Vol.3, No.6, 816-821 (2012) Agricultural Sciences
http://dx.doi.org/10.4236/as.2012.36099
Required amounts of medium and fertilizer for
potted culture of zucchini
Hiromi Ikeura*, Takahiko Tokuda, Yasuyoshi Hayata
School of Agriculture, Meiji University, Kanagawa, Japan; *Corresponding Author: hikeura@meiji.ac.jp
Received 23 July 2012; revised 29 August 2012; accepted 13 September 2012
ABSTRACT
In Japan, zucchini culture has yet to get under-
way, and the current costs of zucchini can be
attributed to damage from soil-borne disease
and the unstable yields due to seasonal change
of female flowers. Eradication of these problems
will lead to st able supply and a conse quent price
reduction of zucchini fruits. We previously clari-
fied the efficacy of potted culture as a new cul-
ture method for zucchini, but potted culture can
be burdensome as the weak water and nutrient
retention capacity of the medium warrants its
regular replacement. To solve this problem, in
this study, we investigated the blend ratio for
mixing rice husk charcoal with peat and the
amount of fertilizer required for potted culture of
zucchini. Results revealed no significant differ-
ences in the length of the largest leaf, total
number of flowers, number of female flowers,
and the ratio of female flowers to total flowers
with different blend ratios of rice husk charcoal
to peat. However, the number of harvested fruits
increased with higher ratios of rice husk char-
coal to peat and was highest at 80:20. The length
of the largest leaf increased with increased
amount s of fertilizer, with the best response was
at 200 g. No significant differences were noted
between the ratio of female flowers to total
flowers in any treatments. In addition, the num-
ber of harvested fruits was highest with 160 g
and 200 g of fertilizer. Taken together, the opti-
mal blend ratio of rice husk charcoal to peat is
80:20, and the optimal amount of fertilizer with
this ratio is 160 g.
Keywords: Zucchini; Rice Husk Charco al; Peat;
Potted Culture; Fertilizer
1. INTRODUCTION
In Japan, large-scale zucchini culture has yet to get
underway, and the current costs of zucchini makes wide-
spread distribution prohibitive. The high cost of zucchini
can be attributed to damage from soil-borne disease and
the unstable yields due to seasonal change of female
flowers. Eradication of these problems will lead to stable
supply and a consequent price reduction of zucchini
fruits, which will open the door for zucchini business
prospects.
Generally, zucchini is produced open culture, but the
culture methods and cultivars are not established due to
difference environmental condition in some areas. Espe-
cially, planting density in zucchini culture is important to
prevent soil-borne disease. In fact, interstrain used in
zucchini culture was from 50 cm to 100 cm, and different
by producers or areas. There are many reports about
study to demonstrate optimum interstrain and cultivar in
zucchini culture [1].
We previously clarified the efficacy of potted culture
as a new culture method for zucchini [2]. However, pot-
ted culture can be burdensome as the weak water and
nutrient retention capacity of the medium warrants its
regular replacement. To solve this problem, we consid-
ered using rice husk charcoal and peat moss as a medium
as both are organic materials with a high cation exchange
capacity and are often used as a medium in soilless cul-
ture [3-9]. Rice husk charcoal and peat moss have been
studied for recycling and the subsequent reclamation of
solid and organic residues produced in agriculture, fam-
ing, forestry, and industry, and they are also being suc-
cessfully used as container media for ornamental plant
production [9,10]. In addition, these organic materials are
available for compost after use and are easily applied in
the field [10,11]. In particular, rice husk charcoal is made
from burning rice husks, which are generated from har-
vested rice, the principal food in Japan and Thailand [12].
In addition, rice husks are typically utilized as a medium
for ornamental crops (e.g., Chrysanthemum morifolium)
and as soil cover for protecting rice in nurseries by cov-
ering with oil paper. Such uses are common because rice
husk charcoal is affordable, has high cation exchange
and aeration properties, has good moisture retentiveness
due to its porosity, and mixes well with other substances
[4,13,14]. Moreover, Inden and Torres (2004) [14] re-
Copyright © 2012 SciRes. OPEN ACCESS
H. Ikeura et al. / Agricultural Sciences 3 (2012) 816-821 817
ported an increase in yield and total soluble solid content
in tomato when using coconut coir or perlite plus car-
bonized rice hulls as a growth substrate. Islam (2008) [15]
described focusing on good aeration and lightweight
properties and thereby found rise husk charcoal to be a
suitable medium for soilless culture. Peat moss, which
has high moisture and nutrient retentiveness as well as a
high buffering ability, is particularly utilized as a growth
medium for strawberry culture [5,16].
