Hydroponics as an advanced technique for vegetable production: An overview

Abstract

Currently hydroponic cultivation is gaining popularity all over the world because of efficient resources management and quality food production. Soil based agriculture is now facing various challenges such as urbanization, natural disaster, climate change, indiscriminate use of chemicals and pesticides which is depleting the land fertility. In this article various hydroponic structures viz. wick, ebb and flow, drip, deep water culture and Nutrient Film Technique (NFT) system; their operations; benefits and limitations; performance of different crops like tomato, cucumber, pepper and leafy greens and water conservation by this technique have been discussed. Several benefits of this technique are less growing time of crops than conventional growing; round the year production; minimal disease and pest incidence and weeding, spraying, watering etc can be eliminated. Commercially NFT technique has been used throughout the world for successful production of leafy as well as other vegetables with 70 to 90% savings of water. Leading countries in hydroponic technology are Netherland, Australia, France, England, Israel, Canada and USA. For successful implementation of commercial hydroponic technology, it is important to develop low cost techniques which are easy to operate and maintain; requires less labour and lower overall setup and operational cost.

Full text

Hydroponics as an advanced technique for vegetable
production: An overview
NISHA SHARMA1, SOMEN ACHARYA2*, KAUSHAL KUMAR3,
NARENDRA SINGH4 and O.P. CHAURASIA5
Received: 03 July 2018; Accepted: 29 November 2018
ABSTRACT
Currently hydroponic cultivation is gaining popularity all over the world because of efficient resources
management and quality food production. Soil based agriculture is now facing various challenges such
as urbanization, natural disaster, climate change, indiscriminate use of chemicals and pesticides which
is depleting the land fertility. In this article various hydroponic structures viz. wick, ebb and flow, drip,
deep water culture and Nutrient Film Technique (NFT) system; their operations; benefits and limitations;
performance of different crops like tomato, cucumber, pepper and leafy greens and water conservation
by this technique have been discussed. Several benefits of this technique are less growing time of crops
than conventional growing; round the year production; minimal disease and pest incidence and weeding,
spraying, watering etc can be eliminated. Commercially NFT technique has been used throughout the
world for successful production of leafy as well as other vegetables with 70 to 90% savings of water.
Leading countries in hydroponic technology are Netherland, Australia, France, England, Israel, Canada
and USA. For successful implementation of commercial hydroponic technology, it is important to develop
low cost techniques which are easy to operate and maintain; requires less labour and lower overall
setup and operational cost.
Key words: Nutrient Film Technique (NFT), water conservation, nutrient management, Hydroponic market
Journal of Soil and Water Conservation 17(4): 364-371, October-December 2018
ISSN: 022-457X (Print); 2455-7145 (Online); DOI: 10.5958/2455-7145.2018.00056.5
1Research Associate, 2,4Scientist, 3JRF, 5Director, Defence Institute of High Altitude Research (DIHAR), DRDO, C/o 56 APO,
Leh-Ladakh, 194101, Jammu and Kashmir
*Corresponding author Email id: someniari@gmail.com
INTRODUCTION
Hydroponics is a technique of growing plants
in nutrient solutions with or without the use of an
inert medium such as gravel, vermiculite, rockwool,
peat moss, saw dust, coir dust, coconut fibre, etc.
to provide mechanical support. The term
Hydroponics was derived from the Greek words
hydro’ means water and ponos’ means labour and
literally means water work. The word hydroponics
was coined by Professor William Gericke in the
early 1930s; describe the growing of plants with
their roots suspended in water containing mineral
nutrients. Researchers at Purdue University
developed the nutriculture system in 1940. During
1960s and 70s, commercial hydroponics farms were
developed in Arizona, Abu Dhabi, Belgium,
California, Denmark, German, Holland, Iran, Italy,
Japan, Russian Federation and other countries.
Most hydroponic systems operate automatically to
control the amount of water, nutrients and
photoperiod based on the requirements of different
plants (Resh, 2013).
