Dissertations / Theses on the topic 'Hydroponic'

Hydroponics is a method of cultivating plants without the use of soil. Soil acts as a growth medium which gives plants stability, provides nutrients and allows roots to be kept wet without drowning. In hydroponics the soil’s functions are replaced by synthesized methods. Stability comes from a substrate (i.e. LECA, rockwool perlite).The 16 essential nutrients are solved in water which are distributed to plants’ roots by different techniques. To generate photosynthesis natural light is replaced by artificial light, especially red light in the proximity of 660 nm. Hydroponics has been used as a cultivation method for at least 2000 years. During the 20th century industrial applications became common since plastics allowed for complex systems engineering. The method also makes it possible to grow the same amount of crops with approximately 10% water usage and 25% of the area compared to conventional cultivation. During the past few years systems for home use has emerged but the product genre is still in its cradle. This master thesis covers a new conceptual design of a hydroponic home system. The project was carried out at Omecon AB in Stockholm as a consulting design project. Omecon AB is an engineering consultant agency within mostly mechanical construction looking to widen the competence base. Using a design process based on Human-Centered Design the project involved the stakeholders users, extreme users, Omecon AB, plant experts, electronics engineering and service as well as plastics design engineering. Additional/supplemental economical–, ecological– and social sustainability aspects has been considered during all phases of the process. By using the Human-Centered Design process the problem range is expanded from its initial state which results in a more complete end result. Common methodology altered with some unorthodox twists has been utilized throughout the project. The final result is a conceptual hydroponic system for home environment which is designed as an interior design product as well as a high-performance cultivation system. By using natural materials such as wood and steel the users expands its life span and thus mitigates the negative environmental impact. Another aspect which prolongs the products life span is the modular usage which lets users vary and choose their preferred settings. All manufactured materials included in the final concept were flow resources and the parts were engineered to be easily separable for future replacement and recycling. A new type of pot was invented along with a new way of adjusting the height-wise position of lamps. The aeroponic technique, which was applied to this concept, is generally considered to generate the largest plants and thus comprises higher performance compared to other home systems. The use of substrate was also eliminated which decreases continous material consumption within hydroponics.
Hydroponik är en metod för att odla växter utan jord. Jord i odling agerar som ett växtmedium som ger plantor stabilitet, tillför näringsämnen och tillåter rötter att vara i väta utan att dränka dem. I hydroponik ersätts jordens funktioner med syntetiska metoder. Stabilitet ges av ett substrat (t.ex. LECA-kulor, stenull eller perlit). De 16 essentiella näringsämnena löses i vatten och distribueras till plantors rötter med hjälp av olika tekniker. For att skapa fotosyntes ersätts naturligt ljus med artificiellt ljus. Speciellt rött ljus i närheten av 660 nm. Hydroponik har använts som odlingsmetod i åtminstånde 2000 år. Under 1900-talet blev industiella applikationer vanliga eftersom plast möjliggjorde tillverkling av komplexa system. Metoden tillåter även att odla samma mängd grödor med 10% av vattenmängden och 25% av ytan jämfört med konventionell odling. Under de senaste åren har system avsedda för användning hemma blivit vanligare men produktgenren är fortfarande ung. Det här examensarbetet täcker en ny konceptuell design av ett hydroponiskt system för hemmabruk. Projektet utfördes på Omecon AB i Stockholm som ett konsultarbete inom design. Omecon AB är en konsultfirma som mestadels är verksamma inom mekanikkonstruktion men de vill vidga sin kompetens. Genom användning av en designprocess som har baserats på Human-Centered Design har projektet involverat intressenterna användare, extrema användare, Omecon AB, växtexperter, en elektronikingenjör samt plastkonstruktion. Vidare har aspekter inom ekonomisk–, ekologisk– och social hållbarhet beaktats genom alla faser av processen. Via användning av Human-Centered Design-processen har problemrummet expanderats från den initiala utgångspunkten vilket resulterar i ett mer komplett slutresultat. Vanlig metodik varvat med okonventionella anpassningar har använts genom projektet. Slutresultatet består av ett konceptuellt hydroponiskt system för hemmabruk som är designat som en inredningsprodukt samt ett odlingssystem med hög prestanda. Genom användning av naturliga material som trä och stål förlänger användarna produktens livslängd och på så sätt förmildras den negativa klimatpåverkan. En annan aspekt som förlänger produktens livslängd är moduläriteten som låter användare variera och välja deras föredragna inställningar. Alla tillverkade material inkluderade i slutkonceptet var flödesresurser och delarna konstruerades så att de går lätt att separera för framtida ersättning och återvinning. En ny typ av kruka uppfanns tillsammans med ett nytt sätt att justera höjden av lamporna. Den aeroponiska tekniken, som används is konceptet, är allmänt ansedd att generera de största plantorna och innefattar därför högre prestanda jämfört med andra hydroponiska hemmasystem. Användning av substrat eliminerades också vilket minskar kontinuerlig materialkonsumption inom hydroponik.

This report includes research into how to automate a small scale system for hydroponics. Hydroponics is a growing technique which features a soil-less environment were the plants roots are exposed to a nutrient-enriched water solution. The research focused mainly on how to regulate the pH and the level of nutrient in the water solvent and finding a system to automate that process. In the research fully grown basil plants were used as test specimens, with the plants roots submerged in a water solvent. The water solvent had sensors that were connected to a micro controller making it possible to monitor the presence of nutrients and pH in the solvent. If the micro controller deemed that the pH and/or the nutrient level was too high or too low, the micro controller would adjust the solvent by activating pumps adding pH down buffer solution and/or nutrient solution to the solvent. The research proved that a way to automate a small scale hydroponics system is by building a computerized system consisting of: • Micro controller. • pH sensor. •EC sensor (to measure nutrient level in solvent). • Temperature sensor. • Fluid pumps connected to pH- and nutrient reservoirs
I denna rapport följer en forskning om hur ett system för hydroponics kan automatiseras. Hydroponics är en odlingsteknik som utesluter nyttjandet av jord. Istället får plantorna näring och vatten via en näringsrik vattenlösning som dess rötter är i kontakt med. Forskningen fokuserade huvudsakligen på hur man reglerar pH och nivån av näringsämnen i en vattenlösning och skapa ett system för att automatisera denna processen. I undersökningen användes fullvuxna basilikaväxter som prover med plantornas rötter nedsänkta i en vattenlösning. Vattenlösningen hade sensorer som var anslutna till en mikrostyrenhet som gjorde det möjligt att övervaka nivån av näringsämnen och pH i vattenlösningen.  Om mikrokontrollen ansåg att pH- och/eller nivån av näringsämnen var felaktig så skulle mikrostyrenheten justera vattenlösningen. Detta skedde genom att mikrostyrenheten aktiverade vätskepumpar som tilsatte pH-buffer och/eller näringslösning. Forskningen visade att ett sätt att automatisera ett hydroponicsystem är att bygga ett datoriserat system som består utav: mikrostyrenhet. pH mätare. EC mätare (används för att mäta näringsnivån i vattenlösningen). Temperaturmätare. Vätskepumpar anslutna till behållare inehållandes pH- och näringslösning.

This report investigates how to build a compact, optimizable and at the same time user friendly hydroponic systemfor growing plants as efficiently as possible. Hydroponics grows plants using water with dissolved nutrients instead of soil, allowing faster and more efficient growth.The focus has been on the implementation and the usability of such a system, centering around monitoring and to some degree controlling important parameters for growth such as humidity, air temperature, nutrition concentration and light intensity, colour and exposure time. The plant is enclosed in a confined space with artificial lighting which allows thorough control of the light environment. In order to achieve the desired level of control over the growth parameters, several sensors along with a microcontroller were used. A touch screen with a custom built graphical user interface was also connected to allow the user to control and monitor important aspects of growth conditions. The conclusion drawn from this project is that there is ahigh order of optimizability within the boundaries of this project. The measured factors are easily read on an intuitive, easily navigated touch screen for direct feedback. Regarding the lights’ effect on plant growth, the conclusionis drawn that plants grow well with many types of lights, but more time is needed to thoroughly investigate different light exposure times, colour and intensity.
I denna rapport undersöks hur man kan bygga ett kompakt, optimerat och samtidigt användarvänligt hydroponiskt system för att odla växter så effektivt som möjligt. Hydroponiska system får plantor att växa genom att användavatten med näring istället för jord, vilket tillåter snabbare och mer effektiv tillväxt. Fokuset i denna rapport har varit på implementeringen och användbarheten av ett sådant system, med tyngpunkt på övervakning och till viss grad styrning av viktiga faktorer i en plantas tillväxt såsom luftfuktighet, temperatur, näringskoncentration och ljusintensitet, färg och exponeringstid. Växten är innesluten i ett begränsat utrymme med artificiellt ljus, vilket tillåter genomgående kontroll av ljusmiljön. För att uppnå önskad kontroll av tillväxtparametrarna, användes ett flertal sensorer tillsammans med en mikrokontroller. Till detta kopplades en pekskärm med ett egen tillverkat användargränssnitt, som tillåter användaren att kontrollera och övervaka viktiga aspekter i tillväxten. Slutsatsen från detta projekt är att det finns en hög grad av optimerbarhet inom denna konstruktion. De uppmätta parametrarna kan enkelt avläsa ljusexponering, ljusintesitet och färg.

It is becoming increasingly evident that agriculture is playing a pivotal role in the socio-economic development of South Africa. The agricultural sector is important because it contributes approximately 2% to the gross domestic product of the country. However, many factors impact on the sustainability of traditional agriculture in South Africa. Unpredictable climatic conditions, land degradation and a lack of information and awareness of innovative farming solutions are among the factors plaguing the South African agricultural landscape. Various farming techniques have been looked at in order to mitigate these challenges. Among these interventions are the introduction of organic agriculture, greenhouse agriculture and hydroponic agriculture, which is the focus area of this study. Hydroponic agriculture is a method of precision agriculture where plants are grown in a mineral nutrient solution instead labour- intensive activity that requires an incessant monitoring of the farm environment in order to ensure a successful harvest. Hydroponic agriculture, however, presents a number of challenges that can be mitigated by leveraging the recent mobile Information and Communication Technologies (ICTs) breakthroughs. This dissertation reports on the development of a wireless ICT monitoring application for hydroponic agriculture: HydroWatcher mobile app. HydroWatcher is a complex system that is composed of several interlacing parts and this study will be focusing on the development of the mobile app, the front-end of the system. This focus is motivated by the fact that in such systems the front-end, being the part that the users interact with, is critical for the acceptance of the system. However, in order to design and develop any part of HydroWatcher, it is crucial to understand the context of hydroponic agriculture in South Africa. Therefore, complementary objectives of this study are to identify the critical factors that impact hydroponic agriculture as well as the challenges faced by hydroponic farmers in South Africa. Thus, it leads to the elicitation of the requirements for the design and development of HydroWatcher. This study followed a mixed methods approach, including interviews, observations, exploration of hydroponic farming, to collect the data, which will best enable the researcher to understand the activities relating to hydroponic agriculture. A qualitative content analysis was followed to analyse the data and to constitute the requirements for the system and later to assert their applicability to the mobile app. HydroWatcher proposes to couple recent advances in mobile technology development, like the Android platform, with the contemporary advances in electronics necessary for the creation of wireless sensor nodes, as well as Human Computer interaction guidelines tailored for developing countries, in order to boost the user experience.

