Development of Water Stress Treatment System for Long-term High Brix Tomato Production in Hydroponic Culture
DEVELOPMENT OF WATER STRESS TREATMENT SYSTEM
FOR LONG-TERM HIGH BRIX TOMATO PRODUCTION
IN HYDROPONIC CULTURE
DRUPADI CIPTANINGTYAS
GRADUATE SCHOOL
BOGOR AGRICULTURAL UNIVERSITY
BOGOR
2014
STATEMENT LETTER OF THESIS AND SOURCE OF
INFORMATION AND DEVOLUTION OF COPYRIGHT
Hereby I genuinely stated that the master thesis entitled Development of
Water Stress Treatment System for Long-term High Brix Tomato Production in
Hydroponic Culture is an authentic work of mine supervised by supervisory
committee and never being presented in any forms and universities. All the
information taken and quoted from published or unpublished works of other
writers had been mentioned in the texts and attached in the references at the end of
the master thesis.
I hereby assign the copyright of my papers to the Bogor Agricultural
University.
Bogor, March 2014
Drupadi Ciptaningtyas
NIM F151110071
RINGKASAN
DRUPADI CIPTANINGTYAS. Membangun Sistem Water Stress Treatment
untuk Produksi Jangka Panjang Tomat Berkadar Gula Tinggi secara Hidroponik.
Dibawah bimbingan HERRY SUHARDIYANTO dan NORIKO TAKAHASHI.
Permintaan tomat berkadar gula tinggi yang lebih dikenal sebagai fruit
tomato semakin meningkat sekarang ini. Banyak penelitian mengungkapkan
bahwa aplikasi water stress treatment dapat digunakan untuk memproduksi tomat
berkadar gula tinggi, namun penelitian-penelitian tersebut dilakukan hanya dalam
waktu singkat dengan kadar air media tanam sekitar 50%-80% (Nuruddin et al.
2003; Patane and Consentino, 2010). Telah banyak penelitan mengenai pengaruh
water stress treatment terhadap pertumbuhan tanaman, namun penelitian
mengenai cara mengoperasikan water stress treatment untuk meningkatkan
kualitas buah tomat belum begitu banyak dilakukan. Menjaga agar tanaman tomat
tetap sehat dalam kondisi water stress tidaklah mudah. Penelitian ini
memperkenalkan visual monitoring system sebagai pengontrol kondisi severe
water stress. Tujuan dari penelitian ini adalah membangun sebuah sistem water
stress treatment untuk produksi jangka panjang tomat berkadar gula tinggi secara
hidroponik dan melakukan evaluasi sistem water stress treatment yang dilakukan
jangka panjang dalam kondisi severe water stress disertai perubahan musim
terhadap kualitas dan kuantitas buah tomat. Selain itu, pengaruh water stress
terhadap pertumbuhan tanaman juga diteliti. Semua data dari penelitian ini dapat
digunakan untuk basis data dalam pembangunan sebuah sistem water stress yang
lebih baik lagi.
Tanaman tomat (Solanum lycoperscium L., Momotaro Sakura) ditanam
secara hidroponik diatas rockwool slabs didalam sebuah rumah tanaman di
Fakultas Pertanian, Universitas Ehime. Luasan daun tanaman tomat dimonitor
oleh sebuah kamera digital yang mengambil gambar setiap 15 menit. Kadar air
rockwool slabs diukur dengan Water Content Meter satu kali sehari pada siang
hari. Terdapat dua perlakuan dalam penelitian ini yaitu, water stress treatment dan
kontrol. Kadar air media tanam dijaga sekitar 20%-30% untuk water stress
treatment dan 60%-70% untuk kontrol. Pemberian irrigasi dilakukan berdasarkan
proyeksi luasan daun dan kadar air media tanam. Ketika proyeksi luasan daun
kurang dari 95% dari proyeksi luasan daun maksimum yang diukur setelah irigasi
terakhir dan kadar air media tanam kurang dari 20%, larutan nutrisi akan dialirkan
ke tanaman hingga kadar air kembali 20%. Untuk pengukuran pertumbuhan
tanaman, diameter dan perpanjangan batang diukur satu kali dalam satu minggu
dengan menggunakan jangka sorong dan meteran. Diameter buah, tingkat
kemanisan dan tingkat keasaman diukur dengan menggunakan ISEKI Grading
Machine. Kalibrasi untuk tingkat kemanisan buah tomat dilakukan secara
destruktif dengan menggunakan Refractometer, sedangkan tingkat keasaman buah
tomat dikalibrasi dengan menggunakan KUBOTA Fruits Selector Machine.
Hasil penelitian menunjukkan bahwa dibutuhkan waktu 1.5 jam untuk
tanaman tomat kembali ke kondisi baik setelah diairi dalam kondisi layu karena
water stress treatment. Beberapa kondisi yang tidak diharapkan terjadi, ketika
radiasi matahari tinggi dan kelembaban relatif rendah, kadar air media tanam
berkisar 11% yang mana lebih rendah dari yang diharapkan. Disisi lain, ketika
radiasi matahari rendah dan kelembaban relatif tinggi, kadar air media tanam
berkisar 40% yang mana lebih tinggi dari harapan. Radiasi matahari yang rendah
dan kelembaban relatif yang tinggi dapat berkontibusi untuk menjaga kadar air
media tanam dalam kondisi cukup tinggi. Diameter batang berkisar 4.4 mm-7.78
mm untuk water stress dan 8.45 mm-11.68 mm untuk kontrol. Perpanjangan
batang berkisar 0.08 m week-1-0.18 m week-1 untuk water stress dan 0.17 m week1
-0.25 m week-1 untuk kontrol. Baik diameter batang maupun perpanjang batang
tanaman tomat pada perlakuan water stress selalu lebih kecil dan lebih lambat dari
tanaman kontrol. Hasil ini meyatakan bahwa perlakuan water stress dapat
mempengaruhi pertumbuhan tanaman.
Pengukuran parameter kuantitas menunjukkan, perbedaan jumlah buah yang
dipanen antara perlakuan water stress dan kontrol tidaklah terlalu besar. Rata-rata
jumlah buah yang dipanen untuk perlakuan water stress adalah 41.8±18.8 fruit
week-1 sedangkan untuk kontrol adalah 50.1±19.4 fruit week-1. Diameter buah
berkisar 634.3 mm-755.2 mm untuk water stress dan 731.9 mm-822.8 mm untuk
kontrol. Meskipun rata-rata jumlah buah yang dipanen untuk kedua perlakuan
tidak berbeda nyata (t-test dengan level 5%), hasil panen dari perlakuan water
stress lebih rendah dibandingkan dengan kontol. Perlakuan water stress akan
menghasilkan buah dengan kadar padatan terlarut yang tinggi dan ini akan terjadi
seiring dengan penurunan massa buah. Hal ini dapat disebabkan oleh keterbatasan
karakteristik physiologi, seperti efisiensi fotosintesis, hubungan sink-source, dan
kehilangan dalam proses respirasi (Davies and Hubson 1981). Hasil ini
menyatakan bahwa penurunan hasil panen pada perlakuan water stress
disebabkan oleh penurunan ukuran buah.
Pengukuran parameter kualitas menunjukkan, tingkat kemanisan buah tomat
dibawah perlakuan water stress selalu lebih tinggi dibandingkan dengan kontrol.
Perbedaan tingkat kemanisan antara perlakuan water stress dan kontrol berkisar
antara 0.2% hingga 2.5%. Patane dan Consentino (2010) melaporkan perbedaan
tingkat kemanisan antara perlakuan water stress dan kontrol berkisar antara
0.55% hingga 1.4% dalam eksperimen jangka pendek. Penelitian mereka
dilakukan dengan kadar air media tanam dijaga sekitar 50%. Kondisi severe water
stress dalam penelitian ini, dengan kadar air media tanam berkisar 20%-30%,
akan menghasilkan tomat dengan tingkat kemanisan yang lebih tinggi
dibandingkan dengan moderate water stress. Tingkat keasaman buah tomat yang
dihasilkan dari perlakuan water stress juga selalu lebih tinggi dari kontrol.
Perbedaan tingkat keasaman antara perlakuan water stress dan kontrol berkisar
antara 0.07% hingga 0.1%. Perbedaan tingkat keasaman antara kedua perlakuan
dalam eksperimen jangka pendek berkisar 0.05% hingga 0.06% (Patane dan
Consentino, 2010). Hasil ini menunjukkan bahwa perlakuan water stress dapat
menghasilkan tomat dengan tingkat kemanisan dan tingkat keasaman yang lebih
tinggi.
Kata kunci: rumah tanaman berteknologi tinggi, kontrol irigasi, tomat berkadar
gula tinggi, water stress
SUMMARY
DRUPADI CIPTANINGTYAS. Development of Water Stress Treatment System
for Long-term High Brix Tomato Production in Hydroponic Culture. Supervised
by HERRY SUHARDIYANTO and NORIKO TAKAHASHI.
Nowadays, the demand of high brix tomato as known as fruit tomato is
increased. Many studies found that water stress treatment can be used for the
production of high brix tomato, however, these are obtained for short-term
experiment in water content around 50%-80% (Nuruddin et al. 2003; Patane and
Consentino, 2010). The effect of water stress treatment on plant growth is well
known, but how to operate the water stress treatment to increase the quality of
tomato fruits is not known very well. It is not easy to grow health plant in water
stress condition. This research introduces visual monitoring system to control
severe water stress condition. The objectives of the present study are to develop a
water stress treatment system for long-term high brix tomato production in
hydroponic culture and evaluate the performance of water stress treatment system
in long-term severe water condition with seasonal change on the quantity and
quality of tomato fruits. Furthermore, the effect of water stress on plants growth
was examined. All data that from this research could be used for database of
development of water stress treatment system on tomato plants.
Tomato (Solanum lycoperscium L., Momotaro Sakura) plants were grown
hydroponically on rock wool slabs in a greenhouse in Faculty of Agriculture,
Ehime University. Water stress treatment was applied at 14 weeks after
transplanting. Leaf area was monitored by digital camera that pictures were
captured every 15 minutes. The water content of the slabs was measured by Water
Content Meter once a day at noon. There are two treatments in this research, water
stress treatment and control. The water content of slab was maintained around
20%-30% for water stress treatment and 60%-70% for control, which was
controlled base on the projected leaf area and water content of slabs. When the
projected leaf area was decreased fewer or less than 95% of the maximum
projected leaf area which was measured after the last irrigation and the water
content of the slab was fewer than 20%, the nutrient solution was supplied to the
plant until recovering to 20%. For the growth rate measurement, stem diameter
and elongation were measured once a week by caliper and measuring tape,
respectively. Fruit diameter, sweetness, and sourness were measured by ISEKI
grading machine. The calibrations for sweetness were conducted by destructive
method with Refractometer, while the sourness was calibrated by KUBOTA
Fruits Selector machine.
The results indicated that it took 1.5 hours from full unfuried condition to
full recover. Some irregular situations were observed when solar radiation was
high and relative humidity was low, water content was around 11% that was
lower than the expectation. On the other hand, when solar radiation was low and
relative humidity was high, water content was around 40% that was not expected.
