Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
Use of saline water for tomato production
in hydroponic greenhouse
NSTIP Project under Advanced and Strategic
Technologies
Sub-Program / Technology Area
Agricultural Technology
Track
Hydroponic Techniques
Sub-Track
Water Relations
Project Duration
Nov 2015 – Nov 2017
Proposed Budget
1,868,975 Saudi Riyal
February, 2015
Precision Agriculture Research Chair (PARC).
College of Food & Agriculture Sciences,
King Saud University,
Riyadh, Saudi Arabia
http://c.ksu.edu.sa/parc
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
Project Team
Principal Investigator:
Dr. Ranga Swamy Madugundu
Co-Investigator(s):
Prof. Dr. Khalid A Al-Gaadi
Prof. Dr. Abdulaziz R. Al-Harbi
Dr. Mahmoud A.E. Wahb-Allah
Research Associate(s):
Dr. ElKamil Tola
Masters Student(s):
Eng. Ahmad Mahmoud Hassan Zeyada
Eng. Ahmed Galal Ahmed Abd Elall Kaiad
External Consultant(s):
Prof. Nick Sigrimis (Agricultural University of Athens, Greece)
Prof. V. C. Patil (Former Chair Professor, PARC, KSU, Riyadh)
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Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
Overview
Hydroponic production technologies in greenhouses ensure increased food production, improve quality,
conserve resources, and protect the environment. Hydroponic production systems can yield 10-20 times
conventional farming systems, while using only 20% of the water. Tomato is one of the most important
vegetable crops grown in Saudi Arabia. However, Saudi Arabia imported 190,000 metric tonnes of
tomatoes worth US $ 62 million in 2009. In the Netherlands, tomato yields of up to 100 kg m-2 per year
under hydroponics have been reported. The water use efficiency has been observed to be 60-70 kg of
tomato per cubic meter of water as compared to 12-15 kg of tomato per cubic meter of water observed
in traditional agricultural practices. Hydroponics is an extremely efficient, environmentally friendly
agricultural production system that is ideally suited to widespread adoption in Saudi Arabia, where
water is becoming increasingly scarce. Saline water can be used for growing salt tolerant or moderately
salt tolerant crops such as tomatoes in hydroponic greenhouses. However, investigations on the use of
saline water without adverse effects on productivity and quality of crops are necessary. The proposed
project envisages use of saline water in hydroponic tomato production. The main objectives of the project
are 1. To study the effects of saline water on the yield and quality of tomatoes in hydroponic
greenhouses. 2. To determine the effects and Best Management Practice of conjunctive use of saline and
non-saline water on the productivity of tomatoes in hydroponic green houses.3.To assess the impact of
grafting on salt tolerant root stock, improved plant nutrition (elevated levels of P, K, Ca, Fe and Si) and
mist cooling on salt tolerance in hydroponic tomatoes. 4. To provide training on hydroponic greenhouse
technology to students and the farming community. Controlled polyethylene/glass green houses with
Open and Closed hydroponic systems will be used in the study. One greenhouse will be earmarked for
the Open system and the other one for the Closed system. Coco coir will be used as the growing medium.
The experiments in both the Open and Closed system greenhouses will be laid out in split- split plot
design with four replications. There will be two strips (main treatments): one for tomato seedlings and the
other for grafted tomato plants. In these two strips, the following two sub-treatments will be allocated.
1. Nutrient solutions at different crop growth stages as recommended by Hochmuth and Hochmuth (2008).
2. Modified nutrient solutions at different crop growth stages with elevated levels of P, K, Ca, Fe (40%
higher than in treatment 1) and Si@ 2.25 mg L1, coupled with mist cooling. In these strips, ten saline
water irrigation treatments with constant EC levels of 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, and differential EC
levels with mid-day reductions in EC to 2.5 dsm-1 (2.5/7.5, 2.5/10.0, 2.5/12.5 and 2.5/15.0 dsm-1 )
will be superimposed as sub-sub treatments. The nutrient solutions will be supplied through drip-irrigation
system. The drip fertigation system will be designed to deliver 100 mL of nutrient solution per plant using
drippers/capillary tubes. One dripper/capillary tube will be provided to each plant. The irrigation
frequency will be based on the crop growth stage, plant transpiration demands and solar radiation.
Drainage will be through a gutter system placed along each row. The minimum percent drainage of EC
nutrient solution of 10-15 %, will be adopted and it will be adjusted by manipulating irrigation frequency
through the automatic irrigation scheduler. A programmable irrigation timing controller will be used to
schedule and control the fertigation cycles and the midday reduction of EC. However, same amounts of
water will be delivered in both the Open and Closed systems. This fertigation system will also have the
capacity to operate automatically to adjust the irrigation frequency when we plan future experiments
to target a specific “drain EC & pH”. Drainage water will be recycled to increase water and nutrientuse efficiency in hydroponic greenhouses and reduce the environmental impact of the drainage water
discharge. The pH, and EC of the influx and efflux of nutrient solutions will be monitored constantly.
