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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.
Content may be subject to copyright.
Hydroponics as an advanced technique for vegetable
production: An overview
Received: 03 July 2018; Accepted: 29 November 2018
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:
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
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
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
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.
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.
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
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.
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
Hydroponic research on lettuce, spinach and other leafy
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
vegetables, nowadays strawberry and different cut
flowers are commercially grown under various
hydroponic systems.
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.
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.
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.
AlShrouf, A. 2017. Hydroponics, aeroponic and aquaponic
as compared with conventional farming. American
Scientific Research Journal for Engineering, Technology, and
Sciences. 27(1): 247-255.
Awad, Y.M., Lee, S.E, Ahmed, M.B.M., Vu, N.T., Farooq,
M., Kim, S., Kim, H.S., Vithanage, M., Usman, A.R.A.,
Wabel, M., Meers, E., Kwon, E.E. and Yong, S.O. 2017.
Biochar, a potential hydroponic growth substrate,
enhances the nutritional status and growth of leafy
vegetables. Journal of Cleaner Production 156: 581-588.
Bulgari, R., Baldi, A., Ferrante, A. and Lenzi, A. 2016. Yield
and quality of basil, swiss chard, and rocket micro
greens grown in a hydroponic system. New Zealand
Journal of Crop and Horticultural Science 45 (2): 119-129.
Butler, J.D. and Oebker, N.F. 2006. Hydroponics as hobby
growing plants without soil. Circular 844, Information
Office, College of Agriculture, University of Illinois,
Urbana, IL 6180p.
Choi, B., Lee, S.S. and Sik Ok, Y. 2012. Effects of waste
nutrient solution on growth of Chinese cabbage
(Brassica campestris L.) in Korea. Korean Journal of
Environmental Agriculture 30 (2): 125-131.
De Kreij, C., Voogt, W. and Baas, R.1999. Nutrient solutions
and water quality for soil-less cultures. Research
Station for Floriculture and Glasshouse Vegetables
(PBG), Naaldwijk the Netherlands, Brochure 196.
Domingues, D.S., Takahashi, H.W., Camara, C.A.P. and
Nixdorf, S.L. 2012. Automated system developed to
control pH and concentration of nutrient solution
evaluated in hydroponic lettuce production. Computers
and Electronics in Agriculture 84: 53-61.
Fallovo, C., Rouphael, Y., Cardarelli, M., Rea, E., Battistelli,
A. and Colla, G. 2009. Yield and quality of leafy lettuce
in response to nutrient solution composition and
growing season. Journal of Food, Agriculture &
Environment 7(2): 456-462.
Frezza, D., Leon, A, Logegaray, V. and Chiesa, V. Desimone,
M. and Diaz, L. 2005. Soilless culture technology for
high quality lettuce. Proc. IS on Soilless Culture and
Hydroponics. Acta Horticulture 697: 43-47.
Gruda, N. 2009. Does soil-less culture systems have an
influence on product quality of vegetables. Journal of
Applied Botany and Food Quality 82(2): 141-147.
Ikeda, H., Koohakan, P. and Jaenaksorn, T. 2002. Problems
and counter measures in there use of the nutrient
solution in soilless production. Acta Horticulturae 578:
Jovicich, E., Cantliffe, D.J. and Stoffella, P.J. 2003. Spanish
pepper trellis system and high plant density can
increase fruit yield, fruit quality and reduce labour in
a hydroponic, passive-ventilated greenhouse. Acta
Horticulturae 614: 255-262.
Lenzi, A., Baldi, A. and Tesi, R. 2011. Growing spinach in a
floating system with different volumes of aerated or
non aerated nutrient solution. Advance Horticulture
Science 25(1): 21-25.
Maboko, M.M. and Plooy, C.P. 2009. Effect of plant spacing
on growth and yield of lettuce (Lactuca sativa L.) in a
soilless production system. South African Journal of Plant
and soil 26(3): 195-198.
Maboko, M.M. and Plooy, C.P. 2013. Effect of plant spacing
and harvesting frequency on the yield of Swiss chard
cultivars (Beta vulgaris L.) in a closed hydroponic
system. African Journal of Agricultural Research 8(10):
Maboko, M.M., Plooy, C.P. and Bertling, I. 2011. Compara-
tive performance of tomato cultivars cultivated in two
hydroponic production systems. South African Journal
of Plant and Soil. 28(2): 97-102.
