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Abstract

Traditionally, crops are cultivated in soil-based open field systems. Seasonality, environmental degradation, urbanization, and food security issues have replaced open-field systems with modern plant production systems. Soilless culture is one of the modern plant production systems, which involves much higher use of available resources. The presented study provides information about currently accessible soilless systems and discussed the aeroponic system. Compared to other soilless systems, aeroponic reduce water usage through continuous water circulation. However, the aeroponic is not entirely implemented among local farmers, and very few farmers have adopted the system due to the lack of research and technical information available in the literature. Therefore, this study was planned to provide information about the development and maintenance tasks required for practicing the aeroponic system. This study could provide knowledge to the researchers, farmers, and those people interested in practicing the aeroponic system.
January, 2020 Int J Agric & Biol Eng Open Access at https://www.ijabe.org Vol. 13 No. 1 1
Overview of the aeroponic agriculture
– An emerging technology for global food security
Imran Ali Lakhiar, Jianmin Gao*, Tabinda Naz Syed, Farman Ali Chandio,
Mazhar Hussain Tunio, Fiaz Ahmad, Kashif Ali Solangi
(School of Agricultural Equipment Engineering, Jiangsu University, Zhenjiang 212013, Jiangsu, China)
Abstract: Traditionally, crops are cultivated in soil-based open field systems. Seasonality, environmental degradation,
urbanization, and food security issues have replaced open-field systems with modern plant production systems. Soilless
culture is one of the modern plant production systems, which involves much higher use of available resources. The presented
study provides information about currently accessible soilless systems and discussed the aeroponic system. Compared to other
soilless systems, aeroponic reduce water usage through continuous water circulation. However, the aeroponic is not entirely
implemented among local farmers, and very few farmers have adopted the system due to the lack of research and technical
information available in the literature. Therefore, this study was planned to provide information about the development and
maintenance tasks required for practicing the aeroponic system. This study could provide knowledge to the researchers,
farmers, and those people interested in practicing the aeroponic system.
Keywords: aeroponic, food security, hydroponic, soilless culture, substrate culture
DOI: 10.25165/j.ijabe.20201301.5156
Citation: Lakhiar I A, Gao J M, Syed T N, Chandio F A, Tunio M H, Ahmad F, et al. Overview of the aeroponic agriculture
– An emerging technology for global food security. Int J Agric & Biol Eng, 2020; 13(1): 1–10.
1 Introduction
In the future, the world population will deal with several
difficulties, problems, and issues that can have adverse impacts on
the overall future food production (FFP) and food security[1-3].
Studies reported that the challenges, problems, and issues are
forecasted due to the continuous effects of unexpected climate
changes, increasing geographic extent of drylands, population
growth, increasing urbanization, rising costs of agribusiness, soil
depletion and degradation, water shortages, water pollution,
overexploitation of groundwater, and reduced production
practices[4-7]. A study by Lam et al.[8] informed that the rapid
increase in urbanization, industrialization, and modernization could
have profound effects on FFP and food safety issues. Besides,
peoples’ living style is rapidly changing from a lower standard to a
higher standard, and they have started to move from small towns to
big cities. This rapid rise in urbanization and infrastructures can
create several problems for the agriculture sector because peoples
have started to convert their arable lands into commercial and
residential areas. Xiao et al.[9] concluded that if we take China as
an example, the rise of urbanization and infrastructure development
in China is increased very fast compared to other countries of the
world. However, the share of the urban population is increased
Received date: 2019-05-20 Accepted date: 2019-12-05
Biographies: Imran Ali Lakhiar, PhD candidate, research interests: fog tilling,
Email: 5103160321@stmail.ujs.edu.cn; Tabinda Naz Syed, PhD candidate,
research interests: aeropoics, Email: 5102160315@stmail.ujs.edu.cn; Farman
Ali Chandio, Associate Professor, research interests: agricultural machinery,
Email: farman@ujs.edu.cn; Mazhar Hussain Tunio, PhD candidate, Lecturer,
research interests: irrigation engineering, Email: mazharhussaintunio@
sau.edu.pk; Fiaz Ahmad, Post-doctorate, research interests: agricultural
michinery, Email:fiazahmad@bzu.edu.pk; Kashif Ali Solangi, PhD candidate,
research interests: soil salinity control, Email: 5103180312@stmail.ujs.edu.cn.
*Corresponding author: Jianmin Gao, Professor, research interests: Soil and
fog tilling, No.301 Xuefu road, Zhenjiang city, Jiangsu Province, China.
Tel: +86-13655282069, Email: gaojianminujs@163.com.
from 21.1% to 58.5% over the period 1982–2017[10-13]. Lakhiar et
al.[2] reported that the global climate change urbanization,
industrialization, and modernization becomes a critical influencing
factor for FFP and the impact cannot be ignored[14,15]. Shamshiri
et al.[16,17] stated that FFP could exemplify by adopting modern
farming techniques such as the implementation of the greenhouse
plant cultivation (GPC) and agricultural robotics technologies
(ART) in traditional agriculture. These modern techniques
involve much higher use of advanced technology and automation
for land-use optimization. By adopting these techniques, modern
farms can expect to produce more yields with higher quality at
lower expenses in a sustainable way[18]. Moreover, the
greenhouse defined as a covered structure that provides plants with
optimally controlled microclimate growth conditions. It reduces
production costs and increases crop yields[19,20]. Another study of
Shamshiri and Ismail[21] informed that over the last decades, the
increasing population had changed the food production scenario.
This study further reported in 91 developing countries, the most of
the available land area is not in use for crop production, which is
2.4 times higher than the area in use for performing the agriculture
activities[22]. Since the available land could not increase, so the
GPC has been employed as a solution to make more effective use
of available space in hands. A study by Chang et al.[23] revealed
that GPC is one of the world’s most significant agricultural
productions system due to its high economic benefits. At present,
it had been in rapid development in both developed and developing
countries of the world for the cultivation of fruits and vegetable
plants[24-27]. Moreover, the adoption of GPC could provide a
flexible solution for high quality and sustainable year-round plant
production, particularly in regions with adverse climate conditions
or limited land and resources with increased productivity. It is
among the most intensive agricultural systems, requiring high
inputs from growers generally greater than growing in the open
field. In GPC, air temperature, relative humidity, light level, and
CO2 concentration are considered necessary parameters to achieve
2 January, 2020 Int J Agric & Biol Eng Open Access at https://www.ijabe.org Vol. 13 No. 1
high yield at low expense and to keep the greenhouse environment
competitive[28,29]. However, several researchers have presented
new innovative studies, tools, approaches, and techniques in GPC
that have been successful in addressing some of these
concerns[30-37]. In addition, soilless culture is a promising and
innovative technique widely applied in GPC due to its multiple
advantages[38,39]. Soilless culture is the realization of all types of
agricultural production in solid or liquid culture. In many
countries of the world, the technique is being significantly used to
cultivate several types of fruits and vegetable crops, and about a
total of 31 000 hm2 of soilless systems are reported in the
literature[40]. Aeroponic cultivation is one of the types of soilless
culture, which is significantly practiced in different countries of the
world[2]. Currently, the aeroponic system is not entirely
implemented among local farmers, and very few farmers have
adopted the technique due to the lack of research and technical
information available in the literature. However, much
information about the system is still scientifically unclear, and
several aspects of the system have yet to be investigated and
improved to get significantly higher plant production[41, 42].
Therefore, this study was planned to provide information about
the development and maintenance tasks required for practicing the
aeroponic system. However, the rest of the paper is organized as
follows: Section 2 describes the soilless culture and its types.
Sections 3 and 4 represent the status of the existing aeroponic
products and systems, development of the aeroponic systems, main
parts of the aeroponic system and additional required material and
manufacturing of the different aeroponic systems. Sections 5, 6, 7,
and 8, 9 describe the evaluation of proposed aeroponic system,
technical challenges, routine and preventative maintenance of the
aeroponic system, advantages of the aeroponic system, future
prospectus. Finally, Section 10 represents the conclusion of the study.
