Com o objetivo de analisar a rentabilidade econômica da produção de mudas de alface produzidas em bandejas com diferentes volumes de substrato e formato de célula, foram realizados levantamentos de custos de um produtor de mudas localizado no estado de São Paulo, nas safras de verão e de inverno. Para avaliar os custos de produção para cada safra de cultivo, foi usado a metodologia adotada pelo Centro de Estudos Avançados em Economia Aplicada (CEPEA), onde se calcula o Custo Total de produção pela soma entre o Custo Anual de Recuperação do Patrimônio (CARP) e o Custo Operacional (CO). O CARP é uma metodologia que considera o fator depreciação e custo de oportunidade do capital imobilizado para aquisição dos bens envolvidos, e o CO envolve todos os custos operacionais da atividade (viveiro de produção de mudas). O custo total de produção por área (m2), custo total de produção por muda e custo total de produção por bandeja foram superiores na safra de inverno em relação à safra de verão. Para o custo de produção por muda, os valores obtidos seguiram a seguinte ordem (R$): 84 células > 105 células > 128 células achatada alta > 128 células achatada baixa > 128 células cônicas > 200 células cônicas. Já para o custo de produção por bandeja, a ordem foi a seguinte: 84 células > 105 células > 128 células achatada alta > 128 células achatada baixa > 200 células cônicas > 128 células cônicas. Para o lucro da atividade, a ordem dos lucros foi (R$): 128 células achatada alta > 128 células achatada baixa > 84 células > 105 células > 200 células cônicas > 128 células cônicas. Além da rentabilidade econômica, dois experimentos foram conduzidos no viveiro especializado na produção de mudas, durante os períodos de 25 de dezembro de 2015 a 3 de fevereiro de 2016 e 26 de janeiro a 26 de fevereiro de 2016. Os períodos de cultivo foram de 28 e 40 dias para o primeiro ciclo (mudas convencionais e \"mudões\", respectivamente) e de 31 dias para todas as bandejas, no segundo ciclo. Os experimentos (primeiro e segundo ciclo) foram instalados em delineamento experimental inteiramente casualizado com quatro repetições, sendo os tratamentos constituídos por 6 diferentes tipos de bandejas para produção de mudas (128 células com formato cônico,128 células achatada baixa, 128 células achatada alta, 84 células, 105 células e 200 células com formato cônico). As mudas convencionais são destinadas para a produção hidropônica com uso de berçário, e os \"mudões\" para sistemas de cultivo hidropônico sem uso de berçário. As características agronômicas avaliadas foram massas frescas e secas das partes aéreas e das raízes, área foliar, comprimento total, área superficial, diâmetro médio, volume total e número total de raízes. Para mudões, que são destinados ao cultivo hidropônico sem a utilização da fase de berçário, as bandejas de 105 células resultaram em mudas com crescimento similar àquelas produzidas em bandejas de 84 células. Através desses resultados é possível recomendar as bandejas de 105 células por possibilitarem maior rendimento por área ao produtor de mudas. As mudas produzidas em bandejas de 84 e 105 células foram mais desenvolvidas, em geral, no primeiro ciclo do que no segundo ciclo. Para mudas convencionais, de maneira geral, as bandejas de 200 células cônicas resultaram em menor desenvolvimento das plântulas comparadas às bandejas de 128 células cônicas, achatadas baixas e achatadas altas. As bandejas de 200 células cônicas resultaram em maior massa fresca da parte aérea, área foliar, comprimento total das raízes e número total de raízes no segundo ciclo em relação ao primeiro, devido ao período de cultivo ter sido superior no segundo ciclo (31 dias após a semeadura). / The objective of this study was to analyze the economic profitability of lettuce seedling production in trays with different cell volume and format through cost survey of production related to a grower located at Sao Paulo State. In order to evaluate the production costs for each growth period, the methodology adopted by Center of Advanced Studies on Applied Economy (CEPEA) was used to calculate the Total Cost of Production by the sum between the Annual Cost of Recovery (CARP) and the Operating Cost (CO). The CARP is a methodology that considers the factor of depreciation and opportunity cost of immobilized capital to acquire the assets involved, and the CO involves all operational costs of the activity (nursery of seedling production). The total cost of production per square meter (m2), total cost of production per seedling and total cost of production per tray were higher in the winter season as compared to the summer season. For the production cost per seedling, the values obtained were in the following order (R $): 84 cells> 105 cells> 128 flattened high cell> 128 flattened low cell> 128 conic cells > 200 conic cells. For the