Effects of Light and Fertilizer Amounts on Seedling Growth of Brachychiton populneus (Schott & Endl.)

Full text

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Abstract: Nutrient application and light intensity are two important abiotic factors that affect the
plant growth and development. This study was carried out to determine the effect of different NPK
fertilizer amount, viz. 0, 1, 2, 3 and 4 g.pot-1, light regimes, viz. 50% full sunlight (inside the lath
house) and 100% full sunlight (the open area) and their interactions on the growth, chlorophyll
contents and biomass of potted Brachychiton populneus seedlings. At the end of the experiment,
(after six months) growth parameter including plant height (cm), stem diameter (mm) and leaf
numbers, chlorophyll contents and biomass allocation were measured. The results indicate that the
greatest stem height increment, stem diameter increment, leaf number increment, stem dry weight
and leaf dry weight were obtained from the seedlings grown in the open area. However, the highest
chlorophyll content and root dry weight were observed from the seedlings grown inside the lath
house. In addition, the seedlings fertilized with 3 and/or 4 g NPK every two months recorded higher
growth traits, chlorophyll content and biomass allocation than other amounts of the fertilizer. Thus,
the present study suggests that in order to obtain optimum growth of B. populneus potted seedlings,
it should be grown in the open area and fertilized with 3 or 4 g NPK every two months.
Key words: Brachychiton populneus, NPK Fertilizer, Light intensity, Growth performance, Chlorophyll Content.
Introduction
Brachychiton populneus (Schott & Endl.) R.
Br. is a tree species which belongs to the
family of Sterculiaceae and native to Eastern
Australia (Eastern Victoria to Townsville). It
is a medium sized tree, that grows 15-20 m in
height and it is considered as a relatively slow
growing tree species (Anderson, 2016). It is
commonly known as Kurrajong or a Bottle
tree because it can store water in its stem;
additionally, it has a very deep root system,
which is responsible for its drought hardiness
(Anderson, 2016; Karim et al., 2020). The
tree is cultivated as ornamental tree in gardens
and roadsides. The bark was used as fibre,
and the soft spongy wood for making shields.
The leaves are also used as an emergency
fodder for drought-affected animal stock. The
seeds are used as a coffee supplement by
roasting and crushing (Anderson, 2016).
Seedling production with a high quality and
healthy depend on biotic and abiotic factors.
Among abiotic factors, nutrient application
and light intensity are two the most important
factors that affect the plant growth and
physiology (Kozlowski & Pallardy, 1997;
Uchida, 2000).
Nitrogen (N), phosphorus (P) and
potassium (K) play a very vital role in plant
growth and development (Uchida, 2000).
Available online at http://bjas.bajas.edu.iq
https://doi.org/10.37077/25200860.2020.33.2.14
College of Agriculture, University of Basrah
Basrah Journal
of Agricultural
Sciences
ISSN 1814 – 5868
Basrah J. Agric. Sci., 33(2): 158-171, 2020
E-ISSN: 2520-0860
Effects of Light and Fertilizer Amounts on Seedling Growth of
Brachychiton populneus (Schott & Endl.)
Sherzad O. Hamad1*, Narin S. Ali1 & Shaima A. Karim1
1Department of Forestry, College of Agricultural Engineering Sciences,
Salahaddin University, Erbil, 440002 Erbil, Kurdistan Region, Iraq
*Corresponding author e-mail: Sherzad.hamad@su.edu.krd
Received 10 July 2020; Accepted 23 September 2020; Available online 21 October 2020