Environmental data inside both the greenhouses will be collected using sensors and climate control
systems. Periodic data on crop growth and yield parameters will be recorded in all the treatments. Fruit
trusses will be harvested weekly based on colour of fruits. A truss in which at least 80% of the fruits
attain red ripeness stage will be harvested. Harvested fruits will be graded, weighed and properly
stored for fruit quality assessment. Fruit quality parameters such as lycopene, chlorophyll and total
soluble solid (TSS) concentrations of fruits will be measured every week for all harvested tomatoes. Data
collected in the experiment will be analyzed using SAS software. Significance among individual
3
‫‪11-AGR1939-02‬‬
‫‪Use of saline water for tomato production in hydroponic‬‬
‫‪greenhouse‬‬
‫‪treatments will be analyzed by analysis of variance (ANOVA) and least significant difference (LSD) test.‬‬
‫‪The salient findings of the project will be documented in the form of bulletins, booklets and folders. The‬‬
‫‪relevant photographs, graphs, tables will be included in these extension education materials. The findings‬‬
‫‪will also be documented in multi-media format which will all be utilized for periodic on-site training of‬‬
‫‪farmers and students.‬‬
‫استخدام املياه املاحلة إلنتاج الطماطم يف البيوت احملمية املائية‬
‫ملخص‬
‫تقنيات االنتاج يف البيوت احملمية املائية ضمان لزايدة اإلنتاج الغذائي‪ ،‬وحتسني اجلودة‪ ،‬واحلفاظ على املوارد ومحاية البيئة‪ .‬ميكن لنظ م الزراعة املتحكم هبا بيئيا ان‬
‫تزيد من العائد ‪ 20 - 10‬مرة من النظم الزراعية التقليدية‪ ،‬يف حني تستخدم ‪ ٪ 20‬فقط من املياه‪ .‬يعترب الطماطم احد أهم حماصيل اخلضروات اليت‬
‫تزرع يف اململكة العربية السعودية‪ .‬ومع ذلك استوردت السعودية ‪ 190000‬طن منه‘ اي ما ميثل ما قيمته ‪ 62‬مليون دوالر يف عام ‪ . 2009‬يف‬
‫هولندا‪ ،‬انتاجية الطماطم تتجاوز ‪ 100‬كجم ‪/‬م ‪ 2‬يف السنة ابستخدام الزراعة املائية‪ .‬وقد لوحظ أن كفاءة استخدام املياه تكون ‪ 70 - 60‬كجم‬
‫من الطماطم لكل مرت مكعب من املياه ابملقارنة مع ‪ 15 - 12‬كجم من الطماطم لكل مرت مكعب من املياه ابستخدام الطريقة التقليدية ابلزراعة املفت وحة‬
‫ابحلقل‪ .‬الزراعة املائية هي فعالة للغاية ونظام انتاج زراعي صديق للبيئة والذي يعترب مثاليا العتماده على نطاق واسع يف اململكة الع ربية السعودية‪ ،‬حيث أن املياه‬
‫أصبحت اندرة بشكل متزايد‪ .‬ميكن استخدام املياه املاحلة لزراعة نبااتت تتحمل بشكل عايل او معتدل مثل الطماطم يف البيوت احملمية امل ائية‪ .‬ومع ذلك‪ ،‬فاالحباب‬
‫املتعلقة ابستخدام املياه املاحلة من دون آاثر سلبية على إالنتاجية وجودة احملاصيل ضرورية‪ .‬يتوخى املشروع املقرتح استخدام املياه امل احلة يف إنتاج الطماطم دون‬
‫تربة‪ .‬األهداف الرئيسية للمشروع هي ‪ . 1 :‬لدراسة اآلاثر النامجة عن استخدام املياه املاحلة على انتاجية وجودة حمصول الطماطم يف البيوت احملمية ا ملائية‪.‬‬
‫‪ . 2‬لتحديد اجلدول الزمين األمثل إلدارة االستخدام املشرتك للمياه املاحلة وغري املاحلة يف البيوت احملمية املائية إلنتاج الطماطم‪ . 3 .‬لتقييم التاثري احملسن للتغذية‬
‫النباتية اجليدة (مستوايت مرتفعة من الفوسفور والبواتسيوم و الكالسيوم واحلديد والسيلكيا) إىل جانب نظام التربيد الضبايب على أت ثريات كفاءة استخدام املياه‬
‫املاحلة و ‪ . 4‬لتوفري التدريب على تقنية الزراعة احملمية املائية املسببة للطالب واجملتمع الذي يعمل ابلزراعة‪ .‬سيتم استخدام البيوت البالستيكية البويل ايثيلني مع‬
‫أنظمة التحكم املائية املفتوحة وشبه املفتوحة يف الدراسة‪ .‬كما سيتم ختصيص أحد البيوت احملمية للنظام املفتوح واآلخر للنظام شبه املفتوح‪ .‬سيتم استخدام بقااي‬
‫الكوكا ابعتباره بيئة جبدة للنمو‪ .‬تصميم التجارب بتصميم وحدات منفصلة شريطية مع أربعة مكررات‪ .‬وسيتم ختصيص املعاملتني ا لرئيسينت احدها للشتالت‬
‫واالخرى للنتات املطعمة‪ .‬وحتت كل معاملة رئيسية ستقام معاملتني فرعيتني مها ‪ . 1‬استخدام حملول مغذي‬
‫)‪ (2008‬بطول موسم النمو يف البيت احملمي ‪ . 2‬حملول غذائي معدل مع رفع مستوايت عناصر‬
‫‪Hochmuth and Hochmuth‬‬
‫‪Fe ، Ca ، K ، P‬‬
‫‪% 40‬و‬
‫‪ Si‬اىل ‪ 2,25‬ملجم‪/‬لرت‪ ،‬إىل جانب التربيد الضبايب‪ .‬يف هذه الشرائط‪ ،‬عشرة معامالت من مياه الري املاحلة مع مستوايت اثبتة من االتوص يل الكهريب للماء‬
‫‪ 15,0 ، 12,5 ، 10,0 ، 7,5 ، 5,0 ، 2,5 ECw‬ديسمنس‪/‬م‪ ،‬ومستوايت من ‪ EC‬مع منتصف النهار خمفضة إىل‬
‫قيمة ‪ 2,5‬ديسمنس‪/‬م ابلنسب التالية ( ‪ ، 10,0 / 2,5 ، 7,5 / 2,5‬و ‪12,5 / 2,5‬‬
‫‪ 15,0 / 2,5‬ديسمنس‪/‬م) وهي‬
‫قيم للمعاملة الفرعية ابلتصميم‪ .‬سيتم تصميم نظام الرمسدة ابلتنقيط العطاء ‪ 100‬مليلرت من احمللول املغذي للنبات ابستخدام الضغط واألانبيب الشعرية ( ‪3‬‬
‫‪4‬‬
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
‫ سيتم ا لتخلص من‬.‫ تكرار الري اعتمادا على االحتيا جات املائية للنبات ومراحل النمو والظروف املناخية اخلارجية‬.‫ بواقع منقط لكل نبات‬،)‫مم من الداخل‬
‫ احلد أالدىن من الصرف للمحلول املغ ذي‬.‫الصرف منها بشكل سليم من خالل إنشاء نظام صرف يوضع على طول كل صف ومن مث إىل اجملاري الصحية‬
.‫ وهي نسبة متارس على نطاق واسع يف إنتاج الطماطم املائية وسيتم تعديله من خالل التحكم يف تكرار الري من خالل جدولة ا لري اآليل‬، ٪ 15 - 10
‫ مع احلرص على ان تصل نفس كميات‬،‫سيتم برجمة الري اليا ابستخدام وحدة التحكم جلدولة دورات الرمسدة واخنفاض قيم التوصيل الكهريب يف منتصف النهار‬
‫ نظام الرمسدة هذا له القدرة على العمل تلقائيا يف ضبط تكرار الري عندما خنطط يف املستقب ل لتجارب حمددة اهلدف "لقيم‬.‫املياه إىل النظم املفتوحة وشبه املفتوحة‬
‫ سيتم اعادة استخدام مياه الصرف لزايدة كفاءة استخدام املياه واملغذايت يف البيوت احملمية املائية واحلد من التأثري ا لبيئي لتصريف مياه‬." pH ‫ و‬EC
‫ و التوصيل الكهريب من تدفق املواد الغذائية إىل النبااتت او الصرف من وسط بيئة النمو ابست مرار ابستخدام عدادات‬، ‫ سيتم رصد الرقم اهليدروجيين‬.‫الصرف‬
‫ سيتم تسجي ل البياانت الدورية على منو‬.‫ سيتم مجع البياانت البيئية داخل البيتني احملميني على حد سواء ابستخدام أجهزة االستشعار واجهزة قياس املناخ‬.‫الرمسدة‬
‫ من‬٪ 80 ‫ سيتم حصادها عندما تص ل‬.‫ سوف حتصد الثمار بناء على لون الفاكهة عموما مرة واحدة كل أسبوع‬.‫احملاصيل وعناصر االنتاج يف مجيع املعامالت‬
‫ وسوف‬.‫ ساعة‬24 ‫ سوف توزن الفواكه وتدرج على الفور بعد احلصاد وختزينها حتت التربيد لتقييم معايري اجلودة الحقا يف غ ضون‬.‫مثار مرحلة النضج احلمراء‬
‫ وسيتم حتليل البياانت اليت مت‬.‫ ) من الفواكه كل أسبوع جلميع طماطم املعامالت‬TSS (‫ واملواد الكلية الذائبة‬،‫ الكلوروفيل‬،‫يقاس تركيزات كل من الليكوبني‬
، ) ANOVA ( ‫ وسيتم حتليل دالالت وأمهية املعاملة بني املعامالت الفردية عن طريق حتليل التباين‬، ) SAS ( ‫مجعها يف التجربة ابستخدام الربجميات‬
،‫ ا لصور ذات الصلة‬.‫ وسيتم توثيق هذه النتائج البارزة للمشروع يف شكل كتيبات ونشرات واحباث منشورة‬.‫ على التوايل‬،) LSD ( ‫واختبار الفرق األقل معنوية‬
‫ كما يتم توثيق النتائج يف شكل وسائط متعددة واليت سوف يتم استخدامه ا كافة لتدريب املزارعني‬.‫والرسوم البيانية واجلداول سوف تدرج يف هذه املواد املنشورة‬
.‫والطالب‬
The Kingdom of Saudi Arabia lies in the tropical and sub-tropical desert region of the Middle East. The
oil resources of the Kingdom have enabled it to be one among the highest per capita GDP nations in the
world. Agriculture is an important sector in the economy of the Kingdom. It assumes strategic significance
