Turning workss without dirt had been known by homo for more than 1000s twelvemonth. The cardinal rule of aquicultures relies on fertilized & A ; aerated H2O which provides both nutrition andA oxygenA to a plant’sA rootA zone. Hydroponics has been recorded back every bit early as the Aztecs and ancient Egypt ( Winterborne 2005 ) . The scientific survey of works fundamental was foremost recorded in 16th century by Jan Van Helmont, his survey found out that workss get substances for growing from H2O ( Resh 2004 ) . In 1666, Robert Boyle reported the first experiments on cultivate workss with their roots sank in H2O. John Woodward proved that works can be grown in H2O but dirt component had to be added to H2O in 1699 ( Gruda et al. 2006 ) . In 1804, Nicolas de Saussure proposed that workss need nutrition for turning. Mid 1900s, Jean Baptiste Boussingault introduced turning workss in sand wood coal and vitreous silica utilizing dissolved food. Later, in 1860, the earliest typical expression for a alimentary solution that could be dissolved in H2O and in which workss could be efficaciously grown was published by Julius von Sachs ( Resh 2004 ) . The first proposal for commercial H2O civilization system was made by Dr. Gericke in 1929 ( Gericke 1929 ) . The term aquicultures was originated by Dr. William Frederick Gericke of the University of California in 1937 to depict the cultivation of workss in a solution of H2O and dissolved foods. The word aquiculture has its beginning from the meeting of two Grecian words, hydro significance H2O and ponos significance labour ( Gericke 1937 ) . In 1938, Gericke ‘s originated system was adopted on Wake island in Pacific ocean to provide riders and crews of limiter plane that use this island as a manner station ( Science News Letter 1938 ) . The first big commercial graduated table executions for aquicultural turning were the systems established by the U.S. Army in the South Pacific during World War II to provide fresh fruits and veggies for military personnels runing in that country ( Jones 1985 ) . However, the first deep H2O aquicultures system described by Gericke was non immensely adopted because they proved to be non profitable and doing inefficient usage of resources ( Schwarz 1968 cited in Gruda et Al. 2006 ) . In the 1970s, Allen Cooper created Nutrient movie technique to get the better of the job of aeration in Gericke ‘s system ( Cooper 1975 ) . At present many research workers is still being carried out to develop aquicultures system.
3.2 Advantages and disadvantages of aquicultures
There are two chief advantages of the aquicultures. First, aquiculture is much greater harvest output ( See table 1 ) ( Douglas 1970 ; Jensen 1990, 1999 ; Olympios 1998 ; FAO 2010 ) . Second, aquicultures can be used in location where regular agribusiness is infeasible ( Douglas 1970 ; Jensen 1990 ; Olympios 1998 ) . These two advantages are besides supported by Resh ( 2004 ) . Furthermore, Resh ( 2004 ) pointed out some other chief advantages of aquicultures which are more competent nutrition direction ( Falivene 2005 ) , effectual and efficient usage of fertilisers and H2O ( FAO 2010 ) .
In add-on, if we compare aquicultures or soilless civilization with soil civilization or ordinary agricultural, we can happen that there are many advantages aquicultures over soil civilization. First, aquicultures requires less labour needed ( Olympios 1998 ; Maejo Hydroponics Information Centre ( MHIC ) 2009a ) . In soil civilization, sterilisation of turning medium can be labour-intensive and clip required is drawn-out. In contrast, aquicultures system requires short clip to sterilise. The dirt readying processes can ensue in big cost in soil civilization. Second, aquicultures system enable agriculturist to wholly pull off over works nutrition, on the other words, aquicultures offers the precise control of works nutrition relation to dirty civilizations as it is easier to try, trial and adjust because nutrition expression is similar to all workss that portion the same armored combat vehicle. Besides, enable agriculturists to command over pH and electrical conduction ( EC ) which is about impossible in dirt civilization ( Olympios 1998 ; Resh 2004 ) . Third, in dirt civilization, there are many soil-borne diseases ( a decrease of biodiversity of dirt beings ) , harvest can be attacked by insects and animate being, as a consequence harvest rotary motion is used to get the better of increasing figure of insects. Conversely, there is no insects or animate beings that can assail harvest, hence harvest rotary motion is non necessary ( Roberto 2000 ; Resh 2004 ) . Fourthly, aquicultures is enabling comparatively efficient usage of H2O. In soil civilization, H2O is lost as drainage past the vegetable root part and by going vapour from dirt. In aquicultures system, these jobs are eliminated by the layout and working design of the aquicultures systems such as alimentary movie technique ( NFT ) ( Olympios 1998 ; Resh 2004 ) . Fifth, big sum of fertilisers drain off from dirt yesteryear works root part which is lead to inefficient usage of fertilisers in dirt civilization. In aquicultures system, the usage of fertilisers is really efficient since fertilisers can non leach beyond root part. Furthermore, comparatively little measure of fertilisers is used but can be circulated to all workss ( Resh 2004 ) . Last, aquicultures system offers about no clip interval between harvests, hence, in the peculiar growing country, the sum of harvests per twelvemonth is greater than in soil civilization ( Olympios 1998 ) .