Hamad et al./ Basrah J. Agric. Sci., 33(2): 158-171, 2020
159
Their functions range from being structural
units to redox-sensitive agents. Growth and
quality of trees are enhanced by the
application of fertilizer (Tripathi et al., 2014).
Plants grown in containers face a number of
limitations, including the lack of growing
space, which provide the required nutrients
(Dang, 2003). Therefore, nutrient application
is commonly used in nurseries to enhance
plant vigour and productivity. Furthermore,
fertilization can improve seedling growth by
either increasing soil resources or by
enhancing the ability of seedlings to gather
resources. Consequently, plants upsurge their
photosynthesis rate, stem diameter, height,
and volume (Razaq et al., 2017).
Light is other essential factor influencing
directly and indirectly on the plant growth. It
contributes directly in seedling growth
through governing its physiological characters
such as photosynthesis, respiration, stomatal
conductance, transpiration, hormone synthesis
and chlorophyll creation (Pallardy, 2008).
Light could also impact the plant growth
indirectly through its influences on air
temperature, humidity, soil temperature and
soil moisture (Bhatla & Lal, 2018). The light
intensity is more significant for growth
performance since both high and low quantity
of sunlight could cause plant stress and at this
situation, the photosynthesis system works
unsatisfactorily, thus plant growth will be
reduced (Lambers et al., 2008).
Subsequently, there is a global interest in
optimizing fertilizer application and light
regimes for different species in the nursery to
achieve healthy and high quality seedlings
(Sherzad et al., 2015; Fu et al., 2017). On the
other hand, there is no previous study on the
growth performance of B. populneus in
responses to fertilizer amount, environmental
situation and their interaction under the
nursery condition. Therefore, the present
study was conducted to determine the effect
of different NPK fertilizer amount, light
regimes and their interactions on the growth,
chlorophyll contents and biomass of potted B.
populneus seedlings.
Material & Methods
The studied species
Healthy one years old B. populneus seedlings
were obtained in the local nursery and used
in this experiment which was carried out in
the Grdarasha field affiliated to the College of
Agricultural Engineering Sciences,
Salahaddin University, Erbil, Iraq from 4th
March until 4th September 2018 (six
months), for this purpose, the seedlings were
planted in black polyethylene bags with 30
cm diameter filled with 5 kg of loamy soil,
the B. populneus seedlings were distributed in
two different light regimes with adding
different amounts of NPK fertilizer.
Moreover, plant height, stem diameter and
leaf number of the species at the beginning of
the study were 36.8 ± 1.3 cm, 3.9 ± 0.16 mm
and 13.5 ± 0.78 respectively.
Experimental design
The experiment was laid in a Factorial
Completely Randomized Design (CRD) with
two factors. The first factor was NPK
fertilizer (20% N: 20% P: 20% K) with five
amounts which were 0 (F0), 1 (F1), 2 (F2), 3
(F3), 4 (F4) g.pot-1 every two months (The
fertilizer amounts were added three times
during the experiment, in the early March,
May and July). The second factor was two
light regimes i.e. inside the lath house (L1),
where light intensity is 50%, and the open
area (L2) where light intensity is 100%, each
treatment with one seedling that replicates
four times, in which there were altogether 40
experimental units.

Hamad et al./ Basrah J. Agric. Sci., 33(2): 158-171, 2020
160
The studied parameters
At the beginning of the experiment, plant
height (cm), stem diameter (mm) and leaf
numbers of the seedlings were recorded. At
the end of the study (September) the
mentioned parameters were re-measured to
find out plant height increment (cm), stem
diameter increment (mm), leaves number
increment.seedling-1 as indicator of seedling
growth. In addition, the biomass parameters
viz. the stem dry weight (g), leaves dry
weight (g) and root dry weight were measured
after separating the seedling into their
components and dried in a furnace at 80°C
until the constant weight obtained (Sherzad et
al., 2017).
Photosynthetic pigments were calculated
by pigments extracted in 95% Ethanol and
Spectrophotometric determination absorbance
taken at 664 nm and 649 nm. Chlorophyll-a
and Chlorophyll-b were calculated using the
following formulas as described by Sumanta
et al. (2014).
Chlorophyll_a = 13.36 A664 − 5.19 A649
Chlorophyll_b = 27.43 A649 − 8.12 A664
Data Analysis
Data of studied parameters were analysed
using two-way analysis of variance
(ANOVA); Duncan test was used to separate
means that were significant at 5% by using
SPSS version 20.
Results & Discussion
Table (1) shows that the light intensities and
the amounts of NPK fertilizer had a
significant effect on the stem height
increment, stem diameter increment and leaf
number increment of B. populneus seedlings.
However, the interaction effect of both factors
had not observed on the mentioned growth
parameters except for the stem height
increment. Moreover, table (2) illustrates that
the seedlings grown in the open area were
recorded significantly higher value of the
stem height increment, stem diameter
increment and leaf number increment (17.9
cm, 5.97 mm and 37.5 respectively) compared
with those grown under the lath house
condition (14.75 cm, 3.61 mm and 15.65
respectively). It means that environmental
factors especially light intensity has played
major role in enhancing growth of B.
populneus seedlings as the seedlings planted
under the full sunlight (the open area) had
better growth than the seedlings planted under
the partial shade (the lath house). This result
confirmed that this species is considered as
light demanding species (Elliot, 2003;
Llamas, 2003).
In addition, the increments of the stem
height, stem diameter and leaf number of the
seedlings fertilized with 3 g NPK.Pot-1 every
two months were greater than those treated
with other fertilizer amounts. The result
highlighted the superiority of the fertilized
seedlings with adequate amount over
unfertilized and poorly fertilized ones in
terms of growth properties. This study
confirmed that the application of an adequate
fertilizer amounts is essential to improve
growth performance of potted seedlings
(Dang, 2003). The same results were reported
by other researchers on different potted tree
seedlings. For instance, Sherzad et al. (2015)
reported that application of 2 g NPK.pot-1.
month-1 significantly increased the height
increment, leaf number increment of Shorea
materialis seedlings compared with
unfertilized seedlings. Han et al. (2016)
investigated that fertilization treatments
significantly increased plant height and root
collar diameter of yellow poplar
(Liriodendron tulipifera L.). AbdelKader et
al. (2016) showed that among NPK fertilizer