2 Soilless culture
Soilless culture is the technique of plant cultivation without the
use of soil by providing water and solid particle as a rooting
medium[43]. It is primarily associated with the method of substrate
culture and water culture (Figure 1). The soilless culture can be
practiced in two conditions: 1) open environment agriculture, and 2)
controlled environment agriculture. Studies suggested that
compared to soil-based cultivation, soilless production is more
cost-effective, higher yields, and quicker harvests from smaller
areas of land[44-46].
Note: CD: Continuous drip; FD: Flood and drain; DWR: Deep water raft culture;
NFT: Nutrient film technique; HP: High-pressure; LP: low-pressure; UF:
Ultrasonic fogger.
Figure 1 Flow chart of plant cultivation techniques
Furthermore, it facilitates many socio-economic benefits,
including it can deal with the increasing global food challenges,
environmental changes for the mitigating, management,
malnutrition, and efficient utilization of the available natural
resources[47]. The technique can provide sustained, sufficient,
fresh, clean, and hygienic vegetable supply throughout the year
without any interval by using minimum inputs and facilitates
multiple plant harvesting with maximum output[1]. The concept
of the soilless culture seeks to offer an innovative solution to
ensure the environmental and economic sustainability of food
supplies with high nutritional quality. It is a highly recommended
plant cultivation technique for all countries having less arable land,
rapid environmental changes, and increasing food challenges with
the indigenous population[48].
2.1 Substrate culture
The substrate culture defined as the cultivation of crops in a
solid, inner, or non-inert medium instead of soil or water culture.
At present, several researchers are using different types of substrate
cultures for their research studies[49]. Moreover, the substrate
material can be constructed from both inorganic and organic
components. The organic substrates include sawdust, coco peat,
peat moss, woodchips, fleece, marc, bark and inorganic substrate
includes perlite, vermiculite, zeolite, gravel, rockwool, sand, glass
wool, pumice, sepiolite, expanded clay, volcanic tuff, and
synthetically produced substrates such as hydrogel, foam mates
(polyurethane), and an oasis (plastic foam)[51-53]. However, the
most commonly used material varies, both locally and globally.
Research studies reported that peat, coir, wood, and composted
materials are the most dominant substrate materials in soilless
cultivation, which are commonly used around the world[54-57].
Barrett[49] reported that before selecting the substrate material,
it must be ensured that the selected substrate material would
perform well in two key areas: 1) The selected material must
possess the physical, chemical, and biological properties.
Because these properties are necessary to provide suitable growth
conditions for plant roots in the challenging environment, 2) The
selected material must meet the functional requirements of the
production system in which it is being utilized. An effective
substrate material must have a physical structure that creates an
appropriate balance of air and water for healthy root development.
This balance must be maintained over an entire crop production
cycle, which can last from several weeks to more than a year[58].
2.2 Water culture
Water culture is another type of soilless system. In water
culture, the plant grows in a water-rich nutrient solution instead of
the substrate material. The roots of the plants are
hanged/submerged in the nutrient solution. While the upper
portion, such as shoots and fruits are placed above the supporting
trays. The water culture is further categorized into three main
types such as hydroponics, aquaponics and aeroponic cultivation
systems[1,59].
2.2.1 Hydroponic cultivation
Hydroponic is a method of growing crops without the use of
soil, where the roots of the plants are submerged in the nutrient
solution[60]. Recently, the use of the technique in agriculture is
significantly increased, as it provides several advantages over
traditional soil-based cultivation[61]. One of the primary
advantages of this method is to allow the more efficient use of
available resources and provides an opportunity to better control
climate and pest factors[62-64]. Hydroponic production increases
crop quality and productivity, which results in higher
January, 2020 Lakhiar I A, et al. Overview of the aeroponic agriculture – An emerging technology for global food security Vol. 13 No.1 3
competitiveness and economic incomes. Furthermore, it requires
low-maintenance as well, insofar as weeding, tilling, kneeling, and
dirt removal are non-issues and provides a less labor-intensive way
to manage more extensive areas of production[65,66]. Studies
reported that there are many types of hydroponic systems, but the
most common types are NFT, DWR (Figure 2), and FD. Also, it
can be classified by the container type (window boxes, troughs,
rails, buckets, bags, slabs, and beds)[67-69].
Figure 2 Hydroponic system
2.2.2 Aquaponic cultivation
The aquaponic system is an advanced food production
technique of modern farming that combines the production of
aquatic organisms with plant production. It is an innovative
method that potentially contributes to both populations’ demand for
animal products and sustainable consumption patterns[70]. It
offers more than 50% of the nutrients for optimal plant growth
through recycling of the nutrient-rich wastewater from feeding the
aquatic organisms into the system. Thus, it reduces the use of
fertilizers of mineral origin and the environmental impact of both
fish and plant production[71-76]. Besides, the aquaculture
wastewater to fertilize the plants can avoid the discharge of
phosphorus- and nitrogen-enriched water into the already
nitrogen-loaded surface- and groundwater[77]. Schröter and
Mergenthaler[78] reported that several research studies suggested
that expansion of the aquaponic sector will probably provide a
solution to the declining global capture fisheries and the future food
production. Figure 3 shows the aquaponic system.
Figure 3 Aquaponics system
2.2.3 Vertical farming
Vertical farming is the practice of growing fruits, vegetables,
and non-edible plants in vertically-stacked layers or multi-story
buildings containing an environment conducive. These “farms”
make use of enclosed structures like warehouses and shipping
containers to provide a controlled environment for growing the
crops in the hydroponic system, aeroponic system, and aquaponics
system. Shamshiri et al.[16] reported that the concept of vertical
farming was not new, and the studies suggested that the technique
was unknown for a long time. In recent years, with the rapid
advancement in technology and increasing land issues, researchers
moved towards vertical farming as an alternative food production
system. Vertical farming offers several benefits, including
independence from arable land, year-round growing capacities, less
water consumption, and improved crop predictability. It can also
promote sustainable agricultural practices compared to
conventional farming[79-81].
2.2.4 Aeroponic cultivation
The aeroponic system is one of the techniques of the soilless
culture, where the plant grows in the air with the assistance of
artificial support instead of soil or substrate culture. The term
aeroponic was taken from the Greek, and Latina terms Aero and
Ponic, which means air and labor. It is an air-water plant growing
technique in which plant lower portions such as roots are hanged
inside the growth chamber under complete darkness. Whereas the
upper portions of the plant, such as leaves, fruits, and the crown
portions are extending outside the growth chamber[82-85]. The
technique is economical in the use of fertilizers and saves water
nutrient solution compared to other soilless systems[86-92]. Several
studies had been practiced the technique for the cultivation of
horticultural ornamental, the root of herbs and root based medicinal
plants. These studies reported that in an aeroponic system, plant
roots quickly nourish under the available nutrients and controlled
conditions. The controlled conditions include uniform nutrients
concentration, EC (Electrical conductivity) and pH, temperature,
relative humidity, light intensity, spraying time, spraying interval,
and 100% oxygen availability in the growth chamber[93-100].
Furthermore, the detailed information about the aeroponic system
is published in the previous studies of Lakhiar et al.[1,2]
3 Status of the existing aeroponic products and
systems
At present, the aeroponic system is practiced for commercial,
experimental, and kitchen gardening. O’Hare airport in Chicago
is one of the most recent examples; it has recently introduced a
highly innovative sustainable food and beverage supply chain
on-site aeroponic system[101]. People are growing plants in the
aeroponic system on their balconies, terrace, and rooms due to its
competed structure[102]. In addition, throughout the literature
review, it was found that several online websites were engaged
with the aeroponic business at local and international levels, and
they were offering several types, sizes, and shapes of the aeroponic
systems. We found that the available structures were expensive,
and they were providing services for limited countries of the world.