Due to rapid urbanization and industrialization
not only the cultivable land is decreasing but also
conventional agricultural practices causing a wide
range of negative impacts on the environment. To
sustainably feed the world’s growing population,
methods for growing sufficient food have to evolve.
Modification in growth medium is an alternative
for sustainable production and to conserve fast
depleting land and available water resources. In the
present scenario, soil less cultivation might be
commenced successfully and considered as
alternative option for growing healthy food plants,
crops or vegetables (Butler and Oebker, 2006).
Agriculture without soil includes hydro agriculture
(Hydroponics), aqua agriculture (Aquaponics) and
aerobic agriculture (Aeroponics) as well as
substrate culture. Among these hydroponics
techniques is gaining popularity because of its
efficient management of resources and food
production. Various commercial and specialty
crops can be grown using hydroponics including
leafy vegetables, tomatoes, cucumbers, peppers,
strawberries, and many more. This article covers
different aspect of hydroponics, vegetables grown
in hydroponics system and global hydroponic
market.

HYDROPONICS: A PROGRESSIVE TECHNIQUE 365October-December 2018]
HYDROPONIC STRUCTURES AND
THEIR OPERATION
Hydroponic system are customised and
modified according to recycling and reuse of
nutrient solution and supporting media.
Commonly used systems are wick, drip, ebb-flow,
deep water culture and nutrient film technique
(NFT) which are described below (Fig. 1).
Wick System
This is simplest hydroponic system requiring
no electricity, pump and aerators (Shrestha and
Dunn, 2013). Plants are placed in an absorbent
medium like coco coir, vermiculite, perlite with a
nylon wick running from plant roots into a reservoir
of nutrient solution. Water or nutrient solution
supplied to plants through capillary action. This
system works well for small plants, herbs and spice
and doesn’t work effectively that needs lot of water.
Ebb and Flow system
This is first commercial hydroponic system
which works on the principle of flood and drain.
Nutrient solution and water from reservoir flooded
Fig. 1. Diagram of various structures of hydroponic system

366 SHARMA et al. [Journal of Soil & Water Conservation 17(4)
through a water pump to grow bed until it reaches
a certain level and stay there for certain period of
time so that it provide nutrients and moisture to
plants. Besides, it is possible to grow different kinds
of crops but the problem of root rot, algae and
mould is very common (Nielsen et al., 2006)
therefore, some modified system with filtration unit
is required.
Drip system
The drip hydroponic system is widely used
method among both home and commercial
growers. Water or nutrient solution from the
reservoir is provided to individual plant roots in
appropriate proportion with the help of pump
(Rouphael and Colla, 2005). Plants are usually
placed in moderately absorbent growing medium
so that the nutrient solution drips slowly. Various
crops can be grown systematically with more
conservation of water.
Deep water culture system
In deep water culture, roots of plants are
suspended in nutrient rich water and air is provided
directly to the roots by an air stone. Hydroponics
buckets system is classical example of this system.
Plants are placed in net pots and roots are
suspended in nutrient solution where they grow
quickly in a large mass. It is mandatory to monitor
the oxygen and nutrient concentrations, salinity and
pH (Domingues et al., 2012) as algae and moulds
can grow rapidly in the reservoir. This system work
well for larger plants that produce fruits especially
cucumber and tomato, grow well in this system.
Nutrient Film Technique (NFT) system
NFT was developed in the mid 1960s in
England by Dr. Alen Cooper to overcome the
shortcomings of ebb and flow system. In this
system, water or a nutrient solution circulates
throughout the entire system; and enters the growth
tray via a water pump without a time control
(Domingues et al., 2012). The system is slightly
slanted so that nutrient solution runs through roots
and down back into a reservoir. Plants are placed
in channel or tube with roots dangling in a
hydroponic solution. Although, roots are
susceptible to fungal infection because they are
constantly immersed in water or nutrient. In this
system, many leafy green can easily be grown and
commercially most widely used for lettuce
production.
