J. Japan. Soc. Hort. Sci. 77 (2): 143–149. 2008.

Available online at www.jstage.jst.go.jp/browse/jjshs1

JSHS © 2008

Effect of Fertigation Management and the Composition of Nutrient Solution on

the Yield and Quality of High Soluble Solid Content Tomatoes

Shahnaz Sarkar1, Yoshikazu Kiriiwa2, Masanobu Endo2, Tomoya Kobayashi2

and Akira Nukaya2*
1
The United Graduate School of Agricultural Science, Gifu University, Yanagido, Gifu 501–1193, Japan
2
Faculty of Agriculture, Shizuoka University, Ohya, Suruga-ku, Shizuoka 422–8529, Japan

The present experiment was conducted to clarify the effects of different fertigation systems (drip or sub fertigation)
in combination with 2 formulae of nutrient solution (modified Enshi formulation or Shizudai tomato formulation)
at EC 4 dS·m−1 on the response of “High soluble solid content tomato” grown in soilless culture systems from
September, 2005 to February, 2006. The growth, total yield and size of fruit decreased in the sub fertigation
system regardless of the nutrient solution formulation. On the other hand, the soluble solid content was higher
in the sub fertigation system. Sub fertigation inhibited water uptake compared to drip fertigation. EC of the
medium solution was higher in the sub than drip fertigation system, and higher with the Shizudai than the Enshi
formulation. The highest and lowest EC values were 29.6 and 16.1 dS·m−1 in Sub × Shizudai and Drip × Enshi
treatment, respectively. The matric potential of medium in the sub fertigation system was higher than that in the
drip fertigation system. The proline concentration of leaves taken on November 17 and December 2 was higher
in the sub than the drip fertigation system regardless of the nutrient solution formulation. Judging from the above
results, growth and yield suppression in the sub fertigation system seems to be mainly caused by salinity stress,
not by water stress.

Key Words: drip fertigation, proline, salinity stress, sub fertigation, water stress.

and Ho, 1986). Differences of salinity sources in the

Introduction
nutrient solution also greatly influence tomato plant
Tomato (Lycopersicon esculentum Mill.) is one of the growth, and the development and quality of fruits. EC
most popular horticultural crops in the world. Recent management is an important strategic tool (Auerswald
studies on consumer habits regarding fresh vegetables et al., 1999; Li et al., 1999; Van Ieperen, 1996) for the
have shown that taste and aroma are the most important production of good quality, with high sugar content,
factors in the selection of fresh produce (Dorais et al., tomato fruits. In commercial farms in Japan, it is common
2000). Currently, there is an ever-increasing demand for to produce high quality tomatoes, the so-called high
high soluble solid content. The quality of tomato fruit sugar content tomatoes or fruit tomatoes by the
is controlled by the interaction of genetic, environmental application of high EC nutrient solution, including NaCl,
and cultural factors. Ho (1999) reported that improve- to induce stress or by restricting the amount of fertigation
ment of fruit quality is an urgent issue for greenhouse or the volume of substrate to apply water stress in soilless
growers who want to meet the ever-increasing demand culture. Therefore, in the present study, two nutrient
of consumers in a highly competitive fresh fruit market. solution formulae as a source of salinity, namely the
Water and salinity stresses have been applied to improve modified Enshi formulation, which consists of major
tomato fruit quality (Zushi et al., 2005). Salinity stress nutrients, and the Shizudai formulation, which includes
in the root zone is known to improve tomato fruit quality NaCl, CaCl2, KCl, and MgCl2 in addition to a basic
by increasing the Brix value (Adams, 1991; Adams and nutrient solution, were used.
Ho, 1989; Cuartero and Fernandez-Munoz, 1999; Ehret Meanwhile, the methods of fertigation also influenced
the plant growth and fruit quality of tomatoes (Dorais
Received; June 18, 2007. Accepted; October 10, 2007. et al., 2001; Incrocci et al., 2006; Santamaria et al.,
* Corresponding author (E-mail: abanuka@agr.shizuoka.ac.jp). 2003). In drip fertigation system, it is common practice