In this study, we investigated the effects of different
ratios of rice husk charcoal to peat moss as a medium as
well as the optimal amount of fertilizer required for zuc-
chini potted culture.
2. MATERIALS AND METHODS
2.1. Culture Conditions
Zucchini seeds “Diner” (Takii Co. Ltd., Kyoto, Japan)
were planted in a plastic tray containing propagation
medium (Coop Chemical Co. Ltd., Tokyo, Japan) and
vermiculite (Showa vermiculite Co. Ltd., Kanagawa,
Japan) (1:1). A hydroponic fertilizer (Otsuka house No. 1
and No. 2) diluted 2-fold in tap water (as a standard
concentration) was added for propagation. Interstrain and
interrow spaces after settled planting were 60 cm and 80
cm, respectively. Agrisheet was laid out in a greenhouse
as the pots should not have contact with regular soil.
Rice husk charcoal and peat were purchased from
Berry’s life Co. (Kagawa, Japan) and Nichias Co. (Tokyo,
Japan). Irrigation after settled planting was conducted at
3 L·pot1 at 7 am daily.
2.2. Blend Ratio of Rice Husk Charcoal to
Peat
Culture was conducted in a greenhouse at Meiji Uni-
versity from July 6, 2008 to October 28, 2008. Zucchini
seeds were planted in 12-cm plastic pots (height 10 cm)
containing propagation medium, and seedlings were cul-
tured until developing 7 leaves. The plants were then
settled in 30.5-cm plastic pots (height 30.5 cm; medium
volume, 15 L; Kaneko Seed Co. Ltd., Gunma, Japan) on
July 28, 2008.
The following four blend ratios of rice husk charcoal
to peat were set: 80:20, 60:40, 40:60, and 20:80. Eighty
grams of delayed release fertilizer, Ecolong 424 (N:P:K
= 14:12:13, JCAM AGRI. Co., Ltd., Tokyo, Japan), and
210 g of compost (Fujimi group, Sizuoka, Japan) were
added, and the pH of each medium was adjusted to the
same level (pH 6.5) by adding 7 g of magnesium lime
(Aiko Sekkai Co., Tochigi, Japan) for 80:20 and 60:40
and 120 g of magnesium lime for 40:60 and 20:80. After
adding each medium, fertilizer, compost, and water were
mixed in a soil mixer and drained. All experiments were
replicated 3 times, with 10 plants per replicate.
2.3. Amount of Fertilizer
Culture was conducted from August 11, 2009 to De-
cember 15, 2009 under the same conditions with differ-
ent blend ratios of rice husk charcoal to peat. Plants were
settled in 30.5-cm plastic pots on August 29, 2009. The
following four amounts of fertilizer were set: 80 g, 120 g,
160 g, and 200 g. Based in the results of the above ex-
periments, the most appropriate ratio of medium was
mixed to a volume of 15 L. Other applied fertilizers were
210 g of compost and 7 g of magnesium lime. All ex-
periments were replicated 3 times, with 10 plants per
replicate.
Growth, Pollination, and Harvest
The length of the largest leaf, the total number of
flowers, and the number of female flowers were meas-
ured once every 7 days to establish the female flower to
total flower ratio. Pollination was conducted at 8 - 9 am,
and fruits were harvested at a size with a market value
(16 - 19 cm).
2.4. Statistical Analysis
Data are presented as mean and standard error values,
and statistical differences between treatments were tested
using the Tukey-Kramer test at P < 0.05.
3. RESULTS AND DISCUSSION
The effect of different ratios of rice husk charcoal to
peat on zucchini growth is shown in Table 1. There was
no significant difference in the length of the largest leaf,
total number of flowers, number of female flowers, or
the ratio of female flowers to the total number of flowers.