Hamad et al./ Basrah J. Agric. Sci., 33(2): 158-171, 2020
161
treatments (0, 1.5, 3.0 and 4.5 g. plant-1), the
medium fertilizer amount 3 g.pot-1 was
optimum for growth of Magnolia grandiflora
L. Razaq et al. (2017) showed that both N and
P application significantly affected plant
height and root collar diameter of Acer mono
and the maximum values of these two
parameters were obtained when 10 g N and 8
g P were used together. So, the application of
macronutrient increases yield, growth, and
quality of trees (Tripathi et al., 2014).
Table (1): Analysis of variance for the effect of different light intensities, NPK
fertilizer amounts and their interactions on, stem height increment, stem diameter
increment and leaf number increment of B. populneus seedlings.
Source of Variation
DF
P- value
Stem height
increment
Stem diameter
increment
Leaf number
increment
Light Intensity (L)
1
0.001
0.000
0.000
NPK Fertilizer (F)
4
0.000
0.000
0.003
L * F
4
0.008
0.177
0.410
Significant occurs when P- value is ≤ 0.05. DF = degree of freedom.
Table (2): Effect of different light intensities and NPK fertilizer amounts on stem
height increment, stem diameter increment and leaf number increment of B.
populneus seedlings.
Factors
Mean of stem
height increment
(cm)
Mean of stem
diameter
increment (mm)
Mean of leaf
number increment
Light Intensity
Lath house (50% of the sunlight)
14.75 b
3.61b
15.65 b
Open area (100% of the sunlight)
17.9 a
5.97 a
37.5 a
NPK Fertilizer (g)
0
9.88 c
3.28 b
18.75 c
1
15.50 b
3.90 b
23.50 bc
2
16.50 b
5.32 a
27.63 ab
3
20.25 a
5.76 a
31.63 a
4
19.50 a
5.70 a
31.38 a
Means with the same letter in a column for each factor are not significantly different by Duncan at p ≤ 0.05.
Fig. (1) exposed that the combination of
both light intensity and NPK fertilizer had a
significant effect only on stem height
increment of the species, where the highest
mean value of this growth character was
obtained from the seedlings grown in the lath