Majdi, Y., Ahmandizadeh, M. and Ebrahimi, R. 2012. Effect
of different substrate on growth indices and yield of
green pepper at hydroponic cultivate. Current Research
Journal of Biological Science 4(4): 496-499.
Manzocco, L., Foschia, M., Tomasi, N., Maifreni, M., Costa,
L.D., Marino, M., Cortella,G. and Cesco, S. 2011.
Influence of hydroponic and soil cultivation on quality
and shelf life of ready-to-eat lamb’s lettuce (Valerianella
locusta L. Laterr). Journal of the Science Food and
Agriculture 91(8): 1373-1380.
Mwazi, F.N., Amoonga, S. and Mubiana, F.S. 2010.
Evaluation of the effect of salinity on spinach (Beta
vulgaris var cicla) grown in hydroponic system along
the coast of Namibia. Agricola 14-17.
Nielsen, C.J., Ferrin, D.M. and Stanghellini, M.E. 2006.
Efficacy of biosurfactants in the management of
Phytophthora capsici on pepper in recirculating
hydroponic systems. Canadian Journal of Plant Pathology
28(3): 450-460.
Polycarpou, P., Neokleous, D., Chimonidou, D. and
Papadopoulos, I. 2005. A closed system for soil less
culture adapted to the Cyprus conditions. In: Hamdy
A. (ed), F. El Gamal, A.N. Lamaddalen, C. Bogliotti,
and R. Guelloubi. Non-conventional water use. Pp.237-
Ranawade, P.S., Tidke, S.D. and Kate, A.K. 2017. Compar-
ative cultivation and biochemical analysis of Spinacia
oleraceae grown in aquaponics, hydroponics and field
conditions. International Journal of Current Microbiology
and Applied Science 6(4): 1007-1013.
Resh, H.M. 2013. Hydroponic Food Production: a Definitive
Guidebook for the Advanced Home Gardener and the
Commercial Hydroponic Grower. CRC Press, Boca Raton,
Rouphael, Y. and Colla, G. 2005. Growth, yield, fruit quality
and nutrient uptake of hydroponically cultivated
zucchini squash as affected by irrigation systems and
growing seasons. Scientia Horticulturae 105 (2): 177-
Schmautz, Z., Loeu, F., Liebisch, F., Graber, A., Mathis, A.,
Bulc, G.T. and Junge R. 2016. Tomato productivity and
quality in aquaponics: comparison of three hydroponic
methods. Water 8: 1-21.
Shrestha, A. and Dunn, B. 2013. Hydroponics. Oklahoma
Cooperative Extension Services HLA-6442.
Touliatos, D., Dodd, I.C. and McAinsh, M. 2016. Vertical
farming increases lettuce yield per unit area compared
to conventional horizontal hydroponics. Food and
Energy Security 5(3): 184-191.
Trejo-Tellez, L.I. and Gomez, M.F.C. 2012. Nutrient
Solutions for Hydroponics Systems, Hydroponics - A
Standard Methodology for Plant Biological Researches,
Dr. Toshiki Asao (eds). ISBN 978-953-51-0386-8.
Wang, L., Chen, X., Guo, W., Li, Y., Yan, H. and Xue, X.
2017. Yield and nutritional quality of water spinach
(Ipomoea Aquatica) as influenced by hydroponic nutrient
solutions with different pH adjustments. International
Journal of Agriculture and Biology 19: 635-642.
Zekki, H., Gauthier, L. and Gosselin, A. 1996. Growth,
productivity, and mineral composition of
hydroponically cultivated greenhouse tomatoes, with
or without nutrient solution recycling. Journal of
American Society of Horticulture Science. 121(6): 1082-
Zhang, P., Senge, P. and Dai, Y. 2016. Effects of salinity stress
on growth, yield, fruit quality and water use efficiency
of tomato under hydroponics system. Reviews in
Agricultural Science 4: 46-55.
... It is important to manage pH of the nutrient solution through chemical methods by addition of acids individually or combined such as nitric acid, sulphuric acid or phosphoric acid and EC can be managed by regular recycling of water (Trejo et al., 2012) [47] . [80] Crops EC (dSm -1 ) pH Asparagus 1.4-1. ...
... The optimum range of EC and pH values for vegetables grown in hydroponics crops(Sharma et al., 2018) ...
