Mini-dissertation submitted in partial compliance with the requirements of the Master’s Degree in Technology: Homoeopathy, Durban University of Technology, 2012. / Lettuce is a cool season crop and requires an optimum growing temperature of 18°C. Lettuce is popular in summer as a salad ingredient but supply cannot always keep up with demand due to high spoilage rates, because of bolting and tip-burn as a result of heat stress while growing (Maboko &Du Plooy 2007). Heat stress reduces oxygen availability. This study sought to demonstrate that administration of homoeopathic Ozonum to hydroponic nutrient solution in a nutrient film technique design improves the growth ability and quality of lettuce during the summer season by increasing or improving its ability to absorb oxygen. The research was conducted at the Agricultural Research Council – Vegetable and Ornamental Plant Institute (ARC-VOPI) facility at Roodeplaat (near Pretoria), South Africa. The trial was conducted in a 40% shade net structure in the summer months of February to April 2012. Purpose The general aim was to measure the effect of homoeopathic Ozonum 6CH, Ozonum 15CH and Ozonum 30CH compared to a placebo control (96% alcohol only) on the growth and yield of leafy lettuce, Lollo Bionda Lobi cultivar grown in a closed hydroponic system in South African summer climatic conditions. Objectives:  Determine the increase in growth and yield of leafy lettuce as affected by Ozonum concentration in terms of: (i) leaf fresh mass; (ii) leaf dry mass; (iii) number of leaves; (iv) leaf area; (v) chlorophyll content; (vi) root fresh mass; (vii) root dry mass;  Determine the impact of heat stress in terms of bolting and tip-burn;  Determine the differences in specific plant leaf mineral content between the experimental groups and control group; and,  Determine the differences between dissolved oxygen (DO) concentrations in the nutrient solution of the verum group and control group. Methodology This was a placebo controlled randomized plant experiment. A total of 384 plants were laid out in a randomized complete block design with 4 treatments (Ozonum 6CH, Ozonum 15CH Ozonum 30CH and a control) and replicated 4 times. The total number of plants per plot was 24 and the middle 8 plants were selected as data plants while other plants were regarded as border plants. Thus, data was gathered from 96 plants per treatment in total. Leafy lettuce seeds of cultivar Lollo Bionda Lobi, were sown in polystyrene trays. The seedlings were transplanted 28 days after sowing into a gravel-film technique hydroponic system. Ozonum and the placebo was added to the nutrient solution on the first day and every 6 days thereafter, at the same time as the nutrient solution was changed. Various daily measurements were recorded. Plants were harvested 27 days after transplanting when final measurements of nutrient content and growth were made. Data Analysis Data was collected over time as repeated measurements; the time factor was included as a sub-plot factor in the analysis of variance (ANOVA). All data items collected were subjected to an appropriate analysis of variance using the GenStat statistical system (VSN International, 2011). The residuals were examined for deviations from normality and outliers causing skewness were removed. Fisher’s protected t-LSD (Least Significant Difference) was calculated to compare treatment means of significant effects (Snedecor & Cochran, 1980). Results The results for (i) lettuce yield criteria, (ii) DO concentration, (iii) leaf chlorophyll content and (iv) specific mineral content of lettuce leaves (Appendix B) indicate that there was no significant difference between Ozonum treatments and the control. The incidence of bolting was not observed in lettuce plants among the treatment or control groups. Results showed a reduced tendency in tip-burn percentage for treatment Ozonum 30CH although not significantly different to Ozonum 15CH or the control. Conclusion The conclusion derived from this study is that homoeopathic Ozonum was not effective at improving dissolved oxygen levels in the nutrient solution, or in stimulating growth in lettuce under South African summer climatic conditions (February to April). Further research is needed to explore the effect Ozonum 30CH may have on tip-burn.

No description available.

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.

