227–235 Original Paper
https://doi.org/10.17221/47/2020-JFS
Germinative capacity and energy of critically
endangered Ojców birch (Betula oycoviensis Besser)
in the Czech Republic
Josef Gallo*, Zdeněk Vacek, Martin Baláš, Stanislav Vacek
Department of Silviculture, Faculty of Forestry and Wood Sciences,
Czech University of Life Sciences Prague, Prague, Czech Republic
*Corresponding author: gallo@fld.czu.cz
Citation: Gallo J., Vacek Z., Baláš M., Vacek S. (2020): Germinative capacity and energy of critically endangered Ojców birch
(Betula oycoviensis Besser) in the Czech Republic. J. For. Sci., 66: 227–235.
Abstract: Ojców birch (Betula oycoviensis Besser) is a rare and critically endangered taxon of the genus Betula.
Its distribution is limited to few countries in Europe. In the Czech Republic, this taxon, characterized by typical shrubby
habitus, has been found in fewer than 70 tree individuals, prevailingly in the studied locality Volyně, West Bohemia.
This study was focused on the germinative capacity and germinative energy of this taxon, as it is an important indica-
tor of possible regeneration of the trees in nature and for conservation. Non-stratified seeds (2 200 pcs) and stratified
ones (2 200 pcs) were compared to each other and in relation to dendrometric tree parameters. The results showed no
significant (P > 0.1) differences between stratification variants in total germination (higher by 0.8% in stratified), though
stratification improved germinative energy. Germination was in 1st week higher by 6.0% in stratified variant, respectively
marginally (P < 0.1) higher in 2nd week in non-stratified variant. However, both germinative capacity and germina-
tive energy were significantly (P < 0.01) variable between individual trees. The germinative capacity was significantly
(P < 0.05) positively correlated with tree defoliation. Tiny seeds and triploid trees exhibited very low and zero germi-
native capacity and energy, respectively. Totally, seeds exhibited sufficient germinative capacity and germinative energy
of 23.1% (0.0–62.5%). This suggests that the trees can be potentially used for this type of Ojców birch regeneration i.e.
generatively from seeds, although rather in controlled artificial conditions.
Keywords: germination; stratification; silviculture; Ore Mts.; Central Europe
Birches (Betula L.) are an essential ecological the other hand, birch may have commercial impor-
component in European forests (Hynynen et al. tance, especially silver birch (Betula pendula Roth)
2010; Vacek et al. 2016). This genus plays an im- and downy birch (Betula pubescens Ehrh.) (Val-
portant role in the Czech Republic in terms of in- konen, Valsta 2001; Hynynen et al. 2010).
creasing biodiversity, complex forest structure and In Czech Republic, rare taxon of the genus Betula
improving soil properties (Podrázský et al. 2009). Ojców birch (Betula oycoviensis Besser) occurs in
Birches are light-demanding pioneer tree species, addition to the two species mentioned above (Kar-
which rapidly occupy open areas after forest fires, lík et al. 2010; Baláš et al. 2016). Its distribution is
post-mining landscape and clear-cuttings due to limited to several countries in Central, Northern
their prolific seed production and fast juvenile and Eastern Europe (Staszkiewicz 2013; Vítámvás
growth (Fischer et al. 2002; Vacek et al. 2018a). On et al. 2020). At the study area Volyně, Ojców birch
Supported by the Czech University of Life Sciences Prague, Project IGA FLD No. A/19/24 and by the TAČR Agency,
Project No. TAČR TH03030339.
