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.

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Thesis (Ph. D.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains viii, 128 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references (p. 108-115).

Red clover (Trifolium pratense L.) cvs 'Altaswede' (2n=2X=14) and 'Norseman' (2n=4X=28) were used in the present study to investigate tissue culture initiation, plant regeneration and the occurrence of somaclonal variation. Hypocotyl explants of aseptic seedlings were inoculated into L2 medium containing 0.06 mg/1 Picloram and 0.1 mg/1 benzyladenine for callus induction. Calli were usually induced after two weeks of culture. Callus induction frequency was 60% to 85% of the explants cultured with 'Altaswede' showing a slightly higher frequency than 'Norseman'. Satisfactory results were obtained under dark or light conditions using either test tubes or petri plates, as culture vessels. After callus induction, an experiment was conducted to regulate shoot induction by subculturing the calli on L2 medium containing 0.01 mg/1 2,4-dichlorophenoxy acetic acid and 2 mg/1 adenine (LSE) and on B₅ medium containing 2 mg/1 naphthalene acetic acid and 2 mg/1 adenine, media which have been reported to be shoot-supportive. However, both media failed to initiate shoots under the present experimental conditions. Further tests confirmed that LSE medium did not induce shoots from these calli and that callus growth on LSE medium steadily deteriorated over several subcultures. Subsequently, various media were tested with an emphasis on different combinations of growth regulators. Root differentiation from these calli was frequently observed. Shoots were initiated from some calli when they were transferred from SCP medium to media containing naphthalene acetic acid and kinetin. Embryogenic callus of one genotype was selected and maintained on LSP medium, leading to the regeneration of numerous plants. Supplementation with arginine, glutamic acid and casein hydrolysate did not show a significant effect on callus growth and differentiation. The source of callus influenced rates of growth and the occurrence of differentiation. Usually 'Norseman' calli grew faster and produced more roots than 'Altaswede' calli, while shoots were induced only from 'Altaswede' calli. Although 'Norseman' had more shoot tips induced to produce multiple shoots, the multiple shoot number per culture of 'Altaswede' was higher than that of 'Norseman'. Shoot tip cultures were also established to induce multiple shoots and to regenerate plants via root organogenesis. Regenerants from initial multiple shoots (RG1), multiple shoots after two subcultures (RG2), three-month calli (RG3) and one-year calli (RG4) were evaluated for chromosome number stability, morphology and several biochemical traits. When 'Altaswede' plants were analysed for chromosome number, RG1 and RG3 plants were normal, while one RG2 plant and 23% of 119 RG4 plants had tetraploid chromosome numbers. Regenerated plants were quite stable regarding their isozyme patterns of malate dehydrogenase, 6-phosphogluconate dehydrogenase, phosphoglucose isomerase, phosphoglucomutase and shikimate dehydrogenase and their nodule leghaemoglobin profiles. Morphologically, the leaflet length to width ratio of RG1, RG2 and RG3 plants of 'Altaswede' showed significantly more variation than control plants (P≤0.01), while RG4 plants of 'Altaswede' and RG1 and RG2 plants of 'Norseman' were not different from control plants. It is suggested that the absence of detectable differences in the RG4 'Altaswede' plants was a consequence of their origin from one original genotype. Variability and stability of regenerated plants are discussed. / Land and Food Systems, Faculty of / Graduate

Dissertation (PhD)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Pine sawdust-shavings (Pinus spp.) is at present a very popular soilless substrate in South African greenhouses. Growers use fresh pine sawdust-shavings as a substrate, which is biologically highly unstable. The greenhouse industry is looking at alternative organic substrates such as coco peat, which already went through a decomposition process and is more stable. A biological inactive substrate such as sand was included to compare microorganism activity with organic substrates. The main objective of this study was to compare the growth, yield and quality of hydroponically grown tomatoes in response to different growth mediums in combination with nitrogen source, irrigation frequency, period of substrate use and liming. In general the drainage water pH declined with an increase in NlLt+-N in the nutrient solution. Low pH values in the drainage water, especially when coco peat was used, had a detrimental effect on marketable yield. The drainage water pH of pine sawdustshavings increased during the