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Many challenges have come in recent years due to the booming world population. One of the major problems is the reduction of per capita land availability for soil-based farming. Due to these critical circumstances, it has become essential to develop advanced technologies and techniques to overcome the current scenario. Some of the latest technologies to overcome these problems are carried out of the soil and in vitro plant cultivation, few of these are mainly based on soilless crop farming. Soilless agriculture is the latest promising method to improve cultivation strategies to increase income. Other than the restoration of cultivable land, soilless farming with a closed circulation system has enormous advantages like recycling 85-90% of the water used for irrigation. Consequently, improved space and water management method showed better yield than traditional farming with promising results throughout the world. Based on above mentioned recent technologies soilless farming for sustainable and quality vegetable production is emerging as a recent technology for enhancing the productivity.
... The standard concentration (100%) led to a value of 74.34 g plant -1 , but the highest mass was promoted by the concentration of 75% (127.36 g) ( Table 5). According to Sharma et al. (2018), In relation to TNF, the hybrid Beti-R showed higher production at the concentration of 75% of the nutrient solution, with 10.50 fruits per plant, while at the Oliveira et al. (2022) Performance of colored bell pepper... concentration of 100% the cultivars All Big (9.25) and Sucesso (7.0) obtained higher TNF, differing from the cultivar Beti-R. It is observed that the higher the nutrient concentration, the lower the TNF (Table 6). ...
... g plant -1 , for All Big, Beti-R and Sucesso, respectively. As observed for TMF, the TMMF recorded a reduction in fruit mass as a function of the increase of nutrients in the nutrient solutionSharma et al. (2018) point out that, since bell pepper is moderately sensitive to a limit value of electrical conductivity of the solution, maximum of 1.8 dS m -1 , higher values of EC cause reduction of yield. Unlukara et al. (2015) observed that, as the salt concentration increased, the plants corresponded with a reduction in yield, reaching the order of 14%. ...
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Knowledge on the nutritional requirement of the crop under cultivation systems adapted to local realities, in addition to the adequate availability of nutrients in nutrient solution, is of fundamental importance both for plant growth and for the production of quality fruits. Thus, the objective of this study was to evaluate the production performance of colored bell pepper cultivars in an open hydroponic system under different concentrations of nutrient solution. The experiment was carried out in a greenhouse at IFAL, Piranhas Campus, in a completely randomized experimental design with four replicates and in split plots, with plots containing three concentrations of nutrient solution (75%, 100% and 125%) and subplots containing three bell pepper cultivars (All Big, Sucesso and Beti-R). Concentration of nutrients at 75% of the standard nutrient solution differed from the other concentrations for plant height, stem diameter, leaf area and fresh and dry mass of the plant. The total number of fruits and number of marketable fruits were higher in the Beti-R and Sucesso hybrids when subjected to concentrations of 75% and 100%, respectively. The total yields of the Beti-R and Sucesso hybrids were higher at the concentration of 75%, with maximum values of 24.19 t ha-1 and 17.11 t ha-1 , respectively. The concentration of 100% of the standard solution promoted higher results for the All Big cultivar.
... The 30 days old lettuce will be then transplanted into a deep-water The pH of the fertilizer solution will be adjusted to 5. 8-5.9. The root zone of the plant are evenly distributed into the system along with oxygen supplied to the roots using an air stone [33]. The root zone of the plant will be evenly distributed into the system along with oxygen supplied to the roots using an air stone (Sharma et al., 2018). ...
... The root zone of the plant are evenly distributed into the system along with oxygen supplied to the roots using an air stone [33]. The root zone of the plant will be evenly distributed into the system along with oxygen supplied to the roots using an air stone (Sharma et al., 2018). The plants will be arranged in a randomized complete block design with 4 replications of each treatment (n=3) where individual tub will be representing as one experimental unit. ...
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Lettuce is a salt-sensitive crop and has a threshold electrical conductivity of 1.3-2.0 mS cm-1 and above that is considered detrimental. As there has been very little information on the physiological response of different critical stages of lettuce under different salt stress (SS), the current study is focused on investigating the effects of SS on the critical physiological traits influencing the carbon assimilation in different growth stages of lettuce. The experiment was conducted in deep-water culture hydroponic system in a greenhouse condition. Four levels of sodium chloride salt treatments (EC: 20, 16, 8, and 1.8 mS cm-1) were applied. During both growth stages (day 11 (GS1) and day 19 (GS2) after salt treatment), the leaf transpiration rate, stomatal conductance, and inter-cellular CO2 were severely decreased. However, the carbon assimilation rate remained unchanged under SS. Similarly, the water use efficiency increased under the SS. It is concluded that the increasing SS increased stomatal and non-stomatal limiting factors during GS1 suggesting the enhanced limitation in photosynthetic activity while no such trend was observed during GS2. The decreased gm with increased SS at GS1 and GS2 suggested that SS induced the irreversible decrease of gm, which in turn can be responsible for the transient reduction in the Vcmax and Jmax during GS2. Taken together, the evidence from this research recommends that varying the SS levels can significantly affect the physiological performance of lettuce at both growth stages.