227
Original Paper Journal of Forest Science, 66, 2020 (6): 227–235
https://doi.org/10.17221/47/2020-JFS
also suffers from high intensity of deer browsing, active management likely to disappear from its im-
such as other palatable broadleaved tree species portant locations of occurrence. Seed production
(Vacek et al. 2013; Ambrož et al. 2015). Therefore, and subsequent germination play an important
the ability (density and growth) of natural regen- role for successful birch reproduction in terms of
eration and occurrence of young trees is consid- both natural and artificial regeneration (Hester et
erably decreased due to increasing deer popula- al. 1991; Cameron 1996). Moreover, stratification
tion in the Czech Republic (Vacek 2017; Cukor et can improve the germinative capacity of this tree
al. 2019). Moreover, regeneration of Ojców birch species (Ahola, Leinonen 1999; Mir et al. 2018). For
is strictly limited on study site due to dense grass these reasons, presented study is focused on the
sward (Baláš et al. 2016). Climatic extremes in re- germination of this rare taxon, as it is an important
cent years could also contribute to less vigorous indicator of possible generative regeneration of the
growth and regeneration of birch, as it is case of Ojców birch in nature and for conservation. More-
many other tree taxons (Leslie et al. 2017; Vacek over, data and research dealing with germination of
et al. 2017b; Gallo et al. 2020). On the other hand, Ojców birch are missing. The objectives of this re-
birch (especially Carpathian birch [Betula carpati- search were to (1) determine germinative capacity
ca W. et K.]) is relatively vulnerable to climatic ex- and germinative energy, (2) compare difference in
tremes and air pollution load (Balcar, Kacálek 2001; germination of non-stratified and stratified seeds
Novák et al. 2017), that these stresses historically and (3) observe relationship germination, tree pa-
caused decline and large-scale disturbance of other rameters and health status of this rare critically en-
tree species in study mountain range systems (Král dangered taxon.
et al. 2015; Vacek et al. 2017a; Putalová et al. 2019).
For silviculture and forest management, it is par- Material and methods
ticularly important to differentiate between Betula
pendula Roth group and B. pubescens group and Study area. The seed material of Ojców birch was
select them into mixtures according to site specifi- collected in Volyně settlement near Chomutov, West
cations to ensure best possible vitality of the stands Bohemia, Czech Republic. The locality is situated
in future (Linda et al. 2016). B. pubescens (unlike B. in the Ore Mts. of altitude range 711–745 m a.s.l.
pendula) can be successfully in terms of silviculture on nutrient-poor abandoned pastures. Area of in-
in mixtures with, for example, spruce, as it does not terest is located close to Natural Monument Local-
damage spruce crowns by whipping (Poleno et al. ity Ojców birch near Volyně that was established
2009). In this role, B. oycoviensis belongs to the B. in 1986 of size 1.03 ha due to occurrence of criti-
pendula Roth and usually it is not differentiated cally endangered Ojców birch. Soil type is dystric
(Kuneš et al. 2019). This critically endangered tax- cambisol and prevailing bedrock is schist and
on was first described in 1805 (Besser 1809). Ojców gneiss. Mean annual air temperature reaches 6.5 °C
birch has prevailingly a shrubby habitus of height and annual sum of precipitation is 700 mm. The
around 4–7 m, but on some locations it reaches study territory belongs to humid continental climate
dimensions of medium-size trees with maximum characterized by hot and humid summers and cold
height up to 20 m with typical morphology, such to severely cold winters (Dfb) according to Köppen
as curved and dense branching, dormant buds and climate classification (Köppen 1936), respectively by
epicormic shoots (Staszkiewicz, Wójcicki 1992; detailed region Quitt distribution (Quitt 1971) to
Baláš et al. 2016). It is evident that there is no po- a cold climatic region and CH 7 subregion.
tential commercial use of Ojców birch in forestry, Data collection. Seeds were collected in Septem-
however different growing forms of same species ber after seed year 2018 from morphologically typi-
increase the genetic biodiversity of forests (Ivetić cal Ojców birches and from those that carried suffi-
et al. 2016). cient number of full seeds. Seeds were taken at tree
Successful generative reproduction and follow- height 1–4 m from at least 3 whorls and 2 branches.
ing natural or artificial regeneration is one of key Dendrometric parameters and health status (folia-
factors for successful forest management and sil- tion) of sampled trees were measured (Table 1).