Low solar radiation and high relative humidity can be contributed to maintain the
water content at high level. Stem diameter was 4.4 mm-7.78 mm for water stress
and 8.45 mm-11.68 mm for control. Stem elongation rate was 0.08 m week-1-0.18
m week-1 for water stress and 0.17 m week-1-0.25 m week-1 for control. Both of
stem diameter and elongation rate of water stress treatment were smaller than
those of controls. These results suggest that water stress treatment might inhibit
the plant growth.
For the yield, the differences in harvested fruit number between water stress
and control were small. Average harvested fruit number for water stress and
control was 41.8±18.8 fruit week-1 and 50.1±19.4 fruit week-1, respectively. Fruit
diameter was about 634.3 mm-755.2 mm for water stress and 731.9 mm-822.8
mm for control. Although the averages of harvested fruit number for two
treatments have no significant differences (t-test with 5% level), the yield of water
stress was lower than that of control. Water stress treatment will produce high
soluble solid fruits, and this will be happened along with decreasing of fruits load.
This might be caused by the limitation of physiologist characteristic, such as
photosynthesis efficiency, sink-source relationship, and respiratory losses (Davies
and Hubson 1981). These results suggest that the decreased yield of water stress
was resulted from the decreased fruit size.
For the plant quality, sweetness of fruits in water stress treatment was
always higher than that in control. Difference in sweetness between water stress
and control was from 0.2% to 2.5%. Patane and Consentino (2010) reported that a
difference in sweetness between water stress and control was from 0.55% to 1.4%
with short-term experiment. In their report, the water content in water stress was
maintaining 50%. The severe water stress in this study, 20%-30% water content,
would produce higher sweetness tomato compared with moderate water stress.
Sourness of water stress treatment was also higher than that of control. Difference
in sourness between water stress treatment and control was from 0.07% to 0.1%.
The difference in sourness between two treatments in short-term experiment was
from 0.05% to 0.06%, described by Patane and Consentino (2010). The result
showed that water stress treatment can produce high sweetness and sourness
tomato.
Keywords: high technology greenhouse, irrigation control, high brix tomato,
water stress
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DEVELOPMENT OF WATER STRESS TREATMENT SYSTEM
FOR LONG-TERM HIGH BRIX TOMATO PRODUCTION
IN HYDROPONIC CULTURE
DRUPADI CIPTANINGTYAS
Thesis
Submitted in Partial Fulfillment of the requirements
For Magister Sains Degree
In Study Program of Food and Agricultural Machinery Engineering
GRADUATE SCHOOL
BOGOR AGRICULTURAL UNIVERSITY
BOGOR
2014
Final Examiner outside Supervisory Commitee: Dr Ir Rokhani Hasbullah, M Si
Thesis Title : Development of Water Stress Treatment System for Long-term
High Brix Tomato Production in Hydroponic Culture
Name
: Drupadi Ciptaningtyas
Student ID : F151110071
Approved by
Supervisory Committee
Prof Dr Ir Herry Suhardiyanto, M Sc
Chairman
Noriko Takahashi, Ph D
Member
Acknowledged by
Head of Study Program of Food and
Agricultural Machinery Engineering
Dr Ir Y Aris Purwanto, M Sc
Date of final examination:
20 March 2014
Dean of Graduate School
Dr Ir Dahrul Syah, M Sc Agr
Date of graduation:
PREFERENCE
First and foremost, Praise to my Lord Allah SWT for giving me strength to
accomplish my research and master thesis. All Your blessing motivated my self to
achieve my master degree. This master thesis which is entitled “Development of
Water Stress Treatment System for Long-term High Brix Tomato Production in
Hydroponic Culture”, was based on research conducted from August 2011 to
March 2012.
The writer would like to thank to Prof Herry Suhardiyanto and Noriko
Takahashi Ph D as the supervisory committee for their enormous help throughout
the completion of my thesis. The writer also would like to thank to Prof Hiroshige
Nishina and Kotaro Takayama Ph D, for their inspiring advice, warm support and
encouragement, and also the flexibility they gave me in conducting my research.
Dad, Mom, and Brother, I thank you for all your love, support, and pray.
It is truly hoped that this master thesis will give a worthy addition to the
existing knowledge on greenhouse technology area and the readers will get useful
informations.
Bogor, March 2014
Drupadi Ciptaningtyas
v
TABLE OF CONTENTS
TABLE OF CONTENT
LIST OF TABLES
LIST OF FIGURES
APPENDIXES
1 INTRODUCTION
Research Background
Problem Formulation
Objectives of Research
Research Output and Benefit
Data Acquisitions
v
vii
vii
viii
1
1
2
3
3
2 LITERATURE RIVIEW
Water Scarcity
Visual Monitoring System
Water Stress Treatment
5
5
6
3 MATERIALS AND METHODS
Time and Place of the Research
Materials
Equipment
Plant Materials and Growth Conditions
Hydroponic
Visual Monitoring System
Plant Growth Rate Measurement
Fruit Characteristic Measurement
Statistical Analysis
Research Flow Diagram
11
11
11
12
12
12
13
14
15
15
4 RESULT AND DISCUSSION
Environmental Condition
Sweetness
Sourness
Harvested Fruit Number
Fruit Diameter
Yield
Stem Diameter
Stem Elongation Rate
16
19
19
22
24
25
26
28
5 CONCLUSION AND RECOMMENDATION
Conclusion
Recommendation
REFERENCES
APPENDIX
CURRICULUM VITAE
30
32
32
33
38
53
4
7
15
29
vi
LIST OF TABLES
1
2
3
Several studies about the effect of water stress treatment on tomato crops
Several studies about effect of seasonal changes on tomato crops
The doses requirement of tomato’s crop nutrient
9
10
13
LIST OF FIGURES
1 A Schematic of discriminant analysis for determination of threshold value
(k) that divides the diphasic histogram into two groups (Class 1 and Class
2)
2 Subtropical intelligent greenhouse with the type of venlo house (1300 m2),
in Faculty of Agriculture, Ehime University
3 Four tomato crops planted to each rockwool cube on a rockwool slab
4 Schematic diagram of the water stress treatment system that controlled by
digital camera that taken pictures every 15 minutes and by measured
water content of growth medium every day
5 Equipments used for the measurement of fruit quality and quantity:
ISEKI Grading machine (a), Refractrometer for calibration of fruit
sweetness (b), Fruit Selector machine for calibration of fruit sourness (c)
6 Research flow diagram
7 Time course of: outside solar radiation (A), average relative humidity
inside greenhouse (B), maximum, minimum, average air temperature
inside greenhouse (C), and water content of rockwool slab in water stress
treatment (D).
8 The ratio differences of projected leaf area with different water content
(March 25, 2012). The percentage of projected plant area were measured
by compared the pixel number of plant area at that time with
the pixel number of plant area from the picture that took after last
irrigation
9 Variation of fruit sweetness during research period due to: water stress
treatment (A), and seasonal change (B).
10 Variation of fruit sourness during research period due to: water stress
treatment (A), and seasonal change (B).
11 Variation of harvested fruit number during research period due to:
water stress treatment (A), and seasonal change (B).
12 Variation of fruit diameter during research period due to: water stress
treatment (A), and seasonal change (B).
13 Variation of yield during research period due to: water stress treatment
(A), and seasonal change (B).
14 Variation of stem diameter of tomato plants during the research period
due to; water stress treatment (A), seasonal change (B).
15 Stem elongation rates of tomato plants during the research period due to;
water stress treatment (A), seasonal change (B).
7
11
12
14
16
18
20
21
23
24
25
27
28
29
31
vii
1
2
3
4
5
6
7
8
9
10
11
12
13
14
APPENDIXES
Timeline
The effect of water stress treatment on fruit sweetness
The effect of water stress treatment on fruit sourness
The effect of water stress treatment on fruit diameter
The effect of water stress treatment on yield
The effect of water stress treatment on stem diameter
The effect of water stress treatment on stem elongation rate
The effect of seasonal change on fruit sweetness
The effect of seasonal change on fruit sourness
The effect of seasonal change on fruit diameter
The effect of seasonal change on yield
The effect of seasonal change on stem diameter
The effect of seasonal change on stem elongation rate
Assessment of tomato fruit taste
38
40
41
42
43
44
45
46
47
48
49
50
51
52
1
1 INTRODUCTION
Research Background
Water is one of the most important factor in agriculture. Eventhough water
in horticulture is not a limited factor, in fact a water scarcity period will have to be
faced in the near future. Irrigated agriculture is a major consumer of water and
accounts for two thirds of the total fresh water assigned to human uses (Fereres
and Evans 2006). Water management practice can help ensure the survival and
sustainability of agricultural and economic activities related to water (Postel
2000). Maximising water productivity may be more profitable to the farmer than
maximizing crop yield (Pereira et al. 2002).
Deficit irrigation is a way to face this problem. Investigations over last two
decades showed that deficit irrigation methods can aid in coping with situation
where water supply is restricted (FAO 2002). Deficit irrigation could be a
management system to make the agricultural irrigation more effective. For plant
that cultivated on soil, deficit irrigation could be minimize leaching of nutrient
and pesticide into ground water while for plant that cultivated on another growth
medium, deficit irrigation could be minimize the requirement of electricity energy
for irrigation system include the recycle nutrient system.
Tomato is one of the most widely grown vegetables in the world because of
special nutritive value of its fruit (reach source of minerals, vitamins, organic
acids, essentia amino acid, antioxidants, etc). Therefore, any factor influencing
tomato yield has been attracted considerable interest (Jones and Benton 2008;
Jonson et al. 1992; Grange and Andrews 1994). Tomato is one of the world’s
most important irrigated vegetable crops (Gallardo et al. 2006) especially in
greenhouse. Nowadays consumer desire in taste for tomato is changing. They
require higher quality of tomato fruits from several aspects, especially sweetness
of tomato fruits. Tomato has high sweetness is known as fruit tomato. The prices
of fruit tomato generally higher than common tomato fruit, about ¥10,000/kg.
From several studies, it is known that water stress treatment of tomato crop
could used to produce fruit tomato. Water stress is the aplication of deficit
irrigation. The application of deficit irrigation on tomato crops not only increase
water use effeciency but also produce higher quality of tomato. Water stress
treatment on tomato crops not only increase the sweetness of tomato fruit, but also
produce tomato fruit with higher total solid and lower water content (Patane and
Cosentino 2010) and it really profitable for concentrated juice or tomato paste
industry, because they don’t required a lot of time and energy to evaporation, so it
improve processing efficiency (Johnstone et al. 2005).
Most of studies on water stress treatment were conducted using moderate
water stress, for example water content of growth medium was 50%-80% that
produce tomato fruits with the sweetness of 5.11oBrix - 5.82oBrix (Nurruddin et
al. 2003; Patane and Consentino 2010). Several studies on water stress treatment
for tomato were obtained short-term experiment either open-field system or
greenhouse system, for example the water stress treatment were conducted only
for 43 days after fruits appearing (Savic et al. 2008). Nurruddin et al. (2003),
2
Patane and Consentino (2010), and Patane (2011) conduct a partial water stress
treatment on several stage of tomato crop growth (i.e., flowering, fruit set, etc).
Many approaches to detect water stress were reported complicated and
expensive, for example Gallardo et al. (2006) who control the water stress by
using stem diameter variation measured with linear variable transducer sensors.
Savic et al. (2008) used different volume irrigation to the plants. Pulupol et al.
(1996) measure leaf water potential to control the water stress treatment condition.