Vertical hydroponic farming is a developing sector that has the potential to mitigate the adverse effects of conventional farming while also meeting the demands of rapidly urbanizing populations. The global food system is responsible for up to 30% of anthropogenic GHG emissions, with primary production accounting for the majority of these emissions. Hydroponic farming is a type of crop production in which the plants grow without the use of soil. It is mainly done indoors. Hydroponic production has various advantages for the food system, including water efficiency, space efficiency, year-round production, and system productivity. Despite many advantages mentioned in the literature, hydroponic farming has certain drawbacks, including a reliance on electricity to grow, a limited choice of crops appropriate for hydroponic cultivation, and a higher product price.This paper examines the obstacles and describes how integrated modular farms might be implemented in Sweden to improve urban food resilience. This project aims to design a modular solution for a closed hydroponic farm using various data gathering and design methodologies. In one year, the designed hydroponic system generates about one ton of lettuce in a one-square-meter area while saving 91.27% of water compared to conventional farming methods. The secondary goal was to assess the designed system's long -term viability interms of social, environmental, and economic sustainability indicators and study the structure from an engineering standpoint.

Thesis (MTech (Horticultural Sciences))--Cape Peninsula University of Technology, 2017.
The increasing demand for medicinal plants has led into serious over-harvesting of wild populations and presents an opportunity for potential profitable cultivation. Production of medicinal plants in controlled environments particularly hydroponic technology provides opportunities for high quality biomass accumulation and optimizes production of secondary metabolites. Water availability and supplies are becoming scarce, thus search for innovative irrigation practices is desirable and vital. The proper irrigation interval and growing media can play a major role in increasing the water use efficiency. Thus, Siphonochilus aethiopicus was cultivated by means of the hydroponic technique, under various substrate combinations and watering regimes.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior
Traditional soil based strawberry production currently faces some obstacles, both by excessive use of pesticides, as the diseases caused by fungi and other pathogens and ergonomic difficulties of cultivating the soil. Strawberry soilless cultivation combined with greenhouse and the use of substrate promotes some advantages such as: eliminating the use of products for soil disinfection, precocity, increased yields, better crop management conditions and crop protection against adverse weather conditions, pest attacks and diseases.. The objective of the study was to evaluate yield and nutrition of four strawberry cultivars in three cropping systems in Serra da Ibiapaba â CearÃ. The experiment was conducted in 3 x 4 factorial design, randomized blocks, with three cultivation systems arranged in strips (soil, hydroponic in gutters and bags), with four strawberry cultivars (Oso Grande, Albion, and Camarosa and Festival) and five replications. Coconut fiber was used as substrate in the hydroponic systems. In the period between the sixth and thirty-eighth week after transplanting, the number and average fruit weight, yield per plant and yield were determined. From the beginning of flowering, leaves were collected every two months to determine the levels of macro and micronutrients. Hydroponic gutter and bag systems increased the number of fruits per plant, but did not increase average fruit weight. The strawberry yield in hydroponic cultivation system was superior to soil cultivation. Cultivar Festival presented more fruits than the other cultivars in hydroponic systems. The Oso Grande and Festival cultivars stood out as the average fruit weight and yield, respectively, and may be recommended for hydroponic cultivation for the region of Serra da Ibiapaba. Based on the leaf nutrient contents, it is suggested adjustments in concentrations of phosphorus and magnesium in the nutrient solution used in hydroponic strawberry crop. Keywords: Fragaria x ananassa, cultivar, nutrients, crop system,
O cultivo do morangueiro no solo enfrenta atualmente alguns entraves, tanto pelo uso excessivo de defensivos, como pelas doenÃas causadas por fungos e outros patÃgenos e as dificuldades ergonÃmicas do cultivo no solo. O cultivo em sistemas sem solo combinado com ambiente protegido e o uso de substrato proporciona algumas vantagens como: eliminaÃÃo do uso de produtos destinados à desinfecÃÃo do solo, antecipaÃÃo do inÃcio das colheitas, aumento da produÃÃo, proteÃÃo da cultura Ãs condiÃÃes meteorolÃgicas adversas, ataque de pragas e doenÃas e melhores condiÃÃes de manejo da cultura. O experimento teve como objetivo avaliar a produÃÃo e nutriÃÃo de quatro cultivares de morango em trÃs sistemas de cultivo na Serra da Ibiapaba â CearÃ. O experimento foi conduzido em esquema fatorial 3 x 4, em blocos casualizados, sendo trÃs sistemas de cultivo dispostos em faixa (solo, hidropÃnico em calhas e em s a c o l a s ), com quatro cultivares de morangueiro (Oso Grande, Albion, Camarosa e Festival), com cinco repetiÃÃes. No sistema hidropÃnico foi utilizado como substrato fibra de coco. No perÃodo entre a sexta e trigÃsima oitava semana apÃs o transplantio, foi determinado o nÃmero e peso mÃdio de frutos, produÃÃo por planta e produtividade. A partir do inÃcio do florescimento, foram coletadas a cada dois meses folhas para determinaÃÃo dos teores de macro e micronutrientes. Os sistemas hidropÃnicos em calha e em sacolas aumentaram o nÃmero de frutos por planta, porÃm nÃo aumentaram o peso mÃdio de frutos. A produtividade do morangueiro cultivado no sistema hidropÃnico foi superior ao cultivo no solo. A cultivar Festival apresentou maior nÃmero de frutos em relaÃÃo as demais cultivares nos sistemas hidropÃnicos. As cultivares Oso Grande e Festival destacaram-se quanto a peso mÃdio de frutos e produtividade, respectivamente, sendo recomendadas para cultivo hidropÃnico para regiÃo da Serra da Ibiapaba. Com base nos teores de nutirentes na folha sugere-se ajustes nas concentraÃÃes de fÃsforo e magnÃsio na soluÃÃo nutritiva utilizada no cultivo hidropÃnico do morangueiro. Palavras-chaves: Fragaria x ananassa, cultivar, sistema de cultivo, nutrientes.