143
 144 S. Sarkar, Y. Kiriiwa, M. Endo, T. Kobayashi and A. Nukaya

to give an excess amount of nutrient solution at a leaching

Materials and Methods
fraction of 0.2 to 0.3, in order to keep the EC of the
nutrient solution constant to avoid salt accumulation in Tomato seeds ‘House Momotaro’ were sown in non-
the medium by flushing out salts not taken by crops woven fabric pots (12 cm diameter, approximately
(Incrocci et al., 2006; Santamaria et al., 2003). Compared 800 mL volume), which prevented root penetration from
with drip fertigation, sub fertigation apt to leads to salt the pots. These pots were filled with fine coir dust, on
accumulation in the growth medium, especially in the September 14, 2005 after germinating at 25°C for 2 days
upper medium part of the pot (Molitor, 1990; Treder et and raised until the 6 true leaves stage. The pots were
al., 1999), since upward water movement by capillary then placed in troughs (20 cm wide, 4 m long with 3 cm
force and evapo-transpiration-driven mass flow allows side walls), and covered by gray plastic film, with a
soluble salts to accumulate. spacing of 50 cm between pots and 80 cm between
Variations such as the fertigation system and source troughs. The treatments stated below were initiated on
of salinity may affect the growth and yield of tomatoes; October 19, 2005, immediately after setting the pots on
however, there have been few reports on the influence the trough. The experiment was conducted at Shizuoka
of combinations of fertigation system and the source of University in a heated glasshouse in which inside
salinity on the growth, yield and quality of tomatoes. minimum (heating) and ventilation air temperatures were
Therefore, the present study was conducted to clarify 18°C and 23°C, respectively. Plants were grown
the effect of fertigation management (drip fertigation vertically with a single stem and detopped at the 2nd
and sub fertigation) and the composition of nutrient upper leaf above the 4th truss on November 22, 2005.
solution (Enshi formulation and Shizudai formulation) Flowers during anthesis were vibrated manually every
on the response of tomatoes grown in substrate culture day to ensure pollination. The number of fruits was
using non-woven fabric pots filled with a small quantity adjusted to have 4 fruits per cluster at the appropriate
of coir substrate. time. Harvesting of the 1st cluster of fruits commenced
In the present study, the intensity of salinity and water on December 15 and terminated at the 3rd cluster on
stress caused by treatments in the root environment was February 14, 2006.
expressed as the EC of medium solution and matric Treatments consisted of a combination of 2 fertigation
potential of medium, respectively; however, it is difficult systems (sub fertigation and drip fertigation) and 2 kinds
to compare the intensity between salinity and/or water of nutrient solution (modified Enshi formulation,
stress. Recently, proline content in leaves has been abbreviated to Enshi, and Shizudai tomato formulation,
considered a reliable indicator of the environmental abbreviated to Shizudai, as shown in Table 1).
stress imposed on plants (Claussen et al., 2004). Thus, Treatments were abbreviated to Drip × Enshi, Drip ×
the extent of stress intensity among treatments were also Shizudai, Sub × Enshi, Sub × Shizudai as shown in
compared based on the proline content in leaves. Table 2. Both nutrient solutions were adjusted to an
electrical conductivity (EC) of 4 dS·m−1 and pH of 6.0
to 6.7 when prepared. In the drip fertigation system with

Table 1. Composition of nutrient solutions.

EC NO3-N P S Cl K Ca Mg Na
Nutrient solution
(dS·m−1) −1
(me·L )
Modified Enshi formulation (Enshi) 4 24 6 10 0 12 14 10 0
Shizudai tomato formulation (Shizudai) 4 12 3 9 16 10 10 9 9

Table 2. Effects of a combination of nutrient solution and fertigation system on the growth of tomatoes at the end of the experiment.