Notwithstanding many benefits, there are some drawbacks of aquicultures. First, evidently, aquicultures system requires high capital investing for set up ( Olympios 1998 ; Resh 2004 ; MHIC 2009a ) . Second, aquicultures system requires high proficient cognition needed for the direction which is chiefly from sing the complexness of nutrition commixture ( Jensen 1990 ; Olympios 1998 ; Resh 2004 ; MHIC 2009a ) . Third, in aquicultures system, workss are sharing the same nutrition armored combat vehicles, therefore, some diseases such as Fusarium and Verticillium can distribute out really fast to all workss that sharing the same armored combat vehicle ( Resh 2004 ) . However, these disadvantages can be overcome ; capital cost can be controlled by usage of simplified aquicultures technique, diseases can be restrained by usage of proficient cognition.
3.3 Appropriate site for aquicultures
In order to minimise any hazards of failure in aquicultures production, the choice of suited sites for the big commercial aquicultures installing is matter ; we must take the country location that suited to put up aquicultures site. ( MHIC 2009b ) suggested some demand features of the proper location. First, the country should to the full exposes to sunlight in E, South and West with barrier against the air current from north. Following, the country should be somewhat sloped or can be readily to flatten ( Douglas 1985 ) . Following, country should hold a good supply of public public-service corporation such as electricity, telephone and good quality H2O ( at least 6 liters per square meter of turning country per twenty-four hours ) . Following, country should hold a good action of run outing H2O with incursion at least 1 inch per hr. Following, the country that has a good connexion to route and shut to high denseness populating country for easy entree to the market. Following, the part or territory which has maximal supply of sunshine. Finally, North-south oriented layout of turning country. However, it is non specific to hold all features but should run into those demands every bit much as possible.
3.4 Type of aquicultures
At each stage of growing, within a bad aquiculture system, all the O, H2O and foods are provided to the root part of the works at the strength of a solution and temperature that the works requires ( Rural industries research & A ; development corporation ( RIRDC ) 2001 ) . There are two chief types of aquicultural systems: H2O or solution civilization and medium or substrate civilization.
3.4.1 Water civilization
Water civilization, by definition, is classified as true aquicultures. This method does non utilize solid medium for the root, merely merely dissolved alimentary solution. Water civilization was the method of aquicultures used in big scale commercial harvest production and research lab research ( Douglas 1985 ) . Resh ( 2004 ) suggested three demands to be met in order to be successful in operation of H2O civilization ; aeration of the roots and darkness of root zone. First, aeration of the roots. Roots should be provided with adequate O. This may be attained in two ways. The first manner is called forced aeration, by bubbling the air into the alimentary solution utilizing airstone stationed in the armored combat vehicle or at the lowest portion of the bed. The 2nd manner is utilizing the instrument that regulates flow placed at the underside of the armored combat vehicle. Second, darkness of root zone. During the daylight, usually, workss can work with their roots opened to the visible radiation in the status that they are at all clip 100 per centum comparative humidness. Nevertheless, algae will be promoted to growing in visible radiation. Algae will hinder growing of works by postulating for O and foods every bit good as making toxic though its decomposition. Therefore, in order to extinguish algae growing, beds and screen should be made of non crystalline stuffs.