The number of harvested fruits per pot was 2.8 with
20:80, 2.7 with 40:60, 4.2 with 60:40, and 4.8 with 80:20,
respectively; an obvious increasing trend with increasing
rice husk charcoal (Figure 1). Endo et al. (2006) [16]
demonstrated the effects of root zone substrates consist-
ing of coir and peat mixture on the growth and yield of
strawberry and indicated that the marketable yield of
strawberries increased with decreasing peat ratios. Islam
(2008) [15] described that rice husk charcoal gave simi-
lar and/or better crop performance and yield of tomatoes
than rock wool under high-temperature stress conditions
(30˚C and 35˚C versus 25˚C), which showed that rice
husk charcoal can be used successfully as a growing me-
dium amendment for producing greenhouse tomato as
well as other nursery crops. Promchot and Boonprakob
(2007) [12] reported that rice husk charcoal was better
than agar for embryo culture of nectarines and that it
may be a substitute for vermiculite. Thus, rice husk
Copyright © 2012 SciRes. OPEN ACCESS
H. Ikeura et al. / Agricultural Sciences 3 (2012) 816-821
Copyright © 2012 SciRes. OPEN ACCESS
818
Table 1. Effect of different blend ratios of rice husk charcoal to peat on the growth of zucchini.
Days after planting (mean ± S.E.)
Treatment
15 days 22 days 29 days 36 days 43 days 50 days
20:80 71.20 ± 2.86ay 84.20 ± 4.29a 85.20 ± 1.87a 86.70 ± 2.26a 88.80 ± 4.87a 89.44 ± 5.03a
40:60 70.40 ± 4.38a 85.60 ± 3.50a 87.30 ± 2.91a 88.70 ± 2.79a 89.70 ± 2.41a 91.10 ± 3.14a
60:40 70.80 ± 2.66a 84.10 ± 4.56a 86.60 ± 5.06a 88.33 ± 4.80a 90.56 ± 3.21a 91.56 ± 3.00a
The length of
largest leaf (cm)
80:20 68.20 ± 4.76a 80.40 ± 5.62a 84.80 ± 5.55a 87.30 ± 4.81a 88.30 ± 4.90a 89.10 ± 5.03a
20:80 3.00 ± 0.94a 5.80 ± 0.79a 8.50 ± 0.71a 12.20 ± 1.75a 15.80 ± 1.87a 20.33 ± 1.87a
40:60 2.90 ± 0.57a 5.60 ± 0.70a 8.20 ± 0.63a 12.10 ± 1.20a 15.50 ± 1.18a 18.70 ± 1.19a
60:40 3.00 ± 1.05a 5.40 ± 1.11a 7.80 ± 2.10a 11.78 ± 1.72a 15.11 ± 2.37a 18.56 ± 2.35a
A number of female
flowers (flower)
80:20 3.60 ± 1.07a 6.20 ± 0.92a 8.90 ± 1.66a 13.00 ± 2.11a 16.50 ± 2.55a 19.90 ± 3.05a
20:80 20.90 ± 0.88a 28.40 ± 0.97a 34.00 ± 1.25a 42.70 ± 1.42a 50.60 ± 1.78a 57.89 ± 1.96a
40:60 20.10 ± 0.57a 27.30 ± 0.67a 33.80 ± 1.03a 42.30 ± 0.82a 50.10 ± 0.88a 57.40 ± 1.43a
60:40 21.00 ± 1.25a 29.00 ± 1.15a 35.50 ± 1.58a 43.00 ± 1.73a 51.44 ± 1.88a 57.22 ± 1.79a
Total number of
flowers (flower)
80:20 21.20 ± 1.03a 28.50 ± 5.62a 35.30 ± 3.09a 43.00 ± 3.02a 51.40 ± 2.95a 58.00 ± 3.97a
20:80 14.35 ± 1.08a 20.42 ± 0.82a 25.00 ± 0.57a 28.57 ± 1.23a 31.23 ± 1.05a 35.12 ± 0.95a
40:60 14.43 ± 1.00a 20.51 ± 1.04a 24.26 ± 0.61a 28.61 ± 1.45a 30.94 ± 1.35a 32.58 ± 0.83a
60:40 14.29 ± 0.85a 18.62 ± 0.96a 21.97 ± 1.33a 27.39 ± 0.99a 29.37 ± 1.26a 32.43 ± 1.32a
The ratio of female
flowers to the total
number of flowers
(%)
80:20 16.98 ± 1.04a 21.75 ± 0.16a 25.21 ± 0.54a 30.23 ± 0.70a 32.10 ± 0.86a 34.31 ± 0.77a
Days after planting (mean ± S.E.)