... Tehnik budidaya secara hidroponik merupakan solusi dalam budidaya tanaman tanpa menggunakan media tanah yang dapat dilakukan di lahan sempit. Hidroponik memiliki beberapa keunggulan seperti lebih mudah pengaplikasiannya, efisien dalam tenaga kerja, tidak memerlukan lahan yang luas, tidak memerlukan proses pengolahan tanah, hasil panen lebih baik, dan waktu panen lebih cepat (Sharma et al., 2018). ...
... Despite the introduction and experimentation of other mediums of growing crops, which might have looked successful and promising for example hydroponic or soilless practices [2], the soil will continue to play its natural role for the support and the production of crops [3]. In the last 40 years or so, there has been more demand for arable farmlands' for agricultural activities across the globe especially in developing countries [4] and [5]. ...
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We evaluated the impact of cultural practices on arable cropped farmlands of more than 5 years of slash, burn, continuous mixed cropping of crops on physicochemical properties of soils in University of Port Harcourt, Nigeria. 22 cultivated arable farmlands and 3 fallow control sampled in June 2020 as wet and January 2021 as dry season 0-15cm depth from 7 auger borings taken randomly from each of the 22 cultivated and 3 fallows farmlands. Samples air dried in laboratory, prepared for analyses, sent to Fatlab in Ibadan Nigeria. Parameters evaluated for physical properties: sand, clay and silt and for chemical properties; pH, Ca, Mg, K, Na and the trace metals; Mn, Fe, Cu, Zn; available P, OC, ECEC, Acidity and Al. The results revealed sandy loam, differences between the mean values for wet season were slightly higher from the dry season, for example pH, Ca, Mg, K, Na, ECEC, Cu, Silt and Clay. The mean value of P in wet season was 5 times higher than dry season. N in wet and dry season mean value were 0.16% respectively; OC was higher in dry season indicating soil healing process before next season cropping. Slight trace of Al in dry season. However, it was significant (p<0.05) between dry and control season, comparison between wet and dry season revealed P, OC, Mg, K, Na, N, Sand and Clay significant (p<0.05). It was observed slash, burn, continuous tillage, mixed cropping of crops and times of the year influence soil physicochemical properties in arable farmland in humid high rain forest.
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This study investigated the utilization of fish effluents as irrigation water and nutrient sources to close the crop yield gap and increase Swiss chard productivity in a closed-loop sandponics system. The experiment was operated using desalinated water from a Reverse Osmosis plant. The study followed a completely randomized design with four variants, i.e., an aquaponic system (T1) and three sandponics systems; October (T2), Benu Suef (T3) and Fayoum (T4). Results indicated that T2 and T4 significantly recorded the highest plant heights in all cuts. The number of leaves per plant decreased with the increase in cut number. Leaf area and chlorophyll was significantly different between the treatments. T1 significantly had low biomass yields in cuts one and two, almost 40% less than T3 and T4. The various systems efficiently minimized water consumption ranging from 1.5 to 1.96 L/m2/day. The crop protein content ranged from 11.84 to 18.72 mg/100 g dry weight. Mineral composition in cut one was significantly higher compared to cuts two and three. The study recommends a novel technique for increasing crop production using fish effluents under sandponics systems while increasing water and fertilizer efficiency to close the crop yield gap.
Hydroponic growth systems are a practical platform for obtaining healthy seedlings in a non-destructive way and therefore studying whole plant morpho-physiology. Nonetheless, the sunflower is a crop with poor growth and survivability under the hydroponic systems currently used. In this study, our aim was to design a hydroponic cultivation medium to obtain root systems of sunflower seedlings during its early vegetative growth phase. Sunflower seeds were germinated between moistened paper towels for 72 h. Following germination, the seedlings were transferred to plastic containers filled with water. Subsequently, water was replaced by Hoagland solution and each container was connected to the aeration system. When the seedlings were 24 days old, they were removed from the hydroponic system for subsequent determinations. Parameters such as pH, oxygen content, electrical conductivity, and light conditions are provided. The various morpho-anatomical parameters that were quantified include principal root length, number of lateral roots, and insertion angle, among others. We were able to develop a sunflower hydroponic growth system that can be easily and economically constructed and that allows the production of seedlings and the obtaining of a clean root system for subsequent determinations.