Nurruddin et al. (2003) control the water stress treatment by monitoring the
moisture soil status and calculating amount of water added to each plant after
flowering stage. Patane et al. (2011) and Favati et al. (2009) reported to keep the
stress condition depend on evapotranspiration that was calculated from soil water
balance. Those methods are not efficient enough to apply in commercial
greenhouse system.
Due to the requirement of better system to detect water stress treatment for
supporting longer treatment and also produce higher sweetness of tomato fruit as
mentioned above, this research is conducted. This research is aimed to obtain a
better water stress detection system so that the water stress treatment could be
longer, and assess the effect of severe water stress treatment on quality of tomato.
Problem Formulation
Although only eleven percent of total land accounted for arable land, Japan
is one of the most advanced agriculture in the world. Greenhouse area in Japan is
accounted 49,049 hectare in 2011 (Kacira 2011), although this number is
decreasing annually and cover only one percent from total arable land. With that
decreasing trend, Japan still became the fourth largest greenhouse production area
in the world, next to China, Korea, and Spain. Moreover, Japan is one country that
develops tomato production greenhouse intensively, with production reached
690,700 tons in 2010 (Otsuka 2011).
Most of tomato fruit in Japan produced in commercial greenhouse, which
mean the aim of the greenhouse, is to get the highest benefit with an effective and
efficient manner. To support the longer production time, tomato crops are planting
in high technology greenhouse that usually has 10 months of harvesting time. It is
longer than traditional greenhouse that usually has 3 months of harvesting time.
So that the control of water stress treatment should be able to do in the long run.
The application of water stress treatment in a commercial greenhouse
should be controlled by a system that has low maintenance and can easily used by
the growers. Due to the requirement of better system to detect water stress
treatment, new control system should be build. A water stress detection technique
sustainable for use in a commercial greenhouse should satisfy the following
requirements:
1. The water stress index must be stable
2. The measurement should be performed by using inexpensive materials
3. The water stress detection must done automatically
4. Water stress should be detected as early as possible
To meet the requirement, we applying a new technique for detecting water
stress in tomato crops based on projected leaf area calculated from a digital color
image that is captured by a commercially available, inexpensive, digital camera
3
(Nishina et al. 2004; Nishina et al. 2005; Takayama and Nishina 2007). This
system was already developed but never been applied directly in a commercial
greenhouse. To support the digital monitoring system, growth medium also
measured to validate the condition of tomato crops.
Since the sweetness of tomato that produced from moderate water stress
treatment was still too close to the level of sweetness that allowed by the industry
(4.6°Brix), it is necessary to increase the sweetness to higher level. Most tomato
production in Indonesia conducted by open-field cultivation, without the
application of hydroponics, so that the quality and quantity of tomato in Indonesia
quite low. The average of sugar content in tomato fruit from Indonesia is 3.5oBrix
(Lokasari 2011). From Suhardiyanto (2009) the application of greenhouse and
hydroponic would increase the quality and quantity of tomato (per square meter).
Furthermore the water use efficiency can be improved. Severe water stress with
lower water content in growth medium, e.g. 20%-30%, may be able to be used for
producing higher sugar content tomato, but it might be decreased the production
yield and growth rate of tomato crops. So it is necessary to find a relationship
between long-term water stress treatments and the quality and quantity of tomato.
Japan has fall, winter, spring, and summer seasons, which means the
weather or climate is changing significantly. Environmental condition inside the
greenhouse also changes due to the season. Toor et al. (2006) observed the effect
of solar radiation and air temperature on tomato crops for 8 months in subtropical
region and found that higher solar radiation and air temperature increased the fruit
sweetness. Gallardo et al. (2006) observed the effect of solar radiation and air
temperature on tomato crop for 7 months in subtropical region and found that
higher solar radiation decreased the tomato crop growth rate. Since the production
time of tomato reaching almost one year, water stress treatment may vary with
season. The effect of seasonal change on the fruit quantity, fruit quality, and
tomato plant growth rate under water stress treatment was not studied well.
Therefore, research on long-term water stress treatment is necessary for high brix
tomato production in intelligent greenhouse.
Objectives of Research
The objectives of the present study are to develop a water stress treatment
system for long-term high brix tomato production in hydroponic culture and
evaluate the performance of water stress treatment system in long-term severe
water condition with seasonal change on the quantity and quality of tomato fruits.
Furthermore, the effect of water stress on plants growth was examined. All data
that from this research could be used for database of development of water stress
treatment system on tomato plants.
Research Output and Benefit
Agriculture is often associated with the image of inefficiency, being less
profitable than other sector. With the issues of scarcity of water, water use
efficiency is necessary to be gained. Tomato is one of the world’s most important
irrigated vegetable crops, which mean lots of water is requires for tomato
cultivation. By applying the management of deficit irrigation named water stress
4
treatment to tomato crops the water use efficiency for most irrigated vegetable
crops would be gain, which mean water use efficiency of the world would also
significantly gain.
This research was conducted in Japan, where implementation of greenhouse
building for growing plants is developing rapidly. The ratio of vegetables and
fruits grown in greenhouse is in increasing trend annually. Accordingly, this
research could be implemented in another greenhouse. Digital monitoring system
is really necessary for the application of water stress treatment in commercial
greenhouse, because it is neither too expensive nor too complicated to be handled
by the growers. Digital monitoring system is also flexible to apply in many
greenhouses in the world, including in a traditional greenhouse in Indonesia. Even
though the production time of traditional greenhouse is not as long as high
technology greenhouse, the digital monitoring system is still the cheapest and the
most simple water stress controlling system compare with another controlling
system. So it really fits the condition of a developing country like Indonesia to
produce higher quality of tomato.
Tomato fruit from Indonesia usually lost by imported tomato from another
country either in quality or price. To improve the quality and quantity of
Indonesia’s tomato, application of technology such as the application of
greenhouse and hydroponic is required. Indonesia is a blessed country with high
annual solar radiation and stable temperature. Related to several studies, high
solar radiation is support the production of sugar content in tomato fruit.
Therefore Indonesia has the opportunity to become producer of high brix tomato
in the world. The application of water stress treatment for tomato crop that
controlled by digital monitoring system in greenhouse by hydroponic cultivation
would increase the quality and quantity of tomato fruit in Indonesia. So that
tomato fruit from Indonesia could be the winner in its own country moreover it
could be exported to another countries to increase foreign exchange of Indonesia.
Data Acquisitions
1.
2.
3.
4.
Environmental parameters measured were solar radiation outside greenhouse,
average relative humidity inside greenhouse, air temperature (oC) inside
greenhouse (maximum, minimum, and average), and water content of growth
medium (%).
Plant growth rate parameters measured were stem diameter (mm) and stem
elongation rate (m week-1).
Tomato fruit quality parameters measured was fruit sweetness (oBrix) and
fruit sourness (%).
Tomato fruit quantity parameters measured was harvested fruit number (Fruit
week-1), yield (kg week-1) and fruit diameter (mm).
5
2 LITERATURE REVIEW
Water Scarcity
Related to Musiake et al. (2002), it is anticipated that the world’s water
resources will be under more pressure in the first half of this century than any
time during the recorded history. The estimation of the current level of water
stress is important for reliable projections of the severity of the water crisis in the
future. However, most of the previous global analyses on water scarcity have been
carried out on a country basis or a river basin basis. Considering the importance of
global water scarcity, future projections should be valuated by multiple
procedures/models/methods in various organizations, since the reliability of the
estimates will be supported if similar results are obtained from different scientific
approaches, information, and data processing.
For the global estimation of the water supply, observed runoff or
simulated runoff is generally used. Shiklomanov (2000a; 2000b) estimated the
water availability for 26 regions of the world based on observed river discharge at
2500 stations. Takahashi et al. (2000) estimated the monthly water balance in 0.5o
by 0.5o longitude/latitude grid boxes using a bucket model (Manabe 1969) with
potential evapotranspiration by the Penman method using current and future
climate projections (temperature, wind speed, and precipitation) simulated by
GCMs (General Circulation Models) of the Canadian Climate Centre, Max Planck
Institute, and Center for Climate System Research (CCSR), University of Tokyo.
Vorosmarty et al. (2000) adopted a similar approach, but their water supply
estimates were linearly adjusted to observation where discharge information was
available.
Based on Musiake et al. (2002), The regions with severe stress in 1995
will still experience severe stress in the projection for 2050 and the severity will
even increase in most regions. The regions with severe stress will also spread to
the neighboring areas. Such regions with increased water scarcity are mostly
located in developing countries. The increase of discharge associated with global
warming can mitigate the water scarcity in some regions. However, the effect of
the population growth compensates such mitigation, or even increases the severity
in such regions. The worse situation can be seen in the developing regions with a
high population growth rate and with a decreased discharge under global warming
conditions. As a whole, the effect of population change will be the major factor
contributing to the increased severity of water scarcity in the future. Even though
the amount of available water in Asia is large, population and current water
withdrawal particularly agricultural water demand are very high, and the water
stress ratio is the highest among the continents. Intensified water scarcity was
found mainly in and close to the regions of water scarcity under the current
conditions. The population growth in the future will exert a major effect on the
severity of water scarcity compared to climate change.
6
A growing scarcity of water relative to human demand occurs in many
parts of the world, but appropriate water management practices can help ensure
the survival and sustainability of agricultural and economic activities related to
water (Postel 2000). The sustainable use of water in agriculture has become a
priority and the adoption of irrigation strategies which may allow saving irrigation
water and maintaining satisfactory yield, thus improving water use efficiency,
may contribute to the preservation of this even more restricted resource (Parry et
al. 2005; Topcu et al. 2007). Water deficits and insufficient water are the main
limiting factors affecting worldwide crop production. Deficit irrigation (DI) can
reduce production cost, conserve water and minimize leaching of nutrients and
pesticides into ground water. While this has primarily been a concern in field
crops, the disposal of nutrient and pesticide-laden waters from large greenhouse
complexes has come under scrutiny. Establishing DI as a management tool for
tomatoes could be a very effective in situations where water is scare and also
reducing effluent contamination. This is especially important since tomato is a
popular greenhouse-grown vegetable, grown extensively through the world
(Nurruddin et al. 2003).
The goal of DI is to increase crop water use efficiency by reducing the
amount of water applied with watering or by reducing the number of irrigation
events (Kirda 2002). DI involves the use of appropriate irrigation schedules,
which mostly derive from field trials (Oweis and Hachum 2001). In this case, the
optimal irrigation schedules are often based on the concept of water productivity
(Oweis and Zhang 1998). Water use efficiency can be improved by drip irrigation.
It is significantly reducing runoff and crop evapotranspiration losses (Stanghellini
et al. 2003; Jones and Benton 2008; Kirnak and Demitras 2006).
Visual Monitoring System
Figure 1 shows a schematic of the discriminant analysis for the
determination of threshold value (k). The discriminant analysis automatically
determines a threshold value (k), which divides a bimodal histogram into two
groups (Classes 1 and 2, shown in Figure 1) with maximizing of the interclass
variance [�� ! � ] of the two groups. The interclass variance is calculated with the
following equation:
�� ! � = �! (�! − �! )! + �! (�! − � ! )!
in which k is threshold value for dividing the bimodal histogram into two groups
(Class 1 and Class 2) �! is an average of Class 1, �! is an average of Class 2, � ! is
an average of the whole histogram, �! is the ratio of the frequency of Class 1 to
the frequency of the whole histogram, and �! is the ratio of the frequency of Class
2 to the frequency of the whole histogram (Torii 1996). The color (hue) histogram
of a digital color image of a tomato plant with a blue background shows such a
bimodal histogram, so we used the discriminant analysis method for automatic
determination of the plant area with a digital color image (Nishina et al. 2007).