vicultural practise (Karlsson 2001; Vacek et al. Diameter at breast height (DBH) was measured by
2017c), such as in given species. Ojców birch is Blue Mantax caliper (Haglöf, Sweden) to an accu-
a rare and declining tree taxon, which is without racy of 1 mm. Tree height, base of live crown and
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Journal of Forest Science, 66, 2020 (6): 227–235 Original Paper
https://doi.org/10.17221/47/2020-JFS
Table 1. Characteristics of trees sampled for seed material in the locality Volyně
GPS Altitude Height DBH Crown width Crown base Foliation
Tree ID* SQ
Northing Easting (m a.s.l.) (m) (cm) (cm) (cm) (%)
VOL-24D 50.44233 13.21838 713 5.0 11.5 43.5 3.0 2.5 80
VOL-16D 50.44249 13.21829 716 4.6 8.0 57.5 2.2 1.9 40
VOL-06D 50.44553 13.20653 718 2.3 3.8 60.5 2.3 1.5 55
VOL-03D 50.44485 13.21222 745 11.8 12.4 95.2 4.1 6.5 50
VOL-15D 50.44263 13.21842 717 11.5 10.8 106.5 4.8 6.0 55
VOL-25D 50.44235 13.21862 711 2.5 4.5 55.6 1.5 1.3 35
VOL-30D 50.44251 13.21845 715 6.4 9.2 69.6 2.5 2.2 40
VOL-32D 50.44285 13.21868 714 4.4 6.0 73.3 1.9 2.2 30
VOL-05D 50.44553 13.20652 718 3.6 4.8 75.0 1.9 1.8 60
VOL-07D 50.44554 13.20653 718 3.5 3.5 100.0 1.4 1.6 40
VOL-38T 50.44128 13.22095 686 4.0 3.5 114.3 2.0 1.0 95
*last letter indicates chromosome number: D – diploid, T – triploid; DBH – diameter at breast height, SQ– slenderness
quotient (height to diameter ratio)
crown width were measured by Vertex ultrasonic germination were tested in STATISTICA 12 (Stat-
hypsometer (Haglöf, Sweden) to an accuracy of Soft) using nonparametric Mann-Whitney U test.
0.1 m. Tree foliation (health status indicator) was Kruskal-Wallis ANOVA test was used to compare
estimated to the nearest 5% according to methodol- the differences in germination of individual trees.
ogy used in the international project of ICP-Forests Spearman correlation was used to determine the
and ICP-Focus (Lorenz 1995). Defoliation was cal- relationship with dendrometric characteristics of
culated as difference between 100% and foliation. trees (height, DBH, SQ, crown base, crown width),
All trees were tested as diploids, while one tree was health status (foliation) and germination. Statistical
triploid individual (VOL-38T) (Baláš et al. 2019). differences among data were recorded as follows:
The seeds were stored in cooling box (fridge) significant (P < 0.05, P < 0.01), marginal (P < 0.1)
at –2 °C. Two variants were tested: non-stratified and non-significant (P > 0.1). The analysis of the
and stratified. Seeds of stratified variant were first principal components (PCA) was performed in Ca-
placed in sand and stored in cooling box for one noco 5 software (Šmilauer, Lepš 2014) to evaluate
month (cold stratification) before testing. Seeds the relationship between germination, stratificati-
were not exposed to light prior the experiment. on, tree individuals and tree parameters. Data were
For each tree, 4 transparent plastic boxes (with log-transformed and standardized before analysis.
100 seeds in one box) with double-layered moisten The results of multidimensional PCA analysis were
filter paper (ČSN 50 04) were prepared. For each visualized in the form of ordination diagram.
tree, altogether 400 seeds (200 seeds per variant)
were tested, according to ČSN 48 1211 standard.