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Aquaponics is a technique where a recirculating aquaculture system (RAS) and hydroponics are integrated to grow plants and fish in a closed system. We investigated if the growth of rainbow trout (Oncorhynchus mykiss) and baby spinach (Spinacia oleracea) would be affected in a coupled aquaponic system compared to the growth of the fish in RAS or plants in a hydroponic system, all systems as three replicates. We also investigated the possible effects of plants on the onset of nitrification in biofilters and on the concentration of off-flavor-causing agents geosmin (GSM) and 2-methylisoborneol (MIB) in rainbow trout flesh and spinach. For the fish grown in aquaponics, the weight gain and specific growth rates were higher, and the feed conversion ratio was lower than those grown in RAS. In spinach, there were no significant differences in growth between aquaponic and hydroponic treatments. The concentration of GSM was significantly higher in the roots and MIB in the shoots of spinach grown in aquaponics than in hydroponics. In fish, the concentrations of MIB did not differ, but the concentrations of GSM were lower in aquaponics than in RAS. The onset of nitrification was faster in the aquaponic system than in RAS. In conclusion, spinach grew equally well in aquaponics and hydroponic systems. However, the aquaponic system was better than RAS in terms of onset of nitrification, fish growth, and lower concentrations of GSM in fish flesh.
The study investigated the economic viability of producing 60 heads of lettuce using a vertical non-circulating hydroponic system outside the green house as a low cost sustainable urban food production prospect for Africa. Capital budgeting techniques were used for the analysis, that is; Net Present Value (NPV), Profitability index (PI), Internal Rate of Return (IRR) and Non-discounted Pay Back Period (NDPBP). A sensitivity and scenario analysis were adopted for risk analysis while regression analysis was considered for forecasting purposes. A discount rate of 10% was considered for the analysis based on the borrowing rate. The unit production cost equaled to 0.46$/head and sale cost was estimated at 0.75/head. Initial costs deemed necessary for annual production were estimated at 171.1$. Results showed the following economic values: NPV (16.37$), IRR (12.57%), PI (1.1) and NDPBP (4,5) for annual Crop production of 6 cycles. NPV was sensitive to changes in discount rate and unit price while revenue varied with a change in quantities sold and unit price. Adoption of vertical hydroponic lettuce production can be considered an equally cost-effective venture with substantial profits cetris paribus and the potential to increase food security and sustainability around urbanities. Further research needs to be done to assess the profitability of producing other vegetables using the same system across various seasons and cities.
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Comparison between aquaponics, hydroponics and traditional method for cultivation of spinach was carried out. In this study, spinach was grown in the soilless media like perlite and sphagnum moss. Media were used to support plant growth. From these Media the perlite media was used in aquaponics and sphagnum moss was used in hydroponics. This study was carried out to examine different morphological characters like height, germination period, surface area, the yield of spinach, and biochemical analysis like protein, carbohydrate, chlorophyll content. The height and surface area of the traditionally cultivated spinach (Height- 23 cm) (Surface area- 79 was more than the hydroponically (Height- 18 cm) (Surface area- 70 and aquaponically (Height- 20.5) (Surface area- 72 cultivated spinach. But the germination period of aquaponically and hydroponically cultivated spinach (4th day) was earlier than traditionally cultivated spinach (5th day). The protein and carbohydrate content was more in aquaponically (Protein – 2.9%), (Carbohydrate – 3.9) and hydroponically (Protein - 2.7%), (Carbohydrate – 3.8) cultivated spinach than traditionally (Protein– 2.6%), (Carbohydrate– 3.8) cultivated spinach. Chlorophyll content was highest (0.07%) in the traditionally grown spinach and (0.06%) in aquaponically as well as hydroponically grown spinach. In traditionally and hydroponically cultivated spinach, plants were provided with all the nutritional requirements externally but in aquaponics nutrients were provided naturally through fish excrete. In hydroponics nutrient requirement was less compared to the traditional method. In this work, guppy fishes were used in aquaponics as a source of nutrients. For hydroponics, the N: P: K fertilizer named 19:19:19 was given in small quantities. For traditionally cultivated spinach the fertilizers like Urea, 19:19:19 and 15:15:15 were applied. The yield of the aquaponically cultivated spinach was measured (4455Kg/acre); it was slightly more than hydroponically cultivated spinach (3780 Kg/acre) and much more than the traditionally cultivated spinach (1615 Kg/acre).