not only in attaining food security but also in generating gainful employment to the rural people. The
agriculture sector witnessed an impressive annual growth rate of 10.9 per cent as compared to GDP
growth of 11.6 per cent between 1969 and 2004. This was possible due to private sector investment in
agriculture, adoption of modern technologies and substantial financial support by the Government. As a
result, the country not only achieved self-sufficiency in wheat, milk, and vegetables, etc., but also
exported wheat for some time. The rapid progress witnessed in agriculture sector was at the cost of the
fast dwindling non – renewable underground water resources. Thus, the country is now faced with a
formidable challenge of adopting a sustainable agricultural policy to meet food requirements of a
population of 27 million people, growing at the rate of 2.9 per cent annually. This challenge necessitates
striking a delicate balance between Food Security and Water Security. Soil and water resources coupled
with use of fertilizers determine the production potential of agricultural ecosystems. Increased crop yields
are associated with increased water and fertilizer use and modern research is focused on maximizing
the Water and Fertilizer Use Efficiency (WFUE). The fast dwindling global fresh water and renewable
water resources coupled with increased demands for water from agricultural sector are threatening the
food and water security of nations around the world. As a result, approaches to water resources
management are also changing dramatically. This “Changing Water Paradigm” has many components:
a shift away from reliance on finding new sources of supply, a growing emphasis on ecological values,
a re-emphasis on meeting human water needs and a conscious breaking of the ties between economic
growth and water use (Gleick, 2000).
5
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
Agricultural situation in Saudi Arabia: The nation’s cultivated area in 2007 was 1.074 million hectares
(m. ha) with a production of 2.967 million tons (m.t.) of grains, 2.6 m.t. of vegetables and 1.581 m.t. of
fruits including 982,000 tons of dates. Saudi Arabia imported 190,000 metric tonnes of tomatoes worth
US $ 62 million in 2009.The soils in Saudi Arabia are sandy in nature, with low organic matter content
and poor water and nutrient holding capacities. The long term annual precipitation of the country has
been estimated at 114 mm per year. The annual water demand has been steadily increasing due to
comprehensive development in all sectors coupled with high growth rates in population and living
standards. Agricultural sector utilizes around 80 per cent of the total quantity of water used in the
Kingdom (Abderrahman 2001). The available surface and ground water resources are limited,
precipitation rates are low and evaporation is high. Such eco-physical conditions pose significant
challenges to agricultural activities. The sustainability of agro-ecosystems of Saudi Arabia depends
heavily on conservation of natural resources such as soil and water. However, steady decline in finite
water resources and continued degradation of soil resources make the task much more challenging.
Besides, the external inputs required for agricultural production are becoming scarcer and costlier. Thus
there is an urgent need to conserve the natural resources and to increase the input use efficiencies to
achieve sustainability of agriculture in the kingdom. Greenhouse construction and protected cultivations
alter microclimate conditions to favour plants’ productivity but they also predominantly reduce
transpiration and increase water productivity (litres of water per Kg of production) by a factor of 3-5.
Hydroponics: Increasing demand for food and rising food prices have created a dire need for adoption
of sustainable food production strategies. In recent times, skyrocketing of food prices have led to social
unrest in many parts of the world. Production of crops in hydroponic greenhouses results in increased
food production, improved quality, conservation of resources, and protection of the environment.
Hydroponics means cultivation of plants without soil. It is also referred to as nutrient-solution culture,
soilless culture, water culture, gravel culture and nutriculture (Marr, 1994). Soil is medium of plant growth
that offers mechanical support to the plant, stores water and provides plants with the required nutrients.
However, continuous and intensive use of soil in greenhouses has led to infestation by plant pathogens
and deficiency of essential nutrients. This has resulted in the use of soil disinfections leading to pollution
of the environment and damage to fertigation systems. Hydroponics is a viable system that overcomes
these problems. Growing of plants in nutrient solutions (water and fertilizers) with or without the use of
rooting medium (e.g., rock wool, perlite, peat, vermiculite, gravel, coir, sand, gravel, and sawdust) is
known as hydroponics. There are two types of hydroponic systems:1. Open System, where in, nutrient
solution that is fed to plants is drained out and not reused 2.Closed System where in the excess nutrient
solution is reused. In hydroponics, either organic substrates or inert substrates are used as media or there
could be total absence of substrate. In the latter, there will be a thin water film which is known as Nutrient
Film Technique (NFT). The substrates used in hydroponics, act as anchorage to plants and have a very
low cost of replacement; and there will be no need for costly disinfections. Extensive research on plant
nutrition in hydroponic systems has been carried out. Hydroponic systems that are automated use
considerably less water and yield much higher than the conventional agricultural systems. The ecological
footprint is improved and this leads to “zero emissions” greenhouse or the “green” greenhouse. Saline
water can be used for growing salt tolerant or moderately salt tolerant crops such as tomatoes in
hydroponic greenhouses. In Saudi Arabia, water is not only scarce but also precious. In such a situation,
studies on the use of saline water without sacrificing on yield and quality of crops are very much
necessary to determine appropriate water management practices. The various options that facilitate for
the use of saline water are: conjunctive use of saline water with non-saline water, improved plant nutrition,
mist cooling and elevated levels of CO2. However, in Closed systems the salinity build up that occurs due
to recirculation of excess nutrient solution can be dealt with by practicing a ‘run-to-waste’ system.
