Anatomical Characteristics of Ethiopian Lowland bamboo ...

Anatomical Characteristics of Ethiopian
Lowland bamboo (Oxytenanthera abyssinica)
By
Seyoum Kelemwork (PhD)
International Center for Bamboo & Rattan
January 16,2008
Beijing ,China

Acknowledgements
‣ First and foremost I would like to express my sincere
gratitude and appreciation to International center for
bamboo and rattan for providing me an opportunity to
carry out this research.
‣ A special thanks is extended to Dr. Yu Yan for his
constant support throughout the research work
‣ Many thanks to Mr.Tian for all his assistance at several
stages of my laboratory work
‣ My sincere thanks extends to Mr Honghai Dai for all his
hospitality and assistance during my stay in ICBR
‣ Appreciation and thanks extend for Miss Song Ye, all
ICBR staff members and graduate students who helped
me in all aspects during my stay in China

Potential and Utilization of Bamboo
resource in Africa & Ethiopia
‣ Africa possesses about 43 species of bamboo
under 11 genera, covering an area of over 1.5
million hectares
‣ The most widely distributed African bamboo is
categorized under three genera: Arundinaria,
Oreobambos and Oxytenanthera.
‣ The greatest potential bamboo richness is in
East Africa (Ethiopia,Kenya,Sudan& Ugana)
‣ The highest diversity of bamboo in Africa about
33 species are found in Madagascar

The Resource potential of Bamboo in
Ethiopia
‣ Ethiopia which is
unique among
African countries
has over million ha
of bamboo
resources
‣ The ancient
Ethiopian monarchy
had a history of 3
thousand years and
maintained the
countries freedom
from colonial rule,
with the exception of
the 1936-41 Italian
occupation during
World War II

Cont…
‣ Ethiopia with a total
land area of 112.3
million hectares is
located at 3ο 30’ N to
15ο N latitude and of
330 E to 48ο E
longitude in the north
eastern horn of Africa
‣ The country has two
indigenous bamboo
species The highland
bamboo (Arundinaria
alpina K.Schumann Lin;
synonym: Yushania
alpina) and the
monotypic genus
lowland bamboo
Oxythenantera
abyssinica (A. Richard)
Munro.

Cont…
‣ The Ethiopian natural
bamboo forest is about
1 million ha, which is
about 7% of the world
total and 67% of the
African bamboo forest
area
‣ It’s very important to
point out that Ethiopia is
the only country in Africa
which has over 850,000000
ha of Oxythenantera
abyssinica natural
bamboo forest
(Abyssinia )

‣Oxythenantera abyssinica is a clumping
(sympodial) type bamboo with solid culm at
maturing age. It has an average culm
diameter of 5 cm, and is 7 m high
‣This species grows at an elevation of
between 1000 to 1800 m above sea level
and is widely distributed in lowland areas of
the country.
‣It grows naturally in warm climates with
average temperature of 35o C and mean
annual rainfall between 900 to 1400 mm
(Anonymous, 1997).
‣About 85% of the total bamboo forest of the
country is covered by this species

Cont…
Traditionally bamboo
has been widely
used for the
construction of
houses, fuel, feed,
fodder, beehives,
hats, mats, baskets,
handicrafts, small
furniture and other
countless products

‣ In Ethiopia, the economic
potential of bamboo has not
yet tbeen explored and dthe
role of bamboo resources in
national economies is
negligible.
‣ Bamboo plays an important
role only in ecology and
biodiversity conservation in
the country.
‣ Inherent natural properties of
bamboo such as anatomical,
physical and chemical
properties are not studied
‣ There is lack of information
to use these resource for
industrial applications such
as pulp p and paper p production
or in any other large-scale
bamboo industry
Cont…

‣ Oxythenantera
t
abyssinica which uses
for house construction
for sell in the market
‣ Furniture made from
Yushania alpina culms

Objectives of the study
The main objective of this study was
‣ to investigate major anatomical characteristics of
Oxytenanthera abyssinica culms.
Specifically this study attempts to investigate the
followings:
‣ -to evaluate the distribution of vascular bundles.
‣ - to evaluate metaxylem e vessels s distribution
‣ -to evaluate fiber sheath percentage, fiber length
and fiber diameter