A clear bimodal distribution of hues of the digital color image can be
recognized in the color histogram. The interclass variance of the color histogram
shows a single-peaked pattern. Therefore, the threshold value, i.e. hue=146°, can
7
be determined automatically. Using the threshold value, the plant area represented
in green was clearly extracted and the pixel number within the plant area could be
used as a relative value of the projected plant area to diagnose the water stress in
the tomato plant (Nishina et al. 2005).
Figure 1
A Schematic of discriminant analysis for determination of threshold
value (k) that divides the diphasic histogram into two groups (Class 1
and Class 2)
Water Stress Treatment
There are several stress treatment usually apply to plant for some reason.
Stress treatments for plant usually applied are drought stress, heat stress, cold
stress, mineral stress, and Salinity stress. However, drought stress or water stress
is the most famous one, because of the issue of water scarcity. The physiology of
water stress resistance has been quite extensively in recent years. As will be seen,
in some respects the physiology of drought resistance is open to controversy,
while in other respects knowledge is just emerging and is far from being put to
use in plant breeding. An understanding of the physiology of drought resistance
requires some introductory notes on the physiological consequences of plantwater deficit, with emphasis on processes affecting plant production (Blum 1988).
In general, reducing water supply by: (1) reducing irrigation frequency, or
(2) increasing environmental demand, will reduce growth. An example is
providing by Hanan and Jasper’s work on carnations (1967). Different irrigation
regimes will influence branching, stem length, quality and yield. Water stress may
have far-reaching effect, influencing keeping life and resistance to air pollution.
However, if a crop is planted single stem (chrysanthemums or snapdragons),
yield is fixed. It can be desirable to reduce water application or decrease humidity
in order to obtain a more compact flower head, or to reduce brittleness. The same
8
may be necessary with foliage, bedding, or potted plants where some judicious
stress will improve ability to withstand transplanting shock, or the new
environment provided by the consumer. The exact effect of stress will depend
upon how large the stress is, how long stress is imposed, how the plant was
treated previously (part history), species, and stage of growth. With continuously
flowering plants, undue stress at any stage may several restrict stem length and
branching. For single cropping, high stress at flower initiation may reduce flower
number and size (Hanan et al. 1978).
The general effect on some physiological processes in herbaceous plants
was provided by Boyer (1970a, b). Stresses of less than -4 bars were sufficient to
reduce elongation, and beyond -8 bars, photosynthesis was decreased. These are
not extreme when, as a general rule, a soil suction of -15 bars is often acceptable
as the value where most field plants will permanently wilt. Internal water
potentials approaching -15 bars have been measured by often, reduce
photosynthesis to such an extent that solar energy cannot be efficiently utilized
(Boyer 1970b).
If low stress is necessary for maximum growth, it does not follow that zero
stress is best. Heydecker et al. (1970) showed that abnormal growth could result
where there was no pressure gradient from the leaf to the air. Another problem at
low stress conditions is increased damage from foliar disease such as Botrytis or
mildew (Winspear et al. 1970). If there is no stress, it is highly unlikely that a
plant is actively producing food. If there is sufficient energy (sunlight) to
manufacture sugars, there will be sufficient energy to evaporate water and induce
stress.
From Hanan et al. (1987), there are several ways to control water demand,
or reduce the transpiration rate in greenhouse plants:
I.
Reduce vapor pressure gradient between leaf and air
1. Increase relative humidity
a. Add water to air
b. Reduce air temperature
2. Reduce leaf temperature
a. Syringe or mist with water
b. Reduce light intensity by shading
II.
Increase resistance to water vapor flow from leaf to air
1. Reduce stomata aperture by
a. Application of chemical to close stomata
b. Reduce stomata opening by increasing CO2 concentration
2. Increasing length of diffusion path-length from leaf to air by
reducing air velocity
This outline shows that water loss is determined by: (1) the difference in
water vapor concentration between inside the leaf and outside; and (2) by the
resistance to movement of water molecules from inside the leaf to outside. The
resistance varies according to the length of the path that water molecules must
traverse, and the size of the stomata opening. Table 1 shows the result of several
studies about water stress treatment in tomato crops, while Table 2 shows the
result of several studies about the effect of seasonal change on tomato crops.
9
Table 1. Several studies about the effect of water stress treatment on tomato crops.
No.
1.
2.
3.
4.
Writer
Gallardo et
al. (2006)
-
Savic et al.
(2008)
50% of growth
medium
Mitchell and
Shennan
(1991)
50–75 day
cutoff
irrigation
Pulupol et al.
(1996)
5.
Nurruddin et
al. (2003)
6.
Patane et al.
(2011)
7.
8.
Treatment
Patane and
Cosentino
(2010)
Favati et al.
(2009)
-1.0 to -1.2
MPa leaf water
potential
65%-80% of
growth
medium
50% ETc
restoration
50% ETc at
short and long
season
50% ETc
Quality
-
Increase
sweetness
(4.58oBrix5.58oBrix)
Increased
sourness (0.28%0.34%)
Increased
sweetness (6.80
o
Brix–9.18 oBrix)
Increased color
index (32.7–
39.5)
Increased
sweetness
(4.90oBrix–7.60
o
Brix)
Increased
sourness
(0.25%–0.36%)
Increased
vitamin C
(27.46%–
48.89%)
Increased
sweetness
(4.40oBrix–6.35
o
Brix)
Increased
sourness
(0.28%–0.36%)
Increased
vitamin C
(27.46%–
48.89%)
Increased
sweetness
Effect
Yield
Decreased fruit
number
Decreased fruit
diameter
(59.6mm –
72.5mm)
Decreased fruit
yield
Growth rate
Decreased
stem
diameter
-
-
Decreased fruit
yield, and fruit
number
Decreased yield,
and fruit diameter
(48.2mm–
56.7mm)
Decreased
vegetative
growth
Retard
flowering
Decreased total
yield, and fruit
size (34.4g–
68.9g)
-
Decreased total
yield, and fruit
size (44.1g–
73.3g)
-
Decreased fruit
yield and fruit
-
10
(5.30oBrix–
5.82oBrix)
Increased
sourness
(0.33%–0.39%)
Increased
vitamin C
(18.61%–
12.44%)
mean weight
Table 2. Several studies about effect of seasonal changes on tomato crops.
No.
Writer
1.
Gallardo et
al. (2006)
2.
3.
Hamner et
al. (1944)
Gautier et
al. (2008)
4.
Demers et
al. (1998)
5.
Toor et al.
(2006)
Quality
-
Effect
Yield
Yield in spring is
higher than yield
in autumn
Lower
temperature
or
lower photoperiod produce
lower acidity.
Stronger solar radiation
produces higher acidity.
Lower solar radiation or
higher temperature
produces higher carotenoid
content.
Longer photoperiod
Longer
produce higher sugar
photoperiod
content of tomato
produce higher
tomato yield.
Higher solar radiation and
temperature produce higher
sweetness, lycopene
content, and acidity
Growth rate
Increase with the
increasing of air
temperature and
solar radiation
-
Longer photoperiod
decreased the growth
rate.
-
11
3 MATERIALS AND METHODS
Time and Places of the Research
This research was conduted for seven months (August 2011 to March 2012).
Tomato seeds were sown on August and transplanting to rockwool cube on
September. The treatment of water stress is started on November and harvesting is
started from January untill March. Comprehensive timeline is shows in Appendix
1.
The research was conducted in a high technology greenhouse (1300 m2) in
Faculty of Agriculture, Ehime University, Japan (Figure 2). The greenhouse has
full controlling system, like cooling and heating system to support the seasonal
change, supplemental lighting, CO2 distribution system, etc. The measurements of
some fruit characteristic was conducted in the Research Center of Departement of
Bio-mechanical System, Faculty of Agriculture, Ehime University. This research
introduces visual monitoring system to control severe water stress condition by
using digital still camera.
Figure 2
Subtropical intelligent greenhouse with the type of venlo house (1300
m2), in Faculty of Agriculture, Ehime University
Materials
The materials used for this research were 288 tomato crops (Solanum
lycoperscium L) with variety of Momotaro sakura, 288 rockwool cubes (10 cm
[W] x 10 cm [H] x 10 cm [D]), 72 rockwool slabs (30 cm [W] x 25 cm [W] x 91
cm [L]) (Grotop Expert, Grodan. Inc), and nutrient solution (A-type recipe of
Otsuka House Solution, Otsuka Chemical co., Ltd).
12
Equipment
The equipment used for this research was divided in to some parts growth
system, visual monitoring system, and measurements of plant growth rate and
fruit characteristic. Environmental monitoring system (MC–5013, NEPON) that
automatically measures solar radiation, air temperature, and relative humidity
inside and outside the greenhouse, a drip irrigation system and nutrient tank were
used for the growth system. Water content meter (Sensor 300 Baud, Grodan. Inc),
digital camera (G700SE, Ricoh company, Ltd. Japan), Wi-Fi system, personal
computer and commercial available software (X6, CorelDRAW, Corel
Corporation, Canada) were used for visual monitoring system. Measuring tape,
board marker, and Digital Caliper Ruler (BLD-100, Niigata Seiki co., Ltd) were
used for plant growth rate measurement, furthermore grading machine (SSW1APQ-6R, ISEKI & Co., Ltd), weight scale, refractometer, and fruits selector
machine (K-BA100R, Kubota. Co) were used for fruit characteristic measurement
and calibration.
Plant Materials and Growth Conditions
Tomato crops were grown hydroponically in an intelligent greenhouse. The
greenhouse that used in this research is a subtropical greenhouse with the type of
venlo house, which covered by glass but in the special condition like a very high
temperature in summer, wall of the greenhouse covered by net. The greenhouse is
passively ventilated. Climatic parameters were continuously monitored within the
greenhouse. Solar radiation, air temperature and relative humidity were measured
inside and outside the greenhouse with MC–5013, NEPON. These data recorded
once a day.
There are two treatments that conducted in this research, water stress
treatment and control. Water stress treatment was started on 17 November 2011
after the plants reach 1 month old. 36 rockwool slabs were used for each treatment.
The irrigation for water stress treatment controlled by visual monitoring system
based on projected leaf area and water content of rockwool slabs, on the other
hand the irrigation of the control treatment is given for 3 minutes every 15
minutes. Water content for both treatments is measured once a day. Water content
is maintained from 20% to 30% for water stress treatment and 60% to 70% for
control.
