- Title
- The effect of top dressing treatments on stolon weaning and keeping quality on two potato cultivars in the Gamtoos river valley
- Creator
- Murray, Roger Benjamin
- Subject
- Plants -- Effect of nitrates on
- Date Issued
- 2020
- Date
- 2020
- Type
- Thesis
- Type
- Masters
- Type
- MTech
- Identifier
- http://hdl.handle.net/10948/48522
- Identifier
- vital:40884
- Description
- Potatoes are an important crop in the Eastern Cape, and in South Africa as a whole, as a nutritious staple food. For consumers, they provide a quality, relatively low-priced form of carbohydrate and, for farmers, they are a valuable cash crop. The nutritional requirements of Solanum tuberosum L., in particular its nitrogen (N) needs, during cultivation is an aspect warranting further research. The Eastern Cape is a prime potato-producing region and, as such, is an appropriate and logical choice in terms of a suitable location for the required study. Improper farming practices with regards to improper fertilizer application techniques can adversely affect yields, and excessive application of fertilizer is fundamentally economically unsound, adverse towards the environment and potentially detrimental to the crop. It is therefore imperative that nutrients – and nitrogen in particular – are available to the crop in the correct quantities at the correct time. The objective of this dissertation was to accurately identify the nitrogen fertilizer needs of potatoes – with specific emphasis on whether or not nitrogen affects stolon growth and development. The potato cultivar used in the research trial was Mondial, which is a cultivar well-established in the region. Nitrogen applications needed to be closely monitored with regards to the total seasonal amount of nitrogen applied, the timing of applications and the amount applied at each application. Meaningful data accumulated from this study will help farmers in the area to accurately assess the efficiency of their farming operations. Excessive or insufficient plant nutrition affects tuber bulking and quality. The objective was to accurately identify this “sweet spot” (i.e. the optimal measure and timing) with regards to fertilization, especially nitrogen, while also taking into account various other factors that affect healthy tuber development and stolon formation. The untested assertion that prompted this study was that too much nitrogen adversely affects the number of stolons – and therefore, the number of tubers, since tubers grow from the stolons. It is generally accepted that too little N will adversely affect yields and yield potential will not be achieved, and that too much N will adversely affect yields, incur unnecessary costs and potentially degrade the environment. Optimum nitrogen application quantities were therefore identified, along with points at which deviations from optimum yields occurred. There were 8 distinct treatment combinations – namely: a rate of 150kg/ha, 250kg/ha, 350kg/ha and 450kg/ha – of nitrogen (N) throughout the growing season, administered at 2 different timings (hereafter referred to as the Application Timings). The applications of nitrogen were administered as follows: Application Timing 1 (50% N at planting : 25% N as Topdressing 1 : 25% N as Topdressing 2) and Application Timing 2 (75% N at planting : 12.5% N as Topdressing 1 : 12.5% N as Topdressing 2). The findings suggest that while nitrogen played a role in increasing yield, there was no conclusive evidence to suggest that stolons were weaned by excessive amounts of nitrogen throughout the growing season. The results obtained from statistical analysis showed that, between Application Timing 1 (50%:25%:25%) and Application Timing 2 (75%:12.5%:12.5%), neither split application timing was superior to the other in terms of tuber yield or effect on the average number of stolons when data from all three plantings were combined. In some instances, high stolon numbers were observed in the high N application plots. The highest stolon count in a single data collection in Planting 1 was in the 450kg/ha App. 1 plots in the 3rd data collection. The highest stolon count in a single data collection in Planting 2 was in the 250kg/ha App. 2 plots in the 2nd data collection. The highest stolon count in a single data collection was in the 350kg/ha App. 2 plots in the 3rd data collection. The conjecture that excessive nitrogen causes stolon weaning in potatoes was not supported by the findings of the experiments conducted in the three trial plantings which constituted this research study.
- Format
- Xvii, 174 leaves
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela University
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Murray, R 975119 Dissertation April 2020.pdf | 4 MB | Adobe Acrobat PDF | View Details Download |