Material and method
Sample collection
‣ O.abyssinica culms used in this
study are harvested from Ethiopia
‣ Two, three and four year old Culms
were used for this study
‣ Randomly selected culms were cut
at 30 cm height above ground level
and the merchantable length of culm
was fixed at 6m length
‣ The stem of each culm was marked
and cut at about 2 m, into three
equal portions (bottom,middle and
top)
‣ The 2nd internodes from the bottom
‣ The 2nd internodes from the bottom
side of each portion were chosen for
this experiment

Cont…
Sample preparation
Specimens of bamboo splits of 3 cm length had been
prepared from
‣ three age groups (2, 3 & 4 year-old)
‣ three portions (bottom ,middle & top)
‣ three culm wall layer ( Inner ,middle & outer)
to evaluate basic anatomical parameters
Leica light microscope with the magnification of 5x
was used for
‣ vascular bundles distribution
‣ percentage fiber sheath
‣ percent of metaxylem vessels and
‣ radial/ tangential ration measurements.
Four fields with an area of 2174641 µm2 were
observed in each section.

Cont…
For
‣ Fiber length
‣ Fiber diameter and
‣ Fiber wall thickness
about 1-2 cm length were macerated in a solution of
50% acetic acid and 50% hydrogen peroxide
From
‣ Each age –group
‣ Each culm portion and
‣ Each culm layer
‣ A total of 945 randomly selected fibers were
measured using Leica light microscope

Result and Discussion
The vascular bundles
of O.abyssinica was
examined ed and
classified according
to the classification
of vascular bundles
by Grossert and
Liese (1971).
O.abyssinica may
be categorized
under type III,
consisting of two
parts central
vascular strand and
one fiber strand

Cont…
‣ The vascular bundles
of O.abyssinica
are
formed by two large
metaxylem vessels
two protoxylem
elements, the
phloem, the
sclenrenchyma
sheath and fiber
sheath
‣ vascular bundles
have significant
variations among
the, culm height and
across the culm wall
thickness and have
no variation among
age-groups.

vascular a bundles distribution across culm wall thickness
‣ Across the culm layer vascular
bundles distribution changes
consistently from outer layer
towards the inner layer of the
culm
‣ The highest distribution across
140
the culm wall layer was
120
observed in the outer layer of 3
and 4 year-old culms (about
100
183 bundles/cm2) followed in
80
middle layer of the same age
which has about 149 60
bundles/cm2.
‣ The lowest distribution was
found in the inner layer of 2
year-old culms (about 80
bundles/cm2).
•
2 )
t io n ( bundles/cm 2
bundles distribut
V ascular
200
180
160
40
20
0
Vascualr bundlesmdistribution across the culm layer
bottom middle top
Inner middle outer
Culm wall layer

vascular distribution of bundles anong the culms height
‣ The distribution of
vascular bundles
varied widely along
the culm’s height
Vascular bundles along the culm height
age 2 age3 age4
200
s/cm 2 )
Vascular bundles distribution (bundle
180
160
140
120
100
80
60
40
20
The heights distribution
was observed in the top
portion of 4 year-old and
the lowest was found in
bottom portion of 2 years
old culms
0
bottom middle top
culm portion

Radial and Tangential Ratio of vascular bundles
‣ The shape and size of
vascular bundle was
measured in two
directions as radial and
tangential
3
Radial /Tangential Ratio
age 2 age3 age4
‣ The result of
radial/tangential ratio
shows that a vascular
bundle size varies across
the culm wall layer.
‣ No variation was
observed along the culm
height and among agesgroups.
‣ They are larger in the
middle layers than inner
and outer layers
2.5
R a d ia l/ T a n g e
n t ia l R a t io
2
1.5
1
0.5
0
inner middle outer
Culm layer

Percentage of Metaxylem vessels
• The metaxylem of
O.abyssinica consists of
two large vessels
separated by
parenchyma and serve
for water transport
• The percentage of
metaxylem vessels
varied widely among
culm’s of different age –
groups and height
• No variation across the
culm walls thickness.