Guizhen[103], Gao[104], and NASA[105] reported that the aeroponic
system has mainly four types of structures, including seedbed type,
vertical barrel type, prototype, and pyramid type. These types are
commonly practiced around the globe for growing the various
types of fruits, vegetables, and medicinal based plants. These
structures are the basic structures of the aeroponic system and
simple to build by using wood, aluminum, and plastic material.
4 Development of the aeroponic systems
Throughout this review, it was found that no scientifically
recommended and convenient aeroponic system developed for
plant growth. Several researchers, scientists, and local farmers
developed aeroponic systems according to their requirements and
available space. A study by Juncal et al.[106] informed that
aeroponic had been in use for decades, besides up to now, no
adequate structural arrangements are created and recommended for
designing the aeroponic system. In addition, the aeroponic
4 January, 2020 Int J Agric & Biol Eng Open Access at https://www.ijabe.org Vol. 13 No. 1
systems are mainly comprised of the three main portions, including
1) growth chamber, 2) plant supporting portion, and 3) nutrient
supply system. For the present study, we selected two types of
aeroponic structures (seedbed type and pyramid type), and a total
of eight different aeroponic systems were developed. Among
them, seven systems were the seedbed type, and one system was
the pyramid type. Aeroponic systems were developed by using
two types of atomization nozzles (mechanical atomizer and
ultrasonic foggers). The mechanical nozzles were included three
air-assisted atomizers and one centrifugal atomizer. The
ultrasonic nozzles were included three atomization ultrasonic
frequencies high-frequency medium-frequency and low-frequency.
Furthermore, the aeroponic systems were built with mechanical
atomizers and one low-frequency ultrasonic atomizer developed in
three main portions, including a growth chamber, nutrient reservoir,
and stand to fix the growth box. The aeroponic system with
high-frequency and medium-frequency ultrasonic aeroponic
atomizers was developed in two main portions, including the
growth chamber and a stand to fix the growth chamber.
Additionally, the aeroponic system developed with wood is
considered as more durable and cheaper, but the system developed
with wooden frames is easily susceptible to rapid water damages.
Therefore, aluminum frame and plastic material were used to
develop different aeroponic systems.
4.1 Main parts and required material of the aeroponic system
In an aeroponic system, the growth chamber and a nutrient
reservoir are the same types of containers that are used to hold the
plant roots, aeroponic atomization nozzles, and store the nutrient
solution. Therefore, the growth chamber and nutrient reservoir
can be considered as one of the important parts of the aeroponic
system. Moreover, the growth chamber is designed to openly
hold the plant roots in the air under complete darkness and to
provide suitable growth conditions for the plants such as humidity,
temperature, dissolved oxygen, and nutrient spray. Also, the
aeroponic atomization nozzles are assembled in the growth
chamber where atomizers atomize the direct nutrient spray on the
plant roots. The growth chamber and nutrient solution reservoir
can be made from wood, plastic, and aluminum materials.
However, wooden frames must be lined with plastic sheeting for
avoiding the water leakages from both reservoirs. Another
important consideration is the color of the reservoirs, the dark color
is recommended, but any significantly opaque plastic can be used
to develop both reservoirs. It should be avoided to use the
translucent plastic as it allows light to enter the reservoirs, and
encourage the growth of algae. Also, it should be ensured to
protect both reservoirs to prevent light penetration and to reduce
the amount of dirt and debris. In an aeroponic system, plant roots
receive direct nutrient mist supply ejecting from the different types
of the atomization nozzles (air-assisted, centrifugal and ultrasonic
high-, medium- and low-frequency)[108-110]. Until now, several
research studies developed the different types and sizes of the
aeroponic systems. However, no single study had intensely
focused and briefly discussed the selection of the suitable
aeroponic atomization nozzles[111-116]. Moreover, this study was
first to develop the aeroponic system using electrostatic spray
technology in the aeroponic system. Samuel et al.[117] reported
that electrostatic spray technology is the process of spraying an
electrostatically charged mist into the surfaces and selected objects.
The electrostatic spray uses a specialized solution combined with
air and atomized by an electrode inside the sprayer. The
air-assisted electrostatic sprayers can produce the droplets smaller
than those produced by conventional or hydraulic sprayers[118,119].
In addition, the selected atomizers were such as Hartmann
air-assisted atomization nozzle with resonance tube; air-assisted
atomization nozzle with and without electrostatic spray; centrifugal
atomization nozzle; 1.7 MHz high-frequency ultrasonic fogger
atomization nozzle with three ultrasonic transducers, 1.7 MHz
high-frequency ultrasonic fogger atomization nozzle with one
ultrasonic transducers, 107 kHz medium-frequency ultrasonic
fogger atomization nozzle, and 28 kHz low-frequency ultrasonic
fogger atomization nozzle. The additional required material is
shown in Figure 4.
A1 A2 A3 A4 A5 A6 A7 A8
A9 A10 A11 A12 A13 A14 A15 A16
A17 A18 A19 A20 A21 A22 A23 A24
Figure 4 Components and material required for developing the aeroponic system
Moreover, the additional required material for developing the
aeroponic systems were A1 = aluminum frame 745 mm × 550 m ×
800 mm and 745 mm × 450 mm × 800 mm, A2 = stainless steel
growth box 800 mm × 300 mm × 800 mm with total height
1100 mm, A3 = plant supporting tray 800 mm × 300 mm × 800 mm,
A4 = plastic box 740 mm × 540 mm × 400 mm, A5 = polystyrene
foam box 740 mm × 440 mm × 300 mm, A6 = Styrofoam 760 mm
× 560 mm × 10 mm and 745 mm × 445 mm × 10 mm, A7 = plastic
January, 2020 Lakhiar I A, et al. Overview of the aeroponic agriculture – An emerging technology for global food security Vol. 13 No.1 5
cup to hold the plant 45 mm × 30 mm × 45 mm, A8 = cotton round
hole 25 mm × 25 mm × 25 mm, A9 = plastic tank for nutrient
solution 50 L and 25 L, A10 = LED lights (Model:
WT-ZWD-3R2B1W-600MM-9W, 900 lm, Xiamen Plants
Agricultural Photoelectricity Technology Co., Ltd. P.R China),
A11 = 12 V axial fan, A12 = 12 V high voltage electrostatic
generator, A13 and A14 = demographic pumps, model name
(Model PLD1204 and 1206, 12 V, 0.45 MPa and 1 MPa,
Shijiazhuang City Prandy Electromechanical Equipment Co., Ltd.) ,
A15 = air compressor (Model 750-30<2530>, Zhejiang Shengyuan
Air Compressor Manufacturing Co., Ltd.), A16 = demographic
pump pressure regulator, A17 = demographic pump pressure meter,
A18 = water flow meter, A19 = air flow meter, A20 = air pressure
meter, A21 = flexible polyethylene water supply line 6 mm × 8 mm,
8 mm × 10 mm and 12 mm × 14 mm, A22 = plastic filter with
stainless steel net, A23 = pneumatic three-way connector 6 mm ×
6 mm × 6 mm, A24 = pneumatic reducer air pipe joint 8 mm ×
12 mm.
4.2 Manufacturing of the different aeroponic systems
The aeroponic systems developed with Hartmann air-assisted
atomization nozzle with resonance tube, air-assisted atomization
nozzle with and without electrostatic spray were mainly composed
of a growth chamber, a plant supporting tray, an atomization nozzle,
a nutrient delivery line, a nutrient drain line, and a nutrient
reservoir. Firstly, the dimensions of the aeroponic systems were
finalized, which were based on the experiment requirement and
available space. The system can be any size and shape.
However, the further procedure is given in the below sections.