BENEFITS AND LIMITATIONS
OF HYDROPONICS
Recently hydroponic technique is becoming
popular because this is clean and relatively easy
method and there is no chance of soil-borne disease,
insect or pest infection to the crops thereby reducing
or eliminating use of pesticides and their resulting
toxicity. Besides, plants require less growing time
as compared to crop grown in field and growth of
plant is faster as there is no mechanical hindrance
to the roots and the entire nutrient are readily
available for plants. This technique is very useful
for the area where environmental stress (cold, heat,
dessert etc) is a major problem (Polycarpou et al.,
2005). Crops in hydroponic system are not
influenced by climate change therefore, can be
cultivated year-round and considered as off season
(Manzocco et al., 2011). Further, commercial
hydroponic systems are automatically operated and
expected to reduce labour and several traditional
agricultural practices can be eliminated, such as
weeding, spraying, watering and tilling (Jovicich
et al., 2003). Hydroponics saves large amount of
water as irrigation and other kind of sprays is not
needed and water logging never occurs. The
problem of pest and disease can be controlled easily
while weed is practically non-existent. Higher
yields can be obtained since the number of plants
per unit is higher compared to conventional
agriculture.
Although soil-less cultivation is an advanta-
geous technique but some limitations are
significant. Technical knowledge and higher initial
cost is fundamental requirement for commercial
scale cultivation (Resh, 2013). Plant in a
hydroponics system is sharing the exact same
nutrient, and water borne diseases can easily spread
from one plant to another (Ikeda et al., 2002). Hot
weather and limited oxygenation may limit
production and can result in loss of crops.
Maintenance of pH, EC and proper concentration
of the nutrient solution is of prime importance.
Finally, light and energy supply is required to run
the system under protected structure.
pH AND ELECTRICAL CONDUCTIVITY
(EC) MANAGEMENT
Plant nutrients used in hydroponics are
dissolved in water and are mostly in inorganic and
ionic forms. All 17 elements essential for plant
growth are supplied using different chemical
combinations. Hoagland’s solution is used as most
common nutrient solutions for hydroponic systems.

HYDROPONICS: A PROGRESSIVE TECHNIQUE 367October-December 2018]
Cooper’s 1988 and Imai’s 1987 nutrient solutions
were also used for growing leafy vegetables,
tomatoes and cucumber. Proper pH and EC of the
nutrient solution is very essential and should be
maintained properly for optimum plant
performance.
Optimum range of EC and pH values for
different hydroponic crops is shown in Table 1.
Ideal EC range for hydroponics for most of the
crops is between 1.5 and 2.5 dS m-1. Higher EC will
prevent nutrient absorption due to osmotic
pressure and lower level severely affect plant health
and yield. So, appropriate management of EC in
hydroponics technique can give effective tool for
improving vegetable yield and quality (Gruda,
2009). As an example, yield of tomato under
hydroponic system increased as EC of nutrient
solution increased from 0 to 3 dSm-1 and decreased
as the EC increased from 3 to 5 dS m-1 due to
increase of water stress (Zhang et al., 2016). Level
of EC @1.5, 2 and 3 dS m-1 at vegetative, middle
vegetative and generative phase, respectively had
increased crop height, fruit number and pepper
fresh weight.
In a nutrient solution, pH determines the
availability of essential plant elements. Optimum
pH range of nutrient solution for development of
plants is 5.5 to 6.5 (Trejo-Tellez and Gomez, 2012)
for most species but some can differ from this range.
Once the plants grows, it will change the
composition of nutrient solution by depleting
specific nutrients more rapidly than others,
removing water from the solution and altering the
pH by excretion of either acidity or alkalinity. Wang
et al. (2017) found that mixture of three (HNO3,
H3PO4 and H2SO4) acids was much more effective
than only single acid for maintaining an optimal
solution pH of 5.5 to 6.5. Change in pH may cause
nutrient imbalance and plant will show some
deficiency or toxicity symptoms. Hence, care is
required for maintaining optimum pH, EC and
nutrient level in hydroponic solution. Crops such
as vegetables, spices, flower and ornamentals,
medicinal plants, fodders and up to some extent
cereals can be raised through soil less hydroponic
technique and is mentioned in Table 2.