Hamad et al./ Basrah J. Agric. Sci., 33(2): 158-171, 2020
162
Fig. (1): Interaction effect of the light intensities (the lath house (L1) and the open
area (L2)) and NPK fertilizers (0 (F0), 1 (F1), 2 (F2), 3 (F3), 4 (F4) g.pot-1) on stem
height increment value of B. populneus.
house condition and fertilized with 3 g
NPK.pot-1 (L1F3) followed by L2F4, L2F3,
L2F2 and L1F4, while the lowest mean value
was found in the seedlings grown in the lath
house and unfertilized (L1F0). This result
revealed that even though B. populneus is
considered as light demanding tree species, it
can grow well under the shade when
sufficient amount of nutrients is available.
The previous studies reported the same results
about shade tolerant tree species as they
displayed that shade tolerant species are able
to survive and grow agreeably under the full
sunlight during establishment stages if the
seedlings are supported by a suitable amount
of nutrients (Nussbaum et al., 1995; Amrhein
et al., 2012; Tripathi & Raghubanshi, 2014).
Thus, existent of a suitable amount of
nutrients may be a compensation for
inadequate sunlight for growing and survival
tree seedlings. The analysis of variance for
the effect of different light intensities, NPK
fertilizer and their interactions displayed that
both studied factors and their combinations
had a high significant effect on, Chlorophyll-a
(Chl.a), and Chlorophyll-b (Chl.b) of B.
populneus seedlings (Table 3). Furthermore,
the results in table (4) demonstrated that the
seedlings under the lath house had
significantly higher Chlorophyll-a (Chl.a:
1.86 mg g-1 F.W), and Chlorophyll-b (Chl.b:
0.69 mg.g-1 F.W) compared with those under
the full sunlight (Chl.a:1.38 mg. g-1 F.W,
Chl.b: 0.56 mg. g-1 F.W). It means that the
chlorophyll content (Chl.a and Chl.b) of the
seedlings under the shade was higher than
those under the full sunlight. The same result
for different tree species was informed by
many investigators (Lambers et al., 2008;
Mitamura et al., 2008; Kenzo et al., 2011;
Perrin & Mitchell, 2013; Sherzad et al.,
2015). Extra chlorophyll content in the leaf of
seedlings developed under the shade is a
physiological mechanism to adapt with low
light intensity. This phenomenon contributes
5.75 d
13.50 c
14.50 bc
21.50 a
18.50 ab
14.00 c
17.50 abc
18.50 ab
19.00 a
20.50 a
0
5
10
15
20
25
L1 F0 L1 F1 L1 F2 L1 F3 L1 F4 L2 F0 L2 F1 L2 F2 L2 F3 L2 F4
Stem Height Increment (cm)
Light Intensities X NPK Fertilizers

Hamad et al./ Basrah J. Agric. Sci., 33(2): 158-171, 2020
163
to the light-capturing efficiency at low light
condition (Kenzo et al., 2011).
Table (4) also revealed that the amount of
these two pigments increased statistically with
increasing fertilizer NPK, where the highest
value of the pigments (Chl.a: 2.05 mg g-1
F.W, Chl.b: 0.80 mg g-1 F.W) were recorded
from the seedlings treated by 4 g NPK.pot-1
and the lowest value of the pigments (Chl.a:
1.36 mg.g-1 F.W, Chl.b: 0.52 mg.g-1 F.W)
were noted from unfertilized seedlings. This
result displays that usage of NPK fertilizer
particularly nitrogen element directly leads to
rising chlorophyll content of the plants
because nitrogen is one of the main elements
to make chlorophyll molecular (Pallardy,
2008). This result is in agreement with those
achieved by Hokmalipour & Darbandi (2011),
as they found that nitrogen application
significantly increased chlorophyll content.
Razaq et al. (2017) also showed that both N
and P application significantly affected
chlorophyll content of Acer mono and the
maximum values of chlorophyll content, was
obtained when 10 g N and 8 g P were used
together.
Table (3): Analysis of variance for the effect of different light intensities, NPK
fertilizer amounts and their interactions on, Chlorophyll-a, and Chlorophyll-b of B.
populneus.
Source of variation
DF
P- Value
Chlorophyll- a
Chlorophyll- b
Light intensity (L)
1
0.000
0.000
NPK Fertilizer (F)
4
0.000
0.000
L * F
4
0.000
0.000
Significant occurs when P- value is ≤ 0.05. DF = degree of freedom.
Table (4): Effect of different light intensities and NPK fertilizer amounts on
Chlorophyll-a, and Chlorophyll-b of B. populneus seedlings
Factors
Chlorophyll-a
(mg g-1 F.W)
Chlorophyll-b
(mg g-1 F.W)
Light intensity
Lath house (50% of the sunlight)
1.86 a
0.69 a
Open area (100% of the sunlight)
1.38 b
0.56 b
NPK Fertilizer (g)
0
1.36 e
0.52 e
1
1.39 d
0.56 d
2
1.48 c
0.57 c
3
1.81 b
0.66 b
4
2.05 a
0.80 a
Means with the same letter in a column for each factor are not significantly different by Duncan at p ≤ 0.05.
The interaction effect of the light intensity
and NPK fertilizer on the chlorophyll content
in the leaves of B. populneus showed that the
maximum mean value of chlorophyll-a and
chlorophyll-b were significantly achieved
from the seedlings grown in the lath house
and received 4 g NPK.pot-1 (L1F4). However,
the minimum mean value of both chlorophyll