cost of production per tray, the order was as follows: 84 cells> 105 cells> 128 flattened high cells> 128 flattened low cells > 200 conic cells > 128 conic cells. For the profit of the activity, the order of profits was (R $): 128 flattened high cells > 128 flattened low cells > 84 cells> 105 cells> 200 conic cells> 128 conic cells. Besides the economic profitability, two experiments were conducted in the nursery specialized in the seedling production of lettuce during the periods of December 25, 2015 to February 3, 2016 and January 26 to February 26, 2016. The growing periods were 28 And 40 days for the first cycle (conventional seedlings and \"large seedlings\", respectively) and 31 days for all trays in the second cycle. The experiments (first and second cycle) were installed in a completely randomized experimental design with four replicates, and the treatments consisted of 6 different types of trays for seedlings production (128 cells with conical shape, 128 flattened low cells, 128 flattened high cells, 84 cells, 105 cells and 200 cells with conical shape). The conventional seedlings are destined for hydroponic production with the use of nursery phase and the \"large seedlings\" are used to hydroponic systems without of nursery phase. The agronomic characteristics evaluated were fresh and dry masses of the aerial parts and roots, leaf area, total length, surface area, mean diameter, total volume and total number of roots. For \"large seedlings\", trays of 105 cells resulted in seedlings with growth similar to those produced in trays of 84 cells. Through these results, it is possible to recommend the trays of 105 cells because they allow greater yield per square meter to the grower of seedlings. The seedlings produced in trays of 84 and 105 cells, in general, were more developed in the first cycle than in the second cycle. For conventional seedlings, the trays of 200 conical cells resulted in lower seedling development as compared to trays of 128 conical cells, flattened low and flattened tall cells. The trays of 200 conical cells resulted in higher fresh shoot mass, leaf area, total root length and total number of roots in the second cycle as compared to the first, because the growing period was higher in the second cycle (31 days after sowing).

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 / Doctor of Agricultural Science / Kyoto University / DFAM

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.

<p><a>Facing challenges for increasing demands for agricultural land, water, and energy, aquaponics has emerged as a sustainable solution that can contribute to global food production while minimizing environmental impacts. In a recirculating aquaponic system, the waste produced by aquatic animals is processed through microbes and breaks down into compounds for plant uptake. By recycling nutrients and water between hydroponics and aquaculture systems, aquaponics can reduce the waste of fish feeds and the use of chemical fertilizers and use 90-99% less water than conventional aquaculture. However, a few studies reported that nutrient use efficiency is still low in aquaponics, and only 10-37% and 20-30% of nitrogen (N) is typically assimilated by plants and fish, respectively. Yield reduction is commonly reported for plants in aquaponics. Due to the unique water physical and chemical environment, the microbiomes are more diverse in aquaponics than in hydroponics. While the most important microbial group is considered nitrifying bacteria, <i>Nitrosomonas</i> spp. and <i>Nitrobacter</i> spp. mediating the N conversion process from ammonia into nitrate,</a> some plant growth-promoting bacteria (PGPB) in soils were found in aquaponics indicating their important function in the system. Meanwhile, the use of aquaculture wastewater can introduce and promote the growth of harmful microbial pathogens, posing a food safety concern. </p> The goal of this research is to investigate the effects of microbiomes in aquaponic systems. A series of studies were conducted to examine the effects of different bacterial groups on food crop yield and quality and investigate the potential risk of contamination with enteric pathogens in aquaponic systems. The specific objectives are: to 1) examine whether enteric pathogens present in aquaponics and hydroponics; 2) investigate the effects of plant age and root damage on internalization of STEC <i>E. coli</i> in leafy vegetables and herbs. 3) examine the effects of pH on the plant yield in aquaponics; and 4) investigate the effects of PGPB on lettuce in aquaponics and hydroponics3. The data obtained from this research will fill the knowledge gap and provide new management strategies for cultivating crops in aquaponics, which will greatly promote the application of aquaponics to provide a solution for the increasing food demands in the future.

