STOMATA PROPERTIES OF INVASIVE PLANT Reynoutria japonica

STOMATA PROPERTIES OF INVASIVE PLANT Reynoutria japonica
Houtt. IN THE AREA OF TOPCIDER RIVER SIDES
Matilda Djukić, Danijela Djunisijević Bojović, Dragica Obratov Petković, Mihailo
Grbić, Ivana Bjedov, Dragana Skočajić and Milica Milojević
[email protected]
University in Belgrade, Faculty of Forestry, Department for Landscape
Architecture and Horticulture, Kneza Višeslava 1, 11030 Belgrade, Serbia
Abstract: Reynoutria japonica Houtt. (Poligonaceae) is one of the most invasive
plants with a great spreading potential and it was ranked in a group of 100 the most
invasive organisms by the International Union for Conservation of Nature (IUCN). It is
very common and with luxury growth on the sunny, open and wet habitats. It can be
found near the roads, railways, river banks and on degraded urban areas. In the paper
are presented the results of spreading of this plant in the area of Topcider River sides.
as well as some eco-physiological properties such as stomata density and stomata index
of leaves of various age, physiological vitality and ecological conditions. It was found
that stomata index was significantly different between chlorotic and vital leaves but
there were no differences between young, undeveloped and totally developed leaves. It
was also found that stomata index was significantly higher at plant leaves that grew on
the more sunny sites in compare with plants in shade. Number of stomata was larger on
the lower side than on the upper side of leaves in all populations and ecological
conditions.
Stomata analysis can help in better understanding of physiological processes, water
regime and photosynthesis. The damages of invasive plants are the great challenge in
environment protection and for that reason it is important to have detailed information
of their ecological and physiological properties, reproduction, spreading, taxonomy and
other characteristics which can help to found the best measures how to control and
destroy them.
Key words: Reynoutria japonica Houtt., invasive plants, speading, vitality, stomatal
density and index
1. INTRODUCTION
Invasive plants are generally considered non-indigenous species that ecologically and
economically affect the habitat of which won. Some native species can also take on
characteristics of invasive when heavily colonize specific habitat.
The degree of invasiveness can be estimated on the basis of some biological features,
such as fast growth, early onset of flowering period, often and abundant fruiting, and
the reproductive strategy, dispersal of seeds and fruits. Reynourtria japonica has all the
features of these plants.
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World Association for Conservation of Nature (IUCN) has classified this plant in the
group of 100 the most invasive organisms (Lowe et al 2000). In Switzerland it is on the
black list of invasive non-indigenous plants. The United Kingdom prohibited its
dissemination and in 39 U.S. states all species of the genus Reynoutria have been
declared dangerous weeds and in some are banned and there is a tendency to
completely eradicate because they are classified in the highest category of harmful
invasive plants.
Therefore, the study of ecological, physiological and reproductive characteristics of
this plant is very intensively the last two decades (Bailey, 1990).
The study of stomata characteristics is important because it enables closer knowledge
of the physiological properties of certain plants due to be carried out through them to
receive CO2 necessary to carry out photosynthesis, revealing the water and oxygen.
The plants during their growing season subject to various stress conditions (drought,
floods, extreme low and high temperature). The stomata system is a device physical
mechanism that allows plants to react to short-term and transient adverse effects of
external conditions as a mechanism for homeostasis-stability of the internal
environment. As the stoma respond to a number of internal and external factors the
density, size and the degree of their openness is an integrated feature of all these
factors.
This paper presents the results of the distribution Reynoutria japonica in the
valley of the Topcider River, the presence of a large area along the river course.
The aim was also to determine whether environmental factors (light, shadow), leaf
growth stages (young, elderly), physiological vitality (chlorotic, healthy) and the
position of stomata (face, reverse side) have an impact on the number of stomata. We
analyzed the characteristics of the stomata (density and index) on the leaves of
different ages and environmental conditions in the habitat.
Data on density and stomata index can indicate the properties of the water regime of
the plant. Individuals with a number of stomata have a higher intensity of transpiration,
greater absorption of water and minerals and thus enhance photosynthetic production,
i.e. faster growth and development and the negative impact on the local flora and the
environment.
For further information on the origin, taxonomy, distribution, biology and control
measures are very important because the damage from invasive weeds and now is
perhaps the biggest challenge in protecting the environment.
1.1. Characteristics of the species
Reynoutria japonica (Poligonaceae) is determined by the taxonomic Houttuyn 1777th.
Independently Siebold 1846th was described as Polygonum cuspidatum. It was not
showed that it is the same type until the early 20.th century, although in recent times is
also adopted Meissner's classification in 1856. as Fallopia japonica var. japonica
(Bailey, 1990). Today, authors in different countries use different names.
Reynoutia japonica (Japanese knotweed, Japanese bamboo) comes from the Japanese
Islands, Korea, China and Taiwan (Beerling et al., 1994) where it occurs on mountain
slopes in open, sunny places and is mainly successive species. It can be expanded in
the forest but also in open areas while in the shadow of the forest canopy is more
difficult to manage.
