No description available.

Thesis (M. Phil.)--University of Hong Kong, 1980.

The effect of activated charcoal, autoclaving and culture media on sucrose hydrolysis in tissue culture media was investigated. Activated charcoal acidified an aqueous sucrose (5%) solution and culture media by about 1 to 2 units after autoclaving . Sucrose hydrolysis in tissue culture media and/or aqueous sucrose (5%) solutions containing activated charcoal (buffered to pH 5.8) was dependent on both the hydrogen ion concentration (pH) and autoclaving. After autoclaving, 70%, 56% and 53% sucrose hydrolysis were respectively recorded in a 5.0% sucrose solution, Murashige and Skoog (MS) and Gamborg B5 (B5) liquid media in the presence of 1.0% activated charcoal, added before autoclaving . In the absence of activated charcoal, autoclaving resulted in about 20% of the sucrose being hydrolysed The adsorption of 2, 4-dichlorophenoxyacetic acid (2,4-D) by activated charcoal from methanol and aqueous solutions was determinated using HPLC. The amount of the added 2,4-D decreased in both methanol and aqueous solutions in the presence of activated charcoal, compared with those in the absence of activated charcoal. In methanol and aqueous solutions, activated charcoal used at the level of 0.1% significantly reduced 2,4-D. About 68.4% and 60.9% respectively of the added 2,4-D was adsorbed by activated charcoal (1.0%) from these solutions. The changes of inorganic elements in MS-salt solutions, in the presence of activated charcoal, were analysed by SEM-EDX. The concentrations of magnesium (Mg), calcium (Ca), iron (Fe) and zinc (Zn) deceased in the presence of activated charcoal, while the concentrations of potassium (K), copper (Cu), manganese (Mn), phosphorus (P), and sulphur (S) increased in the MS salt solution in the presence of activated charcoal compared with no activated charcoal in the medium. This suggests that activated charcoal adsorbed calcium, magnesium, iron and zinc and released copper, manganese, phosphorus and sulphur. Rooting occurred when 7-day-old seedling hypocotyls of Daucus carota L. Cape Market were placed on MS medium supplemented with 2,4-D, and IAN/NAA in the presence of activated charcoal. Hypocotyls did not produce roots on the 2,4-D containing media in the absence of activated charcoal. The roots were produced polarly on the NAA/IAA-containing media in the presence of activated charcoal. No-polarity of root formation was observed on media supplemented with NAA/IAA without activated charcoal. Different responses of hypocotyls to a series of 2,4-D concentrations (0.5, 1.0, 3.05.0, 8.0, and 10.0 mg l ¯¹) were observed on media supplemented with 0.02, 0.1 and 0.5% activated charcoal. In the NAA/IAA containing media in the presence of activated charcoal, root number per hypocotyl decreased. Root number perhypocotyl, on the media supplemented with NAA and IAA, increased when hypocotyls were pre-cultured on MS medium supplemented with 2,4-D (1.0 mg l ¯¹) for 2-3 days. When hypocotyls were pre-cultured on a 2,4-D containing MS medium for 5 days, embryos emerged from the hypocotyls directly on the medium supplemented with 2,4-D in the presence of activated charcoal. Addition of activated charcoal to MS medium supplemented with 2,4-D resulted in somatic embryogenesis of Daucus carota. Somatic embryos were not formed on the medium in the absence of activated charcoal. In suspension culture, the incorporation of 0.01 to 1.0% concentrations of activated charcoal to the MS medium, irrespective of 2,4-D, increased the number of somatic embryos produced. The maximum number of somatic embryos were produced with 1.0% activated charcoal. Further development of embryos of Daucus carota occurred on the media in the presence of activated charcoal, and the embryos subsequently regenerated normal plantlets. Abnormal somatic embryos followed the addition of 3.0% activated charcoal to the medium. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2000.

In South Africa, clonal forestry of Eucalyptus and its hybrids has been implemented to increase the productivity on existing forestry lands and marginal sites and to facilitate the production of desired fibre types for timber processing operations. The cold-tolerant Eucalyptus grandis x E. nitens hybrids have produced consistently high yields, and are propagated clonally with limited success via a macro-cutting system currently in use for other hybrid species. The heart of vegetative propagation operations is the clonal hedge and its management, and nutrition in particular, is an important element of any vegetative propagation programme. However, achieving and sustaining an optimum nutritional balance in macrohedges is difficult in practice and, in order to accurately predetermine the optimum plant nutrition required all year round and to ensure optimal levels of rooting, a more controllable nutrient environment is essential. Hydroponics may facilitate this control of nutrition. At the same time it may be possible to manipulate the system to determine accurately what levels of each nutrient may contribute to the highest rooting and more importantly allow forest nursery managers to maintain those levels in a practical manner. The main aims of the present work were to obtain and compare cuttings and rooting yields from hydro-ramets in different hydroponic substrates and systems and to investigate the possible roles of essential nutrients on those parameters. Modified Nutrient Film Technique (NFT), ebb-and-flow and aeroponic tables were used in this study. The former consisted of eight individual gutters, allowing for eight different substrates to be tested simultaneously. One gutter was set up as an unmodified NFT table and the other seven gutters had gravel, Leca, peat, perlite, perlite: vermiculite mix, Rockwool® and sand as substrates; all were supplied with the same nutrient solution. Three commercial clones were used throughout these trials: GN107, GN156 and NHOO. Rooting results and data from plant elemental analyses indicated that certain elements (Ca, Cu, Zn, Mn and B) appeared to play a more important role in rooting than others (N, P, K, Mg, Na and Fe). It was also found that when comparing the hydroponic systems, the substrate and / or method of irrigation affected the availability and uptake of different nutrients, which in turn affected the rooting of coppice collected from those ramets. The rooting performance of coppice from the eight different substrates tested in the NFT system was compared. Within each of the four harvests undertaken, both clone and substrate had a significant effect on the rooting performance. However, when the four harvests were compared, only harvest number/time had a significant effect on the rooting performance of the cuttings derived from the hydro-hedges . For both the ebb-and-flow and aeroponics systems (where there was no substrate), only the clone had a significant effect on the rooting performance. In addition to this, the plants from the ebb-and-flow system produced the highest number of cuttings to be placed overall (7.9 cuttings per mother plant per harvest) while those from the gravel substrate had the highest rooting percentage overall (26.9 %). When combining these two factors into a success rate, the perlite substrate rated highest (1.7 rooted cuttings per mother plant per harvest). From a cost efficiency perspective, perlite was the most cost effective substrate, as it required the least initial capital outlay to produce one million rooted clones per year from a hydroponics system (R6 533 655). The plants in the perlite substrate also produced the highest number (6 700) of rooted cuttings per year from 1 000 mother plants with a low cost per plant (R2.33 per rooted plant). / Thesis (M.Sc.)-University of KwaZulu- Natal, Durban, 2004.