growing season when 100 % N03--N was used. Due to the higher cation exchange capacity of coco peat, the drainage water electrical conductivity tends to increase more rapidly than with pine sawdust-shavings, during conditions with high temperatures and when insufficient irrigation volumes per irrigation cycle is applied. As expected the drainage water N03--N content decreased as the NlLt+-N content increased in the nutrient solution. Pine sawdust-shavings recorded a much lower N03--N and NlLt+-N content than sand and coco peat and thus supports the hypothesis that microbiological activity is higher in pine sawdustshavings, especially in the second season of substrate use. Coco peat produced the highest number of marketable fruit and yield per plant, followed by pine sawdustshavings and sand in the first season of substrate use. The number of marketable fruit and yield decreased with an increase in NlLt+-N content in the nutrient solution during production in warmer, summer conditions. Contrary to these fmdings, production in cooler, winter conditions recorded high yields when only N03--N or 80% N03--N : 20% NRt +-N was applied. The unmarketable yield increased with an increase in NlLt+-N in the nutrient solution. Visual evaluations showed that blossom-end rot (BER) was the main contributor to unmarketable yield. Increasing levels ofN03--N as nitrogen source in the nutrient solution, reduced weight loss and increased the loss of fruit firmness of tomatoes during storage. Increasing levels of N03 --N also increased fruit pH and reduced total titratable acidity. Coco peat produced fruit with a higher pH than pine sawdust-shavings. An increase in irrigation frequency affected fruit firmness negatively when coco peat was used as substrate. Different irrigation and fertigation practices are needed for different growth mediums and management needs to be adapted according to the growing season (winter vs. summer). / AFRIKAANSE OPSOMMING: 'n Mengsel van dennesaagsels en -skaafsels (Pinus spp.) word tans deur Suid- Afrikaanse kweekbuisprodusente gebruik as grondlose groeimedium. Hierdie groeimedium word nie vooraf gekomposteer nie en is dus biologies onstabiel. Die kweekbuisindustrie ondersoek tans die gebruik van alternatiewe, gekomposteerde en stabiele organiese groeimediums soos kokosveen. 'n Biologies onaktiewe groeimedium soos sand is ook ingesluit om met organiese groeimediums te kan vergelyk. Die hoof doelwit van die studie was om plantontwikkeling, opbrengs en kwaliteit van hidroponies geproduseerde tamaties te evalueer in verskillende groeimediums en in kombinasie met stikstofbron-verhouding, periode van groeimedium gebruik, besproeiingsfrekwensie en bekalking. Oor die algemeen het die pH in die dreinaat gedurende die groeiseisoen toegeneem soos die NH/-N inhoud verhoog het in die voedingsoplossing. Lae pH waardes in die dreinaat, veral waar kokosveen gebruik was, het 'n nadelige effek op bemarkbare opbrengs gehad. Die pH in die dreinaat van dennesaagsels en -skaafsels het gedurende die groeiseisoen toegeneem met die gebruik van 100% NO)--N in die voedingsoplossing. Die elektriese geleiding in die dreinaat van kokosveen neem vinniger toe gedurende toestande waarin hoë temperature en onder besproeiing voorkom, as in dreinaat van dennesaagsels en -skaafsels. Die NO)--N inhoud in die dreinaat het soos verwag afgeneem soos die NRt+-N inhoud in die voedingsoplossing toegeneem het. 'n Baie laer NO)--N en NRt+-N inhoud is by dennesaagsels en -skaafsels aangeteken wat dus die hipotese ondersteun dat mikrobiologiese aktiwiteit, veral in die tweede seisoen van gebruik, hoër is in dennesaagsels en -skaafsels as in sand en kokosveen. Kokosveen het die hoogste aantal bemarkbare vrugte en massa per plant geproduseer, gevolg deur dennesaagsels en -skaafsels en sand. Die aantal bemarkbare vrugte en opbrengs het verlaag met 'n verhoging in NRt+-N in die voedingsoplossing gedurende warm, somer toestande. In teenstelling met vorige resultate is gevind dat 100% NO)-- N of 80% NO)--N : 20% NRt+-N hoë opbrengste gelewer het gedurende koeler, winter toestande. Die onbemarkbare opbrengs het verhoog met hoër NRt+-N vlakke. Visuele waarnemings het aangedui dat blom-end verrotting die grootste bydrae tot onbemarkbare opbrengs gelewer het. 'n Verhoging in NO)--N vlakke het massaverlies beperk en die verlies in fermheid verhoog gedurende opberging. Hoër NO)--N vlakke het ook die pH van vrugte verhoog en die totale titreerbare suur verlaag. Kokosveen het vrugte met 'n hoër pH as dennesaagsels en -skaafsels geproduseer. 'n Toename in besproeiingsfrekwensie het vrug fermheid negatief beïnvloed wanneer kokosveen as groeimedium gebruik was. Verskillende besproeiings- en voedingspraktyke word benodig vir verskillende groeimediums en bestuur van die groeimediums moet aangepas word by klimaatstoestande gedurende die spesifieke produksieseisoen.