4.2.1 Aeroponic system developed with air-assisted atomizers
The aeroponic systems with air-assisted atomizers were
developed by using one atomization nozzle. The selected nozzle
was placed into the center of the growth chambers. However, the
selected dimensions of the aeroponic growth chambers, stand
frames, and the nutrient reservoirs were 740 mm × 540 mm ×
400 mm (A4), 745 mm × 550 mm × 800 mm (A1), 50 L capacity
(A9), respectively. In addition, firstly, the drill machine was used
to make the holes for the atomization nozzle, and the water recycles
line in the growth chamber (A4). After that, the one atomization
nozzle and one pneumatic male thread joint connector were located
in the center of the growth box (A4). Further, the two pneumatic
male thread joint connectors (8 mm × 10 mm) were assembled
within the atomization nozzle water inlet valve and the air inlet
valve. In order to avoid the water and air leakages from the air
and water inlet valves, the thread joint connectors were wrapped
with a couple of layers of Teflon tape before assembly. The
nozzle water inlet and air inlet valves connected with the pneumatic
copper male thread joint connectors (8 mm × 10 mm) were further
linked with the flexible polyethylene line (A21 (8 mm × 10 mm))
to receive the water and air supply. The water supply line was
further linked with the nutrient storage tank (A9) through the water
supply system. However, the water supply system consisted of
the pressure pump (A13), fluid pressure measuring pump (A17),
and liquid flow meter (A17). Briefly, the pressure pump suction
side and water delivery portion were connected with a flexible
polyethylene water line (A21 (12 mm × 14 mm)). The suction
line was further connected with the filter (A22) and dipped in the
nutrient reservoir (A9), whereas the water delivery portion of the
pressure pump (A13) was connected with the pneumatic reducer air
pipe joint (A24). Further, the pneumatic joint (A24) was
connected with a flexible polyethylene water supply line (A21
(8 mm × 10 mm)). In next step, the flexible polyethylene line
(A21 (8 mm × 10 mm)) coming from the pressure pump was
connected with the fluid pressure measuring pump (A17), and
liquid flow meter (A18) through the pneumatic copper male thread
joint connector (8 mm × 10 mm). Furthermore, the flexible
polyethylene line (A21 (8 mm × 10 mm)) coming from the fluid
pressure measuring pump (A17) was attached with the nozzle
through the pneumatic copper internal thread straight connector
(8 mm × 10 mm). Moreover, the air supply system consisted of
the air compressor (A15), air pressure meter (A20), and airflow
meter (A19). The air compressor connected with the flexible
polyethylene line (A21 (8 mm × 10 mm)) was further connected
with the air pressure meter (A20) and airflow meter (A19) through
the pneumatic copper male thread joint connectors (8 mm ×
10 mm). After that, the air supply line coming from airflow meter
(A19) was further connected with the flexible polyethylene line
(A21 (8 mm × 10 mm)) and finally attached with the nozzle air
inlet valve through pneumatic copper male thread joint connector
(8 mm × 10 mm). Besides, for nutrient solution recycling from
the growth chamber (A4), the flexible polyethylene line (A21
(8 mm × 10 mm)) was coupled in the pneumatic male thread joint
connector and fixed in the center of the aeroponic growth chamber.
After that, the nutrient solution recycling line was placed in the
nutrient reservoir (A9). In the next step, the PVC pipe (25 mm)
was fastened with the aluminum frame (A1) to provide support to
the LED lights (A10). Therefore, the PVC elbow and tee (25 mm)
were used to make the frame of the PVC pipes (25 mm).
Moreover, the PVC pipes were tightly fastened with a plastic strip.
Three LED lights (A10) were placed on the developed PVC frame.
The LED lights were further tightly fastened with PVC pipes with
the plastic strips. The final step was to prepare the artificial plant
supporting layer for holding the plants in the aeroponic growth
chamber. Therefore, Styrofoam (A6 (760 mm × 560 mm ×
10 mm)) sheet was chosen as an artificial plant supporting layer for
the aeroponic growth chamber. Further, the drill machine
connected with the steel hole (25 mm diameter) maker was used to
make the holes in the Styrofoam (A6 (760 mm × 560 mm ×
10 mm)) sheet. During making holes in the Styrofoam (A6) sheet,
the drill machine must be held tightly in the selected place. After
making the holes in the Styrofoam sheet, the second step was to
place the plant holders in the Styrofoam sheet. Therefore, the
plastic cups (A7 (45 mm × 30 mm × 45 mm)) and cotton round
holes (A8 (25 mm × 25 mm × 25 mm)) were selected as a plant
holder material. Finally, the power supply line of the pressure
pump, air compressor, and LED lights were attached in the
extension to supply the power while the timer was used to control
the spraying time and spraying interval of the atomization nozzle.
Furthermore, the same material, methodology and strategy were
used to develop the three aeroponic systems with the air-assisted
atomizers. The mean difference between the three aeroponic
systems was the type of the aeroponic atomization nozzle, whereas
the air-assisted atomization nozzle with electrostatic spraying
technology was additionally attached to the electrostatic generator
(A12) and voltage distributor.
4.2.2 Aeroponic system developed with centrifugal atomization
nozzle
The aeroponic system with centrifugal atomization nozzle was
developed by using five atomization nozzles. Four nozzles were
located in the middle and one nozzle was located at the center of
the growth chamber (A4). In the developing process, firstly, the
drill machine was used to make the holes in the growth chamber
(A4) for fixing the atomization nozzles and the drain line.
6 January, 2020 Int J Agric & Biol Eng Open Access at https://www.ijabe.org Vol. 13 No. 1
Besides, the copper internal thread straight connectors integrated
with the centrifugal atomization nozzle (D) were tightly fixed in the
growth chamber with a screw nut. Also, the pneumatic copper
male thread joint connector was fixed into the nutrient drain line.
Further, the pneumatic copper internal thread straight connectors
were assembled with each copper internal thread straight
connectors to receive the nutrient supply. However, to prevent the
water leakages, all the threads were wrapped with a couple of
layers of Teflon tape before assembly. After that, the flexible
polyethylene water supply line (A21 (6 mm × 8 mm)) was
connected with each atomization nozzle through a pneumatic
three-way connector (A23). Besides, the flexible polyethylene
line (A21 (6 mm × 8 mm)) was connected to the pneumatic copper
male thread joint connector for recycling the nutrient solution. In
the second step, the growth chamber (A4) assembled with the
nutrient solution supply system and nutrient recycling line was
placed above the aluminum frame (A1 (745 × 550 × 800)). In
addition, the water supply system consisted of the diaphragm
pressure pump (A14), liquid pressure measuring pump (A18), and
liquid flow meter (A17). Briefly, the diaphragm pressure pump
(A14) water suction and water delivery portions were connected
with a flexible polyethylene water line (A21 (12 mm × 14 mm)),
respectively. After that, the diaphragm pressure pump (A14)
water delivery section line (A21 (12 mm × 14 mm)) was further
combined with flexible polyethylene water line (A21 (6 mm ×
8 mm)) through the pneumatic reducer air pipe joint (A24 (6 mm ×
12mm)). Then, the flexible polyethylene line (A21 (6 mm ×
8 mm)) coming from the pressure pump was connected with the
fluid pressure measuring pump (A17), and liquid flow meter (A18)
through the pneumatic copper male thread joint connector
(6 mm × 10 mm). Furthermore, the flexible polyethylene line
(A21 (6 mm × 8 mm)) coming from the fluid pressure measuring
pump (A17) was attached with the centrifugal atomizer through
the pneumatic copper internal thread straight connector. The
water suction line of the diaphragm pressure pump (A14) was
further connected with the filter (A22) and then dipped in the
nutrient reservoir (A9). In the last step, the flexible polyethylene
line (A9 (6 mm × 8 mm)) was connected with the aeroponic
growth chamber (A4) through the pneumatic copper male thread
joint connector and disposed of in the nutrient reservoir (A9) for
nutrient recycling. Additionally, LED light (A10) stand and
artificial plant supporting layer were developed by following the
same methodology as reported for the aeroponic system developed
with air-assisted atomizers.