Made available in DSpace on 2014-08-20T14:22:08Z (GMT). No. of bitstreams: 1 Dissertacao_Luana_Borges_Affonso.pdf: 1352804 bytes, checksum: 985576a4337a31361054cc90e4f0eaa2 (MD5) Previous issue date: 2011-03-04 / This work aimed to study some aspects of the spread and growth of seedlings of strawberry guava. For this, we developed three chapters. The first chapter deals with the rooting of strawberry guava microshoots Irapuã with different concentrations of IBA (0, 1000, 2000, 3000, 4000 mg L-1). We evaluated the survival and rooting percentage, root number, root length, fresh and dry. We observed positive influence of growth regulators on rooting of microcuttings, however, with little difference between concentrations. In chapter two we studied the influence of semi-hydroponic systems and conventional in the development of seedlings produced from Araçazeiro Irapuã micropile. We evaluated the number of shoots, growth of shoots, secondary shoots and plants with shoot length secondary. We did not observe influence of cropping systems in plant development. In the third chapter, was conducted in a semi-hydroponic system microjardim clonal Irapuã strawberry guava, which was conducted monthly collections of microcutting and evaluated the rooting ability of each collection. It was observed that the cultivation of strawberry guava microstumps in semi-hydroponic system is efficient in producing microcuttings, allowing successive collections. The rooting of microcutting microstumps collected in semi-hydroponic system showed low rates of survival and rooting. / O presente trabalho teve como objetivo estudar alguns aspectos relacionados a propagação e ao crescimento de mudas de araçazeiro. Para isso, foram elaborados três capítulos. O primeiro capítulo aborda o enraizamento de microestacas de araçazeiro Irapuã com diferentes concentrações de ácido indolbutírico (0, 1000, 2000, 3000, 4000 mg L-1). Foi avaliada a porcentagem de sobrevivência e enraizamento, número de raízes, comprimento das raízes, massa fresca e seca. Foi observado influência positiva do regulador de crescimento no enraizamento das microestacas, no entanto, com pouca diferença entre as concentrações. No capítulo dois foi estudado a influência dos sistemas semi-hidropônico e convencional no desenvolvimento das mudas de araçazeiro Irapuã produzidas a partir de microestacas. Foi avaliado o número de brotações, crescimento de brotações, plantas com brotações secundárias e comprimento das brotações secundárias. Não foi observado influência dos sistemas de cultivo no desenvolvimento das plantas. No terceiro capitulo, foi conduzido em sistema semi-hidropônico um microjardim clonal de araçazeiro Irapuã, onde foi realizado coletas mensais de microestacas e avaliada a capacidade de enraizamento a cada coleta. Foi observado que o cultivo de microcepas de araçazeiro em sistema semi-hidropônico é eficiente na produção de microestacas, permitindo sucessivas coletas. O enraizamento das microestacas coletadas de microcepas em sistema semi-hidropônico apresentou baixas taxas de sobrevivência e enraizamento.

Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-03-30T12:28:08Z No. of bitstreams: 1 2010 - Marco Andre Alves de Souza.pdf: 5657340 bytes, checksum: becf46e090a1ebcc4a731b733c77fb6a (MD5) / Made available in DSpace on 2017-03-30T12:28:08Z (GMT). No. of bitstreams: 1 2010 - Marco Andre Alves de Souza.pdf: 5657340 bytes, checksum: becf46e090a1ebcc4a731b733c77fb6a (MD5) Previous issue date: 2010-01-18 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / The cultivation of aromatic specimens for obtaining essential oils have great economic importance, mainly by increasing demand in the food, cosmetic and pharmaceutical industry. Brazil is the largest producer of essential oil, however, is what earns less in money value, because, its production is mainly of orange essential oil, with low added value. The essential oil of M. arvensis is rich in menthol (70-80%), a natural products with higher demand in daily life of modern man. Currently, Brazil has become a major importer of menthol which has contributed negatively to the brazilian trade balance. Thus, for the development of this work was chosen to be a specimens of economic interest and social demand, the Mentha arvensis. The purpose of study was to evaluate whether changes in light intensities and different levels of phosphorus promote changes in biomass production and nutrition, with consequences for the biosynthesis of essential oils. We also analyzed the influence of leaf age on the quality of essential oil. To this end, the plant of M. arvensis was grown under the effect of different conditions, which allowed the analysis of the levels of soluble fractions, of photosynthetic pigments, the activities of enzymes related to nitrogen assimilation and the anatomical and histochemical study of trichomes, morphological structure where it is produce the essential oil. The study also included analysis of the expression of genes related to the route of menthol synthesis. The essential oil was obtained by extraction with hydrodestillation in modified Clevenger and the chemical analysis of substances obtained by GC-MS. The Kovats index was used to collaborate in identification of the main substances in essential oil. The results showed that the essential oil quality is determined by physiological conditions and leaf age and that the production is dependent on the synthesis efficiency and density of trichomes on the leaves. In addition, it was found that different concentrations of phosphorus affected some aspects of plant metabolism, which reflected the production of biomass in the soluble fraction, with consequences on production and quality of essential oils. Also showed that variations in light levels affected the expression of six of the eight genes involved in the route of synthesis of menthol, in plants of M. arvensis and that changes in gene expression are probably associated with a transcription factor, which could be acting on the whole pathway. All of this information showed that environmental conditions and / or nutritional affected some aspects of plant metabolism, which reflected the production of biomass, of trichomes and on the expression of genes related to the route of menthol, which reflect on the quality and the production of essential oils / O cultivo de esp?cies arom?ticas para a obten??o de ?leos essenciais tem grande import?ncia econ?mica, principalmente, pela crescente demanda nas ind?strias de alimentos, de cosm?ticos e a farmac?utica. O Brasil ? o maior produtor de ?leo essencial, entretanto, ? o que menos arrecada em valores monet?rios, pois, sua produ??o ? basicamente de ?leo essencial de laranja, com baixo valor agregado. O ?leo essencial de Mentha arvensis L. ? rico em mentol (70-80%), uma dos produtos naturais com maior demanda no dia-a-dia do homem moderno. Atualmente, o Brasil tornou-se um grande importador de mentol o que tem contribu?do negativamente para a balan?a comercial brasileira. Deste modo, para o desenvolvimento deste trabalho escolheu-se a planta M. arvensis. O objetivo do estudo foi avaliar se varia??es nas intensidades luminosas e diferentes concentra??es de f?sforo promovem altera??es na produ??o de biomassa e em aspectos nutricionais, com reflexos na bioss?ntese de ?leos essenciais. Tamb?m foi avaliada a influ?ncia da idade da folha sobre a qualidade do ?leo essencial. Com esta finalidade, a planta de M. arvensis foi cultivada sob o efeito de diferentes condi??es, o que permitiu a an?lise dos teores das fra??es sol?veis, dos pigmentos fotossint?ticos, das atividades das enzimas relacionadas com a assimila??o do nitrog?nio e o estudo histoqu?mico e anat?mico dos tricomas secretores, estrutura morfol?gica onde ? produzido o ?leo essencial. Tamb?m foram realizadas analises da express?o dos genes relacionados com a rota de s?ntese do mentol. O ?leo essencial foi obtido por hidrodestila??o em Clevenger modificado e as analises qu?micas das subst?ncias realizadas por CG/EM. A utiliza??o do ?ndice de Kovats auxiliou na identific??o das principais subst?ncias no ?leo essencial. Os resultados permitiram concluir que a qualidade do ?leo essencial ? determinada pelas condi??es fisiol?gicas e a idade das folhas e que a produ??o ? dependente da efici?ncia de s?ntese e a densidade de tricomas secretores nas folhas. Al?m disso, foi constatado que as diferentes concentra??es de f?sforo afetaram alguns aspectos do metabolismo vegetal, os quais refletiram na produ??o de biomassa, nas fra??es sol?veis, com conseq??ncias na produ??o e qualidade dos ?leos essenciais. Tamb?m, mostraram que varia??es nos n?veis de luminosidade afetaram a express?o de seis entre os oito genes envolvidos com a rota de s?ntese do mentol, em plantas de M. arvensis e que as altera??es na express?o dos genes provavelmente est?o associados a um fator de transcri??o, o qual deve estar atuando sobre toda a rota metab?lica