Hydroponic production of vegetable crops is possible throughout the year without any problems of soil
salinity, adversaries of climate, infestation by weeds, pests and diseases. Since hydroponic production
is possible throughout the year and the quality of the produce is also better, premium rates can be
obtained for the produce obtained during off-season. Tomato yields of 100 kg m-2 per year under
hydroponics have been reported from The Netherlands. The water use efficiency of 60-70 kg of tomato
per cubic meter of water in hydroponics has been reported as compared to 12-15 kg of tomato per
cubic meter of water obtained through traditional agricultural practices. Hydroponics is an extremely
efficient, environmentally friendly agricultural production system and ideally suited to widespread
adoption in Saudi Arabia, where water is becoming increasingly scarce. The country is faced with a
6
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
difficult situation of meeting the food needs of a growing population by reducing the dependence on
imported fresh food produce. At the same time, increasing productivity per drop of water even under
extremely high temperature conditions is really a challenge. Therefore farmers are looking for
sustainable agricultural technologies that also result in conservation of resources. Hydroponic production
technology meets most of these specific requirements.
2. Project Objectives:
1. To study the effects of saline water on the yield and quality of tomatoes in hydroponic green
houses.
2. To determine the effects and Best Management Practice of conjunctive use of saline and
non-saline water on the productivity of tomatoes in hydroponic green houses.
3. To assess the impact of grafting on salt tolerant root stock, improved plant nutrition (elevated
levels of P, K, Ca, Fe and Si) and mist cooling on salt tolerance in hydroponic tomatoes.
4. To provide training on hydroponic greenhouse technology to students and the farming
community.
3. Review of Literature
Types of Hydroponic System: Two types of hydroponic system are exists namely i) Closed and
open/semi open systems
Closed System: The nutrient solution is recirculated in closed systems (Donnan, 1994a). There are two
types of closed systems: Nutrient film Technique (NFT) with continuous recirculation and, flood and drain
system with intermittent recirculation. In NFT, there will be reduced consumption of water and fertilizers
and the environmental pollution that is generally associated with over irrigation of soil- or soilless-grown
greenhouse crops. Closed systems are compulsory in the Netherlands. The systems are leached at a
threshold level of 8 mol m-3 Na+ in tomato (Baas and Berg, 1999). In closed systems, water and nutrient
efficiencies are improved but the EC of nutrient solution increases (Conversa et al, 2003). Lopez et al
(2003) reported negative effect of recirculation of the nutrient solution on the fruit yield and quality of
greenhouse grown tomato. Donnan (1994b) while comparing open and closed systems, reported that
irrigation water and EC management are usually easier in recirculating systems while nutrient
management is difficult; hence, currently no more than 10% of the world’s commercial hydroponic crop
production uses these systems. According to the conclusions of a simulation study carried out by
Stanghellini et al. (2005), closed systems are not financially viable. Anastasiou et al (2009) has concluded
that in closed systems the critical process is the balancing of nutrient solution whereas in open systems
irrigation scheduling is more critical to save water and fertilizers.
Open and Semi Open Systems: In open systems the nutrient solution is not recirculated (Donnan, 1994a).
Also known as run to waste systems, they use dripper irrigation of soilless media in containers. In open
hydroponic systems, since solution is not recovered and recycled, the quality of the irrigation water is
less critical. In Semi open systems, solution is recirculated and drained occasionally. A content of up to
500 ppm of extraneous salts is easily tolerated, and for tomatoes even higher salinities are permissible.
The drainage should be collected and tested periodically for total dissolved salts and if salinity of the
drainage reaches 3,000 ppm or above, the bags must be leached free using plain water in the irrigating
system. Given the fact that hydroponic systems allow for drainage sampling and on-line measuring of
pH and EC, Sigrimis et al (2001) achieved control of watering at high precision of drainage percentage
and fertilizer injection at target EC of drainage solution, irrespective of changes in transpiration
conditions.
Media and irrigation scheduling in hydroponics: Root anchorage and plant support must be supplied
in solution hydroponics systems. Media such as sand, peat gravel, scoria, and mixtures of vermiculite,
7
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
bark, sawdust, peat, and perlite, have been used successfully (Cotter and Corgan 1974; Johnson 1985)
to support the plants in a manner similar to that of soil. A complete plant nutrient solution is regularly
added to these media. Medium solution retention may be limited (particularly with the coarse aggregate
materials), and this requires frequent rewetting throughout the day. Conventional greenhouse and nursery
systems usually deliver nutrient solutions in appropriate quantities and times so that the medium is fully
wetted and a small amount leaches away (about 10-30 percent). In hydroponic culture the nutrient
solution can be recycled or used only once. Frequently one-time use of a solution is convenient. Even more
recently, techniques that deliver complete nutrient solutions to the roots in a continuous nutrient film
(Cooper 1979, 1985; Edwards 1985) have been described and used successfully. Regardless of the
system, the availability of adequate oxygen (O2) in a root zone is essential. The nutrient film technique
(NFT) innovation reported by Cooper (1985) includes the use of a split root technique that alternately
provides dissolved nutrients to one half of the root system at a time. In the other half, root O2 exchange
is enhanced. Donnan (1992) recommended recirculating NFT or flood and drain gravel channels for short
term crops such as lettuce, and non-recirculating, media-based systems for longer term crops or those
very vulnerable to root disease. He further observed that recirculating systems aren’t suitable for water
with high dissolved salts. The level of salts which can be tolerated in the water depends on their
composition and the type of crop is to be grown. Even 50 ppm of sodium can be toxic to plants such as
lettuce, straw berry and rose. In contrast tomato could cope with over 200 ppm (Donnan, 1994a).The
optimum supply of water and nutrients is crucial in hydroponic growing systems in order to use water
efficiently, avoid stress situations and improve production. Adaptive and learning techniques, based on
Solar Radiation (Sigrimis et al 2001) for prediction of system response have attained a drain regulation
accuracy of better than 3%. Lizarraga et al (2003) evaluated two irrigation scheduling techniques for
hydroponic tomato production in Navarra, northern Spain. The results showed that irrigation scheduling
by time clock was not flexible enough to satisfy the varying crop water requirements through the day
and during the season. With constant irrigation intervals and volumes, water and fertilisers were wasted
during the morning (excessive irrigation) whereas during the afternoon, the plants suffered water stress.
Their recommendation of scheduling of irrigation at a radiation level of 0.81 MJ m− 2, with some
supplementary time clock irrigation applications during the hours of darkness (in order to keep the
growing medium wet) has come in to practice. Hochmuth and Hochmuth (2008) reviewed the nutrient
solution formulations designed by them in 1990, for hydroponic tomato production systems. They
reported that the media (perlite, rock wool or NFT) required frequent irrigations during the day, ranging
from 10 to 20 cycles per day, depending on the weather and greenhouse environment, in order to
maintain about 20% solution leach.