Percent of metaxylem vessels along height & age-groups
‣ High percent of
metaxylem vessels are
7
found in younger culms
than older
6
‣ The highest percentage
was observed in the top
5
portion of 3 year-old
culms ( about 6.3%)
4
‣ The lowest was found in
bottom portion of 4 yearold
culms (about 1% ).
‣ Regardless of bamboo
age and culm portion the
percentage of
metaxylem vessels
obtained in this
experiment falls within
the rage of 1 to 6.3
percent
er ce nt 3P a ge of M etaxylem
2
1
0
Percentage of Metaxylem vessels
bottom middle top
age 2 age3 age4
Bamboo Age

• Fibbers are mechanical tissues
and their principal function is
essentially to impart strength to
the culm
• The region with more density in
the vascular bundles is called
fiber sheath and contains
cellulose micro-fibers, which are
responsible for the bamboo
strength.
Fiber sheath Percentage
• The relative area of sheaths in
O.abyssinica a vascular bundle
varies among the culm age and
on the position culm’s wall
thickness
• The fiber sheath percentage
The fiber sheath percentage
along the culm;s height showed
inconsistent variation

Fiber sheath percentage among the age-groups
‣ Fiber sheath percentage
increases from the
30
younger culms towards
the old culms in the
25
middle layers of all age –
groups
20
‣ The fibre sheath
coverage observed at the 15
top portion of 4 year-old
culms was about 28%)
10
‣ At bottom portion of 2
5
year-old culms about
12%) coverage was
0
observed
Fiber sh heath(% )
Fiber sheath Percentage
bottom middle top
age 2 age3 age4
Bamboo age

Fiber sheath percentage across the wall thickness
‣ Highest percentage of
fiber sheath was
observed in bottom
45
portion of 4 year-old
40
outer layer of the culm
wall (40%) than those in
35
middle and inner layers
30
( 30% and 29%
respectively) 25
‣ Regardless of age, culm
portion and culm wall
thickness, fiber sheath
percentage obtained in
this experiment falls
within the rage of 12 to 40
percent.
F ib e r s h e
a t h ( % )
20
15
10
5
0
Fiber sheath across the culm wall layer
bottom middle top
inner middle outer
Culm wall layers

Fiber length, fiber width and wall thicknesses
‣ The fibers in the
culms of O.abyssinica
around vascular
bundles formed a fiber
sheath or fiber cap.
They are long tapered
at both ends
‣ Fiber measurements
results indicated that
O.abyssinica fibers
length differ with age,
culm portion and culm
wall thickness

Fiber length of O.abyssinica culms
• The fiber length is increases
with increase of age
3000
Effect of age on fiber length
bottom middle top
‣ The longer fiber length was
observed in the bottom portion
of 4 year-old culms
(3088.21µm) and the shorter
was found in top portion of 2
year –old culms( 1817 µm)
‣ Fiber length decreases with
increase of culm portion.
Fiber length(µm)
2500
2000
1500
1000
500
0
‣ Regardless of bamboo age
and culm portion the fiber
length obtained in this
experiment falls within the
rage of 1817 to 3088 µm.
age-2
age-
3
Bamboo age
age-4

Fiber diameter and fiber wall thickness
‣ The results indicated that the fiber
wall underwent low thickening
20
from 2 to 4 years growth rate.
bottom middle top
Fiber diameter
‣ The thicker fiber width was
observed in bottom portion of 4
year-old culms (about 18.77 µm)
‣ Thinner was found in top portion
of 2 year-old culms ( about 13.11
µm)
‣ Fiber width showed decreasing
trend from bottom towards top
portion.
‣ Inconsistent variation observed
across the wall thickness .
‣ Regardless of age, height and
culm wall thickness the fiber
diameter observed in this
experiment ranges from 12.77 to
18.77 µm.
18
16
14
12
10
8
6
4
2
0
age 2 age3 age4
Bamboo age

Fiber wall thickness
‣ Increases with increases of
age
7
‣ Thicker wall thickness was
6
observed in bottom portion of
4 year-old (about 6.44 µm)
5
‣ Thinner found in top portion of
4
2 year-old culms (about 4.13
µm)
‣ Decreasing from basal
2
towards the top portion
‣ Across the wall thickness the
fiber wall are thin in the inner
0
layer than middle and outer
layers.
‣ Regardless of age, height and
wall thickness the fiber wall
thickness observed in this
experiment ranges from 3.84
to 6.76 µm.
3wall thickness (µm)
1Fiber
Fiber wall thickness
bottom middle top
age 2 age3 age4
Bamboo age

Conclusion
Based on the results of this study, the following conclusion
may be drawn.
‣ Bottom and middle portion of 3 and 4 year-old
O.abyssinica culms with less vascular bundles
distribution can be used for bamboo-based board’s
applications such as particleboards, medium density
fiber board and strand boards and
for pulp and paper
manufacture
‣ The upper part consists mainly of many smaller vascular
bundles with a high proportion of fibers can be used for
for pulp and paper manufacture, toothpick, match-stick
stick,
incense-sticks, scaffolding sleepers and charcoal
production

Thank you very much