Thesis (MScAgric)--University of Stellenbosch, 2003.
ENGLISH ABSTRACT: An open air hydroponic production system (OHS) is based on classic hydroponic principles, with the difference that it lacks climatological control because the plants are not produced in greenhouses and are cultivated in the outside environment. In these systems the plant is provided with all the essential nutrients through the irrigation system, which is scheduled according to accurate measurements of the available soil water, in three to seven pulses a day. The rationale is that, by delivering nutrients each day, the mixes can be representative of what the plant actually requires for that specific phenological stage. The aim of this study was to monitor the usefulness and impact of OHS on table grape production within the framework of a case study. For this purpose, it was necessary that all factors involved in the development and growth of the plant should be studied and integrated in a multidisciplinary approach. Currently very limited information exists on basic guidelines for the effective implementation of these systems for table grape production, particularly with regard to local conditions. As a start, and to establish some guidelines and measurable parameters for the implementation of these systems, vegetative growth parameters were analysed within the framework of yield and fruit quality. The experiments were performed in a commercial vineyard in the Paarl region and the cultivars used were Dan ben Hannah (DBH) and Waltham Cross (WC). Relevant soil and climatic conditions, irrigation scheduling, fertiliser application, as well as cultivation practices, were taken into account. The soil maps provided information on the soil types identified in the blocks prior to the establishment of the two cultivars. The conventionally treated vines were irrigated and fertilised according to historical block data, and the OHS-treated vines according to programmes established by two different consultants. The experimental layout included a comparison of conventional cultivation methods and vines that had been switched over from conventional methods to OHS in the middle of 2000. All measurements within the different treatments were done at specific measuring points laid out statistically. Ten phenological stages were chosen to monitor the various aspects throughout the season for both cultivars treated conventionally and hydroponically. All relevant climatic parameters were collected for this specific production unit. The growth, fertility and quality indicators of these cultivars under the mentioned cultivation practices are discussed and established through quantitative analysis One of the aims, namely to show that established table grape vines could adapt from micro-irrigation to drip irrigation within two seasons in terms of root adaptation, was proven in this study. Initially the soil types were identified as Cartref, Clovellyand Glenrosa for both cultivars. The WC block contained an Avalon and the DBH a Westleigh soil type as well. The soil pits in all four treatments revealed the soil type to be a Tukulu form with differences in the clay content. Active roots developed underneath the drip lines for the OHS-treated cultivars, while the roots were still evenly distributed over the entire soil profile for the conventionally treated vines. Also, both cultivars adapted to OHS in terms of yield and production within two seasons, especially WC, which produced a higher yield in the 2001/2002 season than in the previous four seasons. DBH showed a strong vegetative reaction to OHS in terms of excessive vegetative growth, which had an indirect effect on fruit quality and bud fertility. A higher rate of bud mite infection in the OHS-treated vines also had a negative influence on bud fertility. The excessive vegetative growth was due to a rainy 2001/2002 growth season, in combination with the irrigation and fertiliser programmes. The irrigation and fertiliser programmes were changed from the 2000/2001 to the 2001/2002 season because of the change in consultants. As a result of this change, the OHS-treated vines were given very high nitrogen, phosphorus, potassium and micronutrient applications in the 2001/2002 season. The penetration of light in the canopy of the OHS-treated DBH was lower than in the conventionally treated DBH as a result of the above-mentioned factors, but the situation in Waltham Cross was the opposite. In the winter season of 2001, both OHS-treated cultivars were not fully adapted to the new system, as their pruning mass was lower than in the conventionally treated cultivars. No significant differences were determined for the winter cane starch content of both cultivars under conventional and OHS treatments. Effective fertiliser uptake proved to be suboptimal, especially in the case of calcium. Fruit analyses showed a lower calcium content in the OHS-treated fruit, which led to a poor skin cell structure and higher Botrytis infection during cold storage. The OHStreated cultivars showed more compact bunches, with an overall smaller rachis structure, which was another reason for the higher Botrytis infection during cold storage. However, the more compact rachis structure could not be explained on the basis of the elemental analyses. The OHS-treated DBH showed a more intense red berry colour, while the OHS-treated WC had a higher Fosscan Brix value. Both OHS-treated cultivars therefore ripened earlier than the conventional treatments. One of the advantages of the use of OHS in table grape production shown in this study was the ability to manipulate the phenology of the grapevine to provide fully ripened grapes a few days earlier than the conventionally treated grapes. This kind of advantage could be used to manipulate the production of table grapes for a better market window. Despite its limitations, this study concluded that the use of OHS for table grape production might be a useful tool for future production management, but that accurate management regarding irrigation and nutrient applications is a prerequisite. This will have to be developed systematically through experimentation to fully unlock the potential of the OHS management system for table grape production. This study provides a starting point for future research to elucidate these aspects and has clearly shown that even established vineyards can be switched to OHS in a relatively short period of time. It is envisaged that the advantages of this system, as long as the correct management protocols are in place, could have a positive effect on the production of high quality fruit for the international market.
AFRIKAANSE OPSOMMING: 'n Oop hidroponiese produksiestelsel (OHS) is gebaseer op klassieke hidroponiese beginsels, met die verskil dat OHS nie klimatologies beheer kan word nie. Die plante word nie in glashuise of tonnelsisteme verbou nie, maar wei onder buitelug toestande. Binne hierdie sisteme word die plante van alle noodsaaklike voedingstowwe deur die besproeiingstelsel voorsien. Hierdie voedingstowwe word in drie tot sewe pulse per dag volgens akkurate beskikbare grondwaterbepalings geskeduleer. Die rasionaal is dat, deur die daaglikse lewering van voedingstowwe, die mengsels verteenwoordigend is van die plant se behoefte vir 'n spesifieke fenologiese stadium. Die doel van die studie was om die bruikbaarheid en impak van OHS op tafeldruifproduksie binne die raamwerk van 'n gevallestudie te monitor. Alle faktore wat by die groei en ontwikkeling van die plant betrokke is, moet in 'n multidissiplinêre benadering bestudeer en geïntegreer word. Daar is tans slegs beperkte inligting oor die basiese riglyne en effektiewe implementering van dié sisteme vir tafeldruifproduksie wat spesifiek is vir plaaslike toestande. As 'n beginpunt, en om sekere riglyne en meetbare parameters vir die implementering van die sisteme te vestig, is vegetatiewe parameters binne die raamwerk van opbrengs en vrugkwaliteit geanaliseer. Alle eksperimente is in kommersiële wingerdblokke in die Paarl-omgewing uitgevoer. Die kultivars wat vir die studie gebruik is, is Dan ben Hannah (DBH) en Waltham Cross (WC). Alle relevante grond- en klimaatstoestande, sowel as besproeiingskedulering, bemestingprogramme en verbouingspraktyke is vir die projek in ag geneem. Ou grondkaarte het inligting ten opsigte van die verskillende grondtipes wat voor die vestiging van die verskillende kultivars geïdentifiseer is, verskaf. Die wingerde, onder konvensionele behandeling, is volgens historiese blokdata besproei en bemes, terwyl die wingerde onder OHS volgens geskeduleerde programme wat vanaf konsultante verkry is, besproei en bemes is. Die eksperimentele uitleg het 'n vergelyking van konvensionele verbouingsmetodes en wingerde wat in die middel van 2000 van konvensionele na OHS-verbouing oorgeskakel is, ingesluit. Alle metings en analises binne die verskillende behandelings het by spesifieke statistiesbepaalde punte plaasgevind. Tien fenologiese stadia is gekies om die verskillende aspekte vir beide kultivars onder konvensionele en OHSbehandeling gedurende die seisoen te monitor. Alle relevante klimaatsdata is vir die spesifieke produksie-eenheid aangevra. Alle groei-, vrugbaarheids- en kwaliteitsparameters van die kultivars onder die bogenoemde behandelingsmetodes is bespreek en gevolglik deur kwantitatiewe analises bepaal. Een van die doelwitte, naamlik om uit te vind of reeds gevestigde ouer wingerde in terme van wortelaanpassing binne twee seisoene kan aanpas van mikrobesproeiing na drup OHS, is deur die studie bevestig. Aanvanklik was die grondtipes geidentifiseer as die vorme, Cartref, Clovelly en Glenrosa vir beide kultivars, met 'n Avalon vorm adisioneel by WC, en 'n Westleigh vorm by die DBH. Grondprofiele het egter getoon dat die grondtipes vir al vier behandelings 'n Tukulu vorm is met verskillende klei inhoude. Aktiewe wortels het vir die OHS-behandelde wingerde onder die druppers ontwikkel, terwyl die wortels in die konvensionele behandeling steeds eweredig oor die hele grondprofiel versprei was. Beide kultivars het ook in terme van opbrengs en produksie binne twee seisoene ná die oorskakeling van die konvensionele behandeling na OHS aangepas. WC het in die 2001/2002 seisoen 'n hoër opbrengs gelewer as in die vorige vier seisoene. Afgesien van die goeie aanpasbaarheid, het DBH 'n sterk vegetatiewe groeireaksie ten opsigte van die OHS-behandeling getoon, wat 'n indirekte effek op vrugkwaliteit en oogvrugbaarheid geopenbaar het. 'n Hoër mate van knopmiet infeksie in die OHSbehandelde stokke kon ook 'n negatiewe bydrae tot oogvrugbaarheid gemaak het. Die sterk vegetatiewe groei kon aan die hoër reënval gedurende die 200112002 groeiseisoen, tesame met die besproeiings- en bemestingsprogramme, toegeskryf word. Die besproeiings- en bemestingsprogramme is verander van die 2000/2001 seisoen na die 2001/2002 seisoen weens die aanstelling van 'n ander konsultant. As gevolg van hierdie verandering het die OHS-behandelde stokke baie hoë toedienings van stikstof, fosfaat, kalium en mikroelemente in die 2001/2002 seisoen ontvang. Sonligpenetrasie in die wingerdlower van die OHS-behandelde DBH was laer as in die konvensionele behandeling as gevolg van die bogenoemde faktore. Die situasie vir WC was egter die teenoorgestelde. Tydens die winterseisoen van 2001 was beide oorgeskakelde kultivars nie ten volle by die nuwe OHS-behandeling aangepas nie, soos gesien kan word in die laer lootmassas in vergelyking met die konvensionele kultivars. Geen beduidende verskil is vir die hoeveelheid stysel in die winterlote van beide kultivars onder konvensionele en OHS-behandeling verkry nie. Effektiewe voedingstofopname was suboptimaal, veral betreffende kalsium. Vruganalises het 'n laer kalsiuminhoud in die OHS-behandelde druiwe getoon, wat aanleiding gegee het tot 'n swakker seistruktuur in die druiwedoppe en 'n hoor mate van Bottytis-infeksie gedurende koelopberging. Die OHS-behandelde kultivars het meer kompakte trosse getoon met kleiner trosraamwerke, wat ook aanleiding kon gegee het tot 'n hoër Botrytis-infeksie. Die kleiner trosraamwerke kon nie deur voedingstofanalises verklaar word nie. Die OHS-behandelde DBH het 'n hoër kleurintensiteit getoon, en die OHS-behandelde WC het 'n hoër suikerinhoud getoon ten opsigte van die konvensionele behandeling. Beide OHS-behandelde kultivars was dus vroeër ryp as die konvensionele behandelings. Een van die voordele van OHS wat uit die studie voortspruit, is die vermoë om wingerdfenologie te manipuleer om ryper druiwe vroeër in die seisoen te verkry. Hierdie tipe voordeel kan aangewend word om druiwe vir "n beter markvenster te produseer. Hierdie studie, tesame met al sy beperkinge, kom tot die gevolgtrekking dat die gebruik van OHS vir tafeldruifproduksie 'n nuttige instrument vir toekomstige produksiebestuur is, maar dat die optimale bestuur van besproeiing en bemesting as kritiese faktore beskou moet word. Hierdie faktore sal sistematies deur intensiewe navorsing ontwikkel moet word om die volle potensiaal van OHS te ontsluit, spesifiek vir tafeldruifproduksie. Hierdie studie kan as 'n beginpunt gebruik word vir toekomstige navorsing vir meer toegeligte verklarings van die bogenoemde aspekte, veral met die voordeel dat reeds gevestigde wingerde maklik en vinnig by OHS kan aanpas. Die voordele van OHS kan 'n groot positiewe invloed op die produksie van hoër kwaliteit tafeldruiwe vir die internasionale mark hê, mits die regte bestuursriglyne in plek is en toegepas word.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Although it had been early developed aiming to search on the plants mineral nutrition, the hydroponic gained more importance between the growers due to possibility a better nutritional control that confers greater plant quality and minor incidence of pests. Some hydroponic systems have been considered for the lettuce grown, between them NFT (Nutrient Film Technique) and Floating System. This last one consists of the use of great amounts of nutrient solution in tanks where the plants are floating on plates with its roots flooded. This system has been showing promising for hot climates where the high temperatures can to limit the growing in other systems as the NFT. Therefore, a trial was carried out to evaluate the floating system in its diverse characteristics as stability of the electrical conductivity and pH, availability of dissolved oxygen to the plants and temperature of the nutrient solution. Also was evaluated, through the total fresh weight and root length, the cultivars VerÃnica and Vera, which are spread out between the growers that use hydroponic systems, in regards to its adaptability to the floating system. Each one of the cultivars were submitted at two levels of electrical conductivity (1,5mS/cm and 2,5 mS/cm) and two levels of artificial aeration (20min/h and 60min/h) in split-split-plot design. The study showed that the cultivar Vera was significantly better than VerÃnica concerning to the total fresh weight and root length. It did not have significant difference between the studied levels of electrical conductivity and artificial aeration in the development of the plants. It could still be observed that the system revealed sufficiently steady in regards to the evaluated parameters.
Embora tenha sido desenvolvida primeiramente com o objetivo de pesquisar sobre a nutriÃÃo mineral das plantas, a hidroponia ganhou bastante importÃncia entre os produtores devido à possibilidade do controle nutricional mais estreito que confere maior qualidade Ãs plantas e menor incidÃncia de problemas fitossanitÃrios. VÃrios sistemas hidropÃnicos tÃm sido propostos para o cultivo de alface, entre eles o NFT (Nutrient Film Technique) e o sistema de leito flutuante (Floating System). Este Ãltimo consiste da utilizaÃÃo de grandes quantidades de soluÃÃo nutritiva dispostas em tanques onde as plantas ficam flutuando sobre placas de material leve com suas raÃzes imersas. Este sistema tem se mostrado promissor para climas quentes onde as altas temperaturas podem ser limitantes ao cultivo em outros sistemas como o NFT. Diante do exposto foi realizado trabalho no sentido de avaliar o sistema de leito flutuante em suas diversas caracterÃstica como estabilidade da condutividade elÃtrica e pH, disponibilidade de oxigÃnio dissolvido Ãs plantas e temperatura da soluÃÃo nutritiva. TambÃm foram avaliadas, atravÃs da matÃria fresca total e comprimento radicular, os cultivares VerÃnica e Vera, os quais sÃo os mais difundidos entre os produtores que utilizam o sistema hidropÃnico, quanto à sua adaptabilidade ao sistema de leito flutuante. Para isso cada cultivar foi submetido a dois nÃveis de condutividade elÃtrica (1,5mS/cm e 2,5 mS/cm) e dois nÃveis de aeraÃÃo artificial (20min/h e 60min/h) utilizando o delineamento em parcelas subsubdivididas. O estudo mostrou que o cultivar Vera foi significativamente superior ao VerÃnica em relaÃÃo à matÃria fresca total e comprimento radicular. NÃo houve diferenÃa significativa entre os nÃveis de condutividade elÃtrica e aeraÃÃo artificial estudados no desenvolvimento das plantas. PÃde-se observar ainda que o sistema mostrou-se bastante estÃvel em relaÃÃo Ãs variÃveis avaliadas.