Treatment Stem length Stem diameterz Fresh weight (g/plant)

Fertigation system Nutrient solution Abbreviation (cm) 1st cluster 3rd cluster Stem Leaf Stem + Leaf
Drip Enshi Drip × Enshi 132 16.1 11.2 157 381 538
Drip Shizudai Drip × Shizudai 136 15.1 10.2 174 438 612
Sub Enshi Sub × Enshi 134 16.5 11.6 123 217 339
Sub Shizudai Sub × Shizudai 125 15.9 9.9 119 157 276
Nutrient solutiony NS * ** NS NS NS
Fertigation systemy NS NS NS *** *** ***
Interaction NS NS NS NS NS NS
z
Measured at the 1st leaf just below each cluster at flowering time.
y
*, **, and *** means significantly different at 5%, 1%, and 0.1% level, by t-test, respectively and NS means not significant.
 J. Japan. Soc. Hort. Sci. 77 (2): 143–149. 2008. 145

free drainage, the nutrient solution was distributed from proline concentration of the leaf lamina adjacent to the
a single reservoir tank for each treatment and was 1st cluster on November 2, the 1st and 2nd clusters on
administrated through one emitter per pot, each having November 17, and the 1st to 3rd clusters on December
a flow rate of 25 mL per min. The leaching fraction (i.e. 2 was measured as described by Bates et al. (1973). The
the ratio between drainage and fertigation volume) was matric potential of coir substrate in pots was measured
around 0 to 0.05 and 0.1 to 0.2 in the first and second by tensiometer (Model AG-T-200, Ishiguro Nozai Co.
halves of the growing season, respectively. The drained Ltd., Japan), which was buried 3 cm from the stem basis,
solution was collected at the bottom end of each trough at an interval of 5 minutes from December 9 to January
to measure the volume and to monitor the EC and pH 16, and the data were collected by a datalogger (Model
every day. In the sub fertigation system, nutrient solution 21x, Campbell Scientific, Inc., USA). Medium solutions
was distributed from a PVC tube (13 cm diameter, 4 m were extracted using a porous cup buried in the pot and
long) with 17 holes, 20 cm apart, which was laid along sucked up with a syringe during the night on December
the trough wall with a flow rate of around 1 L/min/plant 27, December 28, January 12, and January 24, to measure
and collected in a 90 L recirculating tank. the EC and major elemental contents.
The fertigation schedule was controlled by an All data were subjected to ANOVA and Scheffe’s
operation timer and the nutrient solution was applied 21 Multiple Range Test, as and when necessary.
times a day (mostly every 30 minutes) from 6:00 to
Results
17:00, October 19 through November 8, and 20 times a
day from 6:00 to 16:30, November 9 through February There was no significant interaction in stem length,
14, 2006 in both systems. The duration of fertigation stem diameter, fresh weight of stem and fresh weight of
(30 to 180 seconds per time) was determined by daily leaves among the treatments (Table 2). Stem length was
manual operation according to weather conditions in not affected by treatments both before pinching and at
order to apply the nutrient solution just before the leaves the end of the experiment (data not shown). Stem
start showing wilting symptoms on the upper part of diameter was significantly greater in Enshi than Shizudai
tomato plants. The amount of residual volume, the EC formulation, regardless of the fertigation system. On the
and pH of reservoir tanks in the drip fertigation system other hand, the fresh weight of stem and leaves was
and those of recirculating tanks in the sub fertigation greater in the drip fertigation system than the sub
system were measured every day. The amount of water fertigation system, regardless of the nutrient solution
consumption was calculated every day by deducting the formulation. The flowering date of each cluster was not
drained solution from the amount of applied nutrient affected by the treatment (data not shown).
solution. The nutrient solution in the tanks of both Fruit fresh weight was greatest in the Drip × Enshi
systems was refilled with full-strength original solution, and Drip × Shizudai (67 g for both systems), followed
as shown in Table 1, to compensate for crop water by Sub × Enshi (55 g), and then Sub × Shizudai (44 g),
consumption every day. The nutrient solution in sub as shown in Table 3. Most of the fruits were classified
fertigation was renewed twice during the experiment on as M size, between 40 and 80 g/fruit. The number of M
November 7 and December 8 and the EC finally reached size fruit was 7.9, 8.4, 6.8, and 7.1 fruit/plant in Drip ×
8.6 and 7.7 dS·m−1 in Enshi and Shizudai, respectively, Enshi, Drip × Shizudai, Sub × Enshi and Sub × Shizudai,
at the end of the experiment (data not shown). A complete respectively; however, the number of S size fruits (less
randomized block experimental design was adopted with than 40 g) increased in the sub fertigation system and
2 blocks for 4 treatments in Table 2. Each treatment that of L size fruit (more than 80 g) increased in the drip
consisted of 16 plants (8 plants per trough); thus, 64 fertigation system. As a result, total yield was
plants were used for the whole experiment. significantly higher in the drip fertigation system (810
During the experiment, the diameter of the main stem and 795 g/plant in Drip × Enshi and Drip × Shizudai,
just below the fruit clusters during each flowering time respectively) than in the sub fertigation system (592 and
was measured. Stem length and the fresh weight of leaves 489 g/plant in Sub × Enshi and Sub × Shizudai,
and stems were measured at the end of the experiment. respectively). Also, the number of fruits harvested per
In addition to the weight and number of fruits harvested plant decreased in the sub fertigation system regardless
in due course in the ripening stage, the incidence of non- of the nutrient solution formulation, because of a slightly
marketable fruit was also recorded. Soluble solid content higher occurrence of blossom end-rotted fruit. On the
of fruit juice of each cluster, squeezed by hand with other hand, soluble solid content was higher in the sub
cheesecloth, was determined with a hand refractometer fertigation system (11.0%) than in the drip fertigation
(Model FR-100, Atago Co. Ltd., Japan). Major elements, system (10.0%). Also, it was affected by the nutrient
Na and Cl contents, of fruit harvested in the 3rd cluster solution formulation and was higher in Shizudai (10.7%)
were measured by the method of Nukaya et al. (1977), than in Enshi (10.3%). The highest value (11.2%) was
after drying the fruit pulp at 80°C for 2 days in a observed in the Sub × Shizudai treatment, as shown in
ventilated oven. Table 3.
In order to measure the stress level of plants, the The root system was distributed throughout the pot
 146 S. Sarkar, Y. Kiriiwa, M. Endo, T. Kobayashi and A. Nukaya