Effects of saline water on yield of hydroponic tomato fruits
Tomato has been reported to be a moderately salt-tolerant crop (Maas, 1986) with differences among
the cultivars (Dasgan et al., 2002). Salt stress was found to result in reduced growth and yield (Yurtseven
et al., 2005). However, salt stress produced fruits of better quality which fetched higher market price
(Zushi and Matsuzoe, 2009). The crops that can be grown with saline water in hydroponics are limited
to salt tolerant and moderately salt tolerant species such as tomato, asparagus, cucumber, rose and
carnation. Even among salt tolerant species, varietal differences may exist. Varietal trials need to be
conducted to determine the most tolerant varieties. Salt tolerance of varieties, stage of development,
frequency of irrigation and addition of deficit nutrients are some factors to be considered in using saline
water. Tomato has been reported to be salt sensitive during early development (Kütük et al. 2004).
Olympios et al. (2003) reported that tomato is more susceptible to high salinity (8.7 dSm-1) at an early
stage of development than in the later growing stages. However,Stanghellini et al. (2002) observed that
the effects of salinity on tomato were reversible and the leaching of the salts from the root environment
resulted in full recovery of growth in the plant parts that had not reached the rapid growth phase at
salinity of EC 9 dS m− 1. The optimum EC range for tomato is 2 to 3.5 ds m-1. The concentration expressed
by 0.4 atm osmotic pressure was recommended as best for good development of tomato plants in
tropical areas (Steines, 1968). Schwarz (1968) reported yield reductions of 10-15 per cent in tomatoes
grown with water containing 3000 ppm of salts. He found that extremely high osmotic pressures (over
10 atm) for short periods are less damaging than long periods of moderately high pressures (4-5 atm).
Increasing the EC to greater than 2.3 dSm-1 has shown to increase TSS yet decrease tomato yield (Adams
and Ho, 1989). The reduction in yield of tomatoes under high EC was attributed to smaller fruit weight
8
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
and fewer fruits harvested (Adams, 1991; Adams and Holder, 1992). Another problem often observed
in tomato grown under high EC is the increased incidence of blossom end rot (BER) caused by a reduction
of calcium (Ca2+) uptake by roots and increased resistance to xylem transport inside the fruit (Ho and
Adams, 1989). However, increasing levels of only Ca2+ to the nutrient solution reduced the incidence of
BER (Adams and Holder, 1992). Dorais et al. (2001) reported that tomato yields at 4.6, 8.0, and 12.0
dSm-1 were lower compared with 2.3 dS m-1. Yield at 4.6 and 8.0 dS m-1 was reduced because of fruit
weight, whereas at 12.0 dSm-1, fruit number and weight were reduced. Another study reported yield
reduction when EC was increased from 2.3 to 5.1 dSm-1, whereas fruit quality was improved when EC
was increased from 3.5 to 9.0 dSm-1 (Dorais et al., 2001). Yield and fruit weight of cultivars with smaller
fruit size, such as cherry tomato, are less affected by higher EC than cultivars with larger fruit size
(Cuartero and Ferna´ndez-Munoz,1999). Therefore, growing cultivars with smaller fruit size may be
advantageous where water salinity is moderate or high. However, Alarcon et al. (1994) showed that
cherry tomato yield was lower due to reduced number of fruits that were smaller in size at EC of 14 dS
m-1, whereas fruit quality was increased with the high EC. Adams (1991) grew tomato plants in rockwool
and compared a salinity of 3000 µmhos/cm with those at 8000 and 12000 µmhos/cm and reported
that the highest yields were obtained at 3000 µmhos/cm and the lowest at12000 µmhos/cm. CropKing,
Inc. (1993) recommended the following EC ranges of a feeding solution at each of the following growth
stages of tomato: for germination and the early growth stage: EC between 1800 and 2000 µmhos/cm;
for the seedling stage: EC between 2300 and 2500 µmhos/cm; for vegetative, early fruiting, and mature
fruiting stages, EC between 2300 and 2500 µmhos/cm on sunny days, and between 3500 and 4000
µmhos/cm in the dark winter conditions. Tomato fruit yield decreases by 5.1 % per dSm-1 above 2 dSm1 (Ling Li et al., 2001). Mpelasoka and Nichols (2003) conducted two experiments in a greenhouse, one
in the winter and the other in the summer using the Nutrient Film Technique (NFT) at four EClevels: 2.0,
4.0, 6.0, 8.0 mScm-1. They observed reduction in yield with increasing EC for the summer crop, but no
reduction in yield was found with increasing conductivity for the winter crop. Magán et al (2003) studied
the effects of five salinity levels (2.5, 3, 4, 6 and 8 dSm-1) on greenhouse tomatoes grown in perlite
containers with re-circulation. They observed smaller fruits with lower fresh and dry weights with
increasing salinity. The percentage of dry matter in fruit increased linearly with salinity. Agong et al.,
(2003) evaluated the performance of thirteen tomato genotypes under hydroponics at salt applications
ranging from 0 to 2% NaCl, with the resultant EC values of 1.4 to 37 dSm-1. Among them two tomato
genotypes ('Siozawa' and 'Gambaru Ne-3') displayed superior performance. Chadirin et al (2007)
evaluated the application of Deep Sea Water (DSW) as a nutrient supplement for tomato cultivation.
They observed highest tomato fruit yield in nutrient film technique (NFT) system circulated with nutrient
solution of 10 dSm-1 EC as compared to 1.5 dS m-1(control), 15 dSm-1 and 20 dSm-1 EC levels.
Effects of saline water on the quality of hydroponic tomato fruits: Saline water has been used on
field-grown tomato crops to improve fruit quality and is a well-proven technique. Moderate brackish
water is particularly recommended for production of high quality tomatoes. However, the improvement
gained in the quality of tomato fruits by water deficit or saline water irrigation are usually accompanied
by reduced yields. Schwarz (1968) reported that saline waters have some favourable effects on
tomatoes in giving them a sweeter taste than those grown with fresh water. Increasing the salinity from
3000 to 8000 µmhos/cm improved both the quality and composition of tomato fruits (Adams, 1991).