Treatment
57 day 64 day 71 day 78 day 85 day 92 day
20:80 89.44 ± 5.03a 89.75 ± 5.26a 89.75 ± 5.26a 89.75 ± 5.26a 89.75 ± 5.26a 89.75 ± 5.26a
40:60 91.60 ± 3.50a 91.60 ± 3.50a 91.60 ± 3.50a 91.60 ± 3.50a 91.22 ± 3.49a 91.22 ± 3.49a
60:40 91.50 ± 2.78a 91.50 ± 2.78a 91.43 ± 2.99a 91.43 ± 2.99a 91.43 ± 2.99a 91.43 ± 2.99a
The length of largest
leaf (cm)
80:20 89.10 ± 5.30a 89.67 ± 5.29a 89.67 ± 5.29a 89.67 ± 5.29a 89.67 ± 5.29a 89.67 ± 5.29a
20:80 22.89 ± 2.52a 25.50 ± 2.73a 27.00 ± 3.38a 28.88 ± 4.22a 30.50 ± 4.78a 31.38 ± 4.78a
40:60 20.70 ± 2.21a 22.70 ± 1.64a 24.10 ± 1.79a 26.10 ± 2.13a 28.78 ± 2.64a 29.00 ± 2.40a
60:40 20.78 ± 3.15a 22.88 ± 3.87a 24.86 ± 4.74a 26.43 ± 4.72a 28.43 ± 4.93a 30.29 ± 4.57a
A number of female
flowers (flower)
80:20 21.80 ± 2.94a 24.00 ± 3.20a 25.67 ± 3.46a 27.56 ± 3.54a 29.22 ± 4.38a 29.67 ± 3.61a
20:80 62.89 ± 2.62a 67.13 ± 2.36a 70.75 ± 2.49a 74.25 ± 4.65a 77.63 ± 5.66a 80.00 ± 6.61a
40:60 62.80 ± 1.55a 66.60 ± 1.65a 69.80 ± 2.20a 74.20 ± 3.33a 79.44 ± 2.96a 83.22 ± 2.82a
60:40 63.25 ± 2.12a 67.25 ± 2.25a 71.00 ± 2.00a 74.71 ± 2.06a 78.00 ± 2.52a 81.14 ± 2.54a
Total number of
flowers (flower)
80:20 61.90 ± 5.02a 66.67 ± 2.60a 69.89 ± 2.67a 73.67 ± 2.92a 77.22 ± 2.82a 80.44 ± 3.05a
20:80 36.40 ± 0.96a 37.99 ± 1.16a 38.16 ± 1.36a 38.89 ± 0.91a 39.29 ± 0.85a 39.22 ± 0.72a
40:60 32.96 ± 1.43a 34.08 ± 0.99a 34.53 ± 0.81a 35.18 ± 0.64a 36.22 ± 0.89a 34.85 ± 0.85a
60:40 32.85 ± 1.49a 34.01 ± 1.72a 35.01 ± 2.37a 35.37 ± 2.29a 36.45 ± 1.96a 37.32 ± 1.80a
The ratio of female
flowers to the total
number of flowers
(%)
80:20 35.22 ± 0.58a 36.00 ± 1.23a 36.72 ± 1.30a 37.41 ± 1.21a 37.84 ± 1.55a 36.88 ± 1.18a
The ratio of female flowers to the total number of flowers = a number of female/total number of flowers × 100; yDifferent letter indicate statistical differences
etween treatments were tested using the Turkey-Kramer test at P < 0.05 (n = 10). b
H. Ikeura et al. / Agricultural Sciences 3 (2012) 816-821 819
aa
b
c
0
1
2
3
4
5
6
20%R 40%R 60%R 80%R
A number of harvest fruits per pot
Figure 1. Effect of different blend ratios of rice husk charcoal
to peat on the number of harvested zucchini fruits Vertical bars
represent one standard deviation of the mean. Different letters
indicate significant difference at the 5% level according to the
Tukey-Kramer test between treatments (n = 10).
charcoal has various effects on plant variety and growth
stages, but its most prominent effect is as a culture me-
dium. In addition, variety-specific responses should be
considered when giving recommendations for adding the
optimum proportion of organic material amendments to
horticultural potting substrate [17].