Hydroponics is used extensively in food production and plant research, allowing optimal control over the supply of elements to the plant. In hydroponics, nutrient can be delivered via a solution that is supplied to the growing plant or as a seed coat or treatment that is applied to the seed before sowing and germination. The form in which the nutrients are supplied to the plant influences their bioavailability, up-take, and distribution within the plant. Commercially produced hydroponic nutrients are typically supplied as two separate concentrated solutions. If these are mixed before being diluted then precipitates are formed which limit the bioavailability of certain elements in the nutrient solution. The chemical nature of the precipitate has been investigated by XRD, XRF, ion-chromatography and IR and Raman spectroscopies, with the aim of understanding its composition. Mass spectrometry is a highly sensitive analytical technique which has been applied to the monitoring of uptake and distribution of elements and compounds in plant tissue. Techniques including MALDI-MS, LA-ICP-MS and HPLC-ICP-MS have been utilized in the work presented here to demonstrate the distribution and accumulation of elements and compounds within plant material that has been grown hydroponically. The use of a zinc based seed coating as a nutrient source for barley seeds in a hydroponic fodder production system has been investigated. The effect of the zinc on the yield and dry mass of the fodder was determined. The total zinc content in the fodder has been determined using ICP mass spectrometry. A method to map the location and distribution of zinc and other metallic elements in seeds and the fodder plants using Laser-Ablation ICP Mass Spectrometry LA-ICP-MS has been developed. Selenium is an essential element for human health. Broccoli is known to be a hyper-accumulator of selenium and the use of selenium-containing hydroponic nutrients for the biofortification of broccoli with selenium is presented. Laser-Ablation ICP Mass Spectrometry LA-ICP-MS has been used to monitor the accumulation and distribution of selenium in the broccoli plants. Imaging MALDI-MS has allowed the demonstration of the nitrogen cycle in plants and to show pictorially that atoms and molecules from dead plants are incorporated into new life. Radish plants were grown hydroponically using a nutrient solution system containing isotopically-enriched nitrogen-15 KNO3 (98% labelled) as the only source of nitrogen. Plants were cropped and left to ferment in water for 2 weeks to create a radish "tea", which was used as a source of nitrogen for radish grown in a second hydroponics experiment. After 5 weeks of growth, the radish plants were harvested and cryosectioned, and sections were imaged by positive-ion MALDI imaging. The presence of labelled species in the plants grown using 15N KNO3 as nutrient and those grown from the radish "tea" was readily discernible. The uptake of 15N into several identifiable metabolites has been studied by MALDI-MS imaging.

Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第21155号
農博第2281号
新制||農||1059(附属図書館)
学位論文||H30||N5129(農学部図書室)
京都大学大学院農学研究科地域環境科学専攻
(主査)教授 川島 茂人, 教授 星野 敏, 教授 藤原 正幸
学位規則第4条第1項該当

Food systems are considered one of the most important anthropogenic activities contributing to climate change. On the other hand, climate change influences the conditions for growth with more frequent droughts and heatwaves. This contradiction poses a significant challenge to future food systems, which need not only become more sustainable, but also increase its production to feed a growing population, as stated in both the United Nations Sustainable Development Goals, and the Swedish action plan on food. This has given rise to alternative ways of producing food, such as urban farming and, in particular vertical hydroponic farming, where food is grown indoors in a controlled environment with artificial lighting and with a minimum use of water and without pesticides. In this study, a vertical hydroponic farm located in Stockholm, Sweden, is examined using life cycle assessment in terms of environmental sustainability. The farm, located in a basement space, works together with the building in a symbiotic network, where the farm provides the building with excess heat from the lighting, and in turn obtains carbon dioxide from an office floor. The findings from the study show that electricity is a major contributor to the environmental performance of the farm, along with the infrastructure employed. The impacts of water use in the farm, is very low, along with the impacts associated with the delivery of the crops; illustrating the advantages of producing food locally. By substituting the synthetic fertilizers employed to biofertilizers, and by substituting the plastic bag material to renewable material, reductions in greenhouse gases are possible. The symbiotic development between the farm and the building is shown very beneficial to the farm, highlighting the importance of synergies between actors in urban areas.
Livsmedelsindustrin anses vara en av de största antropogena drivkrafterna bakom klimatförändringarna. Å andra sidan så förändrar klimatförändringar i sig förutsättningarna för hållbar odling, med mer frekventa torrperioder, extrem värme och extrem nederbörd. Denna konträra situation ställer stora krav på framtidens livsmedelsindustri, som dessutom måste producera mer mat för att mätta en ökande befolkning; ett åtagande som står angivet både i FN:s globala mål och i den svenska Livsmedelsstrategin. Många forskare menar att dagens livsmedelsindustri inte kommer klara denna omställning, och att alternativa metoder för att producera mat behövs. Urban odling har föreslagits som en del av lösningen, och i synnerhet vertikal hydroponisk odling där grödor växer inomhus i en kontrollerad miljö med artificiell belysning, låg vattenanvändning och utan bekämpningsmedel. Den här studien undersökte en vertikal hydroponisk odling i Stockholm, och bedömde dess miljömässiga hållbarhet med hjälp av en livscykelanalys. Odlingen, som sker i en källarlokal, samarbetar med den omslutande byggnaden i en urban symbios, där odlingen förser byggnaden med spillvärme från belysningen, och får i sin tur koldioxid från en kontorslokal. Enligt resultat från studien bidrar elektriciteten till den största miljöpåverkan, men även infrastruktur har stor påverkan. Vattenanvändningen i odlingen är däremot väldigt låg, och miljöpåverkan från leveransen av varorna är mycket låg, vilket belyser fördelarna med att odla mat lokalt. Odlingen kan bland annat minska sin miljöpåverkan genom att byta ut det nuvarande konstgödslet till biogödsel och genom att byta ut plastpåsarnas material till förnybar plast. Symbiosen mellan odlingen och byggnaden visade sig vara väldigt gynnsam, vilket vidare belyser vikten av samspel mellan olika aktörer i den urbana miljön.

In a world with an ever growing population, the ability to grow food eciently is essential. One way to improve the eciency is by automation. The purpose of this project is therefore to investigate how the identification of a plant’s stage in its growth cycle that can be made autonomous. This was done with the method of measuring the amount of green pixels in an image of the plant. To be able to answer our research questions a demonstrator was built. The demonstrator is a greenhouse with a non regulated aeroponic system, a regulation system for humidity and an identification system for determining the plant growth stage. The plant chosen to test the identification system was basil. The identification system successfully identified the stage of plants well into the adult stage, in the seed stage and in the middle of the sprout stage. It was however not always successful in the identification of plants transitioning from the sprout stage into the adult stage.
I en värld med en ständigt växande befolkning är förmågan att odla mat effektivt nödvändig. En metod för att öka denna effektivitet är genom automatisering. Syftet för detta projekt är därför att undersöka hur identifieringen av en plantans stadie i dess växtcykel kan automatiseras. Detta gjordes genom att mäta antalet gröna pixlar i en bild av plantan. För att kunna svara våra forskningsfrågor byggdes en testmiljö. Testmiljön bestod av ett växthus med ett oreglerat aeroponiskt system, ett regulationssystem för luftfuktighet och ett identifikationsssystem för att avgöra en plantas stadie i dess växtcykel. Plantan som valdes för att testa identifikationssystemet var basilika. Identifikationssystemet som togs fram kunde med framgång identifiera stadiet av en planta som är långt in i dess vuxna stadie, i förstadiet eller i mitten av dess groddstadie. Plantor som precis övergått från grodd till vuxet stadie blev däremot inte alltid identifierade korrekt.

Thesis (Ph. D.)--Ohio State University, 1995.
Advisor: T.H. Short, Dept. of Agricultural Engineering. Includes bibliographical references (leaves 146-152). Available online via OhioLINK's ETD Center

Master of Science
Department of Biological and Agricultural Engineering
Stacy L. Hutchinson
The energy sector needs to transition to renewable energy to provide energy and economic security in the future (Murray & King, 2012). Liquid biofuels are an important renewable fuel in this transition because they are the preferred renewable energy source in the transportation sector (Lange, 2007), and the only renewable energy alternative for the aviation industry [International Air Transport Association (IATA), 2015]. Biofuels produced from food crops (first-generation biofuels) are being produced at an industrial scale, but they create several environmental and social conflicts (Mohr & Raman, 2013). Currently, there is a demand for the next generation of biofuels to resolve the environmental and social conflicts associated with first-generation biofuels. Salicornia, a salt tolerant oil seed crop (Panta et al., 2014), is one feedstock that might be able to resolve some of those conflicts because it can be irrigated with saline water (Warshay et al., 2017). The ability of Salicornia to tolerate saline environments suggests that it might be able to be cultivated in a hydroponic system designed to treat industrial wastewater. A hydroponic system designed to treat industrial wastewater and produce Salicornia as a biofuel feedstock could prevent some of the detrimental effects of industrial sources of saline water on terrestrial and aquatic ecosystems (Gerhart et al., 2006), and produce a feedstock that resolves some of the issues with first-generation biofuels. The first step in the development of the proposed hydroponic system is to determine if Salicornia can be cultivated with industrial wastewater in a hydroponic system. Studies were conducted with two sources of industrial wastewater, Flue Gas Desulfurization (FGD) wastewater and Cooling Tower Blowdown Water (CTBW), to determine how the composition of water affects the germination, survivability, early seedling growth, and lignocellulosic composition of Salicornia. The composition of water was shown to have no effect on seed germination and visual signs of phytotoxicity. These studies found that full strength CTBW and 20% FGD wastewater could be used to cultivate Salicornia in a hydroponic system if nutrients are added. Full strength FGD wastewater was shown to have a negative impact on seedling growth. These studies also found that Salicornia is not a good lignocellulosic biofuel feedstock because of its low lignocellulosic composition (e.g. 14.9-9.1% glucan, 13.2-6.7% xylan, 5.2-2.4% arabinan, and 9.8-6.2% lignin). However, a large percentage of the extractives content is unidentified and could have a monetary value. Additional research is needed to determine if a hydroponic system that cultivates Salicornia is able to provide any water quality treatment.