4.2.3 Aeroponic system developed with ultrasonic fogger
atomization nozzle
The aeroponic systems developed with E and F ultrasonic
foggers were the same in the size and shape, but the difference was
the nozzle type and number of the nozzle. While four E, six F,
eight G, and four H ultrasonic foggers were located in each
aeroponic system. The aeroponic systems developed with E and F
were mainly composed of a growth chamber, plant supporting tray,
and aluminum frame. The aeroponic systems developed with G
and H were mainly composed of a growth chamber, plant
supporting tray, aluminum frame, and nutrient reservoir.
Furthermore, the aeroponic systems with ultrasonic fogger
atomization nozzles were developed by following a similar
methodology, as reported for air-assisted and centrifugal aeroponic
atomization nozzles. However, the aeroponic systems developed
with E and F ultrasonic foggers were easy to develop compared to
the air-assisted, centrifugal atomizer, and other ultrasonic foggers.
In this system, the polystyrene foam (A5) was used to develop the
aeroponic growth chamber. At the same, the growth chamber was
used as a nutrient solution reservoir. Briefly, the drill machine
was used to make the hole in the polystyrene foam (A5) for
crossing the power lines of the ultrasonic foggers. After that, we
placed the E and F ultrasonic foggers in aeroponic growth
chambers, respectively, and placed the growth chambers on the
aluminum frames (A1). Additionally, the plant supporting trays
(A6 (745 mm × 445 mm × 10 mm)) and LED frames were
developed by following a similar procedure as reported for
air-assisted atomization nozzle and centrifugal atomization nozzle.
Finally, the axial fans (A11) were placed into the plant supporting
trays (A6 (745 mm × 445 mm × 10 mm)) for spreading the nutrient
fog in the growth chambers (A5). The aeroponic system
developed with medium-frequency ultrasonic nozzle (G) was
mainly composed of a growth chamber, nutrient supply line,
nutrient recycles line, nutrient reservoir, and an axial fan. Briefly,
the growth chamber (A2) combined with a plant supporting tray
(A3) and pneumatic copper male thread joint connector for nutrient
recycling was manufactured from the local market. Firstly, the
PVC pipe (A38 (75 mm)) was connected with the growth chamber
(A2) by using PVC tee (75 mm). Further, the PVC pipe (75 mm)
was fixed in the wooden sheet. After that, the PVC pipe (75 mm)
attached to the wooden sheet was located above the nutrient
reservoir (A9). Besides, an axial fan (A11) with a PVC pipe
(75 mm) was set on the wooden sheet. At the same time, the
flexible polyethylene line (8 mm × 10 mm) was fixed with the
growth chamber by using the pneumatic copper male thread joint
connector for recycling the used nutrient solution. In the second
step, the medium-frequency ultrasonic nozzles (G) were placed
within the nutrient reservoir (A9). Moreover, the working
principle of the aeroponic system developed with
medium-frequency atomizer was: firstly, the foggers were
subjected to work in the nutrient reservoir and create a fog. The
axial fan was used for spreading the small nutrient fog into the air
like a cloud and transfer the fog into the growth chamber through
the PVC pipe. Finally, the aeroponic system developed with
low-frequency ultrasonic atomization nozzle (H) was mainly
composed growth chamber, nutrient reservoir, plant supporting tray,
and axial fan. Briefly, the system was developed by using four
atomization nozzles (H). The atomization nozzles were located in
the middle of the growth chamber (A4). The distance between
each nozzle was 240 mm × 180 mm apart from each other. The
total height of the proposed aeroponic system was 1000 mm above
the ground level. Moreover, we followed a similar procedure
discussed in the above sections to make the holes in the growth
chamber (A4). Besides, the LED light frame, plant supporting
tray, and axial fans were developed by the same procedure as
reported for the other aeroponic systems. In the first step, we
developed the growth chamber, plant supporting tray, and LED
light stand and fixed the low-frequency ultrasonic nozzles (H) in
the growth chamber (A4) by using the sealed plastic glue gun.
After that, we connected the water supply system line and water
recycles line with the atomization nozzles and growth chamber,
respectively. The water supply and water recycle lines were
developed as reported for the centrifugal atomization nozzles. In
addition, the low-frequency ultrasonic nozzle (H) working principle
was different as compared to the high-frequency ultrasonic and
medium-frequency ultrasonic nozzles. The low-frequency
ultrasonic nozzles were receiving the nutrient solution through the
pressure pump (A14).
January, 2020 Lakhiar I A, et al. Overview of the aeroponic agriculture – An emerging technology for global food security Vol. 13 No.1 7
5 Evaluation of the proposed aeroponics system
In order to evaluate the performance of the proposed
aeroponics system, the systems were used to grow the lettuce and
tomato plant in the greenhouse environment and under control
conditions. It was observed that the plants successfully grew in
the designed system. In addition, based on the obtained result, it
could be concluded that the proposed design revealed a good
sturdiness and relevance for plant cultivation in the future. The
proposed design has a perspective for a sustainable future. The
system is easy to design and has competed for structure. Thus,
peoples could grow the plant in the system on their balconies,
terrace, and rooms.
6 Technical challenges
The development of aeroponic system can be considered as a
highly multidisciplinary approach drawing from environmental,
mechanical, and civil engineering design concepts and plant-related
biology, biochemistry, and biotechnology. Sometimes, specific
measurements, schematic view, and control technologies also
required abundant knowledge of subjects related to the field of
computer science for automatic control systems. This high level
of complexity necessarily demands in-depth knowledge and
expertise of all involved fields. Furthermore, the electricity
connection should be independent of the aeroponic system.
Besides, in case of an emergency, additional power sources such as
a stand-by generator or battery should always be ready with the
system. For those places where power failures are frequent, that
areas must need a good generator with an automatic startup system.
Considering, the initial costs for components and installation, the
aeroponic systems with air-assisted and centrifugal atomization
nozzle are more expensive than ultrasonic fogger (high-frequency
atomization nozzle). In addition, over time, if components are
well maintained and used for many years, these higher initial costs
can be recovered by reducing the labor costs, minimum inputs of
fertilizers and pesticides with significantly higher plant yields.
7 Routine and preventative maintenance of the
aeroponic system
In order to consider the aeroponic system, an efficient,
trouble-free operation, low-cost, high production of plants for the
long term, a routine, and regularly scheduled maintenance program
must be carried out according to the requirements. Furthermore, it
must be ensured that the aeroponic system is functional and
protected from extreme weather conditions. Because of aeroponic
cultivation is susceptible to the extreme or low climatic condition
of the growth chamber. However, some of the key routine and
preventative maintenance points are given below: 1) check that the
power source is okay; 2) check that the nutrient reservoir tank is
full; 3) change the nutrient solution on time; 4) check that the air
pressure pumps are working properly; 5) check the leakages such
as nutrient delivery and drain line; 6) check that atomization
nozzles are working under satisfactory conditions such as clogging
of the nozzles; 7) check that the chemical properties of the nutrient
solution are in desired range; 8) check the environmental
parameters are under the suitable range.
8 Advantages of the proposed aeroponic systems
The aeroponic systems proposed in this study are easy to
redevelop. Even the local growers and untrained person can
quickly redevelop the proposed aeroponic systems. The
aeroponic systems were developed by purchasing the material from
local markets. However, the system was developed in three main
portions included a growth chamber, nutrient reservoir and the
frame for growth chamber. The proposed systems had a compact
structure, which makes the systems more efficient, easier to operate,
and maintain. Moreover, it is suitable for big cities having less
arable space and increasing rapid urbanization.
9 Future prospectuses
In a short time, aeroponic was adopted in many situations,
from indoor laboratory experimental analysis to greenhouse
cultivation. Several research studies developed aeroponic systems
and used for the laboratory-scale plant cultivation. Few studies
involved aeroponic systems that are representative of commercial
or home operations. Until now, the system is not popular among
the local growers, but the concept is dominated in the literature for
laboratory-scale plant cultivation. The aeroponic has not yet been
adopted on a broader scale and is still mostly unknown in several
countries of the world because still many information about the
system is hidden, such as the maintenance tasks and development
of the aeroponic system. Therefore, the attempts would be made
to provide brief information about the development, maintenance
task, and benefits of the aeroponic system among farmers and the
local community.