3.4.2 Substrate civilization
In substrate civilization, the alimentary solution is provided to workss by H2O supplied through the media which allow the excess solution to be recirculated or run to blow in some instance. The medium is besides supplying support and environment workss. The medium should non keep back or lock up any food. Therefore, workss will be able to absorb food they need every bit much as possible and whenever they need. Harmonizing to Olympios ( 1998 ) , there are two classs of medium that usage in the substrate civilization ; inorganic and organic media. For illustration, rockwool, sand, and crushed rock for inorganic. The subsequently such as sawdust, bark, wood french friess, and peat.
3.5 Hydroponicss techniques
There are many aquicultures techniques that developed and in pattern presents, nevertheless, this paper will stress on techniques that widely use in commercial production.
3.5.1 Nutrient Film Technique
The alimentary movie technique ( NFT ) was pioneered in 1965 at the Glasshouse Crops Research Institute in Littlehampton, UK by Dr. Allen Cooper ( Winsor et al. 1979 cited in Jensen 1999 ) . The standard characteristics of NFT consisted of alimentary solution armored combat vehicle, electronic pump to present the solution through pipes, and troughs ( See Fiqure XX ) . A assortment of types of stuff can be used to build a trough ; for illustration, coated metal, PVC pipe, and polythene, depending on the harvest and size of the trough ( van Os et Al. 2008 ) . The workss are grown in superficial trough or channel such as PVC pipe which is provided with a really swallow flowing movie ( 1 – 2 centimeters ) of continuously recirculated alimentary solution ( Marr 1994 ) . The minerals are supplied consecutive to the root system. The alimentary solution is delivered from alimentary armored combat vehicle to the higher terminal of the channel at the rate of 2 – 3 liters per proceedingss, so flows past the works roots by gravitation to run out hole and to alimentary solution armored combat vehicle, the incline should be between 1:50 – 1:100 depends on works harvest ( Adams 1981 ) . The alimentary solution should be monitored for the comparative sum of salt contained within a solution before recycling. The necessities for the managing of recirculating aquicultural turning systems were discussed by Bugbee ( 2003 ) . The add-on of make-up H2O, the demand for reconstructing the pH and alimentary component component, filtering, and sterilisation are processs that need to be adopted. In add-on, on status that the flow velocity is excessively low, the issue is non lacking of H2O, but insufficient of foods, peculiarly for workss whose roots are traveling in the way in which a alimentary solution flows in the trough and are disclosed to H2O from which many other workss have obtained some foods before. The last workss in the row acquire the least foods, particularly K. As a consequence, this can be created the job of slow growing ( van Os et Al. 2008 ) .The alimentary movie technique is suited for works with 120 – 150 yearss rhythm or leafy veggies such as boodle ( Pardossi and Sciortino 2004 ) . Conversely, sing to Resh ( 2004 ) , in the past NFT was used to turn vine harvests such as tomato, Cucumis sativus and Piper nigrums but due to aeration job of NFT in turning vine harvests, rockwool is used to turn these vine harvests alternatively. Significant facet of NFT is to do certain that equal O is gettable to the works. This may necessitate either aeration of the food within the armored combat vehicle or leting air to make the alimentary solution within the channels.
There are many advantages of alimentary movie technique. First, an advantage of this system in comparing with others is that the needed volume of alimentary solution is a greatly reduced ( Jensen 1990 ) . Second, another benefit is preservation of H2O by the usage of recirculated H2O instead than an unfastened system. Third, it is easier to sanitize roots and hardware compared to other system types. Fourth, plague and disease control is simplified by usage of systematic insect powders and antifungals in the alimentary solution to command insects and diseases ( Cooper 1975 ) . Fifth, NFT is simple to put up and has comparatively low cost of edifice stuffs ( Jones 2005 ) .
There are some drawbacks that possible come up from the pattern of NFT ( RIRDC 2001 ) . First, the roots will dry out if the circulation of alimentary solution is interrupted even for short length of clip and quickly go stressed. Therefore, electricity supply to the system is important. Second, hard state of affairs can be the immoderate high temperature of troughs in freshly planted systems. Third, roots of really healthy turning workss can go an obstructor in troughs which makes motion or flux hard or impossible.