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This plant has been introduced from Japan, present in Europe from the 1840th
(Beerling et al., 1994) and today it is widespread in all of Serbia. There were recorded
few hundred sites in the Belgrade area, mostly near rivers and along roads and railways
where Japanese knotweed was probably spread by different vectors (water, transport,
waste land and other material ...). Species of the genus Reynoutria are the fast-growing
perennials that form dense shrubs with an abundance of leaves that occur early in the
spring and falling in autumn.
1.2.Habitat
Topčiderska River is about 23 km long and its basin the largest in the city, has over 35
streams. About 40% of the coast is protected from strong floods. In the rest of the flow
as well as on a number of tributaries there is the usual torrential flooding and soil
erosion (Studija integralnog uređenja Topčiderske reke).
Geological substrates are sandstone, marls and shale are the dominant soil is with
eutric camisole properties. Climatic characteristics of the area are the continental
climate with annual rainfall 600-700 mm.
The most important forest resources in this area are Kosutnjak and Topcider forest. It
included several forest associations such as climatogenous community (QuercetumFarnetto-cerris Rud.), hornbeam and oak (Querco-Carpinetum sebicum Rud.). S
Carpino-Quercetum farnetto-cerris (Rud.) Gajic is on the western slope of the
Rakovica creek and railroad.
2. MATERIAL AND METHODS
Distribution of Japanese knotweed was investigated along the lower course of the
Topcider River where it occurs to a large extent while in the upstream it was not
recorded. The areas covered with this plant were measured in 31 populations in the part
of the settlement Rakovica to the delta. The number of plants per square meter was
calculated.
It was analyzed the density of stomata on the upper side (abaxial epidermis) and lower
side (adaxial epidermis) of the leaf and stomatal index in six selected populations. The
analysis was done on the fully developed, vital leaves in conditions of full light in the
populations 1,2,3,4,5,6 and young, not fully developed (4a), chlorotic leaves (3a) and
leaves developed in conditions of shade (5a) in order to observe differences in the
properties of stomata.
It was analyzed five plants from each population and samples of epidermal tissue were
taken from the middle part of the plant and the middle part of leave blade near the main
vein. Three samples of every leaf were taken for making permanent preparations.
Determination of the number of stomata and epidermal cells per mm ² was estimated
using light microscopy with ocular scale and stage micrometer scale. For each sample
it was calculated number of epidermal cells, number of stomata and stomatal index.
The mean value of these three calculations was considered mean value for a plant and
mean value for 5 plants, as a mean value for a population. Stomatal index (IS) was
calculated by standard formula IS = S / (S + E) X 100 where S is the number of
stomata per unit area and E the total number of epithelial cells per unit area (mm2).
All results were processed in the statistical analysis of data STATGRAPHIC.
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The conclusions were made on the basis of analysis of variance (ANOVA) and LSD
test was used to determine significant differences among mean values of the treatments
(p<0.05).
3. RESULTS
The study of Japanese knotweed populations in the lower part of the Topcider River
show that there is different size of populations, from smaller, initial of few m2 to a
very developed, larger of 1000 m2. The total area of 31 populations is 11.116 m2.
(Chart 1). Individuals in all populations are very closely spaced, so the number of
plants per m2 varies from 50 to 65.
Population area
1600
1400
1200
1000
m2
800
600
400
200
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
population
Chart 1. Area of 31 populations in the lower part of the Topcider River area
Mean values of stomatal index in 6 selected and investigated populations was
approximately 10 times higher on the lower side of leaves. The variability of stomatal
index on the upper epidermis was much greater (Chart 2, Table 1).
Chart 2. Mean values of stomatal index on
the upper epidermis
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stomatal density on the
lower epidermis [stomata
no. / mm²]
no. of
replicatio
ns
populations
stomatal index for the
lower epidermis
3
119, 667 b
28, 7567 a
pop. 2
3
102, 667
c
23, 6733 b
pop. 3
3
78, 3333
d
23, 1
16, 04
pop. 1
bc
pop. 3a
3
38, 6667
g
pop. 4
3
60, 6667
ef
18, 3033
d
3
d
17, 8933
d
de
23, 8733
b
18, 7467
cd
pop. 4a
87, 0
pop. 5
3
73, 0
pop. 5a
3
57, 0
pop. 6
3
f
141, 667
a
26, 11
d
ab
Table 1. Mean values of stomata density and stomatal index for the lower epidermis in
six Reynoutria japonica populations
Characters a, b, c, d, e as exponent show a homogenous group.
The data in the table 1. show the density of stomata, and the mean values of stomatal
index for the lower epidermis of six populations (including the plants within the same
population that were grown in different environmental conditions 3a, 4a and 5a).
In the analysis of stomatal index in relation to physiological vitality has been
shown that there is a significant difference in the number of stomata. Stomatal index in
healthy leaves was higher, compared to the chlorotic leaves (3, 3a).This is to confirm
that the physiological vitality can affect stomatal characteristics i.e. the anatomy of the
leaf.
The analysis of stomatal index compared to that stage of development, leaves
size show no significant differences between the old, fully developed and young
leaves, yet undeveloped leaves (4, 4a) which confirm that this property is characteristic
for the species in similar ecological conditions.