Figure 3
Four tomato crops planted to each rockwool cube on a rockwool slab
13
Hydroponic
The seed were sown in spongy material on 29 August 2011 and transplanted
on 12 September 2011 to rockwool cubes on the rockwool slabs. Four plants
transplanted to each rockwool slabs (Figure 3). The plants watered daily with a
nutrient solution, which distributed by drip irrigation system. Drip irrigation type
placed on the surface of the rockwool with 1.5 m spacing between drip lines and
20 cm spacing between emitters within drip lines. The irrigation water had an
electrical conductivity around 0.27 dS m-1 to 3.8 dS m-1. The dose for tomato’s
crop nutrient is shows in Table 3. Nutrients for control treatment applied through
the irrigation system, in accordance with local practice. There are four lines of
tomato crops that used in this r
FOR LONG-TERM HIGH BRIX TOMATO PRODUCTION
IN HYDROPONIC CULTURE
DRUPADI CIPTANINGTYAS
GRADUATE SCHOOL
BOGOR AGRICULTURAL UNIVERSITY
BOGOR
2014
STATEMENT LETTER OF THESIS AND SOURCE OF
INFORMATION AND DEVOLUTION OF COPYRIGHT
Hereby I genuinely stated that the master thesis entitled Development of
Water Stress Treatment System for Long-term High Brix Tomato Production in
Hydroponic Culture is an authentic work of mine supervised by supervisory
committee and never being presented in any forms and universities. All the
information taken and quoted from published or unpublished works of other
writers had been mentioned in the texts and attached in the references at the end of
the master thesis.
I hereby assign the copyright of my papers to the Bogor Agricultural
University.
Bogor, March 2014
Drupadi Ciptaningtyas
NIM F151110071
RINGKASAN
DRUPADI CIPTANINGTYAS. Membangun Sistem Water Stress Treatment
untuk Produksi Jangka Panjang Tomat Berkadar Gula Tinggi secara Hidroponik.
Dibawah bimbingan HERRY SUHARDIYANTO dan NORIKO TAKAHASHI.
Permintaan tomat berkadar gula tinggi yang lebih dikenal sebagai fruit
tomato semakin meningkat sekarang ini. Banyak penelitian mengungkapkan
bahwa aplikasi water stress treatment dapat digunakan untuk memproduksi tomat
berkadar gula tinggi, namun penelitian-penelitian tersebut dilakukan hanya dalam
waktu singkat dengan kadar air media tanam sekitar 50%-80% (Nuruddin et al.
2003; Patane and Consentino, 2010). Telah banyak penelitan mengenai pengaruh
water stress treatment terhadap pertumbuhan tanaman, namun penelitian
mengenai cara mengoperasikan water stress treatment untuk meningkatkan
kualitas buah tomat belum begitu banyak dilakukan. Menjaga agar tanaman tomat
tetap sehat dalam kondisi water stress tidaklah mudah. Penelitian ini
memperkenalkan visual monitoring system sebagai pengontrol kondisi severe
water stress. Tujuan dari penelitian ini adalah membangun sebuah sistem water
stress treatment untuk produksi jangka panjang tomat berkadar gula tinggi secara
hidroponik dan melakukan evaluasi sistem water stress treatment yang dilakukan
jangka panjang dalam kondisi severe water stress disertai perubahan musim
terhadap kualitas dan kuantitas buah tomat. Selain itu, pengaruh water stress
terhadap pertumbuhan tanaman juga diteliti. Semua data dari penelitian ini dapat
digunakan untuk basis data dalam pembangunan sebuah sistem water stress yang
lebih baik lagi.
Tanaman tomat (Solanum lycoperscium L., Momotaro Sakura) ditanam
secara hidroponik diatas rockwool slabs didalam sebuah rumah tanaman di
Fakultas Pertanian, Universitas Ehime. Luasan daun tanaman tomat dimonitor
oleh sebuah kamera digital yang mengambil gambar setiap 15 menit. Kadar air
rockwool slabs diukur dengan Water Content Meter satu kali sehari pada siang
hari. Terdapat dua perlakuan dalam penelitian ini yaitu, water stress treatment dan
kontrol. Kadar air media tanam dijaga sekitar 20%-30% untuk water stress
treatment dan 60%-70% untuk kontrol. Pemberian irrigasi dilakukan berdasarkan
proyeksi luasan daun dan kadar air media tanam. Ketika proyeksi luasan daun
kurang dari 95% dari proyeksi luasan daun maksimum yang diukur setelah irigasi
terakhir dan kadar air media tanam kurang dari 20%, larutan nutrisi akan dialirkan
ke tanaman hingga kadar air kembali 20%. Untuk pengukuran pertumbuhan
tanaman, diameter dan perpanjangan batang diukur satu kali dalam satu minggu
dengan menggunakan jangka sorong dan meteran. Diameter buah, tingkat
kemanisan dan tingkat keasaman diukur dengan menggunakan ISEKI Grading
Machine. Kalibrasi untuk tingkat kemanisan buah tomat dilakukan secara
destruktif dengan menggunakan Refractometer, sedangkan tingkat keasaman buah
tomat dikalibrasi dengan menggunakan KUBOTA Fruits Selector Machine.
Hasil penelitian menunjukkan bahwa dibutuhkan waktu 1.5 jam untuk
tanaman tomat kembali ke kondisi baik setelah diairi dalam kondisi layu karena
water stress treatment. Beberapa kondisi yang tidak diharapkan terjadi, ketika
radiasi matahari tinggi dan kelembaban relatif rendah, kadar air media tanam
berkisar 11% yang mana lebih rendah dari yang diharapkan. Disisi lain, ketika
radiasi matahari rendah dan kelembaban relatif tinggi, kadar air media tanam
berkisar 40% yang mana lebih tinggi dari harapan. Radiasi matahari yang rendah
dan kelembaban relatif yang tinggi dapat berkontibusi untuk menjaga kadar air
media tanam dalam kondisi cukup tinggi. Diameter batang berkisar 4.4 mm-7.78
mm untuk water stress dan 8.45 mm-11.68 mm untuk kontrol. Perpanjangan
batang berkisar 0.08 m week-1-0.18 m week-1 untuk water stress dan 0.17 m week1
-0.25 m week-1 untuk kontrol. Baik diameter batang maupun perpanjang batang
tanaman tomat pada perlakuan water stress selalu lebih kecil dan lebih lambat dari
tanaman kontrol. Hasil ini meyatakan bahwa perlakuan water stress dapat
mempengaruhi pertumbuhan tanaman.
Pengukuran parameter kuantitas menunjukkan, perbedaan jumlah buah yang
dipanen antara perlakuan water stress dan kontrol tidaklah terlalu besar. Rata-rata
jumlah buah yang dipanen untuk perlakuan water stress adalah 41.8±18.8 fruit
week-1 sedangkan untuk kontrol adalah 50.1±19.4 fruit week-1. Diameter buah
berkisar 634.3 mm-755.2 mm untuk water stress dan 731.9 mm-822.8 mm untuk
kontrol. Meskipun rata-rata jumlah buah yang dipanen untuk kedua perlakuan
tidak berbeda nyata (t-test dengan level 5%), hasil panen dari perlakuan water
stress lebih rendah dibandingkan dengan kontol. Perlakuan water stress akan
menghasilkan buah dengan kadar padatan terlarut yang tinggi dan ini akan terjadi
seiring dengan penurunan massa buah. Hal ini dapat disebabkan oleh keterbatasan
karakteristik physiologi, seperti efisiensi fotosintesis, hubungan sink-source, dan
kehilangan dalam proses respirasi (Davies and Hubson 1981). Hasil ini
menyatakan bahwa penurunan hasil panen pada perlakuan water stress
disebabkan oleh penurunan ukuran buah.
Pengukuran parameter kualitas menunjukkan, tingkat kemanisan buah tomat
dibawah perlakuan water stress selalu lebih tinggi dibandingkan dengan kontrol.
Perbedaan tingkat kemanisan antara perlakuan water stress dan kontrol berkisar
antara 0.2% hingga 2.5%. Patane dan Consentino (2010) melaporkan perbedaan
tingkat kemanisan antara perlakuan water stress dan kontrol berkisar antara
0.55% hingga 1.4% dalam eksperimen jangka pendek. Penelitian mereka
dilakukan dengan kadar air media tanam dijaga sekitar 50%. Kondisi severe water
stress dalam penelitian ini, dengan kadar air media tanam berkisar 20%-30%,
akan menghasilkan tomat dengan tingkat kemanisan yang lebih tinggi
dibandingkan dengan moderate water stress. Tingkat keasaman buah tomat yang
dihasilkan dari perlakuan water stress juga selalu lebih tinggi dari kontrol.
Perbedaan tingkat keasaman antara perlakuan water stress dan kontrol berkisar
antara 0.07% hingga 0.1%. Perbedaan tingkat keasaman antara kedua perlakuan
dalam eksperimen jangka pendek berkisar 0.05% hingga 0.06% (Patane dan
Consentino, 2010). Hasil ini menunjukkan bahwa perlakuan water stress dapat
menghasilkan tomat dengan tingkat kemanisan dan tingkat keasaman yang lebih
tinggi.
Kata kunci: rumah tanaman berteknologi tinggi, kontrol irigasi, tomat berkadar
gula tinggi, water stress
SUMMARY
DRUPADI CIPTANINGTYAS. Development of Water Stress Treatment System
for Long-term High Brix Tomato Production in Hydroponic Culture. Supervised
by HERRY SUHARDIYANTO and NORIKO TAKAHASHI.
Nowadays, the demand of high brix tomato as known as fruit tomato is
increased. Many studies found that water stress treatment can be used for the
production of high brix tomato, however, these are obtained for short-term
experiment in water content around 50%-80% (Nuruddin et al. 2003; Patane and
Consentino, 2010). The effect of water stress treatment on plant growth is well
known, but how to operate the water stress treatment to increase the quality of
tomato fruits is not known very well. It is not easy to grow health plant in water
stress condition. This research introduces visual monitoring system to control
severe water stress condition. The objectives of the present study are to develop a
water stress treatment system for long-term high brix tomato production in
hydroponic culture and evaluate the performance of water stress treatment system
in long-term severe water condition with seasonal change on the quantity and
quality of tomato fruits. Furthermore, the effect of water stress on plants growth
was examined. All data that from this research could be used for database of
development of water stress treatment system on tomato plants.
Tomato (Solanum lycoperscium L., Momotaro Sakura) plants were grown
hydroponically on rock wool slabs in a greenhouse in Faculty of Agriculture,
Ehime University. Water stress treatment was applied at 14 weeks after
transplanting. Leaf area was monitored by digital camera that pictures were
captured every 15 minutes. The water content of the slabs was measured by Water
Content Meter once a day at noon. There are two treatments in this research, water
stress treatment and control. The water content of slab was maintained around
20%-30% for water stress treatment and 60%-70% for control, which was
controlled base on the projected leaf area and water content of slabs. When the
projected leaf area was decreased fewer or less than 95% of the maximum
projected leaf area which was measured after the last irrigation and the water
content of the slab was fewer than 20%, the nutrient solution was supplied to the
plant until recovering to 20%. For the growth rate measurement, stem diameter
and elongation were measured once a week by caliper and measuring tape,
respectively. Fruit diameter, sweetness, and sourness were measured by ISEKI
grading machine. The calibrations for sweetness were conducted by destructive
method with Refractometer, while the sourness was calibrated by KUBOTA
Fruits Selector machine.
The results indicated that it took 1.5 hours from full unfuried condition to
full recover. Some irregular situations were observed when solar radiation was
high and relative humidity was low, water content was around 11% that was
lower than the expectation. On the other hand, when solar radiation was low and
relative humidity was high, water content was around 40% that was not expected.
Low solar radiation and high relative humidity can be contributed to maintain the
water content at high level. Stem diameter was 4.4 mm-7.78 mm for water stress
and 8.45 mm-11.68 mm for control. Stem elongation rate was 0.08 m week-1-0.18
m week-1 for water stress and 0.17 m week-1-0.25 m week-1 for control. Both of
stem diameter and elongation rate of water stress treatment were smaller than
those of controls. These results suggest that water stress treatment might inhibit
the plant growth.
