The effect of Phosphorus on the growth, plant mineral content and essential oil composition of Buchu (Agathosma betulina)

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dc.contributor.advisor Agenbag, G. A.
dc.contributor.advisor Langenhoven, P.
dc.contributor.author De Villiers, Chris Johan en_ZA
dc.contributor.other University of Stellenbosch. Faculty of Agrisciences. Dept. of Agronomy.
dc.date.accessioned 2008-02-19T07:51:08Z en_ZA
dc.date.accessioned 2010-06-01T08:35:12Z
dc.date.available 2008-02-19T07:51:08Z en_ZA
dc.date.available 2010-06-01T08:35:12Z
dc.date.issued 2007-12 en_ZA
dc.identifier.uri http://hdl.handle.net/10019.1/1867
dc.description Thesis (MScAgric (Agronomy)--University of Stellenbosch, 2007. en_ZA
dc.description.abstract An increase in the demand of buchu (Agathosma betulina) oil has lead to an increase in the commercial cultivation of buchu in fields and also in hydroponic systems. A nutrient solution for hydroponically grown buchu is still required to ensure optimal growth and yield. ASNAPP (Agribusiness in Sustainable Natural African Plant Products) South Africa has done some trials to achieve optimal EC and pH in the nutrient solution. Phosphate concentrations in the nutrient solution might play a significant role due to reports by a variety of researchers on the sensitivity of Protea plants to phosphate. Buchu and Proteas are both part of the Fynbos biome and are found in regions with similar soil (sandy soils with a low pH and mineral contents) and climatic conditions. Two separate experiments were conducted to determine the effect of increasing phosphate concentrations (ranging from 0.00 to 1.40 me L-1) in the nutrient solution on buchu growth. The first experiment was done in a plastic covered structure with a pad and fan and the objective of this trial was to determine the effect of increasing phosphate concentrations in the nutrient solution on the general growth, biomass production, oil composition, mortality rate and chemical composition of the buchu plants. The second experiment was done in a glasshouse with mechanical temperature control and the aim of this trial was to determine the response of buchu to increasing concentrations of P at two different root temperatures. A chemical analysis of the plants was done and the general growth, yield and root mass were recorded to determine the response of buchu plants to the phosphate and temperature treatments. In the greenhouse experiment an optimum growth and yield response of buchu plants was found at a phosphate concentration of 0.7 me L-1 in the nutrient solution. Phosphate concentrations lower or higher than 0.7 me L-1 lead to a decrease in growth and yield. An increase in the phosphate concentration in the nutrient solution lead to a general increase in N, P, K, Ca, Mg and B content in the buchu plants and a decrease in Fe content. The mortality rate of the buchu plants increased with an increase in the phosphate concentration from 0.0 to 1.4 me L-1 in the nutrient solution. The phosphate concentration in the nutrient solution only made a significant difference on one major component of the buchu oil which was Ψ-Diosphenol, but no general trend with Ψ-Diosphenol content and P concentration could be found and the significant difference in Ψ-Diosphenol observed in this trial may only have been due to genetic variation between the plants. The effect of the different root temperatures in the glasshouse experiment was very clear. The buchu plants grown at the high root temperature (20°C) produced a higher yield and better overall growth than the plants grown at lower (10°C) temperatures. The buchu plants grown at 20°C had a significantly higher N, K, Na and B content than plants grown at 10°C. Buchu plants grown at 10°C showed no significant response in terms of growth and yield to the phosphate concentration in the nutrient solution, but plants grown at 20°C exhibited growth and yield peaks at phosphate concentrations of 0.35 and 1.4 me L-1. The peak observed in the plants growth at high phosphate concentrations is unexplainable and can possibly be ascribed to the limitation of the plants per experimental unit and/or amount of replications. The increase in P concentration in the nutrient solution caused a general increase in N, P and K content in the buchu plants. A significant interaction between the phosphate concentration and root temperature was observed for the P, Mn en Zn contents of the plants which meant that the buchu plants respond differently towards phosphate concentrations at different root temperatures. en_ZA
dc.format.extent 3002729 bytes en_ZA
dc.format.mimetype application/pdf en_ZA
dc.language.iso en en_ZA
dc.publisher Stellenbosch : University of Stellenbosch en_ZA
dc.subject Buchu en_ZA
dc.subject Phosphorus en_ZA
dc.subject Buchu -- Growth en_ZA
dc.subject Dissertations -- Agriculture en_ZA
dc.subject Theses -- Agriculture en_ZA
dc.subject Dissertations -- Agronomy en_ZA
dc.subject Theses -- Agronomy en_ZA
dc.subject Hydroponics en_ZA
dc.subject Agathosma betulina en_ZA
dc.title The effect of Phosphorus on the growth, plant mineral content and essential oil composition of Buchu (Agathosma betulina) en_ZA
dc.type Thesis en_ZA
dc.rights.holder University of Stellenbosch en_ZA


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