Intensive livestock farming in feedlot producing large amounts of manure and wastewater. Hydroponic and electrolysis treatments were studied for the remediation of nutrients from feedlot runoff. Water hyacinth, water lettuce, and sorghum were hydroponically grown in 10 L of feedlot runoff and Hoagland solution individually in plastic bucket in batches in a greenhouse. All three plants performed well in uptaking NH3-N (more than 90%) in feedlot runoff. From the feedlot runoff, TP reduction by sorghum, water hyacinth, and water lettuce ranged from 70% to 100% , 61% to 74%, and 49% to 93%, respectively. With electrolysis process, 500 mL of feedlot runoff was treated with two rectangular parallel aluminum (Al-Al), iron (Fe-Fe), or hybrid (Al-Fe) electrode at 5 V, 10 V, and 15 V DC up to 30 minutes. The TP reductions were higher (100%) followed by COD (50 % to 75%) and TN (25% to 60%) by tested electrode.
North Dakota Department of Health (EPA section 319 grants)

The use of hydroponic feeding systems for horses has gained in popularity during recent years. Typically, this feeding system allows for a more efficient use of the whole plant, including the shoot, root, and seed remnants rather than traditional grazing in which only the shoot of the plant is consumed. Vertical systems have practical uses in largely developed areas where traditional forage sources are limited, in arid countries or in areas with severe droughts where forage growth is minimal. Though there is some research on fodder utilization in production animals, there are currently no published data on the effects of fodder in horses. Our study, approved by the Southern Illinois University Institutional Animal Care and Use Committee (#13-043) utilized eight Quarter Horse mares randomly assigned to one of two diets. Control (CON) horses were offered 2% of their body weight (BW) in hay (DM) and treatment (TRT) horses received 1% of their BW in hay (DM) and 1% of BW in fresh wheat fodder (AF) twice daily. Body weight and hoof temperature data were recorded weekly. Fecal samples were collected weekly and analyzed for pH, NH3, and VFA concentration as well as DM, ash, NDF, ADF, N, CP, and EE. Hay and fodder samples were also collected weekly to monitor nutrient profiles of the two forage types for the duration of the study. Additionally, nutrient profiles from seed to mature (8 d growth) were developed for fodder. Data were analyzed as a completely randomized design using PROC MIXED of SAS (v. 9.4) and significance was established at P < 0.05. There were no significant differences in body weight, left or right front hoof temperatures between treatments. Fecal pH was significantly lower (P ≤ 0.01) in the TRT when compared to CON, and isobutyric acid was significantly (P ≤ 0.05) higher in TRT as compared to CON. A comparison of the nutrient values of the two forages demonstrated significantly higher DM, ash, NDF, and ADF (P <0.0001) in hay while N, CP, and EE (P <0.0001) were significantly higher in fodder overall. Daily growth of the fodder decreased DM content (P <0.0001) while ash, NDF, ADF, N, CP, and EE (P <0.0001) increased as the fodder reached maturity. These results indicate that utilizing fodder affects fecal metabolites associated with digestion.

The imbalance between global population growth and resource consumption is indicative of unsustainable practices and foreshadows a grim future of continued resource depletion, food and water scarcity, social inequality, and deteriorating public and environmental health. Meanwhile, the urban centers of the world continue to experience exponential growth resulting in overwhelmed food, water, and sanitation infrastructure. Decentralized and satellite wastewater treatment technologies capable of resource recovery, such as anaerobic membrane bioreactors (AnMBR), foster synergistic opportunities to help manage the food, energy, and water sectors of urban environments. Specifically, the nutrient concentration and high effluent quality of permeate produced by AnMBR systems present applicability in controlled environment agriculture (CEA). The efficacy of AnMBR permeate is evaluated in a hydroponics growth study of cucumber (Cucumis sativus) grown in an outdoor greenhouse and tomato (Lycopersicon lycopersicum) grown indoors. Nutrient analysis of permeate generated by a small, pilot scale AnMBR developed for the treatment of domestic wastewater at ambient temperature indicated sufficient concentrations of N and P elements, however high proportion of NH4+ in N species decreased growth performance. Opportunities for optimizing AnMBR permeate for hydroponics applications exist and thus imply synergistic integration of decentralized AnMBR technology with controlled environment agriculture (CEA) such as hydroponics. A model is proposed for the integration of decentralized AnMBR and CEA systems capable of producing usable plant products within the urban environment. The integration of these systems is proposed as a solution to the challenges of with food security, stressed water supplies, and environmental degradation associated with unchecked urban growth in the developing and developed world

The world’s population is growing at an average of 1.2 percent per annum and forecasts see the global population reaching 9.6 billion by 2050. This places great demands on the sustained production capacity of agricultural organisations to meet the desperate need for nutrition. This problem will continue to persist if production methods do not evolve to improve production and quality. Hydroponics and Controlled Environment Agriculture (CEA) was first seen in Rome during the 1st Century. Then sixteen Centuries later Greenhouses were developed in France and England as experimental hydroponics for basic laboratory research. Rapid expansion took place from about the 1950’s in areas where traditional openenvironment agriculture was difficult or impossible such as the deserts of Iran, Abu Dhabi and California. Sixty-five years later in 2015 hydroponics and CEA are well established around the world with thousands of hectares under propagation. Hydroponics is a method of agricultural production that has been refined over the years to become an exact science. Through the application of technology and know-how the physiological processes within plants can be manipulated and controlled to produce superior results. These results require less land area and less water to accomplish. It can be seen, based on this development, that hydroponics is such an evolution that has the capacity to meet the needs of a growing global population and its nutritional needs. The challenge lies, though, in the scientific understanding and application of knowledge in growing and managing a hydroponics farm. This study seeks to determine the internal data and external information needs of farmers in the hydroponics industry. This data and information will be integrated into a Farm Management Information System (FMIS) model that will be used for decision making, report generation and documentation. The problem leading to this study is the dissemination of data and information sources that are currently underutilised and difficult to access. In determining the internal data and external information needs, an empirical study was conducted using structured interview. Thirty farm managers were interviewed to assess what their current information system consisted of, whether they had a need for an FMIS and what internal data and external information was needed which related to four functional components of hydroponic farming. The results of this study indicate that there is a need for an FMIS for the hydroponic industry in South Africa. The results also indicate that managers are not fully satisfied with the performance of their current information system and would be interested in considering alternative information systems. Data points relating to the four functional components were assessed and integrated into an FMIS model for the hydroponic industry. This model sets out to integrate internal data and external information for purposes of decision making, report generation and documentation.

Brewery effluent that had undergone treatment in an anaerobic digester (AD) was used as an alternative water and nutrient source for hydroponic crop production. Brewery effluent was demonstrated to contain sufficient nutrients to support the growth, flowering and fruiting of Lycopersicum escolentum "Moneymaker" tomato crops. The adjustment of the effluent pH with phosphoric acid to between pH 6.0 and 6.5 increased the development of the crops by around 100% compared to crops grown in unaltered effluent. The pH adjusted effluent-grown plants grew to a mean height of 831.4 ± 21.1 mm and a dry biomass weight of 42.34 ± 2.76 g compared to the unaltered pH effluent plants which grew to a height of 410.6 ± 20.5 mm and a weight of 7.65 ± 0.68 g after 49 days. Effluent treatment in high-rate algal ponds (HRAP) was determined to have no positive effect on the nutritional potential of the effluent for Moneymaker production. The effluent-grown plants did not perform as well as plants grown in inorganic-fertilizer and municipal water. Plants grown in effluent grew taller but did not produce significantly more fruit when phosphoric acid (height: 1573.3 ± 50.4 mm, 19.4 ± 1.4 fruit per plant) was compared to nitric acid (height: 1254.1 ± 25.4 mm, 15.6 ± 1.5 fruit per plant) as the pH adjustment over 72 days. Direct and secondary plant stresses from effluent alkalinity, ammonium nutrition, nitrogen limitation, sodium concentrations and heat stress among other factors were probably confounding variables in these trials and require further investigation. Considering the raw effluent composition and manipulating the AD operation is a potential opportunity to improve overall AD performance, reduce chemical inputs in the effluent treatment process, reduce the final effluent alkalinity, and increase available nitrogen content in the final effluent. The anaerobic digester discharging >1000 m³ of nutrient enriched effluent every day is a resource with considerable potential. The benefits of developing this resource can contribute to cost-reduction at the brewery, more efficient water, nutrient and energy management at the brewery, and offer opportunities for job creation and potentially benefit local food security.

Thesis (M.S.)--West Virginia University, 2009.
Title from document title page. Document formatted into pages; contains xiii, 178 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references (p. 112-115).

With the recent development of nanotechnology, there has been increased production of engineered nanomaterials but limited containment strategies, resulting in inevitable release of a large amount of engineered nanoparticles (ENPs) in the environment. Many ENPs have potential adverse impacts on the environment, and one of the most commonly used ENPs, silver nanoparticle (AgNP), has attracted increased global concern. The current study focused on phytotoxicity of AgNPs to a model plant, Arabidopsis thaliana. Silver nanoparticles were introduced into the growth medium for the wild type A. thaliana plants and root uptake and translocation of AgNPs were examined in hydroponic growth condition. We also conducted growth stage based phenotypic analysis by growing A. thaliana throughout its life cycle in soil. The result indicated that: (1) wild type seeds germination was not affected by either AgNPs or their dissolved Ag+ ions; (2) AgNPs exposure resulted in a concentration- and size- dependent inhibition effect to the root elongation; (3) confocal and electron microscopy indicated that AgNPs could be taken up by seedling roots, yet most of AgNPs attached to the surface of seedling root cap; (4) AgNPs and their dissolved Ag+ ions at tested concentrations had little influence on the vegetative growth of A. thaliana, but they accelerated the floral development; and (5) the effect on the floral development stage reduced the quality of second-generation (F1) seeds, as indicated by their lower germination rate. In conclusion, AgNPs displayed both acute and chronic phytotoxicity to A. thaliana.