The plants supplied with nutrient solution of higher EC level produced fruits of smaller size (Eltez et al.,
2002; Okano et al., 2002). Tomato fruit quality was found to improve with increased conductivity from
2 to 8 dsm-1 (Mpelasoka and Nichols, 2003). The production and quality of tomato (cv. Naomi) grown in
NFT (Nutrient Film Technique, with discontinuous cycle) at two levels of nutrient solution EC (2-5 and 4-10
dS m-1) was studied by Conversa et al, (2003). They observed higher production from low EC plants than
the high EC plants (2.9 vs. 2.2 kg/plant) due to higher weight and size of fruits. However, the high EC
treatment increased fruit dry matter content (9.0 vs. 7.8%), total soluble solids (7.4 vs. 6.7 °Brix),
titratable acidity (0.70 vs. 0.64 g/100 ml of juice of citric acid), Na+, K+, and Cl- contents. The low EC
plants consumed more water than high EC plants (100 vs. 87 L), but they had the same water use
efficiency. The lycopene (the red pigment and a strong antioxidant) concentration in tomato fruit was
enhanced when plants were grown hydroponically using a nutrient solution with a high electrical
conductivity (EC) of 4.8 dS m-1 compared to those grown under the standard low EC of 2.4 dSm-1 (Wu
et al., 2004). Lycopene concentration in tomato fruit was reportedly increased by manipulating level of
salinity in the nutrient solution (De Pascale et al., 2001; Krauss et al., 2006). Fanasca et al. (2007)
9
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
observed an increase in lycopene concentration on both fresh weight and dry weight basis by raising
the EC from 2.5 to 8 dS m-1. Lycopene content in tomato fruit was enhanced under high EC (Wu and
Kubota, 2008). Kubota (2009) observed significantly higher Brix, lycopene concentration (20% higher)
with some seasonal changes (higher lycopene in summer and lower lycopene in winter), β -carotene,
phenolics, and ascorbic acid of tomato under high EC levels. Suhardiyanto (2009) determined the optimal
EC values of nutrient solution for tomato fruit quality in hydroponic system by using Artificial Neural
Network and Genetic algorithms. They reported the optimal EC values of 1.4, 10.2 and 9.7 mS/cm, in
the flowering, the fruiting and the harvesting stage, respectively. In other experiments, Varlagas et al
(2010) have determined how salinity builds up of different initial salt concentrations as well as the uptake
rate of salt ions, which determine the appearance of salt effects.
Amelioration of the adverse effects of saline water: High salt contents and sulfate concentrations affect
calcium uptake leading to "blossom end rot" symptoms in tomato. Saline conditions reduce the availability
of iron. In addition to chloride and sodium, boron toxicity is also common with saline water. Yield loss
resulting from use of saline water can be minimized by strengthening the root system and reducing plant
stress. High rates of oxygenation in the root zone have recently proved to be highly beneficial under
increased EC treatments in tomatoes. Adding mineral pyrophyllitic clay suspension to the nutrient solution
has also been shown to assist plant growth, yield and fruit composition under conditions of plant stress
(raised salinity levels) in hydroponically-grown tomato crops (Lennard and Morgan, 2004). Silicon was
implicated to ameliorate the adverse effects of salinity (Bradbury and Ahmad, 1990; Liang et al., 1996;
Stamatakis et al.2003). The plants benefit from supplemental soluble silicon. The benefits include greater
tolerance to cold, heat, drought, salinity, mineral toxicity or deficiency, improved growth rates and
resistance to insects and fungi. Silicon gets deposited in epidermal cell walls resulting in increased
mechanical strength. It also enhances metabolic functions and improves pollen fertility, flower and fruit
count. The effects of silicon added to the nutrient solution either at a standard electrical conductivity (EC)
of 2.2 dS m-1 or at an increased EC of 4.8 dS m-1 on yield, nutritional status and fruit quality were
investigated in a tomato crop grown in a closed hydroponic system (Stamatakis et el 2003).The increase
of the EC up to 4.8 dS m-1 by adding NaCl had no significant influence on the fruit yield of tomato, when
Si was added to the saline nutrient solution. In contrast, the fruit yield per plant was significantly restricted
at this level of salinity, when no Si was added to the NaCl-enriched nutrient solution. In a study on the
effects of diurnal fluctuation in nutrient EC, it was found that a 2 dSm–1 daytime EC combined with 6
dSm–1 nighttime EC level did not affect total yield, fruit number, fruit weight, or plant water consumption
(Santamaria et al. 2004). Buck et al (2008) studied the effect of three EC levels on cherry tomatoes and
found that mid-day reduction of high EC level as a potential alternative to a more commonly practiced
continuously high EC treatment in semiarid greenhouses. Inoculation with Arbuscular Mycorrhizal Fungi
(AMF) has been found to enhance plant growth and uptake of nutrients, decrease yield losses of tomato
under saline conditions and improved salt tolerance of tomato (Li et al., 1991 a, b; Ruiz-Lozano, et al.,
1996; Al-Karaki, 2000; Al-Karaki et al., 2001; Huang et al., 2010; Abdel Latef and Chaoxing, 2011;
Basak et al., 2011). The deleterious effects of salinity on tomato biomass production can be ameliorated
by an enhanced supply of calcium (Grattan and Grieve 1999). According to Flores et al. (2001) and
Ben-Oliel et al. (2004), the supply of part of the nitrogen in the form of NH4-N in salt-stressed tomato
seems to increase the rate of N assimilation, as well as the levels of Fe and chlorophyll in the plant tissues,
thereby mitigating salt injury. Furthermore, better root aeration, which enhances the oxygen supply to
the root cells, may considerably enhance the salinity tolerance of tomato (Bhattarai et al. 2006).
Grafting tomatoes on salt tolerant root stock to overcome salinity stress: Grafting is an integrative
reciprocal process and, therefore, both scion and rootstock influence salt tolerance of grafted plants
(Etehadnia et al., 2008). The possible reasons for grafting-induced salt tolerance are: higher
accumulation of proline and sugar in the leaves (Ruiz et al.,2005); higher antioxidant capacity in the
leaves (López-Gómez et al., 2007); and lower accumulation of Na+ and/or Cl− in the leaves (FernándezGarcía et al., 2004; Esta˜n et al., 2005; Goreta et al., 2008; Zhu et al., 2008a,b). Grafting tomato with
tolerant rootstock has been highly effective at producing a saline-tolerant plant and research indicates
that several rootstocks prevented the translocation of sodium and chloride into the shoot. Scion genotypes
play an important role in the growth of grafted tomato plants, regardless of the salinity in the growing
media, whereas rootstock has little influence (Chen et al. 2003). In tomatoes, characteristics of the
rootstock conferring salt tolerance depend also on the salt tolerance of the shoot genotype (Santa-Cruz
10
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
et al., 2002). Colla et.al. (2010) while presenting an overview of the recent literature on the salinity
response and the mechanisms of salt tolerance of grafted plants, observed that grafting tomato plants
for increased salinity tolerance is a promising practice. Improved growth and higher fruit yield was
obtained at higher salinity (50 nM NaCl) by grafting a salt sensitive tomato variety (Moneymaker) on
to a salt tolerant rootstock Pera than self-grafted plants (Santa-Cruz et al. 2001). Estan et al. (2005)
reported improved salt tolerance and fruit yield in a tomato hybrid (Jaguar) grafted on to different
rootstocks (Radja, Volgogradskij, Pera, and Volgogradskij×Pera) and inferred that the tolerance
induced by the rootstock in the shoot was related to ionic rather than osmotic stress caused by salinity.