Syfte: En långsam utveckling av levande väggar i Sverige beror bland annat på bristande erfarenhet och kunskap inom byggbranschen. Tidigare studier visar bland annat utmaningar gällande teknikens anpassning till ett svenskt klimat och ett krävande underhåll beroende av kompetens, planering och samverkan. Målet med studien är att analysera ett hållbart underhåll utifrån teknik och underhållsplanering av systemet levande väggar för att kunna besvara dessa problem. Metod: Studien är av kvalitativ karaktär där använda metoder är dokumentanalys, intervju och observation. Dokumentanalys ger en lägesbild av implementerade lösningar i södra Sverige och strategier för underhållsplanering. Intervju med relevanta aktörer bidrar med erfarenheter om teknik, underhåll och planering. Observation bekräftar information om teknik. Resultat: Studien visar på att ingen av de studerade konstruktionslösningarna kan anses fullständigt hållbara, men det finns systemlösningar som har mer eller mindre hållbara egenskaper. Levande väggar har starka sociala och ekologiska fördelar, där växtligheten bidrar till att öka ekosystemtjänsterna i urban miljö. En mindre resursanvändning är nödvändig för en hållbar teknik, där naturlig bevattning, lokala tåliga växter, varaktig konstruktion samt återvunna materialkomponenter främjar hållbar miljö och ekonomi. Filtdukssystem är enklare i design medan modulsystem är mer flexibelt. Ett gemensamt mål bland studerade projekt är att skapa ett så underhållsfritt system som möjligt där väggen får leva på naturlig väg. Acceptans för vilande växter under vinterhalvåret kan sänka krav på underhållet. Teknisk övervakning underlättar men manuell tillsyn är vital för väggens överlevnad. Frekvensen på underhållet varierar från projekt till projekt där kundens önskemål, placering, typ av vägg, storlek, växtval och årstid påverkar. Därför är det viktigt med planering och kontinuerlig utvärdering av behov. Majoriteten av studerade projekt har ingen tydlig underhållplanering, men studien visar på framgångar av ett tydligt gemensamt mål, tidig involvering av driftpersonal, platsanalys, målinriktad underhållsplan och erfarenhetsåterkoppling. Konsekvenser: Studiens slutsats är att tekniken för levande väggar behöver utvecklas för att för att lämna ett mindre fotavtryck på miljö och ekonomi. Utvecklingen går mot ett så underhållsfritt system som möjligt, men den manuella tillsynen kan inte ersättas helt av avancerad teknik. Varje anläggnings unika förutsättningar kräver noggrann planering och kontinuerlig utvärdering av behov. Begränsningar: Studien behandlar levande väggar i ett svenskt urbant klimat, där resultatet baseras på erfarenheter från projekt utförda i södra Sverige. Annan geografisk placering skapar andra förutsättningar för teknik och underhåll. Mer generella antaganden kan göras gällande underhållsplanering. Fler intervjuer med underhållstekniker kan bidra med andra aspekter i analysen. / Purpose: A slow development of living walls in Sweden is partly due to lack of experience and knowledge in the construction industry. Former studies point at challenges of adapting the technique in a Swedish climate and the importance of planning, knowledge and cooperation for the maintenance. The objective of the study is to analyse a sustainable maintenance by technique and maintenance planning of the system living walls in order to answer these challenges.   Method: The study is based on a qualitative approach where the methods are document analysis, interview and observation. Document analysis gives a status report of the implemented living walls in Sweden and introduces strategies for maintenance planning. Interview with relevant participants contributes with experiences concerning technique, maintenance and maintenance planning. Observation confirms the information about the technique. Findings: The study shows that none of the observed solutions can be considered completely sustainable, though they do have some sustainable qualities. Living walls have strong social and ecological benefits, where the vegetation contributes to increase ecosystem services in urban environment. A less use of resources is necessary for a sustainable technique where the use of stormwater, local resistant plants, lasting construction and recycled components promotes a sustainable environment and economy. The felt system is simpler in its design while the