PERFORMANCE OF VEGETABLES
UNDER HYDROPONICS SYSTEM
A large number of plants and crops or
vegetables can grow by hydroponics system.
Quality of produce, taste and nutritive value of end
products is generally higher than the natural soil
based cultivation. Various experimental findings
outlines that leafy greens (lettuce, spinach, parsley,
Table 2. Various species of plants grown under soil less hydroponic system
Type of crops Name of the crops
Cereals Rice, Maize
Fruits Strawberry
Vegetables Tomato, Chilli, Brinjal, Green bean, Beet, Winged bean, Bell pepper, Cucumbers,
Melons, green Onion
Leafy vegetables Lettuce, Spinach, Celery, Swiss chard, Atriplex
Condiments Coriander leaves, Methi, Parsley, Mint, Sweet basil, Oregano
Flower / Ornamental crops Marigold, Roses, Carnations, Chrysanthemum
Medicinal crops Indian Aloe, Coleus
Fodder crops Sorghum, Alfa alfa, Bermuda grass, Carpet grass
Table 1. Optimum range of EC and pH values for hydro-
ponic crops
Crops EC (dSm-1)pH
Asparagus 1.4 to 1.8 6.0 to 6.8
African Violet 1.2 to 1.5 6.0 to 7.0
Basil 1.0 to 1.6 5.5 to 6.0
Bean 2.0 to 4.0 6.0
Banana 1.8 to 2.2 5.5 to 6.5
Broccoli 2.8 to 3.5 6.0 to 6.8
Cabbage 2.5 to 3.0 6.5 to 7.0
Celery 1.8 to 2.4 6.5
Carnation 2.0 to 3.5 6.0
Courgettes 1.8 to 2.4 6.0
Cucumber 1.7 to 2.0 5.0 to 5.5
Egg plant 2.5 to 3.5 6.0
Ficus 1.6 to 2.4 5.5 to 6.0
Leek 1.4 to 1.8 6.5 to 7.0
Lettuce 1.2 to 1.8 6.0 to 7.0
Pak Choi 1.5 to 2.0 7.0
Peppers 0.8 to 1.8 5.5 to 6.0
Parsley 1.8 to 2.2 6.0 to 6.5
Rhubarb 1.6 to 2.0 5.5 to 6.0
Rose 1.5 to 2.5 5.5 to 6.0
Spinach 1.8 to 2.3 6.0 to 7.0
Strawberry 1.8 to 2.2 6.0
Sage 1.0 to 1.6 5.5 to 6.5
Tomato 2.0 to 4.0 6.0 to 6.5

368 SHARMA et al. [Journal of Soil & Water Conservation 17(4)
celery and atriplex etc) can be successfully and
easily grown in hydroponic systems. Lettuce and
spinach are most promising species to grow in
integrated hydroponics and aquaculture systems
because of its higher growth and nutrient uptake
capacity.
Hydroponic research on lettuce, spinach and other leafy
vegetables
Life cycle of hydroponic lettuce is very short
compared to traditionally grown lettuce.
Hydroponic lettuce can be harvested after 35 to 40
days of production. Lettuce can be successfully
grown in NFT system and more than 8 crops per
year can be grown efficiently in this system.
Horizontal and vertical hydroponic system was also
evaluated with different nutrient solutions for yield
optimization of lettuce (Touliatos et al., 2016).
Growing of lettuce in recirculating hydroponic
system at spacing of 50 plants m-2 significantly
increased yield and yield components (Maboko and
Plooy, 2009). Frezza et al. (2005) found that there is
significant difference in productivity and nitrate
content of lettuce in both soil less (floating system
and substrate culture) and soil culture however,
other traits like leaf area, dry weight and ascorbic
acid content were remain unaffected. In non
circulated and non-aerated system, air space
between nutrient solution and tank cover also
determines optimum lettuce yield. Another study
observed that marketable yield, shoot biomass and
leaf area index of lettuce grown in floating system
was not affected by nutrient solution composition
(Fallovo et al., 2009). In other experiment, it was
observed that both the hydroponic and organic
system perform equal in terms of lettuce yield,
quality and nitrate content, whereas, delayed
harvesting not only increased yield but lower down
nitrate level and reduced health hazards.