Rapid advancement of nanotechnology has caused serious concerns about the potential release and accumulation of engineered nanoparticles (ENPs) in the environment. As the most popular ENP in commercial products, the phytotoxicity of AgNPs has been extensively investigated. While it is now generally agreed that AgNP itself exerts unique toxicity to plants in addition to that of dissolved silver ion, the accumulation and fate of different forms of silver in plant tissues are unknown. The first part of this study investigated the phytotoxicity, accumulation and transport of Ag with different physical and chemical characteristics (e.g. ionic, nanoparticles, and bulk) in two agricultural crop species: Glycine max (soybean) and Triticum aestivum (wheat). The results showed that different forms of Ag demonstrated differential toxicity to these two species, with the Ag+ at the same nominal concentration displaying the strongest effect on plant growth. Exposure to 5 mg/L of elemental Ag in different forms all resulted in significant deposition on the root surface but its morphology and distribution patterns varied considerably. Internalization was observed for all forms of Ag. However, when Ag enters into plant roots, the upward transport efficiency from roots to shoots varied with both Ag type and plant species. In addition to AgNPs, gold nanoparticles (AuNPs) has also attracted significant attention due to their broad applications. However, most previous toxicity studies have been heavily geared towards animal and human cell lines, with limited information available for the AuNP plant interactions. The second part of this study concentrated on elucidating the impact of surface coating on the phytotoxicity and plant uptake of AuNPs by Phaseolus vulgarisi (bush bean). The results showed that the impact of 5 mg/L of AuNPs on several physiological processes of plants was insignificant, regardless of the surface coating materials. However, AuNPs with different surface properties displayed significant differences in some biochemical parameters including the concentrations of hydrogen peroxide in plant roots and the activities of some enzymatic antioxidants. Similar to AgNPs, deposition of AuNPs on plant root surface was observed for all coatings. Surface coatings also affected the internalization of AuNPs in plant root cells and their subcellular localization. Overall, the study demonstrated that the physical and chemical properties of Ag and Au NPs play important roles in their interactions with plants and consideration of the unique properties of nanoparticles is critical in assessing their food safety concerns.

Thesis (MTech (Horticultural Science))--Cape Peninsula University of Technology, 2016.
This aim of this study was to investigate the viability of growing P. tomentosum in deep water culture (DWC) hydroponics and to assess the effects of various methods of oxygenating the nutrient solution with regards to growth, development and chlorophyll responses. The experiment was conducted over a period of 74 days. In chapter 3, 16 different methods of oxygenation were applied to 9 replicates. The control had passive aeration. The treatments were made up of air-pumps, vortex oxygenators and the application of hydrogen peroxide (H2O2) at various frequency intervals; these were combined with each other and run as separate oxygenation methods.

Halogeton (Halogeton glomeratus) is a halophytic, invasive species that displaces Gardner’s saltbush (Atriplex gardneri) on saline rangelands. Forage kochia (Bassia prostrata) is a potential species to rehabilitate these ecosystems. This study compared the salinity tolerance of these species and tall wheatgrass (Thinopyrum ponticum) and alfalfa (Medicago sativa). Plants were evaluated for 28 days in hydroponics where they were maintained at 0, 150, 200, 300, 400, 600, and 800 mM NaCl. Shoot growth and ion accumulation were determined. Alfalfa and tall wheatgrass were severely affected by salt with both species’ shoot mass just 32% of control at 150 mM NaCl. Alfalfa did not survive above 300 mM NaCl, while, tall wheatgrass did not survive at salt levels above 400 mM NaCl. In contrast, forage kochia survived to 600 mM, but produced little shoot mass at that level. Halogeton exhibited ‘halophytic’ shoot growth, reaching maximum mass at 141 mM, and not less mass than the control until salinity reached 400 mM. Gardner’s saltbush did not show a dramatic decrease in dry mass produced until it reached salt levels of 600 and 800 mM NaCl. Forage kochia yielded high amounts of dry mass in the absence of salt, but also managed to survive up to 600 mM NaCl. Salt tolerance ranking (GR50 = 50% reduction in shoot mass) was Gardner’s saltbush=halogeton>forage kochia> alfalfa>tall wheatgrass. Both halogeton and Gardner’s saltbush actively accumulated sodium in shoots, indicating that Na+ was the principle ion in osmotic adjustment. In contrast, forage kochia exhibited a linear increase (e.g. passive uptake) in Na+ accumulation as salinity increased. This study confirmed that halogeton is a halophytic species and thus well adapted to salt-desert shrubland ecosystems. Gardner’s saltbush, also a halophyte, was equally salt tolerant, suggesting other factors are responsible for halogeton displacement of Gardner’s saltbush. Forage kochia is a halophytic species that can survive salinity equal to seawater, but is not as salt tolerant as Gardner’s saltbush and halogeton.

The long-term effects of low and high NH4+/ NO3- uptake ratios in a system with rigorous control of pH and nitrogen concentration are poorly understood. In two replicate studies, two cultivars of wheat (Triticum aestivum) were grown to maturity with three NH4+/ NO3- ratios in hydroponic solution: 0/100, 25/75, and 85/15%. Nitrogen was controlled at ample levels throughout the 70-d life cycle and pH was controlled at 5.8 ± 0.2. An equimolar ratio of NH4+ to Cl- was used to facilitate charge balance. Nitrogen consumption and transpiration were measured daily. Flag leaves were analyzed at 10-d intervals for total nitrogen, NO3--N, and essential elements. Essential nutrient elements in the biomass and seeds were measured at harvest. Yield components , nitrogen recovery, and nitrogen assimilation were calculated. There was no difference between the NO3- only (0/100) and the low NH4+ (25/75) treatments . The high NH4+ treatment (85/15) did not reduce vegetative biomass, but decreased seed yield and harvest index by 20%. The decrease was associated with a 23% reduction in seed number head-1. The high NH4+ treatment increased percent root mass by 50% and percent sterile heads by 800%, but increased assimilated N in the seeds by 30% and in the biomass by 130%. Supplemental additions of K were effective in preventing the reduction of K concentration in the wheat tissues typically caused by high NH4+, but the high NH4+ treatment decreased the concentrations of Ca, Mn, and Zn, and increased the concentrations of S, P, Fe, and B in the wheat tissue . The uptake of Mg and Cu was similar among all three treatments. Chloride concentrations in the flag leaves increased from 0.8% in the NO3- only treatment to 2.0% in the two NH4+ treatments. This research indicates that hydroponic wheat can be grown to maturity with high levels of NH4+ with a small reduction in grain yield.

Städerna växer och samtidigt ökar efterfrågan på närodlade och ekologiska grödor. För att klara av att producera närodlat och mer hållbart skulle ett alternativ vara att odla i så kallade vertikala växthus. I Kiruna finns Sveriges största malmgruva som drivs av företaget LKAB vars olika processer leder till spillvärme. I Kiruna är klimatet kallt jämfört med större delen av Sverige och därför erfordras uppvärmning om odling ska kunna ske året runt i ett växthus. Examensarbetets uppgift är därför att undersöka hur man kan utnyttja spillvärme till ett vertikalt växthus i samband med en ny kontorsbyggnad på LKABs gruvområde. LKABs nya kontorsbyggnad har ett kvadratiskt avtryck på marken med ett hörn i sydlig riktning. Fördelningen mellan växthus och kontor kan förenklas genom att kvadraten delas på diagonalen där den södra halvan är växthus och den norra halvan kontor. Eftersom solförhållandena för odling är speciella i Kiruna har växthusets väggar en lutning som är anpassad efter solens låga infallsvinkel vilket gör att växthusets area minskar med varje våningsplan. Som yttermaterial till växthuset används glas och som stommaterial används stål. Ett hydroponiskt odlingssystem används där plantorna sätts direkt i en cirkulerande näringslösning och på så sätt kan systemet utformas med horisontella odlingsrör i flera vertikala odlingsplan. För uppvärmning av växthuset kommer spillvärme från LKABs verksamhet att utnyttjas, i examensarbetet undersöks två olika alternativ av spillvärmekällor och resultatet är att båda de alternativ som undersökts kan utnyttjas för uppvärmning av hela växthusdelens volym.
While the cities are expanding the demand for locally grown and organic crops is increasing. To be able to produce locally and more sustainable crops, one option could be to grow in a so-called vertical greenhouse. In Kiruna the largest ore mine in Sweden is operated by the company LKAB. Various processes in the mining industry lead to waste heat. In Kiruna, the climate is cold compared to most parts of Sweden, and therefore requires heating for the cultivation to be able to take place all year round in a greenhouse. The project’s task is to explore how to utilize waste heat from the mine to a vertical greenhouse in the context of a new office building at LKAB's mining area. LKAB's new office building has a square footprint on the ground with one of the corners in the south direction. The division between the greenhouse and the office can be simplified by the square divided diagonally where the southern half is the greenhouse and the northern half the office. Since the sunlight is limited in Kiruna the greenhouse walls has been design to adjust to the sun’s low position. The sun’s low position requires a sloped facade in the south direction. The greenhouse’s floor area decreases with each floor. As the external material for the greenhouse glass is used and as framing material steel is used. A hydroponically system is used where the seedlings are put directly in a circulating nutrient solution and in this way the system can be designed with horizontal pipes in several vertical cultivated floors. The greenhouse will be heated with waste heat from LKAB's industry, the project examines two alternatives of waste heat sources, and the result is that both of the alternatives studied can be used to heat the entire volume of the greenhouse.

Controlled environment agriculture offers a solution to challenges including less available land, water deficits, and consumer demand for pesticide free produce. However, control of soil-borne diseases is a major limiting factor. The goal of this dissertation was to examine predictions of the hypothesis that border cells function to protect plant health by controlling microorganisms associated with plants grown in hydroponic culture. Border cells separate from root tips upon immersion in water, and appear to have important roles in the defense mechanisms of plant roots. The general objectives were (1) to study the delivery of border cells in hydroponics; (2) to evaluate interactions between border cells and microorganisms in hydroponics; and (3) to explore approaches to alter border cell production for improved root disease control. In this study it was confirmed that border cells can be released continuously into the solution of hydroponic culture suggesting that plants grown in this system may use extra energy in the production of new border cells. Free border cells interacted with microorganisms present in the hydroponic solution by secreting an extracellular capsule. Previous studies showed that proteins are a key component of this capsule, including lectins. The interaction of pea lectin and Nectria haematococca spores therefore was explored. Results demonstrated that pea lectin agglutinates fungal spores in a hapten-specific manner, and inhibits their germination. Lectin had no negative effect on root development suggesting that it could be used as a potential control for soil-borne diseases in hydroponics. To control the production of border cells, subsequent studies measured the impact of a transient exposure of root tips to different metabolites secreted by root caps and border cells. Exposure to specific metabolites altered the production of border cells without measurable effects on root growth and development. This is in contrast to results obtained with altered gene expression. For example, gene silencing of a border cell specific gene resulted in altered root growth.