3.5.2 Aeroponics
Aeroponics technique was foremost researched in 1942 by W. A. Carter and described in his work “ aA method of turning workss in H2O vapour to ease examinationA ofA roots ” ( Rajshekhar 2009 ) . Subsequently, the aeroponics technique is the method that requires no medium. Plants are pensile in the supporting holder where root system is freely suspended and enclosed inside a dark chamber ( see figure XX. ) . To suppress algae growing, that is a ground why chamber has to be dark ( Jensen 1990 ) . The food is supplied to workss continuously as a alimentary mist or fog instead than a alimentary solution through a spray jets which on a regular basis, map 24 hours per twenty-four hours ( Haddad et al. 2009 ) . This method is suited for works that can non be immersed in H2O ( MHIC 2009c ) . Recently, this method is immensely utilizing in research lab surveies, but non much as other methods in large-scale commercial production ( Resh 2004 ) . However, aeroponics is used by some Italian companies to bring forth boodles, tomatoes, Cucumis sativuss and melons for commercial graduated table production.
There are many advantages of aeroponics system. First of all, environment of root system is good supplied of O as all roots are exposed to the air in the chamber which benefits to the workss. From the survey of Kratky ( 2005 ) showed that sum of air in the chamber has positive relationship to harvest outputs. However, to forestall a deficient in O, the chamber should be aerated. Second, an scrutiny of the roots for indicants of disease or growing cheque can be easy done and with minimum perturbation as there is no medium at root part ( Kratsch et al. 2006 ) . Third, fundamentally, bacteriums that can possible harm harvest workss by and large grow and become more legion in a medium. Therefore, this can be less of a concern with aeroponics.
On the other custodies, aeroponics besides has some disadvantages. To get down with, the system is vulnerable to a power outage or pump failure. As a consequence, exposed roots will quickly dry out and kill the works. Next, salt in food can be build up quickly because H2O can vapor really fast, unless we can command the vaporization rate in the chamber by sealed the chamber to minimise vapour flow out.
3.5.3 Deep Flow Technique
This technique was first developed in Japan in 1973 ( Kao 1991 ) . Deep flow technique ( DFT ) can be described as a method that the roots ever exposed to fluxing alimentary solution similar to the principal of NFT. The alimentary movie is every bit thin as possible in NFT, in contrast, in DFT method, the uninterruptedly streamlined alimentary solution has about 5-15 centimeters deep with invariably depth ( van Os et Al. 2008 ) ( see figure xx ) . This system has alimentary solution stagnated in the trough invariably. Therefore, it is suited for workss that do non necessitate much O and like H2O such as boodle and Chinese Apium graveolens dulce. Trough might be made from PVC 2.5 to 4.0 inches in diameter. Plants are fixed in holes on PVC pipe by utilizations of medium such as polyurethane froth. This system requires air pump to increase O in the alimentary solution as workss roots are submerged in the alimentary solution.
The benefit of this system is that the high circulation rate and big volume of the alimentary solution makes it possible to command entire organic C of the solution and give the solution a good aeration ( Vestergaard 1998 ) . The drawback is that high energy demand for pumping the alimentary solution throughout the system.
3.5.4 Floating Technique
A natation system is a fluctuation of DFT. In this technique, workss are grown in big channels or basins. The workss are fixed to a piece of styroform and left drifting on the surface of the H2O which lets the roots to be suspended in the H2O below ( Vestergaard 1998 ) ( see figure xx ) . This system besides called raceway or raft system. The paradigm of commercial size raft system was developed by Dr. Merle Jensen during 1981 -1982 ( Resh 2004 ) . Plants are grown in the beds of alimentary solution for illustration ; the theoretical account of Jensen, a bed dimension is 60 centimeter broad by 20 centimeters deep by 30 m long. The natation boards are made of Styrofoam which enable them to drift on the alimentary solution. The dimension can be ; for illustration, 2.5 centimeter deep by 15 centimeters long by 58 centimeters broad, that can suit to the bed size. Crop will be hold in the hole on the board with about 3 centimeters diameter. Plant roots are immersed in the solution and the works to be supported on a piece of froth above the solution. Harmonizing to Resh ( 2004 ) as the alimentary solution bed is big, the volume of solution per bed ( from the illustration dimension ) is 3,600 liters, hence, the alimentary solution demand to be sterilize before recirculating to forestall bacteriums or sources that can do diseases. The alimentary solution is recirculated through a alimentary armored combat vehicle of about 4,000 – 5,000 litres. Between the harvests rhythm, the boards need to be clean and sterilise. Furthermore, in high temperature, this system can utilize chiller unit to chill the H2O to the suited temperature.