These prepared variants were cultivated in growing RESULTS
chamber (Q-Cell, Poland) with conditions accord-
ing to standard: temperature 30 °C and light for Germinative capacity and energy
8 hours followed by 16 hours in 20 °C and dark. Results of individual trees and variants (stratified
Number of germinated seeds was counted week- × non-stratified) summarized together and com-
ly as number of healthy and fully developed seeds. pared are in Table 2. In total, 500 seeds (mean 45
Germinative energy was evaluated as the counting ± 37 SD) of non-stratified variant and 518 seeds
after first week of experiment. Next three weekly (mean 47 ± 40 SD) of stratified variant germinated
evaluations represented the tests of germinative out of initial 2 200 for each variant. Stratified vari-
capacity. ant showing higher germination in comparison to
Data analysis. The differences between indivi- non-stratified was marked green, and the contrary
dual trees and stratification variants in terms of was marked red in the Table 2. In the first count-
229
Original Paper Journal of Forest Science, 66, 2020 (6): 227–235
https://doi.org/10.17221/47/2020-JFS
Table 2. Germination per individual Ojców birch trees differentiated by stratification variants – stratified × non-
stratified (stratified variant showing higher germination in comparison to non-stratified is marked green, and the
contrary is marked red)
Total initial 1st week 2nd week 3rd week 4th week
Tree ID number non- non- non- non-
per variant stratified stratified stratified stratified
stratified stratified stratified stratified
VOL-24D 200 3 0 0 0 0 0 0 0
VOL-16D 200 11 26 1 0 0 0 0 0
VOL-06D 200 71 57 5 5 0 0 0 1
VOL-03D 200 60 58 3 2 0 0 0 0
VOL-15D 200 52 80 4 6 0 0 0 0
VOL-25D 200 58 66 16 2 0 1 0 0
VOL-30D 200 42 53 8 0 0 0 0 0
VOL-32D 200 109 121 10 9 0 0 1 0
VOL-05D 200 18 8 1 1 0 0 1 0
VOL-07D 200 19 21 7 1 0 0 0 0
VOL-38T 200 0 0 0 0 0 0 0 0
Mean 40 45 5 2 0 0 0 0
Median 42 53 4 1 0 0 0 0
SD 30.9 34.6 4.7 2.9 0.0 0.3 0.4 0.3
Total 443 490 55 26 0 1 2 1
SD – standard error
ing, stratified variant performed better in 6 out of (P > 0.1), respectively marginally (P < 0.1) higher in
10 cases. In the second counting, it was better only 2nd week in non-stratified variant. In stratified vari-
in 3 cases. Statistically, stratification showed no sig- ant, 1st week 88.6% of seeds germinated from the to-
nificant (P > 0.1) differences between stratification tal number of germinated seeds, while it was 94.6%
variants in germinative capacity (higher by 0.8% in in non-stratified variant.
stratified variant), whereas germination was higher Percentage of germinated healthy seeds for whole
in 1st week (germinative energy) in stratified variants period of the experiment per each tree is in Figure 1.
70
non-stratified
60
stratified
Germinated seeds (%)
50
40
30
20
10
0
Tree ID
Figure 1. Percentage of germinated seeds for the whole experiment period per individual Ojców birch trees
230
Journal of Forest Science, 66, 2020 (6): 227–235 Original Paper
https://doi.org/10.17221/47/2020-JFS
Figure 2. Ordination diagram showing
results of principal components analysis of
relationship between germination (total,
in 1st week, in 2nd week), tree parameters
[Height, DBH – diameter at breast height,
SQ – slenderness quotient (height to di-
ameter ratio), Crown base, Crown width],
health status (Foliation), stratification
variants (stratified, non-stratified), set
of chromosomes (diploid, triploid) and
individual Ojców birch trees
Regardless of variant, most successful in terms of dination diagram was height to diameter ratio. The
germinative capacity was tree ID VOL-32D (62.5%) differences between tree individuals and set of birch
followed by VOL-25D (35.8%). Least successful was chromosomes (diploid, triploid) were significant,
tree ID VOL-24D (0.8%) because of extremely tiny while germination difference between stratified and
seeds. Triploid (ID VOL-38T) did not germinate in non-stratified was very low.
both variants. Mean germinative capacity for the Total germination was significantly (P < 0.01)
11 evaluated tree individuals was 23.1% (22.7% and correlated especially with germination in 1st week
23.5% for non-stratified and stratified, respectively). (r = 0.99) and in 2nd week (r = 0.80; Table 3). Tree
When only diploids were involved, mean germina- parameters (DBH, height, crown width, crown
tive capacity was 25.5% (25.0% for non-stratified and base, HDR) have no significant (P > 0.1) effect on
25.9% for stratified seeds). In four tree individuals, germinative capacity and energy, while these pa-
stratification improved overall germinative capac- rameters (except HDR) were significantly positively
ity, in 6 trees the number was lower for the stratified (P < 0.01) correlated to each other (r = 0.77–0.93).
variant. Generally, there were significant (P < 0.01) On the other site, germination was significant-
differences in germination between individual birch ly (P < 0.01) negatively correlated with foliation
trees from the study site. (r = 0.72).
