Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2008. / ‘Brookfield Gala’ apple trees were planted out in July 2003 in a Dundee soil form, consisting
of well-aerated sandy loam soil. During the first 12 months trees received young tree
solutions high in nitrogen. The nutrient solution of the 2nd leaf trees was based on a yield
estimation of 10 ton. ha-1 plus 30%. Nutrient solutions for the 3rd leaf trees were based on 25
ton. ha-1 yield estimations and adapted upwards.
Seasonal uptake and distributions were determined for macro and micro elements, using twoand
three-year-old apple trees during the seasons 2004/2005 and 2005/2006. In the bearing
apple trees the macro nutrient accumulated rapidly from late winter to late autumn. Prior to
leaf drop most of the N, P, S, Mg and a small portion of K were redistributed back into the
permanent parts of the tree. On the other hand, all Ca in the leaves was lost through leaf drop.
Apple fruit contains comparatively large quantities (±60.2%) of K, which are removed during
harvest.
Guidelines for minimum and maximum nutritional requirements based on the amount
necessary to produce 1 kg fruit were determined. For the 3rd leaf trees the minimum macro
nutrient requirements (g. kg-1 yield) of N, P, K, Ca, Mg and S were ±1.7, ±0.3, ±2.3, ±0.5,
±0.2 and ±0.2, respectively. The maximum nutrient requirements (g. kg-1 yield) for N, P, K,
Ca, Mg and S were ±2.6, ±0.4, ±3.3, ±1.9, ±0.4 and ±0.2, respectively. For the 3rd leaf trees
the minimum micro nutrient requirements (mg. kg-1 yield) of Na, Mn, Fe, Cu, Zn, B and Mo
were ±75.1, ±1.3, ±28.7, ±0.9, ±3.0, ±5.7 and ±0.3, respectively. The maximum nutrient
requirements (mg. kg-1 yield) of Na, Mn, Fe, Cu, Zn, B and Mo were ±102.9, ±7.8, ±32.6,
±1.1, ±6.5, ±7.6 and ±0.3, respectively.
Labelled N uptake and distribution for two- and three-year-old apple trees were also
determined during the same seasons. The labelled N uptake and distribution results indicated
that there was a low labelled N uptake in the initial growth stages, suggesting the importance
of internal N reserves for plant development at the beginning of the season. In the active
growing period more than 60% of the labelled N was found in the new growth. Uptake
efficiency improved as the trees grew older. The effect of different nutrient levels on tree growth, yield and fruit quality was assessed:
lower (80%) than the standard (100%) and three higher (120%, 140% and 160%). Results
indicated that different nutrient levels had no effect on yield, blush or TSS during the 18
months of application over two bearing seasons. The application of biological products
(humic acid, and compost plus compost extract) over a period of 18 months had a significant
influence on the TSS, malic acid and citric acid concentrations. A tendency towards an
increase in total fine root number and length occured with the addition of biological
ameliorant.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/1724 |
| Date | 03 1900 |
| Creators | Kangueehi, Grace Nandesora |
| Contributors | Stassen, P. J. C., Theron, K. I., Rosecrance, R., University of Stellenbosch. Faculty of Agrisciences. Dept. of Horticulture. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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