For the yield, the differences in harvested fruit number between water stress
and control were small. Average harvested fruit number for water stress and
control was 41.8±18.8 fruit week-1 and 50.1±19.4 fruit week-1, respectively. Fruit
diameter was about 634.3 mm-755.2 mm for water stress and 731.9 mm-822.8
mm for control. Although the averages of harvested fruit number for two
treatments have no significant differences (t-test with 5% level), the yield of water
stress was lower than that of control. Water stress treatment will produce high
soluble solid fruits, and this will be happened along with decreasing of fruits load.
This might be caused by the limitation of physiologist characteristic, such as
photosynthesis efficiency, sink-source relationship, and respiratory losses (Davies
and Hubson 1981). These results suggest that the decreased yield of water stress
was resulted from the decreased fruit size.
For the plant quality, sweetness of fruits in water stress treatment was
always higher than that in control. Difference in sweetness between water stress
and control was from 0.2% to 2.5%. Patane and Consentino (2010) reported that a
difference in sweetness between water stress and control was from 0.55% to 1.4%
with short-term experiment. In their report, the water content in water stress was
maintaining 50%. The severe water stress in this study, 20%-30% water content,
would produce higher sweetness tomato compared with moderate water stress.
Sourness of water stress treatment was also higher than that of control. Difference
in sourness between water stress treatment and control was from 0.07% to 0.1%.
The difference in sourness between two treatments in short-term experiment was
from 0.05% to 0.06%, described by Patane and Consentino (2010). The result
showed that water stress treatment can produce high sweetness and sourness
tomato.
Keywords: high technology greenhouse, irrigation control, high brix tomato,
water stress
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DEVELOPMENT OF WATER STRESS TREATMENT SYSTEM
FOR LONG-TERM HIGH BRIX TOMATO PRODUCTION
IN HYDROPONIC CULTURE
DRUPADI CIPTANINGTYAS
Thesis
Submitted in Partial Fulfillment of the requirements
For Magister Sains Degree
In Study Program of Food and Agricultural Machinery Engineering
GRADUATE SCHOOL
BOGOR AGRICULTURAL UNIVERSITY
BOGOR
2014
Final Examiner outside Supervisory Commitee: Dr Ir Rokhani Hasbullah, M Si
Thesis Title : Development of Water Stress Treatment System for Long-term
High Brix Tomato Production in Hydroponic Culture
Name
: Drupadi Ciptaningtyas
Student ID : F151110071
Approved by
Supervisory Committee
Prof Dr Ir Herry Suhardiyanto, M Sc
Chairman
Noriko Takahashi, Ph D
Member
Acknowledged by
Head of Study Program of Food and
Agricultural Machinery Engineering
Dr Ir Y Aris Purwanto, M Sc
Date of final examination:
20 March 2014
Dean of Graduate School
Dr Ir Dahrul Syah, M Sc Agr
Date of graduation:
PREFERENCE
First and foremost, Praise to my Lord Allah SWT for giving me strength to
accomplish my research and master thesis. All Your blessing motivated my self to
achieve my master degree. This master thesis which is entitled “Development of
Water Stress Treatment System for Long-term High Brix Tomato Production in
Hydroponic Culture”, was based on research conducted from August 2011 to
March 2012.
The writer would like to thank to Prof Herry Suhardiyanto and Noriko
Takahashi Ph D as the supervisory committee for their enormous help throughout
the completion of my thesis. The writer also would like to thank to Prof Hiroshige
Nishina and Kotaro Takayama Ph D, for their inspiring advice, warm support and
encouragement, and also the flexibility they gave me in conducting my research.
Dad, Mom, and Brother, I thank you for all your love, support, and pray.
It is truly hoped that this master thesis will give a worthy addition to the
existing knowledge on greenhouse technology area and the readers will get useful
informations.
Bogor, March 2014
Drupadi Ciptaningtyas
v
TABLE OF CONTENTS
TABLE OF CONTENT
LIST OF TABLES
LIST OF FIGURES
APPENDIXES
1 INTRODUCTION
Research Background
Problem Formulation
Objectives of Research
Research Output and Benefit
Data Acquisitions
v
vii
vii
viii
1
1
2
3
3
2 LITERATURE RIVIEW
Water Scarcity
Visual Monitoring System
Water Stress Treatment
5
5
6
3 MATERIALS AND METHODS
Time and Place of the Research
Materials
Equipment
Plant Materials and Growth Conditions
Hydroponic
Visual Monitoring System
Plant Growth Rate Measurement
Fruit Characteristic Measurement
Statistical Analysis
Research Flow Diagram
11
11
11
12
12
12
13
14
15
15
4 RESULT AND DISCUSSION
Environmental Condition
Sweetness
Sourness
Harvested Fruit Number
Fruit Diameter
Yield
Stem Diameter
Stem Elongation Rate
16
19
19
22
24
25
26
28
5 CONCLUSION AND RECOMMENDATION
Conclusion
Recommendation
REFERENCES
APPENDIX
CURRICULUM VITAE
30
32
32
33
38
53
4
7
15
29
vi
LIST OF TABLES
1
2
3
Several studies about the effect of water stress treatment on tomato crops
Several studies about effect of seasonal changes on tomato crops
The doses requirement of tomato’s crop nutrient
9
10
13
LIST OF FIGURES
1 A Schematic of discriminant analysis for determination of threshold value
(k) that divides the diphasic histogram into two groups (Class 1 and Class
2)
2 Subtropical intelligent greenhouse with the type of venlo house (1300 m2),
in Faculty of Agriculture, Ehime University
3 Four tomato crops planted to each rockwool cube on a rockwool slab
4 Schematic diagram of the water stress treatment system that controlled by
digital camera that taken pictures every 15 minutes and by measured
water content of growth medium every day
5 Equipments used for the measurement of fruit quality and quantity:
ISEKI Grading machine (a), Refractrometer for calibration of fruit
sweetness (b), Fruit Selector machine for calibration of fruit sourness (c)
6 Research flow diagram
7 Time course of: outside solar radiation (A), average relative humidity
inside greenhouse (B), maximum, minimum, average air temperature
inside greenhouse (C), and water content of rockwool slab in water stress
treatment (D).
8 The ratio differences of projected leaf area with different water content
(March 25, 2012). The percentage of projected plant area were measured
by compared the pixel number of plant area at that time with
the pixel number of plant area from the picture that took after last
irrigation
9 Variation of fruit sweetness during research period due to: water stress
treatment (A), and seasonal change (B).
10 Variation of fruit sourness during research period due to: water stress
treatment (A), and seasonal change (B).
11 Variation of harvested fruit number during research period due to:
water stress treatment (A), and seasonal change (B).
12 Variation of fruit diameter during research period due to: water stress
treatment (A), and seasonal change (B).
13 Variation of yield during research period due to: water stress treatment
(A), and seasonal change (B).
14 Variation of stem diameter of tomato plants during the research period
due to; water stress treatment (A), seasonal change (B).
15 Stem elongation rates of tomato plants during the research period due to;
water stress treatment (A), seasonal change (B).
7
11
12
14
16
18
20
21
23
24
25
27
28
29
31
vii
1
2
3
4
5
6
7
8
9
10
11
12
13
14
APPENDIXES
Timeline
The effect of water stress treatment on fruit sweetness
The effect of water stress treatment on fruit sourness
The effect of water stress treatment on fruit diameter
The effect of water stress treatment on yield
The effect of water stress treatment on stem diameter
The effect of water stress treatment on stem elongation rate
The effect of seasonal change on fruit sweetness
The effect of seasonal change on fruit sourness
The effect of seasonal change on fruit diameter
The effect of seasonal change on yield
The effect of seasonal change on stem diameter
The effect of seasonal change on stem elongation rate
Assessment of tomato fruit taste
38
40
41
42
43
44
45
46
47
48
49
50
51
52
1
1 INTRODUCTION
Research Background
Water is one of the most important factor in agriculture. Eventhough water
in horticulture is not a limited factor, in fact a water scarcity period will have to be
faced in the near future. Irrigated agriculture is a major consumer of water and
accounts for two thirds of the total fresh water assigned to human uses (Fereres
and Evans 2006). Water management practice can help ensure the survival and
sustainability of agricultural and economic activities related to water (Postel
2000). Maximising water productivity may be more profitable to the farmer than
maximizing crop yield (Pereira et al. 2002).
Deficit irrigation is a way to face this problem. Investigations over last two
decades showed that deficit irrigation methods can aid in coping with situation
where water supply is restricted (FAO 2002). Deficit irrigation could be a
management system to make the agricultural irrigation more effective. For plant
that cultivated on soil, deficit irrigation could be minimize leaching of nutrient
and pesticide into ground water while for plant that cultivated on another growth
medium, deficit irrigation could be minimize the requirement of electricity energy
for irrigation system include the recycle nutrient system.
Tomato is one of the most widely grown vegetables in the world because of
special nutritive value of its fruit (reach source of minerals, vitamins, organic
acids, essentia amino acid, antioxidants, etc). Therefore, any factor influencing
tomato yield has been attracted considerable interest (Jones and Benton 2008;
Jonson et al. 1992; Grange and Andrews 1994). Tomato is one of the world’s
most important irrigated vegetable crops (Gallardo et al. 2006) especially in
greenhouse. Nowadays consumer desire in taste for tomato is changing. They
require higher quality of tomato fruits from several aspects, especially sweetness
of tomato fruits. Tomato has high sweetness is known as fruit tomato. The prices
of fruit tomato generally higher than common tomato fruit, about ¥10,000/kg.
From several studies, it is known that water stress treatment of tomato crop
could used to produce fruit tomato. Water stress is the aplication of deficit
irrigation. The application of deficit irrigation on tomato crops not only increase
water use effeciency but also produce higher quality of tomato. Water stress
treatment on tomato crops not only increase the sweetness of tomato fruit, but also
produce tomato fruit with higher total solid and lower water content (Patane and
Cosentino 2010) and it really profitable for concentrated juice or tomato paste
industry, because they don’t required a lot of time and energy to evaporation, so it
improve processing efficiency (Johnstone et al. 2005).
Most of studies on water stress treatment were conducted using moderate
water stress, for example water content of growth medium was 50%-80% that
produce tomato fruits with the sweetness of 5.11oBrix - 5.82oBrix (Nurruddin et
al. 2003; Patane and Consentino 2010). Several studies on water stress treatment
for tomato were obtained short-term experiment either open-field system or
greenhouse system, for example the water stress treatment were conducted only
for 43 days after fruits appearing (Savic et al. 2008). Nurruddin et al. (2003),
2
Patane and Consentino (2010), and Patane (2011) conduct a partial water stress
treatment on several stage of tomato crop growth (i.e., flowering, fruit set, etc).
Many approaches to detect water stress were reported complicated and
expensive, for example Gallardo et al. (2006) who control the water stress by
using stem diameter variation measured with linear variable transducer sensors.
Savic et al. (2008) used different volume irrigation to the plants. Pulupol et al.
(1996) measure leaf water potential to control the water stress treatment condition.