10 Conclusions
This study concluded that the adoption of modern farming
techniques in traditional agriculture could be an alternative solution
to deal with the increasing food security. The modern techniques
involve much higher use of advanced technology and automation
for land-use optimization. The aeroponic system is one of the
revolutionary and more sustainable methods of the soilless system
as it lowers the requirement of water and saves considerable space
and soil. This study can provide important information about the
aeroponic system to the researchers, farmers, and the local
community interested in the aeroponic system but they think that
aeroponic system design and maintenance is a very complicated
task. They can develop the aeroponic system by purchasing the
material from the local market anywhere in the world.
Acknowledgements
This work is financially supported by the National Natural
Science Foundation of China Program (No. 51975255), Jiangsu
Agriculture Science and Technology Innovation FundsJASTIF
(CX (18)3048), Major Projects of Jiangsu University Natural
Science Fund (No. 17KJA416001) and the “Project Funded by the
Priority Academic Program Development of Jiangsu Higher
Education Institutions (No. 37(2014)).
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... In addition, in an aeroponic system, plant roots receive a direct nutrient solution supply sprayed from the atomizers with different droplet sizes [30,31] . A study by Tibbitts et al. [32] reported that with continuous nutrient atomization, plants become dependent on the constant spray, and any interruption of the spray causes loss of plant life. ...
... Therefore, the lettuce was also selected as a test crop. Given the above, the aeroponic atomizer (droplet size), spray time, and interval can be considered as the main parameters influencing the cultivated plant growth [29,30] . However, in our literature review, we found limited research studies regarding the effects of aeroponic atomizer and spray interval on the photosynthesis characteristics and pigments of any specific leafy plant. ...
... The experiment was conducted with the existing aeroponic system previously designed by our research team [30] . This system consisted of a steel frame and high-density polyethylene (HDPE) containers with styrofoam lids and a volumetric capacity of 140 L ( Figure 2a). ...
Article
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The proper selection of the atomizer (droplet size) and nutrient solution spray interval is one of the most important factors to be investigated in aeroponics system for sustainable agriculture. The aim of this study was to research the effects of four aeroponics atomizing nozzles (one air-assisted; A 1 , two air-less; A 2 and A 3 , and one ultrasonic fogger; A 4) with droplet sizes of 11.24 µm, 26.35 µm, 17.38 µm, and 4.89 µm, respectively, four spray intervals (15 min (I 1), 30 min (I 2), 45 min (I 3) and 60 min (I 4)) at a 5 min of constant spray time by atomizing the Hoagland's nutrient solution on growth, root-to-shoot ratio, photosynthesis characteristics, pigments, and nutritional quality of the aeroponically grown lettuce. The experimental results demonstrated that in A 1 atomizer and I 2 interval, the growth, photosynthesis efficiency, chlorophyll, carotenoids, and nutritional values of the lettuce were significantly higher compared to that grown in A 2 and A 3 atomizers at all spray intervals. The shoot developments were more constrained than root, prominent to the alteration of root-to-shoot ratio (fresh and dry) in the influence of different droplet sizes and spray intervals. Moreover, the plants did not grow well in A 4 atomizer associated with proposed spray intervals. The results disclosed that there was an obvious interaction between droplet sizes (atomizers) and spray intervals for growth, the ratio of root to shoot, photosynthesis efficiency, pigments, and nutritional quality of the aeroponically grown lettuce. This research study increases the awareness of the proper droplet size (atomizer) and the regulation of nutrient solution spray interval for leafy vegetables grown in an aeroponics system. Citation: Tunio M H, Gao J M, Qureshi W A, Sheikh S A, Chen J D, Chandio F A, et al. Effects of droplet size and spray interval on root-to-shoot ratio, photosynthesis efficiency, and nutritional quality of aeroponically grown butter head lettuce. Int J Agric & Biol Eng, 2022; 15(1): 79-88.
... Soilless crop production in controlled greenhouse environments has recently received much attention, as it may be able to help sustain a growing world demand for food in the context of water and arable land scarcity as well as climate havoc and a need to lower the environmental impact of agriculture [12][13][14]. Among the multitude of soilless production systems, high-pressure aeroponics (HPA) are relatively recent and have received the greatest amount of interest in the literature [15]. With this technology, the roots are kept bare in a humid atmosphere, and they are regularly sprayed with a very fine mist that is generated from a pressurized nutrient solution. ...
... With this technology, the roots are kept bare in a humid atmosphere, and they are regularly sprayed with a very fine mist that is generated from a pressurized nutrient solution. This method is of particular interest when easy access to the roots is needed or when the artificial substrates used for soilless culture are banned to prevent them from impacting the environment through their disposal or production [15,16]. Noteworthily, HPA-based production of plant-specialized metabolites has found successful applications in the cosmetic and pharmaceutic industries with, for example, the production of prenylated polyphenols [17] and plant-based vaccines [18]. ...
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Vetiver (Chrysopogon zizanioides (L.) Roberty) is a major tropical perfume crop. Access to its essential oil (EO)-filled roots is nevertheless cumbersome and land-damaging. This study, therefore, evaluated the potential of vetiver cultivation under soilless high-pressure aeroponics (HPA) for volatile organic compound (VOC) production. The VOC accumulation in the roots was investigated by transmission electron microscopy, and the composition of these VOCs was analyzed by gas chromatography coupled with mass spectrometry (GC/MS) after sampling by headspace solid-phase microextraction (HS-SPME). The HPA-grown plants were compared to plants that had been grown in potting soil and under axenic conditions. The HPA-grown plants were stunted, demonstrating less root biomass than the plants that had been grown in potting soil. The roots were slender, thinner, more tapered, and lacked the typical vetiver fragrance. HPA cultivation massively impaired the accumulation of the less-volatile hydrocarbon and oxygenated sesquiterpenes that normally form most of the VOCs. The axenic, tissue-cultured plants followed a similar and more exacerbated trend. Ultrastructural analyses revealed that the HPA conditions altered root ontogeny, whereby the roots contained fewer EO-accumulating cells and hosted fewer and more immature intracellular EO droplets. These preliminary results allowed to conclude that HPA-cultivated vetiver suffers from altered development and root ontology disorders that prevent EO accumulation.
... Because people starting to transform their property into commercial and residential areas. The rapid development in urbanization and infrastructures may pose several issues for the agriculture industry [1] Ending hunger and poverty while making agriculture and the food chain sustainable is important factor of current challenges. However, supplying clean and fresh food for future generations is one of our primary concerns, particularly given the world's rising population [2]. ...
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The availability of water and land is one of the significant factors to be investigated for sustainable agriculture all over the world. The present report discusses the aeroponic system and provides information on currently available soilless systems. In this study evaluate the growth of plants concerning their growing mediums. We investigate that coconut peeling is an efficient medium for plant growth. In coconut peeling the plant growth is 6.8cm which was more than the other growing medium. Aeroponic systems use less water than other soilless systems since water is circulated continuously. However, due to a lack of technical skills and sufficient literature, the aeroponic system is not fully implemented among local farmers, and only a few farmers have adopted the technique. Another purpose of this study was to investigate the effect of climatic conditions on plant growth and water consumption. On the first day of the experiment, the temperature is 32-degree celsius and the relative humidity is 35 percent and the average growth rate of plants in different growing media is 1.08 cm. At the end of the experiment, the temperature is 26.5degree celsius, relative humidity is 44 percent and the growth of plants is 5.70 cm. Hence with a decrease in temperature, the plant growth is increase and water consumption is decreased. As a result, the purpose of this research was to learn more about the development and maintenance activities involved in using an aeroponic system and growing plants with less use of water. These findings could help researchers, farmers, and individuals interested in using aeroponic technology learn more.