Besides lettuce, recently various hydroponic
experiments were conducted using spinach as
model crop. Ranawade et al. (2017) have compared
spinach yield in hydroponic, aquaponics and in
traditional system in which perlite (aquaponics)
and sphagnum moss (hydroponics) were used to
support the plants. The yield of the aquaponically
cultivated spinach was slightly more than
hydroponically cultivated spinach. The results of
Mwazi et al. (2010) showed that salinity has negative
impact on vegetative growth, but spinach has some
tolerance to saline water with 5 ppt. When spinach
grown in floating system, lack of aeration and
hypoxia was not severe enough to influence yield
and yield component as spinach is short duration
crop but quality somehow was affected (Lenzi et
al., 2011).
Hydroponic swiss chard when grown in gravel
film technique, plant density of 40 plant m-2 and 14
days of harvesting interval improved crop yield,
leaf area, biomass and leaf fresh weight (Maboko
and Plooy, 2013). Contrary to this, hydroponically
grown swiss chard, lettuce and sweet basil contain
high mineral content, high root/shoot ratio, low
level of nitrates, than grown in soil culture,
however, their nutrient uptake and yield was lower
(Bulgari et al., 2016). Effectiveness of rice husk
biochar alone and in combination with perlite as
substrates was also evaluated in NFT system for
growing crops like cabbage, red lettuce, dill and
mallow (Awad et al., 2017).
Tomato and pepper grown under hydroponics system
Many hydroponic systems can be used for
growing tomatoes but NFT and deep flow
technique (DFT) are commonly used system for
successful tomato production. Growing of tomato
in NFT system with regular recycling of nutrient
solutions improved growth, productivity and
mineral composition whereas, in NFT with
prolonged recycling of nutrient solution yield was
reduced (Zekki et al., 1996). Open and closed
hydroponic systems were evaluated for perfor-
mance of various cultivars of tomato and in closed
system higher marketable yield was obtained as
because of fruit cracking, yield was reduced in open
system (Maboko et al., 2011). Schmautz et al. (2016)
compared yield, quality and overall tomato plant
vitality in three different systems of hydroponics
(NFT, drip system and floating raft) system.
Researchers also investigate effects of plant
population, pruning and plant growth regulators
on yield and quality of hydroponically grown
pepper in various systems. Effectiveness of different
substrate (vermiculite + sand, Peat + perlite,
rockwool) were evaluated on growth and yield of
hydroponically grown green pepper and reported
that peat + perlite had most significant effect on
growing traits and yield of green pepper (Majdi et
al., 2012).
Besides tomato and pepper, cucurbits viz.
cucumber, cantaloupes are successfully grown in
various hydroponic systems. Experiments were
conducted on cucumber for optimization of salinity
level, EC and nutrients in various hydroponic. NFT
system was found to be most suitable for growth
and productivity of cantaloupe. Apart from

HYDROPONICS: A PROGRESSIVE TECHNIQUE 369October-December 2018]
vegetables, nowadays strawberry and different cut
flowers are commercially grown under various
hydroponic systems.
WATER CONSERVATION IN HYDROPONIC
As water becomes scarce and important as a
resource, the use of hydroponics and other water
saving technologies for crop production is needed
now and is poised to popularize in time.
Hydroponics uses substantially less water as
compared to the soil farming. In soil farming, most
of the water that we supply to the plants gets
leached deep into the soil and is unavailable to the
plants roots, whereas in hydroponics, plant roots
are either submerged in water or a film of nutrients
mixed in water is constantly encompassing the root
zone, keeping it hydrated and nourished. Water is
not wasted in this process, as it gets recovered,
filtered, replenished and recycled. Waste nutrient
solution can be used as an alternate water resource
for crop cultivation under hydroponic system (Choi
et al., 2012). Savings in irrigation water, fertilizer
and increase in vegetable and water productivity
under hydroponic system as compared to
conventional agriculture is depicted in Table 3. NFT
based hydroponics can reduce irrigation water
usage by 70% to 90% by recycling the run-off water.