It is considered that the 80:20 medium drained well
because the amount of peat (which retains water) was
decreased and because zucchini is better suited to well-
drained soil. Oshio et al. (1981) [4] discussed that rice
husk charcoal has a porous structure which contributes to
aeration and water retention, which in turn enhances wa-
ter and nutrient (especially potassium and phosporous)
retention. These factors suggest that the number of har-
vested fruits increased because sufficient nutrients were
available as a result of the enhanced water and nutrient
retention in the medium.
Potted culture of zucchini is essential to be cheaper
cost of medium due to consisting mostly medium cost. In
Japan, rice is the staple crop, and rice husk charcoal is
abundant and affordable [14]. Therefore, the cost of rice
husk charcoal medium for potted culture will enable fea-
sible cultivation options for zucchini.
The effect of different amounts of applied fertilizer on
the growth of zucchini is shown in Ta b l e 2 . The length
of the largest leaf, total number of flowers, and the num-
ber of female flowers increased with higher amounts of
applied fertilizer and was highest at 200 g. This was
thought that a number of nude increased to have great
vigor of fruits growth with rise amount of applied fertil-
izer. There was no significant difference in the ratio of
female flowers to the total number of flowers in any
treatments. Temperature is an important external envi-
ronmental factor for female differentiation of Cucurbita-
ceae plants, the family to which zucchini belongs [18].
All experiments in the present study were conducted
under the same conditions in the same greenhouse to
ensure the same external variables. Thus it can be in-
ferred that the ratio of female flowers to the total number
of flowers does not fluctuate.
The effect of different amounts of applied fertilizer on
the number of harvested zucchini fruits is shown in Fig-
ure 2. The number of harvested fruits per pot was 4.6
with 80 g, 6.1 with 120 g, 8.7 with 160 g, and 8.9 with
200 g, and increased with increasing amounts of fertilizer
and was highest with 200 g. There was no significant
difference in the number of harvested fruits and the
growth of zucchini with 160 g and 200 g. It was assumed
that the nutrient uptake ability of the roots was limited
because the roots were restricted by the pot. For effective
tomato culture, Zuraiqi and Battilhi (1992) [19] recom-
mended four applications of nitrogen fertilizer per season
at a rate of 30 kg/ha at two-week intervals. In contrast,
Diez et al. (1997) [20] and Eghball and Power (1999) [21]
obtained no yield differences between crops grown with
compost and those grown with chemical fertilizer.
Evanylo et al. (2008) [22] reported that various treat-
ments with organic fertilizer and a commercial agricul-
tural fertilizer did not affect pumpkin or bell pepper
growth. Reiners and Riggs (1997) [23] demonstrated the
effect of nitrogen application and the variety of pumpkin
(Cucurbita pepo L.) marketable yield and found that
pumpkin yield was unaffected by 67, 112, and 157
kg·N·ha1. On the other hand, Takemyou et al. (2002)
[24] reported that the growth of zucchini and harvested
fruits increased in line with increased amounts of applied
fertilizer and that 80 - 160 g medium from a 10 L volume
is suitable for potted culture of zucchini. In this study,
a
a
bb
0
2
4
6
8
10
12
80 g 120 g160 g200 g
A number of harvest fruits per pot
Figure 2. Effect of different amounts of applied fertilizer on the
number of harvested zucchini fruits Vertical bars represent one
standard deviation of the mean. Different letters indicate sig-
nificant difference at the 5% level according to the Tukey-
ramer test between treatments (n = 10). K
Copyright © 2012 SciRes. OPEN ACCESS
H. Ikeura et al. / Agricultural Sciences 3 (2012) 816-821
820
Table 2. Effect of different amounts of applied fertilizer on the growth of zucchini.
Days after planting (mean ± S.E.)