Relationship between germination, dendromet- Discussion
ric parameters and health status
PCA results expressing the relationship between Generative reproduction is one of possible ways
germinative capacity and energy, tree parameters to regenerate rare tree species (Vincent 1965; Grime
and foliation of individual trees are presented in the 2001). However, seed production is dependent on
form of ordination diagram in Figure 2. The first many factors such as mast year, climatic factors and
ordination axis explains 44.71%, the first two axes soil conditions (Procházková et al. 2002). In natural
77.40% and the four axes together account for 95.40% condition, success of seed reproduction can be signifi-
of data variability. The x-axis represents germination cantly limited due to hares (Lepus) and droughts (Rao
difference between stratification variants and the y- et al. 2003; Vacek et al. 2018b). On study site Volyně,
axis represents the height to diameter ratio. Tree reproduction is also significantly affected by dense
height, DBH and crown parameters were positively grass cover (Baláš et al. 2016), which does not allow
correlated to each other. Total germination was pos- the rooting of the seeds in the soil and subsequently
itively correlated to germination in 1st and 2nd week, it negatively limits seedlings by strong competition
while these parameters were significantly negatively (Vacek et al. 2017c). In controlled conditions, it can
correlated with foliation, respectively positively with be done with success that is however conditioned by
defoliation. The lowest explanatory variable in or- germinative energy and germinative capacity. In our
231
Original Paper Journal of Forest Science, 66, 2020 (6): 227–235
https://doi.org/10.17221/47/2020-JFS
Table 3. Spearman correlation matrix of seed germination (germ.), Ojców birch tree characteristic and health status;
significant differences (P < 0.01) are marked by asterisk and green colour
Total 1st week 2nd week Crown Crown
Height DBH HDR Foliation
germ. germ. germ. base width
Total germ. 1.00
1st week germ. 0.99* 1.00
nd
2 week germ. 0.80* 0.73* 1.00
Height –0.04 0.03 –0.16 1.00
DBH 0.11 0.17 –0.06 0.87* 1.00
HDR –0.07 –0.06 0.03 0.18 –0.24 1.00
Foliation –0.66* –0.66* –0.59* 0.09 0.01 0.27 1.00
Crown base 0.20 0.25 0.07 0.87* 0.93* 0.00 –0.05 1.00
Crown width 0.03 0.06 –0.16 0.77* 0.78* 0.02 0.40 0.72* 1.00
DBH – diameter at breast height, HDR – height to diameter ratio (slenderness quotient)
study, stratified variant of Ojców birch seeds showed treatment (Schubert 1993), as for Sorbus torminalis L.
higher germinative energy (first counting) and over- (Var et al. 2010) or Taxus baccata L. (Melzack et al.
all higher germinative capacity. However, the differ- 1982). In this context, the results of our study are sat-
ences were relatively small and did not change the isfying, because they suggest the possibility of practi-
germinative dynamics of individual trees. The mean cal use of reproduction from seeds.
germinative capacity ranged 23.1% which suggests a The ability to manage species-rich and stable mixed
possibility of generative reproduction in controlled forests is dependent on many factors like natural re-
environment. generation, deer damage (browsing, fraying and bark
Seed germinative capacity is highly variable pa- stripping) and management of disturbances (Simon
rameter (Hoffman et al. 2005; Debnárová, Šmelková et al. 2010). In some cases, the ability of natural re-
2008). Juntilla (1970) reported germinative capac- generation of a native and important species that is
ity around 75% in dwarf birch (Betula nana L.) for enriching forests is limited. Ojców birch in Volyně
seeds exposed to alternating temperatures, but only is a typical example. The only confirmed locality in
10–15% for seeds stratified under a constant tem- Czech Republic suffers from heavy deer browsing
perature. High variability was reported also for paper and lack of active silvicultural management. Also,
birch (Betula papyrifera Marsh.), as from different extreme climatic events could possibly be the partial
provenances it reached 11.1–90.8% (Benowicz et al. reason of recent decline (Gallo et al. 2014; Mikulen-
2001). For Betula pendula, most similar taxon, the ka et al. 2020). Individual Ojców birch trees decline
germinative capacity was reported to be between in time and natural regeneration has not occurred
17.5–48.75% (Reyes et al. 1997), which is compara- (Ondráček 2008). Controlled generative reproduc-
ble to our findings for Betula oycoviensis. Tylkowski tion in combination with artificial regeneration is
(2012) emphasized that the germinability of Betula one of possible ways to conserve the unique birch
pendula is affected by storage time and temperature. stands (Košut 1982). Other ways include different
For the conditions of our methodology, there should types of vegetative reproduction (Vacek et al. 2010;
be no negative impacts as seeds were stored around Vítámvás et al. 2020). Our study showed that dif-
one year in –2 °C. This species supposedly does not ferent seed lots of Ojców birch contain viable seeds
require light pre-treatment for full germinability, as that can be used for regeneration and conservation
some other birches like monarch, Japanese or Erman. of this species, in our case the germinative capacity
(Bonner, Karrfalt 2008). Stratification is recommend- was 23%. It is possible that under various other strat-
ed, but in our case of B. oycoviensis, it did not have ification treatments the germination could be boost-
a significant effect on germination characteristics. ed, but in our case the stratification did not play
It is reported from numerous studies that particu- a crucial role for the germinative parameters. Vin-
larly rare plant and tree species have low germina- cent (1965) also states regarding birch that stratifica-
tive capacity, especially without suitable stratification tion is not necessary, but that seed collection must
232Journal of Forest Science, 66, 2020 (6): 227–235 Original Paper
https://doi.org/10.17221/47/2020-JFS
be done in the right time and that for good germina- of natural regeneration of this rare tree species.
