Masters Degrees (Agronomy)

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Browsing Masters Degrees (Agronomy) by Author "De Villiers, Johannes Jacobus"

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    The influence of different production systems, planting densities and levels of shading on the yield, quality and growth potential of ‘Chandler’ strawberry plants (Fragaria ananassa) grown in coir
    (Stellenbosch : Stellenbosch University, 2008-12) De Villiers, Johannes Jacobus; Agenbag, G. A.; Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy.
    The use of hydroponic strawberry production systems is increasing worldwide. Although higher planting densities are possible in vertical production systems, these higher planting densities may have a negative effect on individual plant yield and fruit quality due to lower light levels when compared to conventional (horizontal) production systems. Optimum planting densities will for this reason be affected by light intensities inside the greenhouse and configuration of the vertical production systems. Two experiments were conducted in a plastic cladded greenhouse, fitted with a wetwall and fan cooling system, at the Department of Agronomy, University of Stellenbosch, South Africa during the period of April 2007 to November 2007 (late autumn to early summer). Mean daily maximum temperatures exceeded 26 oC during most of the 14 week harvest period (22 August to 30 November 2007), while photosynthetic active radiation (PAR), measured at 12h00 on cloudless days, inside the greenhouse increased from about 200 μMol m-2 s-1 to about 460 μMol m-2 s-1 during this period. The first experiment compared the effect of two vertical production systems (vertical system and ‘A-shape’ system), subjected to different planting density (16.7, 23.3 and 33.3 plants m-2) and shading (0%, 20%, 50%) treatments, as measured on selected yield, quality and growth factors. The second experiment studied the effect of different planting density (3.3, 5.6 and 10 plants m-2) and shading (0%, 20%, 50%) treatments on the same yield, quality and growth factors in a conventional production system. A comparison with regard to these factors was also made between the highest planting densities of the conventional-, vertical- and ‘A-shape’ system.