Treatment
3 days 10 days 17 days 24 days 31 days 38 days 45 days 52 days
80 g 28.9 ± 0.5ay35.2 ± 1.1a 51.0 ± 1.5a61.9 ± 1.9a66.3 ± 2.0a73.0 ± 2.0a 75.8 ± 2.4a 78.0 ± 2.0a
120 g 30.4 ± 0.4a34.9 ± 0.5a 49.6 ± 1.1a62.0 ± 1.6ab68.7 ± 1.8a77.6 ± 2.7a 80.7 ± 2.4a 83.1 ± 2.2a
160 g 30.1 ± 0.6a35.2 ± 0.7a 52.2 ± 1.4a65.5 ± 1.3b75.0 ± 2.0a81.3 ± 1.9ab 83.4 ± 1.6ab 84.6 ± 1.6ab
The length of
largest leaf
(cm)
200 g 31.3 ± 1.0a34.7 ± 0.7a 50.0 ± 1.7a63.6 ± 3.0ab75.9 ± 4.0a82.2 ± 2.8b 84.4 ± 3.0b 85.3 ± 3.2b
80 g 6.8 ± 0.1a 11.4 ± 0.3a 17.4 ± 0.3a22.6 ± 0.3a30.0 ± 0.4a32.8 ± 0.4a 37.1 ± 0.5a 40.9 ± 0.7a
120 g 7.0 ± 0.0a 11.5 ± 0.2a 17.4 ± 0.2a23.0 ± 0.3a30.2 ± 0.4a33.9 ± 0.4a 37.8 ± 0.4a 41.0 ± 0.6a
160 g 6.9 ± 0.1a 11.7 ± 0.2a 17.5 ± 0.3a23.4 ± 0.2a31.0 ± 0.3a34.6 ± 0.3a 39.3 ± 0.3a 43.0 ± 0.4ab
A number of
female flowers
(flower)
200 g 6.8 ± 0.1a 11.3 ± 0.2a 17.2 ± 0.2a22.9 ± 0.5a30.7 ± 0.6a34.8 ± 0.6a 39.4 ± 0.7a 43.8 ± 0.7b
80 g 0.0 ± 0.0a 0.1 ± 0.1a 2.2 ± 0.2a 4.9 ± 0.3a 8.0 ± 0.5a 9.2 ± 0.8a 11.3 ± 0.8a 13.0 ± 1.0a
120 g 0.0 ± 0.0a 0.6 ± 0.2a 2.1 ± 0.2a 5.1 ± 0.2a 8.1 ± 0.2a 9.7 ± 0.2ab 11.7 ± 0.4ab 13.4 ± 0.6ab
160 g 0.0 ± 0.0a 0.3 ± 0.2a 2.4 ± 0.3a 5.4 ± 0.4b 8.8 ± 0.3a 10.6 ± 0.5b 12.6 ± 0.6b 14.6 ± 0.9b
Total number
of flowers
(flower)
200 g 0.0 ± 0.0a 0.1 ± 0.1a 1.6 ± 0.2b 4.6 ± 0.5a 7.9 ± 0.5a 9.4 ± 0.6a 11.7 ± 0.6ab 13.4 ± 0.9ab
80 g 0.0 ± 0.0a 1.0 ± 1.0a 12.6 ± 1.4a21.7 ± 1.3a26.8 ± 2.0a27.9 ± 2.1a 30.3 ± 1.8a 31.6 ± 2.0a
120 g 0.0 ± 0.0a 5.2 ± 1.4a 12.1 ± 1.1a22.2 ± 1.0a26.9 ± 0.9a28.7 ± 0.9a 31.0 ± 1.3a 32.8 ± 1.6a
160 g 0.0 ± 0.0a 2.6 ± 1.3a 13.7 ± 1.7a23.1 ± 1.6a28.4 ± 0.9a30.6 ± 1.4a 32.1 ± 1.6a 33.9 ± 1.9a
The ratio of
female flowers
to the total
number of
flowers (%) 200 g 0.0 ± 0.0a 0.8 ± 0.8a 9.2 ± 1.2a 19.9 ± 1.8a25.6 ± 1.3a26.8 ± 1.4a 29.5 ± 1.8a 30.5 ± 1.8a
Days after planting (mean ± S.E.)