Grafting Moneymaker a scion with an ‘excluder’ character on to rootstocks Radja and Pera resulted in
higher tomato fruit yield when grown at 50 mM NaCl (Martinez-Rodriguez et al. 2008). Mohammed
et.al.(2009) grafted tomato cultivar Cecilia F1on to three rootstocks: Beaufort, He- Man and Syrian
local, using tube grafting technique. These grafted plants were grown in glass house in Astra Farms,
Tabuk, north-west of Saudi Arabia. The productivity of grafted tomato on He-Man rootstock increased
by 21 % as compared to control plants. Colla et.al. (2010) inferred that salt tolerance of the shoot
depends on the root system, independently of the genotype used as a scion, although the positive effect
of rootstock may show to a different degree depending on the higher or lower exclusion ability of the
shoot genotype.There are no reports of research on hydroponics from the Kingdom. This proposal would
address the most important and relevant researchable issues such as water management that would
greatly help in overcoming the major constraints in crop production. The major research gap identified
for the project is lack of research on using saline water in hydroponic production of vegetable crops. The
research team consisting of PI, the team of Co-Investigators and Consultants have rich experience in
various facets of hydroponics. The team is truly interdisciplinary, and is capable of implementing the
project for the benefit of farming community of this country.
Research Approach
Objectives
Approaches for achieving the objectives
1. To study the effects of saline water
on the yield and quality of tomatoes in
hydroponic green houses.
A. Assessing the effects of saline water on tomatoes under
both Open and Closed hydroponic systems.
B. Assessing the performance of tomatoes under varying
levels of salinity in hydroponic green houses.
C. Assessing the effects of water of different salinity levels
on the quality of tomato fruits grown in hydroponic
greenhouses under both open and Semi open systems.
2. To determine the effects of
conjunctive use of saline and non-saline
water on the productivity of tomatoes
in hydroponic green houses.
A. Studying the effect of conjunctive use of saline water
and non-saline water on tomato yield.
3. To assess the impact of grafting on
salt tolerant root stock, improved plant
nutrition (elevated levels of P, K, Ca,
Fe and Si) and mist cooling on salt
tolerance in hydroponic tomatoes.
A. Using tomato grafts for salt tolerance.
4. To provide training on hydroponic
greenhouse technology to students and
the farming community.
A. Prepare relevant training material to train students and
farmers.
B. Studying the effect of conjunctive use of saline water
and good quality water on the quality of tomato fruits.
B. Improving plant nutrition and mist cooling for inducing
salt tolerance.
B. Arrange training programmes at regular intervals.
11
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
Research Methodology
The major objectives of the project are to determine the effects of saline water on the productivity and
quality of tomatoes grown in hydroponic green houses. The brief details of the methodology that will be
adopted to achieve the objectives of the project are presented here. The investigations on the effects of
saline water on tomatoes will be carried out in 10 m x 30 m north - south oriented controlled
polyethylene/glass hydroponic greenhouses. The greenhouses will be equipped with fan-and pad
evaporative cooling systems.
Hydroponic Systems and the growing medium: Open and Closed hydroponic systems will be used in
the study. One greenhouse will be earmarked for the Open system and the other one for the Closed
system. Coco coir / Perlite will be used as the growing medium in these greenhouses. Tomato seedlings
and grafts will be transplanted into Coco Coir / Perlite soaked with nutrient solution. The tomato seedlings
and grafts will be placed inside hydroponic plastic channels which lie on the greenhouse floor covered
with white polyethylene film and will be soaked with nutrient solution before transplanting. MACQU
SCADA systems will be used for the research.
MACQU SCADA systems for greenhouse climate control and hydroponics (www.geomations.com)
(www.aua.gr/ns/hortimed/):
MACQU SCADA systems were developed under the support of E.U. and incorporated the latest
technological advancements. With a new sponsorship of E.U., research program HORTIMED extends
MACQU capabilities in the area of maximum water saving and maximum possible usage of saline water
for crop production in the Mediterranean. Hortimed has extended MACQU with a hydroponics simulator
good for examining scenarios for decision making or for education in water scarce regions (students
working in hydroponics, workshops etc).The basic characteristic of MACQU technology is based on an
open system architecture at all levels, from the visual presentation on the PC to the level of control (virtual
variables). Using virtual variables, the user can develop models based on which the climate and
hydroponics control becomes self-adaptive. This technology allows the direct coordination between
climate and hydroponics and provides the means to the development of an integrated way of production.
MACQU systems can adapt to the size of the greenhouse facility to offer to the producer: maximum
water saving (decrease of water usage up to 40%), energy saving (up to 30% in cold places), fertilizers
saving (proportional to the water saving), increase in production (up to 100%) and quality and reduction
of production cost (mainly because of the production increase). The MACQU-C system cooperates with
the hydroponics device MACQU-H for integrated management. The system comprises ready to use
control programs that incorporate the latest scientific progress in greenhouse control. The software
involves: Temperature control, Control of up to 4 window sets, Humidity control, Shading screen, Thermal
screen, Light and black out screen, CO2 control, Fog systems, Cooling panel, Dynamic air ventilation and
Irrigation control.
Grafting on salt tolerant root stock: The most common commercial technique for grafting tomato is Tube
grafting or Japanese Top-Grafting. Tube grafting has been adopted as the primary method for
vegetable grafting as it can be easily carried out with small healing chambers with typical success rates
ranging from 85 to 90 percent. This technique has been highly effective as it can be carried out when
plants are very small, thereby eliminating the need for large healing chambers while increasing the
output. Both grafted tomato plants and seedlings will be used in this study. Tomato grafts will be obtained
by adopting tube grafting method. In tube grafting, severed seedlings of both the scion and salt tolerant
rootstock will be reattached with a small (1.5-2 mm) silicone tube or clip. Tube grafting will be carried
out when the plants are very small.
Experimental Details: The experiments in both the Open and Closed system greenhouses will be laid
out in split- split plot design with four replications. There will be two strips (main treatments): one for
tomato seedlings and the other for grafted tomato plants. In these two strips, the following two subtreatments will be allocated. 1. Nutrient solutions will be supplied at different crop growth stages as
recommended by Hochmuth and Hochmuth (2008) (Table 1). 2. Modified nutrient solutions with elevated
levels of P, K, Ca, Fe (40 % higher than in sub-treatment1) and Si @ 2.25 mg L1, coupled with mist
cooling. In these two sub-treatment strips, ten saline water irrigation treatments with constant EC levels
of 2.5, 5.0, 7.5, 10.0, 12.5, 15.0, and differential EC levels with mid-day reductions in EC to 2.5 dsm-1
12
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
(2.5/7.5, 2.5/10.0, 2.5/12.5 and 2.5/15.0 dsm-1 ) will be superimposed as sub-sub treatments. The
higher EC solutions will be obtained by adding NaCl and CaCl2. During the first 2 weeks in the green
houses, plants will be grown under EC of 2.5 dSm-1 nutrient solution.