tion the seeds must not dry out. Sufficient natural regeneration of this species is
In terms of tree data, germination of the Ojców a prerequisite for the conservation and successful
birch was negatively correlated with tree foliage i.e. development of this valuable population.
positively with defoliation. Many statistical analyses
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Accepted: June 8, 2020
235Original Paper Journal of Forest Science, 66, 2020 (6): 236–243
https://doi.org/10.17221/118/2019-JFS
Induction of tolerance by chlorocholine chloride
in Sequoia sempervirens seedlings under natural cooling
and drought
Shuming Ju,1, 2* Delan Xu,1 Cuiying Zhang,1 Jiaqi Lu,1 Xueqing Jiang,1
Lingzhen Ji1
1
Xuzhou Institute of Technology, Xuzhou Jiangsu, China
2
Jiangsu Laboratory of Pollution Control and Resource Reuse, Xuzhou Jiangsu, China
*Corresponding author: 1239038921@qq.com
Citation: Ju S., Xu D., Zhang C., Lu J., Jiang X., Ji L. (2020): Induction of tolerance by chlorocholine chloride in Sequoia sem-
pervirens seedlings under natural cooling and drought. J. For. Sci., 65: 236–243.
Abstract: Two-years-old Sequoia sempervirens seedlings were foliar sprayed once and twice with chlorocholine chlo-
ride (CCC) at 0, 100, 500, 1 000, 1 500 and 2 000 mg·l–1. The purpose was to investigate the effect of CCC on the growth
and photosynthetic activity of S. sempervirens seedlings under natural cooling and drought in autumn and winter. The
findings showed that the increments of plant height and crown diameter were significantly decreased with the increase
of chlorocholine chloride concentration, and the increment of root collar diameter, net photosynthetic rate, actual
photochemical quantum yield and photosynthetic electron transport rate showed the trend of increasing first and then
decreasing, and reached the maximum at concentrations of 1 000~2 000 mg·l–1. There was not a significant difference
between two applications and single application. It suggests that 1 000~2 000 mg·l–1 chlorocholine chloride can pro-
tect the photosynthetic activity of S. sempervirens seedlings and alleviate the stress induced by low temperatures and
drought in autumn and winter.
Keywords: plant growth regulators; coast redwood; growth indicators; physiological condition; environment stress
Chlorocholine chloride (2-chloroethyltrimethyl- In the practice of agriculture and forestry, a suit-
ammonium chloride, CCC), as a plant growth in- able application method of CCC is usually selected
hibitor, is widely researched and used in plant pro- based on the criteria of minimum restriction of
duction (Wang et al. 2010; Wu et al. 2014; Karimi plant growth, minimum physiological and meta-
et al. 2014). Earlier studies have shown that CCC bolic damage and significant improvement of plant
application can dwarf plant growth and inhibit resistance (Liu et al. 2013; Zhang et al. 2015a).