Nurruddin et al. (2003) control the water stress treatment by monitoring the
moisture soil status and calculating amount of water added to each plant after
flowering stage. Patane et al. (2011) and Favati et al. (2009) reported to keep the
stress condition depend on evapotranspiration that was calculated from soil water
balance. Those methods are not efficient enough to apply in commercial
greenhouse system.
Due to the requirement of better system to detect water stress treatment for
supporting longer treatment and also produce higher sweetness of tomato fruit as
mentioned above, this research is conducted. This research is aimed to obtain a
better water stress detection system so that the water stress treatment could be
longer, and assess the effect of severe water stress treatment on quality of tomato.
Problem Formulation
Although only eleven percent of total land accounted for arable land, Japan
is one of the most advanced agriculture in the world. Greenhouse area in Japan is
accounted 49,049 hectare in 2011 (Kacira 2011), although this number is
decreasing annually and cover only one percent from total arable land. With that
decreasing trend, Japan still became the fourth largest greenhouse production area
in the world, next to China, Korea, and Spain. Moreover, Japan is one country that
develops tomato production greenhouse intensively, with production reached
690,700 tons in 2010 (Otsuka 2011).
Most of tomato fruit in Japan produced in commercial greenhouse, which
mean the aim of the greenhouse, is to get the highest benefit with an effective and
efficient manner. To support the longer production time, tomato crops are planting
in high technology greenhouse that usually has 10 months of harvesting time. It is
longer than traditional greenhouse that usually has 3 months of harvesting time.
So that the control of water stress treatment should be able to do in the long run.
The application of water stress treatment in a commercial greenhouse
should be controlled by a system that has low maintenance and can easily used by
the growers. Due to the requirement of better system to detect water stress
treatment, new control system should be build. A water stress detection technique
sustainable for use in a commercial greenhouse should satisfy the following
requirements:
1. The water stress index must be stable
2. The measurement should be performed by using inexpensive materials
3. The water stress detection must done automatically
4. Water stress should be detected as early as possible
To meet the requirement, we applying a new technique for detecting water
stress in tomato crops based on projected leaf area calculated from a digital color
image that is captured by a commercially available, inexpensive, digital camera
3
(Nishina et al. 2004; Nishina et al. 2005; Takayama and Nishina 2007). This
system was already developed but never been applied directly in a commercial
greenhouse. To support the digital monitoring system, growth medium also
measured to validate the condition of tomato crops.
Since the sweetness of tomato that produced from moderate water stress
treatment was still too close to the level of sweetness that allowed by the industry
(4.6°Brix), it is necessary to increase the sweetness to higher level. Most tomato
production in Indonesia conducted by open-field cultivation, without the
application of hydroponics, so that the quality and quantity of tomato in Indonesia
quite low. The average of sugar content in tomato fruit from Indonesia is 3.5oBrix
(Lokasari 2011). From Suhardiyanto (2009) the application of greenhouse and
hydroponic would increase the quality and quantity of tomato (per square meter).
Furthermore the water use efficiency can be improved. Severe water stress with
lower water content in growth medium, e.g. 20%-30%, may be able to be used for
producing higher sugar content tomato, but it might be decreased the production
yield and growth rate of tomato crops. So it is necessary to find a relationship
between long-term water stress treatments and the quality and quantity of tomato.
Japan has fall, winter, spring, and summer seasons, which means the
weather or climate is changing significantly. Environmental condition inside the
greenhouse also changes due to the season. Toor et al. (2006) observed the effect
of solar radiation and air temperature on tomato crops for 8 months in subtropical
region and found that higher solar radiation and air temperature increased the fruit
sweetness. Gallardo et al. (2006) observed the effect of solar radiation and air
temperature on tomato crop for 7 months in subtropical region and found that
higher solar radiation decreased the tomato crop growth rate. Since the production
time of tomato reaching almost one year, water stress treatment may vary with
season. The effect of seasonal change on the fruit quantity, fruit quality, and
tomato plant growth rate under water stress treatment was not studied well.
Therefore, research on long-term water stress treatment is necessary for high brix
tomato production in intelligent greenhouse.
Objectives of Research
The objectives of the present study are to develop a water stress treatment
system for long-term high brix tomato production in hydroponic culture and
evaluate the performance of water stress treatment system in long-term severe
water condition with seasonal change on the quantity and quality of tomato fruits.
Furthermore, the effect of water stress on plants growth was examined. All data
that from this research could be used for database of development of water stress
treatment system on tomato plants.
Research Output and Benefit
Agriculture is often associated with the image of inefficiency, being less
profitable than other sector. With the issues of scarcity of water, water use
efficiency is necessary to be gained. Tomato is one of the world’s most important
irrigated vegetable crops, which mean lots of water is requires for tomato
cultivation. By applying the management of deficit irrigation named water stress
4
treatment to tomato crops the water use efficiency for most irrigated vegetable
crops would be gain, which mean water use efficiency of the world would also
significantly gain.
This research was conducted in Japan, where implementation of greenhouse
building for growing plants is developing rapidly. The ratio of vegetables and
fruits grown in greenhouse is in increasing trend annually. Accordingly, this
research could be implemented in another greenhouse. Digital monitoring system
is really necessary for the application of water stress treatment in commercial
greenhouse, because it is neither too expensive nor too complicated to be handled
by the growers. Digital monitoring system is also flexible to apply in many
greenhouses in the world, including in a traditional greenhouse in Indonesia. Even
though the production time of traditional greenhouse is not as long as high
technology greenhouse, the digital monitoring system is still the cheapest and the
most simple water stress controlling system compare with another controlling
system. So it really fits the condition of a developing country like Indonesia to
produce higher quality of tomato.
Tomato fruit from Indonesia usually lost by imported tomato from another
country either in quality or price. To improve the quality and quantity of
Indonesia’s tomato, application of technology such as the application of
greenhouse and hydroponic is required. Indonesia is a blessed country with high
annual solar radiation and stable temperature. Related to several studies, high
solar radiation is support the production of sugar content in tomato fruit.
Therefore Indonesia has the opportunity to become producer of high brix tomato
in the world. The application of water stress treatment for tomato crop that
controlled by digital monitoring system in greenhouse by hydroponic cultivation
would increase the quality and quantity of tomato fruit in Indonesia. So that
tomato fruit from Indonesia could be the winner in its own country moreover it
could be exported to another countries to increase foreign exchange of Indonesia.
Data Acquisitions
1.
2.
3.
4.
Environmental parameters measured were solar radiation outside greenhouse,
average relative humidity inside greenhouse, air temperature (oC) inside
greenhouse (maximum, minimum, and average), and water content of growth
medium (%).
Plant growth rate parameters measured were stem diameter (mm) and stem
elongation rate (m week-1).
Tomato fruit quality parameters measured was fruit sweetness (oBrix) and
fruit sourness (%).
Tomato fruit quantity parameters measured was harvested fruit number (Fruit
week-1), yield (kg week-1) and fruit diameter (mm).
5
2 LITERATURE REVIEW
Water Scarcity
Related to Musiake et al. (2002), it is anticipated that the world’s water
resources will be under more pressure in the first half of this century than any
time during the recorded history. The estimation of the current level of water
stress is important for reliable projections of the severity of the water crisis in the
future. However, most of the previous global analyses on water scarcity have been
carried out on a country basis or a river basin basis. Considering the importance of
global water scarcity, future projections should be valuated by multiple
procedures/models/methods in various organizations, since the reliability of the
estimates will be supported if similar results are obtained from different scientific
approaches, information, and data processing.
For the global estimation of the water supply, observed runoff or
simulated runoff is generally used. Shiklomanov (2000a; 2000b) estimated the
water availability for 26 regions of the world based on observed river discharge at
2500 stations. Takahashi et al. (2000) estimated the monthly water balance in 0.5o
by 0.5o longitude/latitude grid boxes using a bucket model (Manabe 1969) with
potential evapotranspiration by the Penman method using current and future
climate projections (temperature, wind speed, and precipitation) simulated by
GCMs (General Circulation Models) of the Canadian Climate Centre, Max Planck
Institute, and Center for Climate System Research (CCSR), University of Tokyo.
Vorosmarty et al. (2000) adopted a similar approach, but their water supply
estimates were linearly adjusted to observation where discharge information was
available.
Based on Musiake et al. (2002), The regions with severe stress in 1995
will still experience severe stress in the projection for 2050 and the severity will
even increase in most regions. The regions with severe stress will also spread to
the neighboring areas. Such regions with increased water scarcity are mostly
located in developing countries. The increase of discharge associated with global
warming can mitigate the water scarcity in some regions. However, the effect of
the population growth compensates such mitigation, or even increases the severity
in such regions. The worse situation can be seen in the developing regions with a
high population growth rate and with a decreased discharge under global warming
conditions. As a whole, the effect of population change will be the major factor
contributing to the increased severity of water scarcity in the future. Even though
the amount of available water in Asia is large, population and current water
withdrawal particularly agricultural water demand are very high, and the water
stress ratio is the highest among the continents. Intensified water scarcity was
found mainly in and close to the regions of water scarcity under the current
conditions. The population growth in the future will exert a major effect on the
severity of water scarcity compared to climate change.
6
A growing scarcity of water relative to human demand occurs in many
parts of the world, but appropriate water management practices can help ensure
the survival and sustainability of agricultural and economic activities related to
water (Postel 2000). The sustainable use of water in agriculture has become a
priority and the adoption of irrigation strategies which may allow saving irrigation
water and maintaining satisfactory yield, thus improving water use efficiency,
may contribute to the preservation of this even more restricted resource (Parry et
al. 2005; Topcu et al. 2007). Water deficits and insufficient water are the main
limiting factors affecting worldwide crop production. Deficit irrigation (DI) can
reduce production cost, conserve water and minimize leaching of nutrients and
pesticides into ground water. While this has primarily been a concern in field
crops, the disposal of nutrient and pesticide-laden waters from large greenhouse
complexes has come under scrutiny. Establishing DI as a management tool for
tomatoes could be a very effective in situations where water is scare and also
reducing effluent contamination. This is especially important since tomato is a
popular greenhouse-grown vegetable, grown extensively through the world
(Nurruddin et al. 2003).
The goal of DI is to increase crop water use efficiency by reducing the
amount of water applied with watering or by reducing the number of irrigation
events (Kirda 2002). DI involves the use of appropriate irrigation schedules,
which mostly derive from field trials (Oweis and Hachum 2001). In this case, the
optimal irrigation schedules are often based on the concept of water productivity
(Oweis and Zhang 1998). Water use efficiency can be improved by drip irrigation.
It is significantly reducing runoff and crop evapotranspiration losses (Stanghellini
et al. 2003; Jones and Benton 2008; Kirnak and Demitras 2006).
Visual Monitoring System
Figure 1 shows a schematic of the discriminant analysis for the
determination of threshold value (k). The discriminant analysis automatically
determines a threshold value (k), which divides a bimodal histogram into two
groups (Classes 1 and 2, shown in Figure 1) with maximizing of the interclass
variance [�� ! � ] of the two groups. The interclass variance is calculated with the
following equation:
�� ! � = �! (�! − �! )! + �! (�! − � ! )!
in which k is threshold value for dividing the bimodal histogram into two groups
(Class 1 and Class 2) �! is an average of Class 1, �! is an average of Class 2, � ! is
an average of the whole histogram, �! is the ratio of the frequency of Class 1 to
the frequency of the whole histogram, and �! is the ratio of the frequency of Class
2 to the frequency of the whole histogram (Torii 1996). The color (hue) histogram
of a digital color image of a tomato plant with a blue background shows such a
bimodal histogram, so we used the discriminant analysis method for automatic
determination of the plant area with a digital color image (Nishina et al. 2007).