Treatment
59 days 66 days 73 days 80 days 87 days 94 days 101 days 108 days
80 g 78.0 ± 2.0a78.0 ± 2.0a 78.0 ± 2.0a78.0 ± 2.0a78.0 ± 2.0a78.0 ± 2.0a 78.0 ± 2.0a 78.0 ± 2.0a
120 g 83.1 ± 2.2a83.1 ± 2.2a 83.1 ± 2.2a83.1 ± 2.2a83.1 ± 2.2a83.1 ± 2.2a 83.1 ± 2.2a 83.1 ± 2.2a
160 g 84.6 ± 1.6ab84.6 ± 1.6ab 84.6 ± 1.6ab84.6 ± 1.6ab84.6 ± 1.6ab84.6 ± 1.6ab 84.6 ± 1.6ab 84.6 ± 1.6ab
The length of
largest leaf
(cm)
200 g 85.3 ± 3.2b85.3 ± 3.2b 85.3 ± 3.2b85.3 ± 3.2b85.3 ± 3.2b85.3 ± 3.2b 85.3 ± 3.2b 85.3 ± 3.2b
80 g 42.8 ± 0.7a46.5 ± 0.8a 50.2 ± 0.8a52.5 ± 0.9a54.7 ± 1.0a56.2 ± 1.1a 57.5 ± 1.4a 59.0 ± 1.5a
120 g 43.6 ± 0.4a46.7 ± 0.6a 50.4 ± 0.7a52.9 ± 0.9a54.9 ± 1.0a56.3 ± 1.2a 58.8 ± 1.4a 59.9 ± 1.6a
160 g 45.4 ± 0.4ab49.6 ± 0.6ab 53.2 ± 0.7ab55.6 ± 0.8ab58.0 ± 1.0ab59.7 ± 1.1ab 61.3 ± 1.3ab 63.1 ± 1.6ab
A number of
female flowers
(flower)
200 g 45.8 ± 0.7b50.1 ± 0.7b 54.5 ± 0.8b57.2 ± 0.7b59.5 ± 0.8b61.8 ± 0.9b 63.7 ± 0.9b 66.1 ± 1.3b
80 g 14.0 ± 1.2a16.2 ± 1.3a 18.9 ± 1.1a20.9 ± 1.0a22.5 ± 1.1a23.8 ± 1.1a 25.3 ± 1.1a 26.4 ± 1.2a
120 g 14.8 ± 0.7ab16.7 ± 1.0ab 19.3 ± 1.0ab21.9 ± 0.9ab23.9 ± 0.7ab25.3 ± 0.6ab 26.6 ± 0.4ab 27.9 ± 0.5ab
160 g 15.8 ± 0.8b18.0 ± 1.2b 21.0 ± 1.0b23.3 ± 0.9b25.2 ± 0.9b26.8 ± 0.8ab 28.4 ± 0.7ab 29.9 ± 0.7ab
Total number
of flowers
(flower)
200 g 14.8 ± 1.0ab16.6 ± 1.2ab 20.2 ± 1.2ab22.9 ± 1.3ab24.7 ± 1.3ab26.9 ± 1.1b 28.6 ± 1.1b 30.8 ± 1.1b
80 g 32.5 ± 2.3a34.6 ± 2.3a 37.6 ± 2.0a39.8 ± 1.7a41.1 ± 1.7a42.3 ± 1.5a 44.0 ± 1.5a 44.7 ± 1.5a
120 g 34.0 ± 1.9a35.9 ± 2.4a 38.6 ± 2.5a41.7 ± 2.2a43.8 ± 2.0a45.3 ± 1.8a 45.6 ± 1.7a 46.9 ± 1.6a
160 g 34.9 ± 2.0a36.3 ± 2.4a 39.6 ± 2.1a42.0 ± 2.0a43.6 ± 2.0a45.1 ± 1.8a 46.5 ± 1.6a 47.6 ± 1.4a
The ratio of
female flowers
to the total
number of
flowers (%) 200 g 32.2 ± 1.9a33.0 ± 2.3a 37.0 ± 2.2a40.0 ± 2.3a41.5 ± 2.2a43.6 ± 2.0a 44.9 ± 1.7a 46.6 ± 1.6a
The ratio of female flowers to the total number of flowers = a number of female/total number of flowers × 100; yDifferent letter indicate statistical differences
etween treatments were tested using the Turkey-Kramer test at P < 0.05 (n = 10). b
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H. Ikeura et al. / Agricultural Sciences 3 (2012) 816-821 821
the volume of medium was 15 L. Water retention and
nutrient capacity of rice husk charcoal differ from those
of peat, suggesting that the amount of applied fertilizer
in the present study is slightly higher than that of Take-
myou et al. (2002) [24].
Taken together, the optimum blend ratio of rice husk
charcoal to peat for potted culture of zucchini is 80:20,
and the optimum amount of fertilizer is 160 - 200 g. In
the future, we intend to examine the effect of timing of
side dressing application on zucchini yield.
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