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Effects of different storage conditions on moringa oleifera lam. Seed : ultrastructure, viability, oil biochemical properties and content
Thesis (PhD (Horticultural Science))--University of Pretoria, 2016.
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2026
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| access_status_str | Open Access |
| author2 | Du Toit, Elsie Sophia |
| author_browse | Du Toit, Elsie Sophia |
| author_facet | Du Toit, Elsie Sophia |
| collection | Thesis |
| description | Thesis (PhD (Horticultural Science))--University of Pretoria, 2016. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/110094 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:39:06.697Z |
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| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
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| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/110094 Effects of different storage conditions on moringa oleifera lam. Seed : ultrastructure, viability, oil biochemical properties and content Du Toit, Elsie Sophia fotouo@yahoo.fr Robbertse, P.J. (Petrus Johannes), 1932- Fotouo-Makouate, Helene Seed storage Ultrastructure Biodiesel Oil properties Thesis (PhD (Horticultural Science))--University of Pretoria, 2016. The growing world population has led to the increase in demand for food, energy and pressure for high potential agricultural land. Global leaders now face the need to rapidly reduce dependence on fossil fuels while providing a sustainable way of life for the increasing population. Using multipurpose plants as an alternative for energy production may be one of the answers to accomplish these enormous tasks. There is, therefore the need to search for other biodiesel feedstocks from non-agricultural food crops which are not staple foods for human consumption and can be grown in less productive soils and be cultivated at much lower cost, compared to those of conventional edible oil crops. Moringa oleifera seed has been cited as one of those unconventional sources. In addition, M. oleifera seed is used as a food/fodder source, as edible oil, for water purification as well as for the iv treatment of various ailments. The demand for high quality seed is therefore on the rise. Unfortunately, seed ageing is one of the main problems responsible for low quality seed. Successful seed storage, however necessitates an understanding and careful exploitation of post-harvest physiology of the seeds. Oilseeds in particular have a poor reputation as they are said to have limited longevity characterised by the progressive loss of viability and lipid content as well as changes in oil composition within a short period. Therefore, the aim of this study was to find appropriate storage conditions to ameliorate seed deterioration and to contribute towards the understanding of seed aging mechanisms in general and M. oleifera seed in particular. Seeds for experiments were obtained from an eight year old orchard at the Hatfield Experimental Farm of University of Pretoria. For one experiment, fruits of M. oleifera harvested during 2009 and 2011, were bagged in open polymesh bags and stored at ambient room temperature for, 2 and 3 years after which seeds were removed from the fruits and assessed for germination vigour and ultrastructural changes. The second experiment consisted of seeds removed from fruits harvested from all 8-year-old bearing trees of the same orchard. Seeds were mixed and divided according to ISTA procedure. Seeds were stored in incubators according to a factorial 4 x 3 x 2 scheme with four temperatures (-19°, 4°, 20° and 30°C), three storage periods (6, 12 and 24 months) and two packaging types (paper bags and sealed aluminium bags) for all treatments. For the seed germination experiment an additional 4 x 3 x 3 scheme with four temperatures (-19°, 4°, 20° and 30°C), three storage periods (6, 12 and 24 months) and 3 moisture content levels (4 ± 0.15, 8 ± 0.05 and 11 ± 0.1%) were performed. Germination, ultrastructural studies, oil quantity and quality and important seed biochemical components were assessed concurrently. The ultastructure and germination studies of seed stored in its fruit revealed for the first time that the remnants of the outer integument and the inner integument remaining tightly attached to the cotyledons when trying to remove the seed coat. Also for the first time the viability test revealed the presence of dormancy in Moringa oleifera seed. It is possible that the remnants of integuments play a role in seed dormancy. The thick cell wall of the inner integument may contain substances such as calcium and xylose in high concentrations that are known to impose dormancy. In the cotyledonary cells of three-year-old seed, the v membranes of the protein bodies had deteriorated, causing lipid bodies to enter the protein body and in some cells of the embryo, the cytoplasm had shrunk and detached from the cell wall (incipient plasmolysis). The decrease in seed viability during storage was found to be associated with loss in membrane integrity visible in the micrographs. This was confirmed by an increase in electrolyte leakage. The germination percentage of one-year-old seed was similar to that of freshly harvested seed but decreased from two years of storage onwards. This original study showed that the longevity of M. oleifera seeds can be extended if they are