The influence of nitrification on the “soil” solution of container media has not been documented. The investigation of this influence is justified since the ionic form of N in a soil solution has a significant influence on plant tissue nutrient content and growth. Three genera of woody plants were grown in one-liter containers filled with pine bark, treated with and without a nitrification inhibitor and fertilized with 210 ml of a 100 ppm NH₄-N solution. Without the inhibitor and over time, “soil” solution NH₄-N concentrations and pH decreased and NO₃-N concentrations increased. “Soil” solution and tissue cation concentrations were generally greater without the inhibitor. In a second experiment, pine bark in one-liter containers was treated with either 0, 3 or 6 kg lime m⁻³. “Soil” solution data and NO₃-N accumulation rate (NAR) data showed an earlier nitrification of NH₄-N at the 6 kg lime compared to the 3 kg lime treatment whereas NO₃-N was not found at the 0 kg lime treatment. In a 3rd experiment, pine bark in one-liter containers was treated with 210 ml of either 25, 100 or 200 ppm NH₄-N. Over time “soil” solution NO₃-N concentrations were greatest and pH values were lowest at the 200 ppm N treatment. The NAR of the 25 ppm N treatment was less than the 100 and 200 ppm N treatment which were not different. The lack of correspondence between the “soil” solution NO₃-N data and the NAR data for the 100 and 200 ppm N treatments was explained on the basis of NH₄-N supply. In a 4th experiment, pine bark in one-liter containers were subjected to either 10°, 20°, 30° or 40° C for 24 days. “Soil” solution NH₄-N concentrations decreased over time at 10°, 20° and 30°. “Soil” solution NH₄-N and NO₃-N concentrations at 40° were considerably higher and lower, respectively, than at other temperatures. Over time the general order of NAR was: 20° = 30° > 10° > 40°. Results of these experiments indicate that nitrification is an important consideration in the nutrition of container-grown plants. / Ph. D.