Hamad et al./ Basrah J. Agric. Sci., 33(2): 158-171, 2020
164
contents were statistically observed from
those present in the open area and no treated
with the fertilizer (L2F0) (Figs. 2 and 3).
Moreover, these two figures (2 and 3)
explained that the chlorophyll-a and
chlorophyll-b in leaves of B. populneus were
increased by increasing NPK fertilizer and
reducing light intensity. Results of
chlorophyll content in the present study
concur with that addressed by Sherzad et al.
(2015) as they investigated that the increased
shade ratio and applied NPK fertilizer play
Fig. (2): Interaction effect of the light intensities (the lath house (L1) and the open
area (L2)) and NPK fertilizers (0 (F0), 1 (F1), 2 (F2), 3 (F3), 4 (F4) g.pot-1) on
chlorophyll-a of B. populneus seedlings.
Fig. (3): Interaction effect of the light intensities (the lath house (L1) and the open
area (L2)) and NPK fertilizers (0 (F0), 1 (F1), 2 (F2), 3 (F3), 4 (F4) g.pot-1) on
chlorophyll-b of B. populneus seedlings.
1.52 f 1.57 e 1.72 d
2.22 b 2.24 a
1.20 i 1.21 i 1.24 h 1.40 g
1.85 c
0.00
0.50
1.00
1.50
2.00
2.50
L1 F0 L1 F1 L1 F2 L1 F3 L1 F4 L2 F0 L2 F1 L2 F2 L2 F3 L2 F4
Chlorophyll-a (mg g-1 F.W)
Light Intensities X NPK Fertilizers
0.56 f 0.60 e 0.62 d
0.77 b
0.88 a
0.48 h 0.51 g 0.52 g 0.56 f
0.72 c
0.00
0.20
0.40
0.60
0.80
1.00
L1 F0 L1 F1 L1 F2 L1 F3 L1 F4 L2 F0 L2 F1 L2 F2 L2 F3 L2 F4
Chlorophyll-b (mg g-1 F.W)
Light Intensities X NPK Fertilizers