It is possible to effectively grow high value, good-
quality vegetables under controlled hydroponic
conditions using 85 to 90% less water than tradi-
tional soil based production. Water sources from
groundwater or dam/river water commonly contain
factors that can influence plant yield and affect
plant condition, including salinity, dissolved solids
and pathogens. While some of these factors can be
beneficial to crops, others need to be minimised.
GLOBAL HYDROPONIC MARKET
AND COMMERCIAL HYDROPONIC
PRODUCTION
The Global Hydroponics Market has been
estimated to cross USD 21203.5 million in 2016. By
crop type, global hydroponics market includes
tomato, cucurbits, lettuce & leafy vegetables,
peppers and other food crops. Tomato forms the
largest market segment and it accounts for 30.4%
share of the global market, during 2018.
Hydroponics crop production is expected to be
more in tomatoes, lettuce and other leafy
vegetables. As the consumers are becoming
increasingly aware of the superiority of quality
greenhouse-grown vegetables, the demand for
hydroponics culture is rising in Europe and Asia-
Pacific. Europe is traditionally the largest market
that is implementing advanced techniques in
hydroponics. Asia-Pacific forms the second largest
market for hydroponics, which is expected to grow
at a steady pace. Leading countries in hydroponic
technology are Netherland, Australia, France,
England, Israel, Canada and USA. Dutch are the
world leader in commercial hydroponic having
total area of 13000 ha under tomato, capsicum,
cucumber and cut flowers (Netherlands
Department of Environment, Food and Rural
Affairs, NDEFRA) and this account 50% of the value
of all fruits and vegetables produced in the country.
Australian hydroponic production of vegetables,
herbs and cut flowers of system valued about 300-
400 million dollar which is approximately 20% of
the total values of vegetables and cut flower
production in Australia reported by Rural
Industries Research and Development Corporation
(RIRDC). Australia is the largest hydroponic lettuce
producers in the world, and having strawberry
cultivation is larger than USA and cut flower
production is almost equal to USA. Canada and
Spain are also expanding the area under
commercial hydroponic system. Japan has started
rice production by hydroponics technique to feed
the people (De Kreij et al., 1999). Israel grows large
quantities of berries, citrus fruits and bananas in
the dry and arid climate. Currently, demand of
hydroponics cultivation has been increased in all
the developing and developed countries (Trejo-
Tellez and Gomez, 2012). In India, several tracts of
wastelands having poor quality soil but plenty of
Table 3. Percentage of water and fertilizer consumption, vegetables yield percentage and the percentage of water productivity
for different hydroponic systems as compared with conventional farming system (AlShrouf, 2017)
Parameters Hydroponic system
Media soilless system Nutrient solution system
Open Closed Open Closed
% Irrigation water saving 80 85 85 90
% Fertilizer saving 55 80 68 85
% Productivity increase 100 150 200 250
% Water productivity 1000 1600 2000 3500

370 SHARMA et al. [Journal of Soil & Water Conservation 17(4)
water can be brought under hydroponics. Now a
day’s peoples in various big cities like Delhi,
Chandigarh, Noida and Bangalore are growing
some leafy greens and small herbs and spices on
their roof tops and balconies for fresh consumption.
The future for hydroponics appears more positive
today than any time over the last 50 years. The
startup costs to implement a hydroponic farm can
vary widely but, they are usually higher than soil-
based farming costs. Therefore, to foster the
hydroponics industry’s growth, it is important to
implement technologies that reduce dependence on
human labour and lower overall startup costs.
CONCLUSIONS
In recent years hydroponics is seen as a
promising strategy for growing different crops. As
it is possible to grow short duration crop like
vegetables round the year in very limited spaces
with low labour, so hydroponics can play a great
contribution in areas with limitation of soil and
water and for the poorer and landless people. In
India, the hydroponic industry is expected to grow
exponentially in near future. To encourage
commercial hydroponic farm, it is important to
develop low cost hydroponic technologies that
reduce dependence on human labour and lower
overall startup and operational costs.
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