Thesis (MTech (Horticultural Science))--Cape Peninsula University of Technology, 2016.
Hydroponics, i.e. plant cultivation in mineral-rich water is a synergy between plant, human, and machine. For decades the hydroponic garden has been offered on horticultural markets, and was repeatedly innovated to better meet consumer horticultural needs. Currently, platform convergences with electronic control systems can possibly enable more efficient products for direct consumer hydroponic cultivation. This means that, like many appliances in the home; hydroponic plant cultivation can become somewhat automated. Marketing and product innovation can help calibrate optimal New Product Development NPD of hydroponic gardens for people. The literature review grasps how consumers are subjected to a changing environment together with changing technology such as hydroponics, plant nutrition, and even garden automation. Market research frameworks namely Morphological Analysis (MA) and Conjoint Analysis (CA) are the tools deployed here for profiling and prioritising these products for horticultural consumers. Firstly, a qualitative analysis identifies conceptual sets for structures, inputs, and controls, which all harmonise into new intersections cultivation, hydroponics, and automation and the e-garden concepts. The MA next produces, and organises secondary data into constraints for the CA. Here, general hydroponic cultivation is first decomposed into all its many component parts which collectively describe the whole, where these parts are then classed along various attributes namely: garden plane xA, automation xB, performance xC, organics xD, and price xE So garden plane is composed of level and vertical gardens, garden automation is composed of manual and automatic gardens, garden performance is composed of casual and high-performance gardens, garden organics is composed of non-organic and organic gardens, and garden price although quantitative is simply composed of R2500 and R5000. These classes of attributed data can now become treated as categorical factors using indicator or dummy variables. Secondly, the CA determines how these attributes are most preferred by horticultural consumers at garden centre clusters. This involves measuring respondent preferences levels, to compute the part-worth utility for each attribute found in the MA. Factors such as garden organics, price, and automation hold adjusted alpha significance. Mainly, garden organics contributed to response effects, while price has negative slope and is second, while automation comes third. A combination of garden automation and organics is found to optimise consumer utility for Hydroponic Garden(s) HG.This research illuminates how horticultural consumers may prefer various HG, by understanding HG and how they can better benefit these people.

This thesis attempts to determine if food-producing plant growth can be incorporated within a building envelope to create an ideal plant growth environment while simultaneously enhancing the thermal properties of the building envelope. A window system was designed as a means of bringing food production into the built environment in an easily accessible fashion from the interior of a high-rise apartment complex. The Ya-Po-Ah Terrace in Eugene, Oregon, was chosen as a case study site for research on how a window could promote health, provide nutrition, and enhance the thermal comfort of the inhabitants. The design of the window unit is founded in precedent research on methods of plant growth in urban environments and systems for growing food in small and efficient ways. The design found that it is possible to create an ideal plant growth environment within a building assembly for use as a food production method for building inhabitants.

In the United States, illnesses associated with fresh produce are increasing in frequency.  While contamination risks are present at every aspect of the farm to fork continuum, post-harvest practices holds the potential for cross-contamination of large amounts of product.  Post-harvest contamination risks for hydroponically grown lettuce packaged with intact roots and sold as "living lettuce"" are poorly understood.  In this study, transmission of Salmonella enterica serotype Enteritidis to the roots and leaves of butterhead lettuce was studied when contamination was introduced during typical handling practices.  The effectiveness of random sampling strategies for selection of Salmonella contaminated leaves was assessed by co-inoculating the Salmonella solution with Glo Germ™ and comparing recovery from blacklight selected leaves.  The recovery of Salmonella was improved by only 0.5 log CFU/g when blacklight was used to select Glo Germ™ contaminated leaves (P=0.05). This suggests random leaf selection as described by current FDA protocols is adequate. In addition, this study showed rapid transfer of Salmonella from liquid to the roots and sub-sequentially to the leaves of living lettuce.  Salmonella persisted but did not grow on leaves when stored at 4˚C for 18-days. Storage at 12˚C was associated with 2 log CFU/g increases in Salmonella on roots after 18-days storage (P=0.0002), while 4˚C storage was associated with a decrease of 0.4 log CFU/g Salmonella on roots (P=0.0001). Growth occurred only under temperature abuse conditions.  This reinforces the need for maintaining temperature control and highlights the importance of identifying risks associated with post-harvest handling during hydroponic production and distribution.
Master of Science in Life Sciences

About 150 rhizobacteria and 49 rhizosphere fungi were isolated from the rhizosphere of grasses and sedges at Nylsvley Nature Reserve, Limpopo Province, South Africa. The rhizobacterial isolated were mostly Gram negative (72%) and rod shaped (73%). The dominant fungal genera were Trichoderma, Aspergillus, Pencillium, Neosartorya and Fusarium. The antagonistic activity of the above isolates were determined in a dual culture assay against a range of plant pathogens namely Colletotrichum gloeosporioides, Pythium irregulare, Penicillium digitatum, Fusarium solani and Geotrichum candidum. All rhizosphere fungal isolates showed positive antagonism against G. candidum (100%) and F. solani (100%). The rhizobacterial isolates showed positive antagonism against G. candidum (71%) and C. gloeosporioides (76%). The growth promotion and biocontrol activity of the rhizosphere isolates that showed broad-spectrum antagonistic activity against the fore mentioned pathogens were further evaluated on Canadian peat substrate under greenhouse condition. Although most of the rhizosphere isolates resulted in improved fresh leaf weight in comparison with the non-inoculated control in final growth promotion experiments, no statistical difference could be found in increasing leaf weight by one of the tested isolates. Some isolates and BactolifeTM prevented root infection by Pythium. However, only isolate 68B showed significant prevention of root infection compared to the Pythium inoculated control. The selected rhizobacteria, fungal and commercial biocontrol products that showed the most effective growth promotion and biocontrol activities were further evaluated in a re-circulating hydroponic system. Overall, isolate BSB (Bacillus subtilis) consistently enhanced the fresh leaf and root weight by 29.82 and 24.31% compared to the untreated control. Treatments with rhizobacteria isolate 91B and 43B significantly increased fresh leaf weight and suppressed Pythium root infection of lettuce. Isolate 91B and 121B significantly decreased the incidence of Pythium after the 1st and 2nd week of inoculation respectively. The combination of rhizobacteria BSB and 43B showed a synergistic effect as reflected in increased fresh leaf weight and total biomass per plant whilst suppressing root rot caused by Pythium group-F. Copyright 2003, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Begashaw, L 2003, Utilisation of rhizosphere microflora in the biocontrol of root rot and growth enhancement of lettuce under hydroponic systems, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-05092005-103113 / > E642/ag
Dissertation (MSc (Agric))--University of Pretoria, 2006.
Microbiology and Plant Pathology
unrestricted

Sustainable alternatives to using mined nutrients in agriculture must be found in order to limit environmental impacts such as eutrophication, habitat destruction and greenhouse gas emis-sions. Biogas slurry and urine recycled to hydroponic food production (a type of soilless agri-culture) have the potential of providing inorganic nitrogen and phosphorus, the main essential nutrients required for plant growth. A Life Cycle Inventory Assessment (LCI) methodology has been used to compare the systems of producing artificial fertilizer, biogas slurry and urine based nutrient solutions for the growth of Brassica rapa L. (Chinese cabbage) in the context of a large scale hydroponic vertical farm. Costs and energy requirements have been the basis of the comparison and results show that both biogas slurry and urine are considerably cheaper than the commercial alternative and based on the nutrient content they have the potential of being successful nutrient solutions after dilution and nutrient supplementation. Filtration might also be required in order to remove suspended particles and pathogens.