Hamad et al./ Basrah J. Agric. Sci., 33(2): 158-171, 2020
165
a major role in rising chlorophyll content of S.
materialis seedlings.
Table (5) illustrates that the stem, leaf and
root dry weight were significantly influenced
by different light intensities, fertilizer
amounts and their interactions. In addition,
table (6) demonstrates that both the stem dry
weight and leaf dry weight of the seedlings
grown in the open area condition were
statistically higher than those grown under the
shade (the lath house) condition. However,
root dry weight of the seedlings grown under
the shade (the lath house) condition was
significantly higher than those grown in the
open area condition. These outcomes
confirmed the results that discovered by Paz
(2003), as investigated that light-demanding
species allocate more biomass to the stem and
less to the roots when the species planted in
the open area. In addition, Minotta & Pinzauti
(1996) demonstrated that stem dry weight,
leaf dry weight, root dry weight and total
plant dry weight of Fagus sylvatica seedlings
were significantly increased by the increasing
of light intensity.
Perrin & Mitchell (2013) demonstrated that
plant biomass of Taxus baccata saplings was
significantly influenced by different light
intensities (3, 7, 27 and 100 % relative light
intensity), where an increase of light played a
significant role on the stimulation of total dry
weight and root to shoot ratio of the studied
species. Giertych et al. (2015) explored that
masses of leaves, stems, total roots, coarse
roots, and fine roots in light-demanding
(Sorbus aucuparia and Betula pendula),
intermediate (Carpinus betulus and Quercus
robur), and shade- tolerant (Acer platanoides
and Fagus sylvatica) trees seedlings were
greater values under the full-sunlight
conditions than under the shade conditions.
Elliott & White (1994) demonstrated that
seedlings of Pinus resinosa grown in high
light had four to five times more biomass than
those in the low light condition.
Furthermore, table (6) also elucidates that
NPK fertilizer plays an important role in
increasing plant biomass of B. populneus
seedlings where the greatest masses of stem
(84.15 g) and leaf (21.40 g) were obtained at
4g NPK.pot-1 and the highest root dry weight
(149.93 g) was obtained at 3g NPK.pot-1.
Conversely, the lowest weight of the three
biomass parameters was observed in the
seedlings that did not treated by fertilizer
NPK. Our results concur with the previous
literatures. For instance, Elliott & White
(1994) reported that nitrogen supply had a
significant effect on biomass components of
Pinus resinosa seedlings. Upadhyaya &
Marak (2014) showed that NPK application
especially 1 g.seedling-1 was significantly
stimulated growth and biomass of
Tamarindus indica seedlings compared to
control. Han et al. (2016) investigated that
fertilization treatments significantly increased
stem dry weight and leaves dry weight of
yellow poplar (Liriodendron tulipifera L.),
compared to the control.
Figs. (4) and (5) represent combination
effect of the light intensity and NPK fertilizer
on the stem dry weight and leaf dry weight of
B. populneus seedlings, where the highest
mean value of the mentioned characters were
significantly achieved from the seedlings
grown in the open area and received 4 g
NPK.pot-1 (L2F4). On the other hand, the
lowest mean value of the stem dry weight was
statistically achieved from those grown in the
lath house and unfertilized (L1F0); the lowest
mean value of the leaf dry weight was
attained from unfertilized seedlings in both
the lath house (L1F0) and the open area
(L2F0).

Hamad et al./ Basrah J. Agric. Sci., 33(2): 158-171, 2020
166
Table (5): Analysis of variance for the effect of different light intensities, NPK
fertilizer amounts and their interactions on, stem dry weight, leaf dry weight, and
root dry weight of B. populneus seedlings.
Source of Variation
DF
P- Value
Stem dry weight
Leaf dry weight
Root dry weight
Light intensity (L)
1
0.000
0.000
0.000
NPK Fertilizer (F)
4
0.000
0.000
0.000
L * F
4
0.000
0.000
0.000
Significant occurs when P- value is ≤ 0.05. DF = degree of freedom.
Table (6): Effect of different light intensities and NPK fertilizer amounts on means
of stem dry weight, leaf dry weight, and root dry weight of B. populneus seedlings.
Factors
Stem dry weight
(g)
Leaf dry weight
(g)
Root dry weight
(g)
Light Intensity
Lath house (50% of the sunlight)
39.61 b
12.52 b
100.86 a
Open area (100% of the sunlight)
68.91 a
17.75 a
87.54 b
NPK Fertilizer (g)
0
19.66 e
4.79 d
61.93 e
1
45.02 d
11.56 c
72.19 d
2
50.56 c
16.74 b
78.11 c
3
71.89 b
21.15 a
149.93 a
4
84.15 a
21.40 a
108.83 b
Means with the same letter in a column for each factor are not significantly different by Duncan at p ≤ 0.05.
Fig. (4): Interaction effect of the light intensities (the lath house (L1) and the open
area (L2)) and NPK fertilizers [0 (F0), 1 (F1), 2 (F2), 3 (F3), 4 (F4) g.pot-1] on stem
dry weight of B. populneus seedlings.
15.47 j
31.24h
35.55 g
75.18 b
40.58 f
23.86 i
58.79 e
65.58 d68.59 c
127.71 a
0.00
20.00
40.00
60.00
80.00
100.00
120.00
140.00
L1 F0 L1 F1 L1 F2 L1 F3 L1 F4 L2 F0 L2 F1 L2 F2 L2 F3 L2 F4
Stem Dry Weight (g)
Light Intensities X NPK Fertilizers