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Salt added to nutrient solution is an easy method that can improve tomato fruit quality, but plant growth and fruit production are negatively affected. Salinity reduces tomato root elongation rate and lateral root growth due to restriction of root cell growth and increased root lesion. Tomato leaf, shoot height and stem diameter reduced under salinity stress caused by photosynthesis reduction, tissues expansion reduction and cell divided inhibition. Salinity also reduces leaf chlorophyll content, stomatal resistance and photosynthetic activities. Total yield of tomato is significantly reduced at salinity equal and above 5 dS m<sup>-1</sup>, and a 7.2% yield reduction per unit increase in salinity. Salinity can decrease root water uptake through its osmotic effect, and subsequently induce water stress. Fruit quality is the only parameter which is positively affected with increased salinity.
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Microgreens are gaining interest for claimed high nutraceutical properties, but data on their chemical composition are so far limited. Although often grown hydroponically, their mineral requirements are still unknown. This study aimed to provide an insight into yield, mineral uptake, and quality of basil, Swiss chard, and rocket microgreens grown in a hydroponic system. With reference to data reported in literature for the same species hydroponically grown but harvested at adult stage, these microgreens yielded about half, with lower dry matter percentage, but higher shoot/root ratio. They showed high concentrations of some minerals, but their nutrient uptake was limited due to low yield. Nitrates content was lower if compared with that usually measured in baby leaf or adult vegetables of the same species, as well as the concentration of chlorophylls, carotenoids, phenols, and sugars. Therefore, microgreens seem to be interesting and innovative low-nitrate-salad crops requiring low fertiliser inputs. Nevertheless, an improvement in yield as well as in the content of nutraceutical compounds would be desirable.
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Aquaponics (AP) is a food production system that combines hydroponic (HP) crop production with recirculating aquaculture. Different types of hydroponic systems have been used for growing crops in aquaponics. However, very few studies have compared their suitability and efficiency in an aquaponic context. The study presented here compares tomato yield, morphological (external) and biochemical (internal) fruit quality, and overall tomato plant vitality from three different HP systems (nutrient film technique, drip irrigation system, and floating raft culture) and examines the distribution of nutrients in different parts of the tomato plant. Three replicate AP systems were set up, each incorporating the three different HP systems coupled with a separate recirculating aquaculture unit growing Nile tilapia. The results showed that the choice of the cultivation system had little influence on most of the above-mentioned properties. Tomato fruit mineral content was found to be in similar range for N, P, K, Ca, Mg, Fe, and Zn as reported in the literature. Yield and fruit quality were similar in all three systems. However, the drip irrigation system did perform slightly better. The slightly higher oxygen radical absorbance capacity (ORAC) of the fruits grown in AP in comparison to commercially produced and supermarket derived tomatoes might indicate a potential for producing fruits with higher health value for humans.
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Vertical farming systems (VFS) have been proposed as an engineering solution to increase productivity per unit area of cultivated land by extending crop production into the vertical dimension. To test whether this approach presents a viable alternative to horizontal crop production systems, a VFS (where plants were grown in upright cylindrical columns) was compared against a conventional horizontal hydroponic system (HHS) using lettuce (Lactuca sativa L. cv. “Little Gem”) as a model crop. Both systems had similar root zone volume and planting density. Half‐strength Hoagland's solution was applied to plants grown in perlite in an indoor controlled environment room, with metal halide lamps providing artificial lighting. Light distribution (photosynthetic photon flux density, PPFD) and yield (shoot fresh weight) within each system were assessed. Although PPFD and shoot fresh weight decreased significantly in the VFS from top to base, the VFS produced more crop per unit of growing floor area when compared with the HHS. Our results clearly demonstrate that VFS presents an attractive alternative to horizontal hydroponic growth systems and suggest that further increases in yield could be achieved by incorporating artificial lighting in the VFS.