The goal of this study was to prove that aquaponic systems can produce lettuce of equal growth and quality compared to hydroponic lettuce production and to determine the stocking density of fish required for plant growth. Aquaponics is the integration of recirculating aquaculture and hydroponic plant production. The project had four objectives. The first objective was to determine the biomass of fish required for plant growth to develop a fish to plant density ratio. The second objective was to compare lettuce grown with aquaponic water and a hydroponic solution under the same environmental conditions. The third objective was to compare the quality of lettuce grown with aquaponics water plus nutrient supplementation with a hydroponic solution. The fourth objective was to determine the nitrogen dynamics in the aquaponic system and to compare the nutrient composition of lettuce grown with aquaponics water with nutrient supplementation and hydroponic solution. It was determined that under the specified environmental conditions 5 kg m⁻³ of Nile tilapia (O. niloticus) fed 2% of their body weight daily yields on average 4.7 kg m⁻² of lettuce (L. sativa cv. Rex) in 35 days. There was no significant difference (p ≤ 0.05) in biomass or chlorophyll concentration index in lettuce (L. sativa cv. Rex) grown with aquaponics water and nutrient supplements versus a hydroponic solution. The aquaponics solution generated equal biomass and chlorophyll concentration indexes compared to the hydroponic solution. Aquaponics water plus supplementation can yield L. sativa cv. Rex with equal biomass accumulation and chlorophyll concentration indexes compared to hydroponics lettuce. Nutrients added to the aquaponics system consisted of iron, manganese, and zinc. These nutrient concentrations became depleted in the aquaponics water over time and were not replenished via the fish feed. Dolomite was added to the aquaponics system every two weeks to increase the buffering capacity of the water and maintain optimal pH levels. Aquaponics lettuce had similar nutrient composition to hydroponic lettuce. One head of L. sativa cv. Rex (176.75 ± 31.03) will assimilate approximately 5.96 grams of nitrogen (3.38% per dry gram lettuce). One kilogram of fish will yield 6.4 lettuce heads (1,128 grams) and fixate 38.13 grams of nitrogen.

No description available.

Thesis(M.S.)--Auburn University, 2006. / Abstract. Includes bibliographic references.

Thesis (MSc Plant Pathology)--University of Pretoria, 2005. / Summary in English. Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on June 14, 2010). Includes bibliographical references (p. 93-104).

A number of techniques were used to obtain a variety of bacterial and fungal species antagonistic to Pythium - F group in hydroponic systems. Isolations were made from roots of ‘escape’ lettuce plants in a commercial hydroponic gravel system as well as Pythium mycelium exposed to the hydroponic solution. Seventy four bacterial and eighteen fungal isolates were obtained and were screened for in vitro activity against Pythium by means of the dual culture method. Twenty-two bacterial isolates rendered between 10.8 and 48 % inhibition and ten fungal isolates rendered between 24.3 and 54 % inhibition of Pythium mycelial growth. Potential biocontrol agents were screened in a static aquaculture system on butterhead lettuce seedlings in the greenhouse prior to evaluation in a re-circulating gravel bed hydroponic system in the greenhouse and field, for both growth promoting and biocontrol ability. Significant increases of between 689 % and 922 % in total fresh yield were obtained from plants preventatively treated with isolates JH49, JH41, JH83, JM6R and JM16W. The eight best performing isolates were further evaluated for biocontrol activity against Pythium as well as growth promotion on butter head lettuce in a re-circulating gravel bed hydroponic system in the greenhouse. Significant increases of 1.5 % - 63.5 % and 0.9 % - 38.8 % in total fresh yield were obtained from plants evaluated for growth promotion and Pythium control, respectively. Based on their performance five of the eight isolates were selected for evaluation in a re-circulating gravel bed hydroponic field system. Treatment with Pseudomonas fluorescens and Bacillus subtilis significantly increased fresh leaf weight of lettuce plants in comparison with the untreated control indicating effective suppression of Pythium. Of the isolates that were previously evaluated against Pythium wilt and root rot of lettuce in a hydroponic system (Chapters 2 and 3), 6 bacteria and 2 fungi were most effective. The following possible modes of action of these isolates, were investigated, namely competition, production of inhibitory substances and induced resistance. The root colonizating ability of the isolates was also assessed. Competition between the isolates and the pathogen were confirmed by testing for siderophore and hydrolytic enzyme production. Five of the isolates produced siderophores much faster than the rest, demonstrating that these isolates were able to take-up iron from the media at a faster rate, thus indicating a significant competitive ability. Antibiotic production by the isolates was confirmed in vitro by means of the dual culture technique. Of the eight isolates screened, only one isolate showed in vitro inhibition of the pathogen. This result was confirmed by a TLC assay, where fluorescent bands were formed by the same isolate, indicating the presence of phenolic compounds. These compounds were separated by HPLC. Analysis of total soluble and cell wall phenolic levels in Pythium infected and non-infected plants treated and untreated with the biocontrol isolates did not render conclusive results. Three of the eight isolates were able to colonize 100% of the lettuce roots. / Dissertation (MSc (Plant Pathology))--University of Pretoria, 2008. / Microbiology and Plant Pathology / unrestricted

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.