branch extension, but it increases photosynthetic Coast redwood (Sequoia sempervirens Endl.) be-
capacity and yield of plant (Wang et al. 2009; Xu longs to relic plants, Taxodiaceae (Zuo et al. 2000;
et al. 2011; Li et al. 2015). Some previous studies Ma et al. 2005; Zhang et al. 2015b), as one of the
have suggested that CCC can increase plant resis- world’s five major landscaping tree species and
tance to salt damage (Liu et al. 2013), UV-B radia- large calibre fast-growing timber species (Olson et
tion (Kreslavskii et al. 2011), lodging (Zhang et al. al. 1990; Zuo et al. 2000, 2003; Ju et al. 2007; Cown
2015a) and leaf spot disease (Kundu et al. 2014). et al. 2013); its successful introduction can beau-
Supported by the National Spark Plan Project (No. S2013C100537), College Natural Fund of Jiangsu Province (No.
07KJD210198), Science and Technology Plan Project of Xuzhou (No. XM13B124); Plan Project of Xuzhou Institute
of Technology (No. XKY201013)
236Journal of Forest Science, 66, 2020 (6): 236–243 Original Paper
https://doi.org/10.17221/118/2019-JFS
tify the environment, enrich biodiversity, improve application would protect coast redwood seed-
the local forestry structure, and bring good eco- lings from damaging effects of natural cooling and
logical, social and economic benefits. Now, it has drought in autumn and winter.
been introduced and cultivated in more than 30
countries, and it has also been successively intro- MATERIAL AND METHODS
duced to many provinces in southern China after
1972 (Zuo et al. 2000, 2003; Liu et al. 2006). Coast Site description. The experimental field is lo-
redwood was introduced to Xuzhou in 2003 (Zuo cated at a nursery base, Xuzhou Institute of Tech-
et al. 2000; Ju et al. 2009). During the Tertiary Pe- nology, in the eastern suburb of Xuzhou, Jiangsu
riod various genera of coast redwoods occurred province (34°15'N, 117°11'W), China, belonging
throughout the northern hemisphere. Coast red- to the warm temperate semi-humid monsoon cli-
wood was eliminated from its former area of distri- mate, with strong spring winds, warm humid sum-
bution by the increasingly drier and cooler climates mer and dry cold winter. The sunshine duration
of the mid and late Tertiary Period. Temperature is 2 284 to 2 495 hours, while the sunshine rate is
and precipitation are the main factors affecting the 52 to 57%, the annual temperature is 14.58 °C, the
survival and distribution of coast redwood (Sim- average lowest temperature is –10.52 °C, the aver-
mons, Thomas 1975; Ma et al. 2005; Zhang et al. age extreme minimum temperature is –37.43 °C, the
2015b). On average, the mean annual temperature annual accumulated temperature is 5 143.5 °C, the
(MAT) for the Sequoia region varies from 13.8 °C average annual frost-free period is about 210 days,
to 11.3 °C, the temperature rarely drops below the average annual rainfall is 853.1 mm. The highest
–9 °C or rises above 38 °C and the mean mini- average temperature in November is 14 °C and the
mum temperature of the coldest month is about lowest average temperature is 4 °C (Figure 1). The
6 °C. Annual precipitation varies between 640 and maximum temperature for the test day is 12 °C and
3 100 mm and mostly winter rains occur in the Se- the minimum temperature is 4 °C.
quoia forest region. It is suggested that the coast Plant culture and CCC treatments. The ex-
redwood was living in a warm and humid subtrop- periments were carried out during September to
ical climate (Ma et al. 2000; Zhang et al. 2015b). November 2014. Uniform 2-years-old seedlings
Xuzhou is located in central and eastern China, it of coast redwood were used as experimental mate-
belongs to the sub-humid warm temperate con- rial. The experiment consisted of 12 treatments: (1)
tinental monsoon climate, four distinct seasons, Single application of CCC (0, 100, 500, 1 000, 1 500,
with hot and rainy summer, low temperature and 2 000 mg·l–1) on September 01, 2014 (2014-9-01);
drought in winter. According to the above analysis, (2) Two applications of CCC (0, 100, 500, 1 000,
the low temperature and drought in autumn and 1 500, 2 000 mg·l–1) on September 01 and Septem-
winter are the main stress factors for successful in- ber 08, 2014 (2014-9-01; 2014-9-08). Six CCC solu-
troduction of coast redwood to Xuzhou. For years, tions were prepared by dissolving the appropriate
studies on adaptability of coast redwood in Xuzhou quantities of 50% CCC water solution in tap water.