A clear bimodal distribution of hues of the digital color image can be
recognized in the color histogram. The interclass variance of the color histogram
shows a single-peaked pattern. Therefore, the threshold value, i.e. hue=146°, can
7
be determined automatically. Using the threshold value, the plant area represented
in green was clearly extracted and the pixel number within the plant area could be
used as a relative value of the projected plant area to diagnose the water stress in
the tomato plant (Nishina et al. 2005).
Figure 1
A Schematic of discriminant analysis for determination of threshold
value (k) that divides the diphasic histogram into two groups (Class 1
and Class 2)
Water Stress Treatment
There are several stress treatment usually apply to plant for some reason.
Stress treatments for plant usually applied are drought stress, heat stress, cold
stress, mineral stress, and Salinity stress. However, drought stress or water stress
is the most famous one, because of the issue of water scarcity. The physiology of
water stress resistance has been quite extensively in recent years. As will be seen,
in some respects the physiology of drought resistance is open to controversy,
while in other respects knowledge is just emerging and is far from being put to
use in plant breeding. An understanding of the physiology of drought resistance
requires some introductory notes on the physiological consequences of plantwater deficit, with emphasis on processes affecting plant production (Blum 1988).
In general, reducing water supply by: (1) reducing irrigation frequency, or
(2) increasing environmental demand, will reduce growth. An example is
providing by Hanan and Jasper’s work on carnations (1967). Different irrigation
regimes will influence branching, stem length, quality and yield. Water stress may
have far-reaching effect, influencing keeping life and resistance to air pollution.
However, if a crop is planted single stem (chrysanthemums or snapdragons),
yield is fixed. It can be desirable to reduce water application or decrease humidity
in order to obtain a more compact flower head, or to reduce brittleness. The same
8
may be necessary with foliage, bedding, or potted plants where some judicious
stress will improve ability to withstand transplanting shock, or the new
environment provided by the consumer. The exact effect of stress will depend
upon how large the stress is, how long stress is imposed, how the plant was
treated previously (part history), species, and stage of growth. With continuously
flowering plants, undue stress at any stage may several restrict stem length and
branching. For single cropping, high stress at flower initiation may reduce flower
number and size (Hanan et al. 1978).
The general effect on some physiological processes in herbaceous plants
was provided by Boyer (1970a, b). Stresses of less than -4 bars were sufficient to
reduce elongation, and beyond -8 bars, photosynthesis was decreased. These are
not extreme when, as a general rule, a soil suction of -15 bars is often acceptable
as the value where most field plants will permanently wilt. Internal water
potentials approaching -15 bars have been measured by often, reduce
photosynthesis to such an extent that solar energy cannot be efficiently utilized
(Boyer 1970b).
If low stress is necessary for maximum growth, it does not follow that zero
stress is best. Heydecker et al. (1970) showed that abnormal growth could result
where there was no pressure gradient from the leaf to the air. Another problem at
low stress conditions is increased damage from foliar disease such as Botrytis or
mildew (Winspear et al. 1970). If there is no stress, it is highly unlikely that a
plant is actively producing food. If there is sufficient energy (sunlight) to
manufacture sugars, there will be sufficient energy to evaporate water and induce
stress.
From Hanan et al. (1987), there are several ways to control water demand,
or reduce the transpiration rate in greenhouse plants:
I.
Reduce vapor pressure gradient between leaf and air
1. Increase relative humidity
a. Add water to air
b. Reduce air temperature
2. Reduce leaf temperature
a. Syringe or mist with water
b. Reduce light intensity by shading
II.
Increase resistance to water vapor flow from leaf to air
1. Reduce stomata aperture by
a. Application of chemical to close stomata
b. Reduce stomata opening by increasing CO2 concentration
2. Increasing length of diffusion path-length from leaf to air by
reducing air velocity
This outline shows that water loss is determined by: (1) the difference in
water vapor concentration between inside the leaf and outside; and (2) by the
resistance to movement of water molecules from inside the leaf to outside. The
resistance varies according to the length of the path that water molecules must
traverse, and the size of the stomata opening. Table 1 shows the result of several
studies about water stress treatment in tomato crops, while Table 2 shows the
result of several studies about the effect of seasonal change on tomato crops.
9
Table 1. Several studies about the effect of water stress treatment on tomato crops.
No.
1.
2.
3.
4.
Writer
Gallardo et
al. (2006)
-
Savic et al.
(2008)
50% of growth
medium
Mitchell and
Shennan
(1991)
50–75 day
cutoff
irrigation
Pulupol et al.
(1996)
5.
Nurruddin et
al. (2003)
6.
Patane et al.
(2011)
7.
8.
Treatment
Patane and
Cosentino
(2010)
Favati et al.
(2009)
-1.0 to -1.2
MPa leaf water
potential
65%-80% of
growth
medium
50% ETc
restoration
50% ETc at
short and long
season
50% ETc
Quality
-
Increase
sweetness
(4.58oBrix5.58oBrix)
Increased
sourness (0.28%0.34%)
Increased
sweetness (6.80
o
Brix–9.18 oBrix)
Increased color
index (32.7–
39.5)
Increased
sweetness
(4.90oBrix–7.60
o
Brix)
Increased
sourness
(0.25%–0.36%)
Increased
vitamin C
(27.46%–
48.89%)
Increased
sweetness
(4.40oBrix–6.35
o
Brix)
Increased
sourness
(0.28%–0.36%)
Increased
vitamin C
(27.46%–
48.89%)
Increased
sweetness
Effect
Yield
Decreased fruit
number
Decreased fruit
diameter
(59.6mm –
72.5mm)
Decreased fruit
yield
Growth rate
Decreased
stem
diameter
-
-
Decreased fruit
yield, and fruit
number
Decreased yield,
and fruit diameter
(48.2mm–
56.7mm)
Decreased
vegetative
growth
Retard
flowering
Decreased total
yield, and fruit
size (34.4g–
68.9g)
-
Decreased total
yield, and fruit
size (44.1g–
73.3g)
-
Decreased fruit
yield and fruit
-
10
(5.30oBrix–
5.82oBrix)
Increased
sourness
(0.33%–0.39%)
Increased
vitamin C
(18.61%–
12.44%)
mean weight
Table 2. Several studies about effect of seasonal changes on tomato crops.
No.
Writer
1.
Gallardo et
al. (2006)
2.
3.
Hamner et
al. (1944)
Gautier et
al. (2008)
4.
Demers et
al. (1998)
5.
Toor et al.
(2006)
Quality
-
Effect
Yield
Yield in spring is
higher than yield
in autumn
Lower
temperature
or
lower photoperiod produce
lower acidity.
Stronger solar radiation
produces higher acidity.
Lower solar radiation or
higher temperature
produces higher carotenoid
content.
Longer photoperiod
Longer
produce higher sugar
photoperiod
content of tomato
produce higher
tomato yield.
Higher solar radiation and
temperature produce higher
sweetness, lycopene
content, and acidity
Growth rate
Increase with the
increasing of air
temperature and
solar radiation
-
Longer photoperiod
decreased the growth
rate.
-
11
3 MATERIALS AND METHODS
Time and Places of the Research
This research was conduted for seven months (August 2011 to March 2012).
Tomato seeds were sown on August and transplanting to rockwool cube on
September. The treatment of water stress is started on November and harvesting is
started from January untill March. Comprehensive timeline is shows in Appendix
1.
The research was conducted in a high technology greenhouse (1300 m2) in
Faculty of Agriculture, Ehime University, Japan (Figure 2). The greenhouse has
full controlling system, like cooling and heating system to support the seasonal
change, supplemental lighting, CO2 distribution system, etc. The measurements of
some fruit characteristic was conducted in the Research Center of Departement of
Bio-mechanical System, Faculty of Agriculture, Ehime University. This research
introduces visual monitoring system to control severe water stress condition by
using digital still camera.
Figure 2
Subtropical intelligent greenhouse with the type of venlo house (1300
m2), in Faculty of Agriculture, Ehime University
Materials
The materials used for this research were 288 tomato crops (Solanum
lycoperscium L) with variety of Momotaro sakura, 288 rockwool cubes (10 cm
[W] x 10 cm [H] x 10 cm [D]), 72 rockwool slabs (30 cm [W] x 25 cm [W] x 91
cm [L]) (Grotop Expert, Grodan. Inc), and nutrient solution (A-type recipe of
Otsuka House Solution, Otsuka Chemical co., Ltd).
12
Equipment
The equipment used for this research was divided in to some parts growth
system, visual monitoring system, and measurements of plant growth rate and
fruit characteristic. Environmental monitoring system (MC–5013, NEPON) that
automatically measures solar radiation, air temperature, and relative humidity
inside and outside the greenhouse, a drip irrigation system and nutrient tank were
used for the growth system. Water content meter (Sensor 300 Baud, Grodan. Inc),
digital camera (G700SE, Ricoh company, Ltd. Japan), Wi-Fi system, personal
computer and commercial available software (X6, CorelDRAW, Corel
Corporation, Canada) were used for visual monitoring system. Measuring tape,
board marker, and Digital Caliper Ruler (BLD-100, Niigata Seiki co., Ltd) were
used for plant growth rate measurement, furthermore grading machine (SSW1APQ-6R, ISEKI & Co., Ltd), weight scale, refractometer, and fruits selector
machine (K-BA100R, Kubota. Co) were used for fruit characteristic measurement
and calibration.
Plant Materials and Growth Conditions
Tomato crops were grown hydroponically in an intelligent greenhouse. The
greenhouse that used in this research is a subtropical greenhouse with the type of
venlo house, which covered by glass but in the special condition like a very high
temperature in summer, wall of the greenhouse covered by net. The greenhouse is
passively ventilated. Climatic parameters were continuously monitored within the
greenhouse. Solar radiation, air temperature and relative humidity were measured
inside and outside the greenhouse with MC–5013, NEPON. These data recorded
once a day.
There are two treatments that conducted in this research, water stress
treatment and control. Water stress treatment was started on 17 November 2011
after the plants reach 1 month old. 36 rockwool slabs were used for each treatment.
The irrigation for water stress treatment controlled by visual monitoring system
based on projected leaf area and water content of rockwool slabs, on the other
hand the irrigation of the control treatment is given for 3 minutes every 15
minutes. Water content for both treatments is measured once a day. Water content
is maintained from 20% to 30% for water stress treatment and 60% to 70% for
control.
Figure 3
Four tomato crops planted to each rockwool cube on a rockwool slab
13
Hydroponic
The seed were sown in spongy material on 29 August 2011 and transplanted
on 12 September 2011 to rockwool cubes on the rockwool slabs. Four plants
transplanted to each rockwool slabs (Figure 3). The plants watered daily with a
nutrient solution, which distributed by drip irrigation system. Drip irrigation type
placed on the surface of the rockwool with 1.5 m spacing between drip lines and
20 cm spacing between emitters within drip lines. The irrigation water had an
electrical conductivity around 0.27 dS m-1 to 3.8 dS m-1. The dose for tomato’s
crop nutrient is shows in Table 3. Nutrients for control treatment applied through
the irrigation system, in accordance with local practice. There are four lines of
tomato crops that used in this r