modular system is more flexible. A common objective among the observed projects is to create a maintenance-free solution as possible. Acceptance for resting plants during winter can lower the demands of the maintenance. Technical monitoring facilitates the maintenance but the manual handling of living walls is crucial. The frequency of the maintenance varies from each project where the client’s choice, placement of the wall, type of solution, size, plant choice and season affect. Therefore, it is important with planning and constantly evaluating a walls needs. The majority of the observed projects do not have a maintenance plan but the study shows success by a common objective, site analysis, goal-oriented maintenance plan and experience feedback. Implications: The conclusion of the study is that the technique of living walls needs to be evolved to leave a smaller footprint on the environment and the economy. The development is towards a maintenance-free solution but the manual handling can not be replaced by advanced technique. Every projects individual conditions demands thorough planning and continuous evaluation of the wall. Limitations: The study discuss living walls in the Swedish urban climate, where the result is based on experiences from projects developed in the southern part of Sweden. Other geographical placement causes different conditions for technique and maintenance. General assumptions can be made concerning the maintenance planning. More interviews with maintenance staff can contribute with other aspects to the analysis.

The tomato is one of the most important vegetable crops grown in the South African community. Most hydroponic tomato growers in South Africa are using sawdust as a growing medium due to its availability and affordability. However, there is little or no information on how particle sizes of sawdust influence tomato yield and quality. The aim of the study was to determine the effect of the particle size of sawdust on plant growth, yield and quality of tomato. Six treatments of different particle sizes of sawdust i.e. fine (F), medium (M), coarse (C) and 50:50 ratio of F: M, C: M, and C: F extracted from pine tree were used for the experiment. Treatments were arranged in a randomized complete block design with four replicates. The size of the sawdust particles did not have a significant effect on plant height, stem diameter, leaf length and width, shelf-life, marketable yield, total yield and unmarketable yield. A tendency to increase marketable and total yield was observed when tomato plants were grown at a 50:50 C: F ratio. Fruit and leaf mineral content were not affected by sawdust particle size. After completion of the experiment, air- filled porosity was significantly high on particle size C, M, and C: M while the water holding capacity was significantly high on F followed by M. The study showed that the suitable growth medium for production of tomatoes under the hydroponics system used was the CF particle substrate. Generally, the experimental crop performed better under the CF particle substrate in terms of growth parameters, and fruit quality, thus leading to the conclusion that the CF growth medium is ideal for hydroponically grown tomato under a non-environmentally controlled polytunne / Agriculture, Animal Health and Human Ecology / M. Sc. (Agriculture)

The tomato is one of the most important vegetable crops grown in the South African community. Most hydroponic tomato growers in South Africa are using sawdust as a growing medium due to its availability and affordability. However, there is little or no information on how particle sizes of sawdust influence tomato yield and quality. The aim of the study was to determine the effect of the particle size of sawdust on plant growth, yield and quality of tomato. Six treatments of different particle sizes of sawdust i.e. fine (F), medium (M), coarse (C) and 50:50 ratio of F: M, C: M, and C: F extracted from pine tree were used for the experiment. Treatments were arranged in a randomized complete block design with four replicates. The size of the sawdust particles did not have a significant effect on plant height, stem diameter, leaf length and width, shelf-life, marketable yield, total yield and unmarketable yield. A tendency to increase marketable and total yield was observed when tomato plants were grown at a 50:50 C: F ratio. Fruit and leaf mineral content were not affected by sawdust particle size. After completion of the experiment, air- filled porosity was significantly high on particle size C, M, and C: M while the water holding capacity was significantly high on F followed by M. The study showed that the suitable growth medium for production of tomatoes under the hydroponics system used was the CF particle substrate. Generally, the experimental crop performed better under the CF particle substrate in terms of growth parameters, and fruit quality, thus leading to the conclusion that the CF growth medium is ideal for hydroponically grown tomato under a non-environmentally controlled polytunne / Agriculture, Animal Health and Human Ecology / M. Sc. (Agriculture)