It is critical to identify effective buffer chemicals which are capable of regulating the pH of nutrient solution to a desirable level for best hydroponic production of crops. Greenhouse experiments were conducted to examine the pH dynamics of nutrient solutions amended with different inorganic acids during hydroponic production and the yield and nutritional quality of the resulting crops. A typical nutrient solution (pH 8.2) was adjusted to a pH of 5.6±0.2 with 1 M HNO3, 1 M H3PO4, 1 M H2SO4, and a 3:1:1 (v/v/v) mixture of all three acids, respectively. Water spinach (Ipomoea aquatica Forsk) was hydroponically grown for 25 d in the unadjusted control and the pH-adjusted nutrient solutions. The different treatments were monitored for pH changes of the nutrient solution, and measured for shoot yield and nutritional quality of the grown water spinach. It showed that the solution pH adjustments introduced additional anions but did not significantly increase the electrical conductivity (EC). The HNO3-H3PO4-H2SO4 mixture was able to achieve an optimal solution pH ranging from 5.5 to 6.5, while any of the acids only failed to maintain the solution pH within optimal range for 48 h after each adjustment. The shoot fresh weight, dry weight, and height of water spinach grown in the mixed acids-treated solution were the greatest among the five treatments. Relative to the control, the acid mixture treatment also increased the vitamin C, soluble sugar and crude protein contents in plants. Thus, the mixed 3:1:1 (v/v/v) HNO3-H3PO4-H2SO4 is recommended for regulating the pH of nutrient solution in hydroponic production of leafy greens.
A hydroponics system developed using a nutrient film technique was used to evaluate the effectiveness of rice husk biochar (RB) alone or in combination with perlite (PL) as substrates for increasing the growth of leafy vegetables compared with that of PL. Seedlings of cabbage, dill, mallow, red lettuce, and tatsoi were grown hydroponically in PL, RB, and PL + RB (1:1 ratio of PL to RB, v/v) substrates for a 30-d under optimal environmental conditions in a greenhouse. Shoot length and fresh/dry masses of cabbage, dill, and red lettuce plants grown in RB substrate were decreased by 49% on average compared to those plants grown in PL substrate. In contrast, PL + RB substrate led to approximately 2-fold increases in shoot length, number of leaves, and fresh/dry masses of leafy vegetable plants compared with those grown in PL substrate. Foliar nutritional composition (Ca, Mg, K, Na, Mn, Fe, and Zn) and nitrogen status (SPAD index) of plants grown in PL + RB and PL substrates suggested the presence of optimal growth conditions for ensuring optimum yield with high quality. In addition, RB substrate contributed to respective increases of 1.2–3.5-fold in leaf K, Mg, Mn, and Zn contents in most vegetable plants compared with those grown in PL substrate. The RB alone or in combination with PL substrates decreased algal growth in the nutrient solutions as confirmed by scanning electron micrographs of microalgae on the RB surface. The results also indicated that use of PL + RB hydroponic substrate could be an alternative and effective technology for the better management of unwanted algal growth in nutrient solutions and high production of leafy vegetables.
The production and quality of red bell pepper (Capsicum annuum L. cv. 'HA3378') fruits were evaluated in a hydroponic system in a passive-ventilated greenhouse during spring and summer 2000 in Gainesville, FL, USA. Two plant growing systems were used: a) "V" trellis system (plants pruned to two stems, individually and vertically trained); and b) "Spanish" system (plants not pruned, with lateral horizontal strings for vertical canopy support). Plants were grown in flat bags or in polyethylene pots, both filled with perlite. Plant population densities were 1.5, 1.9, 3.0, and 3.8 plants per m2. Marketable fruit yields were similar with both growing systems although production of extra-large fruit grade was greater with non-pruned than with pruned plants. Marketable fruit yield per m2 increased linearly with plant density from 3.5 kg·m-2 (1.5 plant/m2) to 7.4 kg·m-2 (3.8 plant/m2). Plants grown in bags and pots produced similar marketable yields. Non-pruned plants had a lower percentage of fruits with blossom-end rot than pruned plants (32 vs. 62%). Non-pruned plants grew to 105 nodes that supported flower buds while pruned plants grew only to 59 nodes. The total fruit that set was lower in nonpruned plants than in pruned plants (34 vs. 50% of the total number of flowers). Fruit set per plant decreased linearly as plant density increased. The "Spanish" trellis system with a density of 3.8 plant/m2 required less labor (25% of the labor needed for the "V" system) and resulted in greater yields of extra-large fruits than with the "V" system during a spring production season in a passive ventilated greenhouse.