Micropropagation of Aloe polyphylla, an endangered species with a high ornamental and medicinal value, is an important part of its conservation. However, the in vitro culture was hindered by the phenomenon of hyperhydricity. The research reported in this thesis was undertaken for two reasons. Firstly, to understand the role of various culture factors involved in the process of hyperhydricity in A. polyphylla and to identify the in vitro conditions, under which this disorder can be prevented. Secondly, we conducted an investigation into the underlying mechanisms of this phenomenon by probing if it was mediated through internal cytokinins. Ammonium (NH4 +) ions, applied cytokinins (CKs) and CK concentrations were tested in multifactorial combinations and significantly influenced the regeneration rate and occurrence of hyperhydricity. Shoots were grown on media with different NH4 + concentrations (10.3, 20.6 and 61.8 mM) and supplemented with BA, zeatin or TDZ at 0, 5 or 15 ìM. Elevating the levels of NH4 +, in the absence of CKs, could not induce hyperhydricity. Similarly, very low hyperhydricity was observed when CKs were added to media containing low NH4 + (10.3 mM). However, in the presence of higher NH4 + concentrations, CKs increased hyperhydricity in a concentrationdependant manner, suggesting that they were capable of inducing this syndrome only when other factors in the culture system were not optimised. High numbers of healthy looking shoots were produced on media with low NH4 + and low BA or zeatin (5 ìM). The use of TDZ resulted in the formation of buds, which did not develop into shoots. In view of the fact that NH4 + was supplied in the form of NH4NO3, it was difficult to determine if NH4 + or nitrate (NO3 -) ions were associated with the increase in hyperhydricity. We further examined the role of nitrogen (N) supplied as inorganic NH4 + or NO3 -, or organic glutamine. The omission of total N from the culture medium resulted in low multiplication and hindered shoot growth. Ammonium as the sole source of N depressed shoot regeneration and growth and escalated the frequency of hyperhydricity to ca. 50%. When NO3 - was used as the sole N source, shoots of fine quality were produced and hyperhydricity was completely eliminated. Overall, the MS N mix was superior to any single N source for multiplication and growth of shoots, suggesting a synergistic effect between NH4 + and NO3 - on shoot regeneration. Furthermore, not only the absolute amount of N, but also the relative amounts of NH4 + and NO3 - influenced the multiplication rate, frequency of hyperhydricity and shoot quality. The highest regeneration was obtained with NH4 + : NO3 - ratios (mM) of 20 : 40, 30 : 30 and 40 : 20. Decreasing the ratio of NH4 + : NO3 - lowered the occurrence of hyperhydricity. The potential of glutamine as the sole source of N was also demonstrated, since its application resulted in the production of good quality shoots and almost no hyperhydricity. Shoot explants grown in static liquid media became hyperhydric and lost their ability to regenerate. The type of gelling agent used to solidify the medium affected greatly hyperhydricity and shoot multiplication. Gelrite resulted in a significantly lower multiplication rate and four times higher hyperhydricity (64.7%) compared to when agar was used. Gelrite was further selected to test the hypothesis if hyperhydricity can be overcome by decreasing the relative matric potential of the media, and respectively the availability of water, as represented by increasing gelrite concentrations. Satisfactory reduction in hyperhydricity was achieved only at 16 g l-1 gelrite, however the regeneration also decreased. The nature of the gelling agent is therefore essential for the successful control of this phenomenon. It appears that a crucial prerequisite for the reduction of hyperhydricity in tissue cultures of A. polyphylla is the gaseous exchange between the in vitro atmosphere and the outside environment. In ventilated cultures, achieved by using a modified lid with a hole (d = 7 mm) covered with polyester or cotton mesh, hyperhydricity was completely eliminated, irrespectively of the type of gelling agent. Ventilation was further advantageous for the in vitro regenerants by increasing their leaf chlorophyll content as well as epicuticular wax deposition, the last one being indicative of the development of the water loss regulation mechanisms of explants. The increased culture ventilation, however, was negatively correlated with the regeneration rate and shoot growth. Endogenous CKs were measured in in vitro regenerants after an eight-week cycle to examine whether the hyperhydricity-inducing effect of exogenous CKs and gelling agents is associated with changes in the endogenous CK content. The content of endogenous CKs, determined by HPLC-mass spectrometry, in the shoots grown on CK-free media comprised isopentenyladenine-, trans-zeatin- and cis-zeatin-type CKs. The application of exogenous CKs resulted in an increase in the CK content of the shoots. Following application of zeatin, dihydrozeatin-type CKs were also detected in the newly-formed shoots. Application of BA to the media led to a transition from isoprenoid CKs to aromatic CKs in the shoots. Shoots grown on gelrite media contained higher levels of endogenous CKs compared to those on agar media. Total CK content of hyperhydric shoots was higher than that of normal shoots grown on the same medium. We suggest that the ability of exogenous CKs and gelrite to induce hyperhydricity in shoots of Aloe polyphylla is at least partially due to up-regulation of endogenous CK levels. However, hyperhydricity is a multifactor process in which different factors intervene. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.