in the drip fertigation system, but existed only in the The EC of the medium solution was higher in the sub
lower part of the pot in the sub fertigation system. The than drip fertigation system, and higher in the Shizudai
root volume and thickness were less in the sub fertigation than in the Enshi formulation. The highest and lowest
system. EC values were 29.6 and 16.1 dS·m−1 in Sub × Shizudai
Water consumption per plant was almost the same and Drip × Enshi treatment, respectively. The NO3-N
among treatments from the first month to the middle of concentration was also higher in the sub fertigation
November; however, it then became lower in the sub system, and lower in the Shizudai formulation than in
fertigation system than in the drip fertigation system, the Enshi formulation. The Na concentration was highest
and was especially lower in the Sub × Shizudai. The in Sub × Shizudai, followed by Drip × Shizudai, and
difference became apparent on November 20, and it then lowest in both Drip × Enshi and Sub × Enshi treatments.
also decreased in the Sub × Enshi on December 5. Sub K and Mg were higher with the sub than drip fertigation
fertigation inhibited water consumption compared to the system. P and Ca were higher in the Enshi than Shizudai
drip fertigation (Fig. 1). formulation, but were not affected by the fertigation
Changes in the matric potential of the medium system (Table 4).
measured on a fine day in December 26 are shown in Na and Cl in fruits tended to be higher in the Shizudai
Figure 2, with a typical pattern of fluctuation. The matric formulation than the Enshi formulation regardless of the
potential in the sub fertigation system fluctuated between fertigation system. NO3-N and Mg were significantly
−0.5 and 0 kPa during the day time and was higher than higher in the sub fertigation system. P and K were not
that in the drip fertigation system between −2.0 and affected by the treatment.
−0.8 kPa. From December 20 to January 16, the matric The proline concentration of the leaves taken just
potential fluctuated between −2.0 (very occasionally below the first flower cluster on November 2 was not
−3.0) and −0.7 kPa in the drip fertigation system, different among treatments; however, that on November
although in the sub fertigation system it fluctuated 17 and December 2 was higher in the sub than drip
between −1.5 and 0 kPa (data not shown). fertigation system regardless of the nutrient solution