... Aeroponic cultivation is a new soilless technology integrating plant nutrition, plant physiology, environmental ecology, agricultural automation, and horticultural crop cultivation [1,2] . In aeroponic cultivation, plant roots are placed in the air, and nutrient solution is regularly and quantitatively sprayed on them to better meet their needs for water, fertilizer, and oxygen [3][4][5] . ...
... The aeroponic method is the latest culture method that can reduce the 40% production time, reduce 100% chemical herbicides and pesticides, reduce 98% water consumption, reduce 30% energy consumption, reduce 60% of chemical fertilizers, and increase 55% of product production, and can easily provide six harvest period per year (Barla et al., 2020;Lakhiar et al., 2020;Song et al., 2021;Uddin & Suliaman, 2021). In addition to the cases described, the aeroponic method can easily provide vertical agriculture near urban areas. ...
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Due to the advantages of aeroponic compared to other cultivation systems, the advantages of piezoelectric ultrasonic compared to other mist makers, and lack of research done to study the parameters affecting the misting rate of nutrient solutions with the approach used in aeroponic systems, the current work was carried out. The effects of dosage of nutrient solution, voltage, horn diameter, and horn height on the misting rate, circuit current, power consumption, amplitude of sound waves, Δ pH, Δ EC (electrical conductivity), and Δ TDS (total dissolved solids) were investigated. Physical properties of the solution (density, viscosity, surface tension, and speed of sound) were measured. Moreover, optimization was performed to determine suitable ranges of independent variables. Obtained results showed that the four mentioned independent variables significantly affect the six dependent variables (P<1%). The misting rate was in the range of 96 to 411.6 g h−1. At the temperature of 25 °C and for different concentrations of fertilizer, the density, surface tension, viscosity, speed of sound in the solution, initial TDS, and initial pH varied between 1002.3–1004.8 kg m−3, 73.33–74.42 mN m−1, 1.009–1.395 mPa s, 1489–1502 m s−1, 1323–8865 mg L−1, and 6.18–6.84, respectively. Also, theoretically calculated mist mean droplet diameter was in the range of 2.868 to 2.880 μm for different fertilizer doses. Mist generation by piezoelectric ceramics is an efficient method for use in aeroponic systems. Although the obtained misting rates in this study differ from the industrial values, the use of several piezoelectric ceramics is the simplest solution to this problem.
... Given the potential of these ryanodanes as bioinsecticides, supercritical and supercritical antisolvent CO 2 (SC or SAS / CO 2 ) selective extraction methods have been developed to separate polar ryanodanes (epiryanodol and related) from alkyl-γ-lactones and related components of low polarity present in P. indica aerial parts [13]. However, the fact that this plant is a unique endemic and protected species from the Macaronesian laurel forest represents a bottleneck in the production of ryanodane-based bioinsecticides. ...
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In this work, we have investigated the accumulation of ryanoids in different plant parts (leaves, stems and roots) of aeroponically grown Persea indica cloned trees (one-year-old cloned individuals) and a selected mature, wild tree. We tested the insect antifeedant (against Spodoptera littoralis, Myzus persicae and Rhopalosiphum padi) and nematicidal (against Meloidogyne javanica) effects of ethanolic extracts from these different plant parts. The HPLC-MS analysis of P. indica extracts showed that mature tree (wild) leaves had two times more chemical diversity than stems. Aeroponic plants showed fewer differences in chemical diversity between leaves and stems, with the lowest diversity found in the roots. Ryanodane epiryanodol (1) was present in all the plant parts, with the mature stems (wild) containing the highest amount. The aeroponic stems also accumulated ryanoids including 1, cinnzeylanol (2) and cinnzeylanone (4). The insect Spodoptera littoralis was strongly affected by the stem extracts, while leaf extracts were moderately active. Based on predicted vs. real antifeedant values, we concluded that the ryanoid content (1 or a combination of 2, 4 and 1) explained the antifeedant effects of the stem extracts, while additional components contributed to the activity of the leaf extracts. Therefore, careful individual selection of P. indica seedlings should be carried out prior to proceeding with aeroponic cultivation in order to obtain ryanodane-rich stem or leaf extracts with strong antifeedant effects on S. littoralis.
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The growing consumer awareness of climate change and the resulting food sustainability issues have led to an increasing adoption of several emerging food trends. Some of these trends have been strengthened by the emergence of the fourth industrial revolution (or Industry 4.0), and its innovations and technologies that have fundamentally reshaped and transformed current strategies and prospects for food production and consumption patterns. In this review a general overview of the industrial revolutions through a food perspective will be provided. Then, the current knowledge base regarding consumer acceptance of eight traditional animal-proteins alternatives (e.g., plant-based foods and insects) and more recent trends (e.g., cell-cultured meat and 3D-printed foods) will be updated. A special focus will be given to the impact of digital technologies and other food Industry 4.0 innovations on the shift toward greener, healthier, and more sustainable diets. Emerging food trends have promising potential to promote nutritious and sustainable alternatives to animal-based products. This literature narrative review showed that plant-based foods are the largest portion of alternative proteins but intensive research is being done with other sources (notably the insects and cell-cultured animal products). Recent technological advances are likely to have significant roles in enhancing sensory and nutritional properties, improving consumer perception of these emerging foods. Thus, consumer acceptance and consumption of new foods are predicted to continue growing, although more effort should be made to make these food products more convenient, nutritious, and affordable, and to market them to consumers positively emphasizing their safety and benefits.
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Hydroponics is a modern cultivation technique that utilizes nutrient solutions instead of soil for crop production. Currently, challenges, such as high cost, high energy consumption, greenhouse gas emission, and significant wastewater generation are drawbacks that limit its scale up. On the other hand, bioelectrochemical systems have emerged as a sustainable technology that resolve some of the aforementioned drawbacks, albeit in other scenarios. Bioelectrochemical systems applications are well documented in desalination, metal recovery, energy generation, contamination remediation etc. This work conceptualizes the integration of bioelectrochemical systems and hydroponics with a view to improving the efficiency and sustainability of hydroponics. Firstly, a systematic review of the main challenges hindering hydroponic agriculture developments is first carried out to identify possible entry points for the proposed systems integration. Thereafter, a conceptualized point-by-point resolution of the main identified challenges of hydroponic systems through bioelectrochemical systems integration is explored. Furthermore, the feasibility, stability, and scalability of the conceptualized hydroponic-bioelectrochemical integrated systems are discussed.
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Aquaponics is an innovative food production method that combines the production of aquatic organisms with plant production. This can have environmental advantages such as reducing land conversion and resource input and waste output through nutrient cycling. To support the dissemination of aquaponics, key stakeholders need to be appropriately informed about this production method, an aspect that has received little attention so far. In this pilot study, visual perception of information about aquaponics was explored using eye tracking combined with a questionnaire. The results show that people distinguish between aquaponics variants when evaluating aquaponics. A production system with a more natural appearance is preferred. Allocation of visual attention is linked to the specific information content and to the assessment of the naturalness of aquaponics production. The results of the present study could form a basis for further research, not only to make information about food production systems more appropriate but also to develop food production systems in a way that people become more aware of the sustainability aspects of production methods and its products.
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Electrostatic spraying application is adopted in crop protection to prevent pest infestation, to improve product quality and to maximize yield. It involves a superposition of charges to pesticide spray droplets to attract substrate ions at obscured surfaces. The droplets wraparound effect reduces off-target deposition, enhances on-target spray and invariably improves spray efficiency. Electrostatic spraying system works effectively at optimum parameters combination of the charging voltages, the application pressures, the spraying height regimes, the flow rate, the travel speed, the electrode material, and the nozzle orientation. Many combinations of the system parameter settings have been systematically used by researchers for the electrostatic application, but there is no known specific optimum parameters combination for pesticide spraying. Since droplets chargeability influences the effectiveness of electrostatic spraying system, the parameters that produce ideal charge to mass ratio determine the functionality of the spraying deposition, retention and surface coverage. This article, therefore, analyses electrostatic system parameters that produce suitably charged droplets characteristics for effective impacting behavior of pesticides on substrates. Increasing applied voltages consequently maximizes charge-mass ratio to optimum and starts declining upon further increase in voltages beyond a critical point. This review further proposes the selection of an optimum electrostatic parameters combination that yields optimum droplets chargeability in pesticide application. Also, there is the need to investigate the charge property of substrates prior to pesticide application in order to superpose the right opposite charge on spray droplets at rupture time during electrostatic spraying system. © 2019, Chinese Society of Agricultural Engineering. All rights reserved.