stored within their capsules (fruit). Seed moisture content (mc) was for the first time explored in this study. Moisture content and temperature were found to be the main factors affecting seed viability when they are separated from the fruit. M. oleifera seed stored in aluminium bags maintained more or less their initial moisture content throughout the storage period as expected. The moisture content of seed stored in paper bags increased or decreased according to the relative humidity and the temperature of the incubator in which they were stored. The germination percentage of seed stored with 8% mc in paper bags at 20° to 30°C was less affected during the 24 months of storage. The optimum germination of M. oleifera seed in this experiment was obtained with seed of which mc was reduced to 4% before storage and stored in aluminium bags at either 4° or 20°C for 24 months. The higher germination percentage of seeds from the above conditions compared to freshly harvested seeds, was the result of dormancy breakage. However, for shorter storage periods, these conditions (mc of 4%) seem to have an inhibiting effect on germination unless the seed is stored at 30°C. It is not known if the patterns of ultrastructure deterioration in seed differ according to the storage conditions. Further ultrastructural studies were performed on sub-epidermal cotyledon cells of seed stored in controlled conditions (seed with 8% mc, stored in paper and aluminium at 4° and 30°C; seed with 4 and 11% mc, stored in aluminium at 4°, 20° and 30°C). Damages similar to those observed in the three-year-old seeds which were stored in their fruits, were visible in seed with 11% mc stored at 20° and 30°C. There was no clear sign of deterioration in seeds stored in other conditions investigated in this study. Although the relationship between ultrastructural changes and storage conditions was not clear, it was evident from this study that high moisture content accelerates seed deterioration. vi No previous scientific study performed on the effect of storage duration on moringa oil was found, so finding optimum conditions for long-term storage is of great economic and nutritional importance. The oil quantity and quality of seeds stored at a wide range of conditions were evaluated as a biodiesel feedstock and as an edible oil. The quality of oil stored in dark bottles at ambient temperature was assessed concurrently. The oil content of M. oleifera seed did not change significantly after 12 months of storage. At 24 months, the oil content of seed stored at 4°C in paper bags and that of seed stored at 20° and 30°C in aluminium bags, decreased significantly. The free fatty acids increased after 12 months at all storage conditions and continued to increase above the recommended value (2%) for biodiesel parent oil at 24 months, except for that of seed stored at -19°C in aluminium bags. The highest increase was recorded in oil from seed in aluminium bags at 30°C (3.48) followed by the oil stored in dark bottles (2.93). The decrease in oil content and increase in free fatty acid was probably due to hydrolysis and oxidation processes that can be accelerated by the high moisture content in the seed. The decrease in density and viscosity of moringa seed oil, although sometimes significantly lower, were generally minimal and were still between the recommended ranges by most biodiesel standards. In order to provide more insight on the process of oil deterioration during storage, additional oil properties such as fatty acid composition, iodine value, induction time, tocopherol content and antioxidant activity also applicable to edible oil, were evaluated. The oil was relatively stable until six months of storage after which it began to deteriorate. At 12 months of storage, the quality of oil extracted from seeds which were stored in aluminium bags at 30°C seemed to have declined the most, followed by oil extracted from seeds stored at 30°C in paper and from the oil stored in bottles. Oil extracted from seeds stored at 4° and -19°C w Plant and Soil Science PhD (Horticultural Science) 2026-05-15T17:26:17Z 2026-05-15T17:26:17Z 16/09/26 2016 Thesis http://hdl.handle.net/2263/110094 en application/pdf |
| spellingShingle | Seed storage Ultrastructure Biodiesel Oil properties Effects of different storage conditions on moringa oleifera lam. Seed : ultrastructure, viability, oil biochemical properties and content |
| title | Effects of different storage conditions on moringa oleifera lam. Seed : ultrastructure, viability, oil biochemical properties and content |
| title_full | Effects of different storage conditions on moringa oleifera lam. Seed : ultrastructure, viability, oil biochemical properties and content |
| title_fullStr | Effects of different storage conditions on moringa oleifera lam. Seed : ultrastructure, viability, oil biochemical properties and content |
| title_full_unstemmed | Effects of different storage conditions on moringa oleifera lam. Seed : ultrastructure, viability, oil biochemical properties and content |
| title_short | Effects of different storage conditions on moringa oleifera lam. Seed : ultrastructure, viability, oil biochemical properties and content |
| title_sort | effects of different storage conditions on moringa oleifera lam seed ultrastructure viability oil biochemical properties and content |
| topic | Seed storage Ultrastructure Biodiesel Oil properties |
| url | http://hdl.handle.net/2263/110094 |