Table 3. Effect of a combination of nutrient solution and fertigation system on the yield of tomatoes at the end of the experiment.

Total yield Marketable yield Number of fruit Fruit fresh weight Soluble solid content
Treatment
(g/plant) (g/plant) (number/plant) (g/plant) (%)
Drip × Enshi 810 802 11.8 67 az 9.8
Drip × Shizudai 795 767 11.4 67 a 10.2
Sub × Enshi 592 561 9.9 55 b 10.8
Sub × Shizudai 489 482 11.2 44 c 11.2
Nutrient solutiony NS NS NS — **
Fertigation systemy *** *** * — ***
Interaction NS NS NS ** NS
z
Mean separation within columns by Scheffe’s multiple range test, at 5% level.
y
Same as Table 2.

Fig. 1. Cumulative consumption of nutrient solution.

 J. Japan. Soc. Hort. Sci. 77 (2): 143–149. 2008. 147

Fig. 2. Changes in matric potential of medium (December 26, fine day).

Table 4. Effect of a combination of nutrient solution and fertigation system on EC and the concentration of
elemental contents in medium solution.

EC NO3-N P K Ca Mg Na
Treatment
(dS·m−1) (me·L−1)
Drip × Enshi 16.1x 173 7 57 37 86 5 cz
Drip × Shizudai 21.9 63 1 52 20 83 95 b
Sub × Enshi 22.5 218 11 71 32 129 6c
Sub × Shizudai 29.6 90 3 68 26 145 145 a
Nutrient solutiony * * * NS * NS —
Fertigation systemy * * NS * NS * —
Interaction NS NS NS NS NS NS ***
z
Same as Table 3.
y
Same as Table 2.
x
Average value of samples taken at December 27 and 28, January 12 and 24 (n = 3).

Fig. 3. Changes in the proline concentration of leaves attached below the 1st cluster.

formulation, as shown in Figure 3. The proline system increased with increasing cluster number, but
concentration, taken just below the first to third flowering that in the drip fertigation system was almost stable
cluster on November 2 was also higher in the sub than among sampling dates (data not shown).
the drip fertigation system; that in the sub fertigation So, the fertigation system significantly differed in leaf
 148 S. Sarkar, Y. Kiriiwa, M. Endo, T. Kobayashi and A. Nukaya