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 69-74)

Thesis--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references.

Thesis (Ph. D.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 173-188).

Thesis (M.Phil.)--University of Hong Kong, 1980. / Also available in print.

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references.

Orientador: Roberto Lyra Villas Bôas / Banca: Dirceu Maximino Fernandes / Banca: João Carlos Cury Saad / Banca: Valdemicio Ferreira de Sousa / Banca: Marcos Vinicius Folegatti / Resumo: O presente trabalho foi desenvolvido com o objetivo de avaliar a aplicação, via fertirrigação, de soluções com diferentes condutividades elétricas, bem como seu monitoramento e controle, no desenvolvimento e qualidade de cultivares de gérbera (Gerbera jamesonii L.) em vaso, como meio de indicar a melhor concentração de sais a ser aplicada. O experimento foi conduzido sob cultivo protegido no Departamento de Recursos Naturais/Ciência do Solo da Fazenda Experimental Lageado, pertencente à Faculdade de Ciências Agronômicas da UNESP Campus de Botucatu, município de Botucatu, Estado de São Paulo. Adotou-se o delineamento experimental em blocos casualizados com quatro repetições em esquema fatorial constando de cinco níveis de condutividade elétrica (CE) e dois cultivares em cada ciclo, totalizando quarenta parcelas. Os níveis de CE (soluções) foram: 0,5; 2,0; 3,5; 5,0 e 6,5 dS m-1, e o monitoramento da concentração de sais da solução do substrato na zona radicular das plantas foi realizado por meio da retirada da solução com extratores, duas vezes por semana. Durante o período de condução de cada experimento foi avaliado o pH, área foliar, fitomassa seca, quantidade de botões florais, teor e acúmulo de macro e micronutrientes na parte aérea da planta e teor de macro e micronutrientes na folha diagnóstico, concentração de nitrato na seiva da folha, concentração de nitrato e potássio na solução do substrato e intensidade de cor verde. Ao final do experimento foram avaliadas a fitomassa seca e o teor e acúmulo de macro e micronutrientes na parte aérea de plantas consideradas no ponto de comercialização e a classificação das plantas quanto à qualidade. Para as análises pósprodução foram avaliadas as seguintes variáveis: altura de plantas no início e ao final do experimento pós-produção, diâmetro da superfície foliar do vaso... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present research was developed with the objective of evaluating application through fertigation of solutions with different electrical conductivities as well as monitoring and control on the development and quality of gerbera (Gerbera jamesonii L.) in potted cultivars in order to find the best salt concentration content to apply. The experiment was conducted under greenhouse conditions at the Natural Resources Department Soil Science area on Lageado Experimental Farm, owned by Agronomy Science Faculty on Botucatu Campus, located in the town of Botucatu, state of Sao Paulo, Brazil. The experimental design were randomized blocks with four repetitions in factorial scheme consisting of five electrical conductivity levels (EC) and two cultivars in each cycle, totalizing forty lots. The levels of EC (solutions) were: 0.5; 2.0; 3.5; 5.0 e 6.5 dS m-1, and the monitoring of salt concentration in the substratum solution in the root zone of the plants was done through the extraction of the solution by means of extractors twice a week. During the conduction of each experiment the following were evaluated: pH, leaf area, dry mass, floral bud quantity, accumulation of macro and trace element contents on the aerial portion of the plant, macro and trace element contents in the diagnostic leaf, nitrate concentration in the sap of the leaf, nitrate and potassium concentration in the substratum solution and green color intensity. At the finish of the experiment were evaluated: dry mass, accumulation of macro and trace element contents on the aerial portion of the plants considered to have reached their point of commercialization, as well as the classification of these plants with regard to their quality. For the post production analysis, the following parameters were evaluated: plant height at the start and at the finish of the post production experiment, diameter of... (Complete abstract click electronic access below) / Doutor