In relation to the light intensity it was found that stomatal index is significantly
higher in plants growing on sites with stronger insolation than those in the shade. (5,
5a).
4. DISCUSION
Results of number and area of over 11 000 m2 on which Japanese knotweed has
already spread show that there is need for its destruction as a necessary measure of
maintenance and care in the Topcider River area. The damage from these and other
invasive weeds represent one of greatest challenges in environmental protection and
environmental sustainability.
It should be noted that the main problem with this species it is very difficult to
eradicate from the place where one appears. Tolerant to all types of soil pH and salinity
and rhizomes survive very low soil temperatures below - 30 ◦ C.
Experience with the destruction of reynoutria at the coast of Topcider River in the part
where it is regulated (Rusanj) to the confluence of the Sava River, show that the
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intensive mowing encourages rhizome development and plant expansionon the new
areas.
One of the most vulnerable areas in the course of the river is a nursery “Srbijasume” in
Topcider area where this plant has spread to the plant growing beds, a few dozen
meters from the river bed. Multiple treatment of total herbicide did not give the desired
results.
Above-ground parts are dried over the winter while the rhizomes survive very long and
penetrate into the depth of 6 m and lateral spread of up to 20 meters. It can be
recovered from very small parts of the rhizomes (1-2 cm), which significantly
complicates the eradication of established populations. Great power of regeneration is
reflected in the ability to form sprouts from the rhizome at a depth of 1 meter, and to
break through a solid obstacles such as the asphalt thickness of 5 cm (Seiger, 1997).
Endangering transport infrastructure, the railway is threatened by urban and rural part
of the basin.
Analysis of data from Table 1, show that the values stomata index for
populations that are growing in uniform habitat conditions has no statistically
significant difference. The results are consistent, which confirms the assumption that
the stomata index genetically determined characteristics of the species.
Stomatal density varies according to plant age and is directly influenced by
environmental conditions (Justo, 2005). However, such characteristic was positively
related to CO2 assimilation (Abrams et al., 1994), due to the positive relation between
stomatal density and gas exchanges (Araus, 1986) and greater stomatal conductance
(Boardman, 1977). Stomatal index is a relatively constant for each species (Cutter,
1986), and has great taxonomic relevance.
Number, size, shape and arrangement of stomata are influenced by environmental
factors such as the humidity habitats, mineral nutrition, temperature, light, and other.
Thus, the analysis of stomata of beech in Kopaonik determined that the stoma at a
higher altitude, the more arid habitats are smaller and denser than those in the forest
community at a lower altitude (Djukic et al 2002).
Stomatal index can be an indicator of the anatomical structure of leaves. Smaller
stomata index show the larger number of epidermal cells per unit area.
In the analysis of stomata index as compared to the light intensity it is
significant higher in plants growing in positions with stronger sun light. Numerous
research of the show that light conditions affect the size and number of stomata and
thus the photosynthetic production (Ichiro, 2006, Djukic, 2002). Stomata
characteristics can help to determinate character physiological processes, water regime
and photosynthesis in specific plant. Plants with more stomata per unit area have more
transpiration intensity and photosynthetic production.
It should be noted that in addition to Japanese knotweed there are a number of
herbaceous invasive plants that have similar properties like the distribution by
rhizomes as in the case of Aster lanceolatus (Obratov Petkovic D, et al., 2009).
Earlier investigation of woody invasive species in Serbia shows that there are great
numbers of species which are very invasive or potentially invasive and their ecology
and physiology should be investigated. These species are among genus Acer,
Ailanthus, Akebia, Amorpha, Broussonetia, Buddleja, Eleagnus, Fraxinus, Gleditsia,
Lantana, Lycium, Achonia, Prunus, Rhus, Robinia (Grbic et al., 2007).
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The successful control of this invasive plant need the seriously research of ecological
and physiological properties.
5. CONCLUSION
Based on the number and size of populations that have affected an area of over
11,000 m2, it was determined that Reynoutria japonica Houtt. quickly settled the
Topcider River banks and surrounding areas by suppressing the existing vegetation.
This plant fast develop a very dense shrubs from spreading rhizomes which parts
pollute coastlines and waterways flow.
Testing of stomata on leaves of different ages, physiological vitality and light intensity
conditions show that the stomatal index, i.e. anatomical characteristics of leaf
epidermis, is the most affected by the reduced physiological vitality caused by
chlorosis and the lowest by leaf age.
It was also found that stomata index was significantly higher at plant leaves
that grew on the more sunny sites in compare with plants in shade.
Analysis of stomata shows that their number was larger about ten times on the
lower epidermis of leaves in all populations and ecological conditions which is the
characteristic of the species.
So, plants with more stomata per unit area have more transpiration intensity
and photosynthetic production.
The damages of invasive plants are the great challenge in environment
protection and that is the reason it is important to have detailed information of their
spreading, taxonomy, ecology, physiology and other properties which can help to
found the best measures to destroy and control them.
Acknowledgment
The work was done under the project: Ecology, monitoring and technical procedures for the control of
invasive plants in the Belgrade area, financed by the Ministry of Science and Technological Development,
Serbia.
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