proline content. No significant difference was found in out by Li et al. (2001) and Willumsen et al. (1996);
the proline content of leaves supplying a different however, growth and yield were not affected by the
formulation of nutrient solution. But both (Drip and Sub) source of salinity, in contrast to the result of Adams
fertigation systems showed a high significant difference (1991) and Ehret and Ho (1986). Increased soluble solid
in the leaf proline content in tomato plants. content with the Shizudai formulation was caused by
not only the reduced size of the fruit, but also higher
Discussion
salinity stress expressed as EC and higher Na
It is widely believed that tomatoes grown under saline concentration in the root environment, as shown in
and/or water stress conditions bear higher quality fruits Table 4. The results of sensory testing experiments
(Cuartero et al., 1999); however, quality varied with the reported by Dorais et al. (2000) and Peterson et al. (1998)
cultural practice and also the composition of nutrient showed that fruit from high EC-treated plants with NaCl
solution i.e. source of salinity. enhanced the sensory evaluation of the sweetness of
With respect to cultural practices, Santamaria et al. tomato fruit and improved the overall flavor intensity of
(2003) observed that the yield of cherry tomato was tomato fruit. In the present experiment, the effect of a
lower with sub irrigation than with traditional free- combination of fertigation management and the
drainage drip irrigation, but the quality was higher in composition of nutrient solution on the sensory
sub irrigation. In contrast, Incrocci et al. (2006) reported evaluation of fruit taste and quality was not investigated.
no significant influence of irrigation methods on fruit Further investigation should be conducted to clarify this
yield and quality, when round tomatoes were cultivated point.
by conventional drip irrigation or by sub irrigation in a Salinity stress expressed as EC of the medium solution
closed system. (Table 4) was higher in the Shizudai than Enshi
On the other hand, with respect to the source of formulation, and to a much greater extent in the sub than
salinity, major nutrients or NaCl may influence the yield drip fertigation system in the present experiment. Na
and quality of tomatoes in a different manner, especially concentration in medium solution was extremely higher
at higher (more than 10 dS·m−1) EC in soilless culture. in the Shizudai formulation. Incrocci et al. (2006) stated
Adams (1991) concluded that yield reduction with that, in sub irrigation treatment, salts, especially Na,
increasing salinity at 12 dS·m−1 by major nutrients, due tended to be concentrated in the upper layer and the
to poorer vegetative growth resulting from deficiencies reverse phenomenon was observed in drip irrigation
of Mg, B and Fe, was greater than that of NaCl, as treatment. On the other hand, the matric potential of the
reported previously for NFT (Adams and Ho, 1989; coir substrate in pots was determined by tensiometer to
Ehret and Ho, 1986), and that this response is general, express water stress, as shown in Figure 2. The matric
irrespective of the osmoticum used (Ho and Adams, potential was always higher in the sub than in the drip
1989). fertigation system during the experiment. This means
The present experiment revealed that the growth, yield that water stress in the medium was always higher in
and water consumption per plant were generally greater the drip fertigation system. Judging from the above
in the drip than the sub fertigation system, but the quality results of EC and the matric potential of medium, growth
expressed as soluble solid content of fruit was higher in and yield suppression in the sub fertigation system seems
the sub than in the drip fertigation system, as reported to be mainly caused by salinity stress, but not by water
by Santamaria et al. (2003). This increased soluble solid stress.
content in the sub fertigation system might be related to However, it is difficult to compare the intensity of
decreased fruit size, as shown in Table 3. Yield reduction salinity and water stress, because the unit of such stress
in the sub fertigation system was caused by a reduction is different. Recently, an increase of proline has been
in fruit weight, but not in the number of fruits, as pointed shown in various plant parts when exposed to various

Table 5. Effect of a combination of fertigation methods and composition of nutrient solution on elemental contents
in fruit (% of dry matter basis).

Treatment NO3-N P K Ca Mg Na Cl
Drip × Enshi 0.39 0.31 2.60 0.03 0.13 0.1 cz 0.12
Drip × Shizudai 0.41 0.27 2.42 0.01 0.14 0.2 b 0.80
Sub × Enshi 0.48 0.26 2.49 0.02 0.18 0.2 c 0.19
Sub × Shizudai 0.46 0.36 2.57 0.02 0.17 0.4 a 0.81
Nutrient solutiony NS NS NS * NS — ***
Fertigation systemy ** NS NS NS * — NS
Interaction NS NS NS NS NS * NS
z
Same as Table 3.
y
Same as Table 2.
 J. Japan. Soc. Hort. Sci. 77 (2): 143–149. 2008. 149

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and other amino acid contents of tomato fruit, changes The influence of drip irrigation or subirrigation on tomato
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