have shown that low temperature and drought in Spraying with pure water served as a control. Differ-
autumn and winter could make the twigs of coast ent concentrations of CCC solutions were sprayed
redwood become withered (Ju et al. 2009), which onto plants until drops began to fall from the fo-
has limited the cultivation and promotion of coast liage. The experiment was arranged in a complete
redwood in central and eastern China. So, improv- randomized design with five replicates for each
ing the resistance of coast redwood has become a treatment and each treatment had five seedlings.
practical problem that needs to be solved urgently Measurements of growth indices. Growth in-
for further application and dissemination. dices, including plant height, crown diameter
We could consider the application of a plant and root collar diameter, were measured before
growth inhibitor to coast redwoods to limit the CCC application and after the CCC treatment for
second growth peak in autumn, increase lignifica- 70 days, computational Equations (1–3):
tion of branches, and improve the resistance to low
temperature and drought, so that they could safely Increment of plant height:
survive in winter in Xuzhou. In the present study,
the purpose was to test the possibility that CCC IPH (cm) = H2 – H1 (1)
237Original Paper Journal of Forest Science, 66, 2020 (6): 236–243
https://doi.org/10.17221/118/2019-JFS
Figure 1. Agricultural mete-
orological indicators: average
maximum and minimum
temperature (°C), average
rainfall (mm) of the month
in Xuzhou area, China (2010
to 2018 years)
–
Increment of crown diameter: sity (PPFD) (Januskaitiene 2011; Zhao et al. 2015).
Measurements for each leaf were taken three times
ICD (cm) = C2 – C1 (2) and averaged, one leaf per seedling and five seed-
lings randomly selected per treatment.
Increment of root collar diameter: Measurements of chlorophyll fluorescence pa-
rameters. The third fully expanded leaf counted
IRCD (mm) = D2 – D1 (3) from the top of each seedling was selected to test
the chlorophyll fluorescence parameters, the actual
H1, C1 and D1 represent the plant height, crown diam-
photochemical quantum yield (Yield) (Genty et al.
eter and root collar diameter of coast redwood seedlings
1989 ) and photosynthetic electron transport rate
determined on September 01, 2014, respectively. H2, C2
(ETR) (Genty et al. 1989; Schreiber 2004) using a
and D2 represent the plant height, crown diameter and
chlorophyll spectrometer (MINI-PAM, Walz, Ger-
root collar diameter of the corresponding plants deter-
many), from 14:00 p.m. to 15:00 p.m. on November
mined on November 09, 2014, respectively.
09, 2014. During the measurements, the photosyn-
The crown diameter (the mean of the minimum thetically active radiation and temperature in a leaf
and maximum canopy diameters) and plant height chamber were set to 1 000 μmol·m–2·s–1 and 10 °C,
(the distance between the base of the stem and the respectively. Three measurements per leaf were re-
top of the canopy) were measured with a measur- corded and averaged, one leaf per seedling and five
ing tape. The root collar diameter (the diameter of randomly selected seedlings per treatment.
the base of the plant measured in cm at 5 cm above Statistical analysis. The means ± standard devi-
the ground) was measured with a calliper to the ation were calculated using SPSS 19 software (IBM,
nearest 1 mm. Armonk, New York, USA). The least significant
Measurements of photosynthetic parame- difference (LSD) between the different treatments
ters. The measurement of the net photosynthetic was analyzed by the one-way analysis of variance
rate (Pn) was performed between 14:00 p.m. and (ANOVA) and the interactions between spraying
15:00 p.m. on November 09, 2014, using a porta- times and concentrations of CCC were analyzed by
ble photosynthetic system (LI-6400, LI-Cor 6400, the two-way ANOVA using SPSS 19 software. Cor-
USA). Measurements were done on the third fully relations between the measured indicators were
expanded leaf counting from the top of each plant analyzed using Origin 8.0 software (OriginLab,
at 20 ± 2 °C, 380 ± 15 μmol·mol–1 atmospheric CO2 Northampton, USA). Student’s t-test was applied
concentration and 600 µmol·m–2·s–1 saturating to determine the significance of the differences be-
light at photosynthetically active photon flux den- tween the individual treatments (P < 0.05 or 0.01).
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