The advantage of drifting system is that the temperature is absorbed by the big volume of H2O, doing the technique practical in parts where the oscillation of alimentary solutions temperature perchance a job ( Ikeda, 1985 ; Ito, 1994 ; Park et al. , 2001 ; Both, 2005 cited in new wave Os et Al. 2008 ) . Another advantage is the use of country as this technique can supply high seting denseness. Third advantage is less ruinous conditions in instance of circulation pump failure due to high volume of alimentary solution in direct touch with the works roots ( Resh 2004 ) . Althrough, disadvantage is the demand of high cost of capital every bit good as the proficient expertness required is high ( Tyson et al. 1999 ) .
3.5.5 Dynamic Root Floating Technique
In 1986, the dynamic root drifting technique ( DRFT ) was developed in Taiwan by Dr. T.C. Kao at The Taichung District Agricultural Improvement Station. The aim in developing this system is to happen a aquiculture technique which suited for the Torrid Zones. The job that found in this part is that high temperature of conditions which leads to high temperature of alimentary solution that workss roots are submerged. This will do less O dissolved in the alimentary solution as a consequence harvests productiveness is decreased and the development of roots is non good plenty because deficient O for workss to turn particularly in summer. The construct of this technique is to bring on workss to develop aero roots to work out the job of deficiency of O, peculiarly, at high temperature. The of import portion of the system is carinate civilization bed. The underside of the bed is in moving ridge form ( see figure layout ) . The concave holes ( No.3 in see figure layout ) below the natation boards provide excess infinite which enable aero roots to turn above the alimentary solution and hence have more O. Alternatively of a non break fluxing alimentary solution system like in the NFT, the H2O pump is often turned on and off to set the deepness of the H2O. As an option, the pump can remain on at all times and a drainage system can be installed to change the deepness utilizing alimentary solution degree adjustor. However, this system can be adapted utilizing PVC pipe alternatively of civilization bed by seting solution degree. ( see figure xx ) Furthermore, different techniques are used to restrict the temperature of the alimentary solution. For illustration, when temperatures rise above 30 degree Celsius, some sunshine is block out by semi-transparent polythene sheets that are hung over the roof. In add-on, the DRFT channels can be are lined with insulating stuff to impede heat transportation from the existent milieus ( Kao 1991 ) .
The chief advantage of this technique is that it can retain the temperature of the alimentary solution. Since O is less soluble in warm H2O, the DRFT is compatible for aquicultural agriculture in tropical and semitropical climes such as those found in Taiwan, Singapore and Thailand ( Kao, 1991 ) .
3.5.6 Flood and Drain
This technique can be called Ebb and flow technique. It is a basically subirrigation technique. The system is formed of a water-resistant inundation and drain tray, tray incorporating an inert rooting medium, such as crushed rock, sand, and rockwool, a alimentary solution reservoir, an electric pump for deliver the alimentary solution from the armored combat vehicle to the inundation and drain tray, and a piping system to help the bringing of the alimentary solution from the reservoir to the inundation and drain tray and its return ( see figure xx ) . Alimentary solution is delivered into a superficial inundation and drain tray by electric pump to about 1 inch deepness for about 20 proceedingss and subsequently allowed to run out back to the alimentary reservoir ( Resh 2004 ) . However, Jones ( 2005 ) suggested that the timing for flood of the turning tray will be conditional on the atmospheric demand and stage of harvest ‘s growing, every bit good as the H2O absorbability of the turning medium. It is really indispensable that the H2O be allowed to run out away exhaustively so as to avoid root diseases. If besotted musca volitanss continue to be around the works, algae growing, root diseases and inconsistent lacrimation will happen ( van Os et Al. 2008 ) .
The inundation and drain technique has advantage over other systems. One of the most important advantages is that this system is able to defy high temperatures because the roots are merely on occasion soaked in alimentary solution. For case, if the alimentary solution becomes higher than a peculiar temperature the works can go more vulnerable to diseases and root harm due to low O around the roots in some aquicultural techniques ( Resh 2004 ) .
Jones ( 2005 ) pointed out some disadvantages of the inundation and drain system. First, sporadically replacement of the rooting medium is indispensable. Following, the inefficient usage of valuable H2O and chemical as the alimentary solution demand to be wholly replaced every 2 – 3 hebdomads. Last, in the big system that has one alimentary solution armored combat vehicle, if there are any diseases infected one works, the consequence will be the full harvests infect with disease.