Hamad et al./ Basrah J. Agric. Sci., 33(2): 158-171, 2020
167
Fig. (5): Interaction effect of the light intensities (the lath house (L1) and the open
area (L2)) and NPK fertilizers [0 (F0), 1 (F1), 2 (F2), 3 (F3), 4 (F4)] g.pot-1 on leaf
dry weight of B. populneus seedlings.
Furthermore, fig. (6) indicate that root dry
weight of the species in both environment
conditions was increased with increased
fertilizer until 3 g NPK.pot-1. Moreover, the
highest mean value of the root dry weight
were obtained from the seedlings grown
under both the lath house condition and the
open area and fertilized with 3 g NPK.pot-1
and the open area condition with 3 g
NPK.pot-1 (L1F3 and L2F3), while the lowest
mean value were obtained from control
treatment in the open area condition (L2F0).
The above results of plant biomass indicated
that a suitable amount of nutrients is the most
important factor to promote biomass of B.
populneus seedlings under both light
intensities. The result also revealed that an
adequate of light intensity is a significant
factor in determining biomass response to
fertilizer addition. Our findings concur with
the previous literatures. For example, Fetcher
et al. (1996) reported that early successional
and pioneer tree species grown under high
light condition responded well to the N and P
application compared with shade-tolerant and
non-pioneer species. Brown et al. (1999)
stated that fertilizer application under an
adequate of light condition stimulated growth
of Shorea johorensis and Dryobalanops
lanceolata. Lawrence (2001) exhibited that
relative growth rate of Persea romosa (shade-
tolerant species) and Macaranga gigantea
(light demanding species) enhanced with the
addition of both N and P under 18% relative
light intensity. Portsmuth & Niinemets (2007)
revealed that relative growth rate of some tree
species (Acer platanoides, Betula pendula, B.
pubescence, Populus tremula and Quercus
robur) in temperate forest was dramatically
enhanced with increasing light intensity and
nutrient application.
4.93 i
8.41 h
12.04 g
19.41 d
17.78 e
4.66 i
14.71 f
21.44 c
22.89 b
25.03 a
0.00
5.00
10.00
15.00
20.00
25.00
30.00
L1 F0 L1 F1 L1 F2 L1 F3 L1 F4 L2 F0 L2 F1 L2 F2 L2 F3 L2 F4
Leaf Dry Weight (g)
Light Intensities X NPK Fertilizers

Hamad et al./ Basrah J. Agric. Sci., 33(2): 158-171, 2020
168
Fig. (6): Interaction effect of the light intensities (the lath house (L1) and the open
area (L2)) and NPK fertilizers [0 (F0), 1 (F1), 2 (F2), 3 (F3), 4 (F4)] g.pot-1 on root
dry weight of B. populneus seedlings.
Conclusion
Results of the current investigation concluded
that the optimum fertilizer amount and light
intensity to enhance growth and development
of B. populneus potted seedlings are 3 or 4 g
NPK.pot-1 every two months and the open
area (100% of the sunlight). Furthermore,
Chlorophyll-a and chlorophyll-b were
increased by increased NPK fertilizer
amounts while they were declined by
increased light intensity. The best value of the
stem and leaf dry weight were achieved in the
open area and 4 g NPK fertilizer. However,
the highest value of root dry weight was
attained under the lath house (50% of the
sunlight) and 3 g NPK fertilizer. Our results
will help nursery man to produce healthy and
a high quality of B. populneus seedlings to
meet plantation programme.
Acknowledgements
We would like to express our deepest
gratitude to Department of Forestry, College
of Agriculture Engineering Sciences,
Salahaddin University, Erbil for their
supporting. We also extend our thanks to all
staffs in Grdarasha field, which belongs to the
mentioned College, for their helping and
facilities during the practical part.
Conflicts of interest
The authors declare that they have no conflict
of interests.
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 Brachychiton populneus (Schott &
Endl.) 

1

1

1
1

 :
NPK



       
Brachychiton populneus
  





  

 



NPK

B. populneus

NPK

Brachychiton populneus
NPK