Thesis (MScAgric)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: The potential importance of soilless production, particularly in tomatoes, in an increasingly water scarce South Africa prompts a need for research under local conditions. In soilless production systems the application and availability of nutrients is closely linked to that of water, necessitating the research of methods to increase water and fertiliser use efficiency in soilless production systems, while diminishing environmental pollution and maintaining, or ultimately improving, tomato yield and quality. Poor management of hydroponic fertigation water results in pollution, and wastes precious water and expensive fertiliser. Pruning is an important cultural practise for ensuring high productivity of hydroponic tomatoes. Adapting pruning practises to climatic conditions could be a cheap and effective manner to improve productivity without increasing inputs. Improving water and fertiliser use efficiency is crucial to ensuring sustainable production of intensive crops, such as the tomato. Three experiments were carried out to investigate the effects of pruning and fertilisation on growth and yield and water and fertiliser use efficiency of hydroponic tomatoes. In the first experiment the effect of EC (electrical conductivity), irrigation frequency and growing media on water use, nutrient uptake, yield and quality of greenhouse tomato was examined. A factorial design with split plots was used. Two EC treatments (1 and 2 mS.cm-1) in factorial arrangement with 3 irrigation treatments (5x, 10x, 20x) were applied to the main plots. Plants grown in different growing media (coir, sand, sawdust) represented the split plots. Plants grown at EC 1 mS.cm-1 were still able to uptake sufficient nutrients to achieve leaf nutrient contents associated with optimal production. Also, increasing the absolute nutrient concentration had a small effect on nutrient uptake. The organic media, coir and sawdust, reduced available N early in the tomato crop life, and tomatoes grown in coir had reduced Ca uptake compared to plants grown in sand and sawdust. Coir grown plants used more water compared to sand and sawdust grown plants. Plants grown at EC 1 mS.cm-1 used less water compared to plants grown at EC 2 mS.cm-1. Tomatoes grown at an EC 1 mS.cm-1 did not differ significantly from higher EC plants in terms of marketable and green fruit yield. Plants cultivated at the lower EC had significantly lower percentage soluble solids content (Brix) compared to the higher EC treatment. The second experiment examined the effect of leaf and fruit pruning on fruit size, total yield and marketable yield of tomatoes. Plants were grown using the high wire system and pruned to two stems. Three different leaf pruning treatments were applied: no leaf pruning, pruning every 2nd young leaf after 1m plant height, and pruning every 2nd young leaf after 2m plant height. Two fruit pruning treatments were also applied: no fruit pruning and trusses pruned to 4 fruits. The experiment used a factorial design. Leaf pruning treatments had no effect and this was probably due to too late a removal of young leaves. Fruit pruning resulted in no significant difference between treatments in terms of marketable yield. Plants with unpruned trusses did have a significantly higher total yield, higher early yield, lower average marketable fruit weight, and higher yield of unmarketable fruit (particularly small fruit compared to the pruned treatment). From these results it can be concluded that fruit pruning isn’t necessary on short tomato crops but this may be different over a longer cropping cycle. The third experiment determined the combined effects of different EC and stem pruning practices on nutrition, growth and early yield of hydroponically grown tomatoes in coir. A factorial design was used, with two EC treatments (1 and 2 mS.cm-1) in factorial arrangement with 2 stem pruning treatments (single and double). Stem pruning had little effect on plant growth but did alter plant development. Plants pruned to two stems produced significantly more trusses, but did not produce a significantly higher DM or leaf area compared to single stem plants. Stem pruning’s major effect appears to be influencing fruit load; this may in the long term result in differences in plant growth and nutrition. EC 1 mS.cm-1 plants produced significantly lower leaf area and organ dry masses but had a significantly higher marketable yield compared to EC 2 mS.cm-1 plants. Over fertilisation in young tomatoes can negatively impact on early yield, whereas lower fertiliser application in early tomato growth improves early yield but limits canopy development which may limit plant productivity in the long term. These differences in growth are believed to be primarily related to differences in N and P nutrition.
AFRIKAANSE OPSOMMING: Die potensiële belang van grondlose produksietegnieke, veral by tamaties, in Suid-Afrika wat toenemend meer water skaars raak, motiveer dat navorsing onder plaaslike toestande gedoen moet word. By grondlose produksie stelsels word die toediening en die beskikbaarheid van voedingstowwe nou gekoppel aan dié van water. Navorsing rakende metodes wat water en kunsmis gebruiks doeltreffendheid sal verhoog en terselfdertyd besoedeling van die omgewing voorkom asook die opbrengste en kwaliteit van tamaties behou of verbeter is dus van uiterste belang. Swak bestuur van bemesting in hidroponiese stelsels gee aanleiding tot water besoedeling en vermorsing van kosbare water en duur kunsmis. Snoei is 'n belangrike kulturele praktyk om hoë produktiwiteit by hidroponiese tamaties te verseker. Die aanpassing van snoei praktyke by klimaatstoestande is 'n goedkoop en doeltreffende manier om produktiwiteit te verbeter sonder om insette te verhoog. Die verbetering van water en kunsmis gebruiks doeltreffendheid is dus noodsaaklik om te verseker dat intensiewe gewasse, soos tamaties, volhoubaar geproduseer word. Drie eksperimente is uitgevoer om die effek van snoei en bemesting op die groei, opbrengs en water en kunsmis gebruiks doeltreffendheid van hidroponiese tamaties te ondersoek. In die eerste eksperiment is die effek van die EG, besproeiings frekwensie en groeimedium op die water gebruik, voedingstofopname, opbrengs en kwaliteit van tamaties ondersoek. 'n Faktoriaal ontwerp met gesplete plotte is gebruik. Twee EG behandelings (1 en 2 mS.cm-1), 3 besproeiings behandelings (5x, 10x, 20x per dag) en 3 groei media (kokos, sand, saagsels) is ondersoek. Selfs by ‘n EG van 1 mS.cm-1 was die voedingstof opname van plante vergelykbaar met waardes wat geassosieer word met blaar ‘n voedingstof inhoud wat voorgeskryf vir optimale produksie. die verhoging van die absolute voedingstof konsentrasie het ook 'n klein uitwerking op voedingstofopname gehad. In die organiese media - kokos en saagsels – het die beskikbare N vroeg in die seisoen verminder, en die tamaties wat in kokos gegroei het, het ook ‘n verminderde Ca opname getoon in vergelyking met die plante wat in sand en saagsels gegroei het. Die plate wat in kokos gegroei het, het meer water gebruik in vergelyking met plante wat in sand en saagsels gegroei het. Plante besproei met ‘n voedingsoplossing van 1 mS.cm-1 EG het minder water gebruik as die plante wat besproei met ‘n voedingsolossing by ‘n EG van 2 mS.cm-1. Tamaties wat gekweek word by 'n EG van 1 mS.cm-1 het nie beduidend verskil van hoër EG plante in terme van bemarkbare en groen vrugte nie. Plante wat gekweek is by die laer EG het ‘n aansienlike laer persentasie oplosbare vastestof inhoud (Brix) in vergelyking met die hoër EG-behandeling gehad. Die tweede eksperiment het die effek van blaar- en vrug snoei op die vruggrootte, totale opbrengs en bemarkbare opbrengs van tamaties ondersoek. Plante is vertikaal opgelei tot by die horisontale draad en na twee stamme gesnoei. Drie verskillende blaar snoei behandelings is toegepas: geen blaar snoei, snoei elke 2de jong blaar na 1m plant hoogte en snoei van elke 2de jong blaar na 2m plant hoogte. Twee vrug snoei behandelings is ook toegepas: geen vrugte gesnoei en trosse gesnoei tot 4 vrugte. ‘n Faktoriale ontwerp is vir hierdie eksperiment gebruik. Blaar snoei behandelings het geen effek gehad nie, waarskynlik omdat die jong blare te laat verwyder was. Met die vrug snoei behandelings was daar geen beduidende verskil tussen die behandelings in terme van bemarkbare opbrengs nie. Plante waarvan die trosse nie gesnoei was nie het 'n aansienlik hoër totale opbrengs gelewer, asook ‘n hoër vroeë opbrengs maar ‘n laer gemiddelde bemarkbare vrug massa en ‘n hoër persentasie onbemarkbare vrugte (baie klein vrugte in vergelyking met die gesnoeide behandeling). Vanuit hierdie resultate kan daar afgelei word dat vrug snoei nie nodig is tydens ‘n kort groeiperiode vir tamaties nie, alhoewel dit wel ‘n rol mag speel gedurende ‘n langer groeiperiode. Met die derde eksperiment is die gekombineerde effek van verskillende EG en stam snoei praktyke op voeding, groei en vroeë opbrengs van hidroponies verboude tamaties bepaal. 'n faktoriale ontwerp is gebruik, met twee EG behandelings (1 en 2 mS.cm-1) en 2 stam snoei behandelings (enkel en dubbel). Stam snoei het ‘n geringe uitwerking op die groei van die plant gehad, maar het wel die ontwikkeling van plante verander. Plante gesnoei na twee stamme het aansienlik meer trosse gehad, maar nie 'n hoër DM of blaar oppervlak as die enkele stam plante nie. Stam snoei se grootste effek blyk te wees op die aantal vrugte per plant en dit kan op die lang termyn lei tot verskille in die groei van plante en hul voeding. EG 1 mS.cm-1 plante het ‘n aansienlik laer blaaroppervlakte en droë massas geproduseer, maar het 'n aansienlik hoër bemarkbare opbrengs in vergelyking met EG 2 mS.cm-1 plante gelewer. Oorbemesting kan 'n negatiewe impak op die vroeë opbrengste van tamaties hê, terwyl laer bemesting in die vroeë stadiums van groei vroeë opbrengs bevoordeel maar blaaroppervlak ontwikkeling beperk wat dan ook produktiwiteit beperk in die lang termyn. Hierdie verskille in groei word hoofsaaklik toegeskryf aan verskille in die N-en P-voeding.

With a continued worldwide trend in population shift from rural to urban areas predicted to increase, new approaches to agricultural production must be considered and implemented. Little academic interest has been applied to determining economically viable urban agriculture crop production sites for business investment. A feasibility model to aid investors in selecting appropriate sites for the development of urban agriculture food production within population centers was created. Lettuce crop trials were performed from August 2015 to December 2015 at the University of Arizona Controlled Environment Agriculture Center to validate the productivity of a unique high density hydroponic system designed for the rooftop environment. The feasibility model is based on this system and with a minimal number of inputs, ranging from size of growing space to growing media costs, determines a wide range of useful outputs. These outputs include crop productivity within the facility, material inputs and a cost breakdown of starting a new agricultural venture. The model utilizes multiple sheets within one excel document to give the user a clear and organized financial perspective of a hypothetical growing operation in the main sheet. With this model, investors into urban agriculture will have a means to gain an objective view of financial considerations before substantial investment is completed.

Nitrogen is the only plant nutrient taken up as both a cation (NH4+) and anion (N03-). Nitrate is considered the "safe" form of N and NH4+ is generally thought to be toxic, especially at high levels. High NH4+/N03- ratios are thought to be toxic because they result in a rhizosphere pH low enough to damage root membranes, induced cation deficiencies, and build-up of NH3 caused by delayed NH4+ assimilation. These factors can be minimized in hydroponic culture. The objective of these studies was to quantify lll the effects of high NH4+/N03- ratios on nitrification and growth of wheat in hydroponics. Two cultivars of wheat (Triticum aestivum L.) were grown to maturity with either 15% or 80% of the N supplied as NH4+. The effect of using Cl- versus SO42- as counter ions to NH4+ was also examined. Yield was not significantly affected by NH4+ ratio or counter ion. Seed protein was increased from 15 to 19% with high NH4+. Harvest index was reduced from 52 to 48% with 80% NH4+, but was unaffected by counter ion. Rates of nitrification in hydroponic culture are not well quantified and could result in significant conversion of NH4+ to NO3- before plant uptake. An isotopic dilution study was conducted to quantify rates of nitrification in hydroponic culture. A 2 x 2 x 2 factorial design was used to examine the effect of pH (5.8 or 7.0), inoculation with nitrifying bacteria, and the presence of plants. This study was done with wheat grown in vigorously-aerated, 2-L bottles. Each bottle contained 10 g of diatomaceous earth to provide surface area for microbial growth. Nitrate began to accumulate in 5 d in unplanted, inoculated bottles at pH 7.0; in 20 d at pH 5.8 with inoculation; but did not begin to accumulate in non-inoculated bottles (pH 5.8 or 7.0) until day 30. Nitrate never accumulated in any of the planted bottles, most likely because plants consumed the NO3- that was produced. Calculations from the isotopic dilution measurements indicated that the rate of nitrification averaged 58 μmol NO3- L-1d-1 in the planted bottles, and averaged 270 μmol NO3- L-1d-1 in unplanted bottles. Nitrification was likely reduced in the planted bottles because the reduced concentration of NH4+ limited nitrification. To provide rapid, inexpensive measurement of nutrient concentration in hydroponic solution, five colorimetric tests were evaluated. Tests for NO3- and PO4 were accurate and reliable, but the tests for SO42- SiO2, and Fe need additional refinement.