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Controlled environment agriculture (CEA) is a growing industry for the production of leafy vegetables and fresh produce in general. Moreover, CEA is a potentially desirable alternative production system, as well as a risk management solution for the food safety challenges within the fresh produce industry. Here, we will focus on hydroponic leafy vegetable production (including lettuce, spinach, microgreens, and herbs), which can be categorized into six types: (1) nutrient film technique (NFT), (2) deep water raft culture (DWC), (3) flood and drain, (4) continuous drip systems, (5) the wick method, and (6) aeroponics. The first five are the most commonly used in the production of leafy vegetables. Each of these systems may confer different risks and advantages in the production of leafy vegetables. This review aims to (i) address the differences in current hydroponic system designs with respect to human pathogen internalization risk, and (ii) identify the preventive control points for reducing risks related to pathogen contamination in leafy greens and related fresh produce products.
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Developing water-saving irrigation regimes has important practical significance not only in alleviating the crucial water shortage, but also in controlling soil salinization for the protected cultivation in eastern China. A field study with six treatments was conducted to evaluate the effects of different irrigation regimes with subdrainage systems on the soil nitrate nitrogen, salinity and moisture, also evaluate the effects on tomato growth, fruit yield and irrigation water use efficiency (IWUE). The treatments were distinguished by three different irrigation amounts of 310 mm, 360 mm and 410 mm, and two irrigation frequency of 7 and 11 times. Results showed that the irrigation amount had significant effects on the soil NO 3⁻ -N and electric conductivity (EC). A positive correlation was detected between soil NO 3⁻ -N (x) and EC (y) at 0-20 m depth after harvest, with a linear equation of y = 0.063x – 0.670. Soil volumetric moisture at 0.10 m and 0.20 m depth was increased as the irrigation amount increased. Moreover, a higher amount of irrigation increased the fruit yield but reduced the IWUE of tomato. It was also found that smaller irrigation amounts combined with frequent intervals could increase fruit yield and IWUE. However, the fruit quality of tomato had a significant (p<0.05) negative correlation with irrigation amount. Therefore, the parameters of irrigation regime including the irrigation amount and intervals should be considered comprehensively in order to find a compromise between salinity control and irrigation water use efficiency improvement.
Chapter
Commercial production of potato, Solanum tuberosum L., is based on vegetative propagation by seed tubers. High-quality seed material is obtained from potato plants grown from minitubers (pre-basic seed potatoes). Likewise, minitubers are produced by acclimation and growth on soil or solid substrate of previously in vitro-propagated, virus-free microplants or microtubers. Aeroponics is a modern, soilless technique for minitubers’ production. In the aeroponic cultivation system, foliage is grown under conventional conditions, while the underground stems and roots of potato plants are located in a dark chamber, module, suspended in the air, and supplied with water and nutrients through a nutrient solution dispersed in the form of fine mist particles. Minitubers (tubers of 5-25 mm in size) are produced on underground stems, namely stolons. Potato minituber propagation in aeroponics has significant advantages over other used systems or techniques. This system enables the production of a high number of minitubers per plant during the production cycle that can usually be repeated during the year. Besides, successive harvesting allows minitubers to reach the desired, uniform size. Tubers grown in an aeroponic system are well-protected from pests and soil-borne diseases. Due to the recirculation of nutrient solution, efficient usage of space, and minimal environmental pollution, aeroponics enables the production of minitubers in an environmentally friendly manner. This chapter summarizes the current knowledge of the aeroponic production of potatoes. The advantages and deficiencies of this interesting production technique are also discussed.
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Highlights The atomizer droplet size should be considered an important factor when designing aeroponic systems. Airless atomizers had significant positive effects on plant growth, total polyphenol content, and antioxidant activity. Airless atomizers and a spraying interval of 20 min on and 3 h off was the best combination for lettuce plants. Abstract. Throughout our literature review, the effects of various aeroponic atomizers (droplet sizes) on specific leafy plant growth and quality were minimally reported. Lettuce ( L.) is one of the most popular leafy vegetables consumed around the world. The present study sought to determine the effects of various aeroponic atomizers (droplet sizes) on the growth, total polyphenol content, and antioxidant activity of lettuce plants. Aeroponic systems were designed and manufactured using three kinds of atomizers: air-based (A1), airless (A2), and ultrasonic fogger (A3). The South China Agricultural leafy vegetable B nutrient solution was selected as the cultivating solution. Additionally, the spraying time and spraying interval were set at 20 min on and 3 h off. The sizes of the droplets generated by these atomizers were measured using a laser particle size analyzer, and the measured average droplet sizes generated by the A1, A2, and A3 atomizers were 23.281, 46.386, and 3.451 µm, respectively. The results showed that the lettuce plants treated with the A2 atomizers exhibited more significant effects on the growth, total polyphenol content, and antioxidant activity of the lettuce compared to those treated with the A1 and A3 atomizers. The results indicated that nutrient solution droplet size should be considered an essential factor when designing an aeroponic system. Keywords: Aeroponic, Antioxidant activity, Soilless, Spraying time, Total polyphenol content.
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China has obtained remarkable major achievements of agricultural and rural development in the past five years, such as advance in agricultural supply-side structural reform, breakthroughs in rural reform, headway in urban-rural integration development, improvement in rural public services and social undertakings, progress in poverty alleviation, a new level in agricultural trade. Specifically speaking, China is witnessing the following development in Information and Communication Technology (ICT) application in rural areas: Internet infrastructure is strengthened; E-commerce in rural areas is thriving; rural information service is upgraded; A solid progress has been made in Agricultural Internet of Things and rapid deployment of big-data technology. This paper summarizes the experiences gained in the development of agricultural and rural informatization in China. Based on this review, some suggestions were presented: Firstly, improving policy systems through innovation; secondly, strengthening ICT infrastructure; thirdly, giving full play to the primary role of market; fourthly, carrying out pilot demonstration and trainings. At the same time, the problems faced by rural e-commerce development were also pointed out. © 2018, Chinese Society of Agricultural Engineering. All rights reserved.
Article
The objectives of this research were to reveal how main working parameters of ultrasonic atomizers would influence key properties of the atomized nutrient solution in an aeroponics system. The Yamazaki tomato nutrient solution was selected as a nutrient example. Uniform design (UD) method U12 (12²×13) was adopted to arrange the test. In this test, spraying time and interval time were taken as quantitative factors with 12 levels (10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, and 120 min, respectively), and ultrasonic atomizer frequency was taken as qualitative factor with 3 conditions (28 kHz, 107 kHz, 1.7 MHz). Based on test data, two regression formulations used to predict the values of ΔEC, and ΔpH of atomized Yamazaki tomato nutrient solution was established and inspected. The spraying interval time of ultrasonic atomizers had no significant effect on EC and pH of the atomized Yamazaki tomato nutrient solution; the ultrasonic atomizer frequency was more effective than spraying time on the values of EC and pH; the values of EC and pH became maximum at (f3, T1) = (1.7 MHz, 120 min) and minimum at (f1, T1) = (28 kHz, 10 min). It was concluded that the effect of high-frequency (1.7 MHz) ultrasonic atomizer on EC and pH of the Yamazaki tomato nutrient solution was beyond the standard value for tomato growth. Therefore, the high-frequency (1.7 MHz) ultrasonic atomizer is not suitable for aeroponics cultivation when using the Yamazaki tomato nutrient solution as aeroponics nutrient solution. © 2018, Chinese Society of Agricultural Engineering. All rights reserved.