Table 1. Fertilizer recommendations for hydroponic tomatoes (Hochmuth and Hochmth, 2008)
Nutrient
Stage of growth
1
2
3
4
5
Transplant to
1st cluster to
2nd cluster to
3rd cluster to
5th cluster to
1st cluster
2nd cluster
3rd cluster
5th cluster
termination
--------------- Final delivered nutrient solution concentration (ppm) --------------
N
70
80
100
120
150
P
50
50
50
50
50
K
120
120
150
150
200
Ca
150
150
150
150
150
Mg
40
40
40
50
50
S
50
50
50
60
60
Fe
2.8
2.8
2.8
2.8
2.8
Cu
0.2
0.2
0.2
0.2
0.2
Mn
0.8
0.8
0.8
0.8
0.8
Zn
0.3
0.3
0.3
0.3
0.3
B
0.7
0.7
0.7
0.7
0.7
Mo
0.05
0.05
0.05
0.05
0.05
NOTE: Ca, Mg, and S concentrations will be varied depending on Ca and Mg concentration in water and amount
of sulfuric acid used for acidification (1ppm = 1mg/liter)
After 2 weeks, plants will be subjected to the different EC treatments. The plant density of 3.0 plants
per m2 will be adopted. The mid day EC reduction treatments will be achieved by supplying higher EC
nutrient solutions to the plants as per the treatments in the morning until 10 am, and then replacing it with
the low EC (2.5 dSm-1 ) nutrient solution until 4 pm. Thereafter, the plants will be provided with higher
EC nutrient solutions as per the treatments until 6 pm in winter and 8 pm in summer months depending on
the ending of feeding cycle. At least one night cycle will be practiced during summer period.
Nutrient and Water Management: The nutrient solutions will be supplied through drip-irrigation system.
The drip fertigation system will be designed to deliver 100 mL of nutrient solution per plant using
drippers/capillary tubes. One dripper/capillary tube will be provided to each plant. Automatic
Irrigation scheduler based on the measured incoming radiation integral will be used. The "irrigation start"
will be set with a certain threshold on accumulated radiation and the "irrigation stop" will be set based
on the dose selected. The irrigation frequency will be based on the crop growth stage, plant transpiration
demands and solar radiation. Drainage will be properly disposed of by creating a gutter system placed
along each row. The minimum percent drainage of EC nutrient solution of 10-15 %, will be adopted and
it will be adjusted by manipulating irrigation frequency through the automatic irrigation scheduler. A
programmable irrigation timing controller will be used to schedule and control the fertigation cycles and
the midday reduction of EC. The irrigation rates will be scheduled based on stage of the plant and
environmental conditions. Threshold day and night air temperature of 240 and 180 C, respectively will
be set to activate temperature control system. Common greenhouse plant maintenance, including weekly
leaf pruning and removing side shoots will be carried out.
Data collection
Crop environmental parameters: The pH, EC, No3, K, Ca and Na of the influx and efflux nutrient
solutions to plants and drained from the growing medium will be monitored frequently, using hand-held
EC and pH meters (HI 98312 and HI 98127, Hanna Instruments, Inc., Woonsocket, RI, USA) and nutrient
meters, which will be calibrated weekly. Environmental data inside the greenhouse on photosynthetic
photon flux (PPF), air temperature, relative humidity (RH), and atmospheric VPD will be collected using
sensors which will be connected to a data logger (CR-1000; Campbell Scientific, Logan, UT, USA). The
PPF will be measured using a LI- 190SA Quantum Sensor (LI-COR, Lincoln, NE) placed over the plant
13
Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
canopy. RH and VPD will be computed by measuring wet and dry bulb temperatures using Type-T
thermocouples placed inside the greenhouse. Solar radiation outside the greenhouse will be obtained
from Weather Station located nearby. Alternatively all above sensors will be connected to a powerful
fertigator which will be able to store data in PC data base as well as use the data for controlling the
greenhouse and the experiments.
Crop growth and yield parameters: Periodic data on crop growth and yield parameters will be
recorded in all the treatments. Periodic canopy chlorophyll measurements will be made using handheld
NDVI meter (Spectrum Technologies, USA). NO3, K and Ca levels in leaf petioles and fruits will be
determined/recorded periodically. Fruit trusses will be harvested based on overall fruit color once every
week. A truss in which at least 80% of the fruits attain red ripeness stage will be harvested. Fruits will
be weighed and graded immediately after the harvest and stored under refrigeration for assessing
quality parameters.
Fruit quality measurements: Fruit quality measurements will be made within 24 h. Lycopene, chlorophyll
and total soluble solid (TSS) concentrations of fruits will be measured every week for all harvested
tomatoes. The lycopene content of tomato fruits will be extracted and determined as per the method
described by Fish et al. (2002). TSS will be determined by a hand refractometer and the measured
values will be corrected to a standard temperature condition of 200C. Chlorophyll of tomato fruit puree
will be extracted and measured using a modified method of Moran (1982). Lycopene and chlorophyll
concentrations will be converted to a dry weight basis using fruit dry/fresh weight ratio obtained each
week.
Statistical analysis of the data: Data collected in the experiment will be analyzed using SAS software.
Significance among individual treatments will be analyzed by analysis of variance (ANOVA) and least
significant difference (LSD) test. Such analysis and subsequent interpretation and inferences will lead to
scientific publications.
Training of students and farmers: The salient findings of the project will be documented in the form of
bulletins, booklets and folders. The relevant photographs, graphs, tables will be included in these
extension education materials. The findings will also be documented in multi-media format which will all
be utilized for training purpose. During the second year Open days for farmers will be organised to
enhance farmers’ and consumers’ awareness about the advantages of the hydroponic systems in both
the quality for the consumer and the greenness of the greenhouse (carbon footprint).
Contingency Plan
1. The system will have capability for manual operation for limited time, until a technician can
deliver "first aid".
2. Internet connectivity will zoom into the possible problem.
3. The User training and the Internet mediated assistance usually takes care of 95% of events.
4. Installation will include local technicians or University technicians so we can deliver "first aid" with
local people within the day. This takes care of another 4% of problems (fixing pressure lines,
sticky valves, wiring problems)
5. Malfunctioning parts (1% of cases) can be identified through Internet within the hour and sent
by courier for next day delivery and replacement by skilled technician. Meanwhile manual
operation will sustain experiments.
6. It is understood that Electricity supply must be backed up by University Infrastructure and the
power of the Unit (the main pump) will have a backup unit within this normal quotation. Other
mechanical units may have local replacement possible and will be identified at project
installation.
Value to the Kingdom:
Technologies developed for use of saline water for tomato production in hydroponic green houses would
result in considerable savings in fresh water resources. The results would facilitate for use of diluted sea
water depending on the EC tolerance level of tomato, which is considered as a moderately salt tolerant
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Use of saline water for tomato production in hydroponic
greenhouse
11-AGR1939-02
crop. The present proposal would determine the threshold EC tolerance level and salinity amelioration
measures for successful tomato production in hydroponic greenhouses using diluted sea water. The results
would thus have tremendous impact on water security of the country. Further, the results would help in
reduced dependence on import of fresh vegetables and increased economic benefits in addition to
associated environmental benefits. The benefits derived from the outcome of the project would result in
sustainability of agriculture in Saudi Arabia. The target end users of the outcome of the project would
be farmers. The technology developed in the project will be transferred to the stake holders through
field days and mass media. The crucial savings made in fresh water resources in agricultural sector can
be diverted to civic use and industrial sectors.
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