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Practices used to reduce the incidence of creasing and improve citrus fruit quality
Thesis (MScAgric)--Stellenbosch University, 2026.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1867614133244919808 |
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| access_status_str | Open Access |
| author | Claassen, Jean Pierre |
| author2 | Raath, P. J. |
| author_browse | Claassen, Jean Pierre Raath, P. J. |
| author_facet | Raath, P. J. Claassen, Jean Pierre |
| author_sort | Claassen, Jean Pierre |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2026. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/135689 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:47:10.728Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/135689 Practices used to reduce the incidence of creasing and improve citrus fruit quality Claassen, Jean Pierre Raath, P. J. Louw, E. L. Stellenbosch University. Faculty of AgriSciences. Dept. of Horticultural Science. Thesis (MScAgric)--Stellenbosch University, 2026. Claassen, J. P. 2026. Practices used to reduce the incidence of creasing and improve citrus fruit quality. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/f6d54af7-b58f-4ec6-ac45-a923ddb80cbe Creasing, a preharvest rind disorder known as albedo breakdown, is characterized by fruit with a creased surface, resulting in low fruit firmness due to the weakened albedo tissue. The disorder is a world-wide phenomenon, leading to high economical losses for citrus fruit growers. Apart from orchard losses, the loss in fruit firmness decreases the fruit’s storage capacity, while the creased fruit surface reduces the visual appeal, thus making the fruit unacceptable for export. Although multiple contributing factors have been identified, creasing remains a problem and the physiological basis of its development is not fully known and understood. Where numerous control measures have been researched and implemented, the search for successful preventative practices continues. The main aim of this study was to evaluate practices that reduced the incidence of creasing and that improve citrus fruit quality. The first objective was to compare the use of foliar calcium (Ca) (with and without boron), and Messenger®, a bio stimulant, with the standard use of GA₃ sprays, while also looking at the effect that soil potassium (K) applications have on rind thickness and whether there is a reduction in the incidence of creasing. Another objective of this study was to determine whether Ca uptake could be increased by stimulating root growth with seaweed extracts and fulvic acids, and whether this would also reduce the incidence of creasing. The study indicated that neither the foliar nor the soil nutrient applications significantly increased the Ca, B or K concentration in the fruit albedo. Applications also did not consistently reduce creasing at neither the Western Cape trial sites (Uitkijk and Zandvliet farms) nor the Limpopo trial site (Alicedale). Variations that occurred in fruit maturity and in canopy position significantly influenced creasing, as more mature fruit at the Uitkijk and Alicedale sites and outside canopy fruit at the Alicedale site displayed higher creasing incidence and severity. Thicker rinds were associated with reduced creasing incidence for the two Western Cape trial sites, but not for the Limpopo trial site. The climatic conditions observed during Stage I of fruit growth on Alicedale appeared to significantly affect creasing development. The canopy conditions on Alicedale also resulted in significant differences in fruit maturity between the inside and outside canopy fruit. This study not only challenges previous studies suggesting that Ca reduces creasing incidence via early accumulation in the albedo, but also highlights the impact of fruit maturity, rind thickness, and climatic stress on creasing development. It is proposed that focus should be placed on understanding the impact that climatic and canopy conditions have on fruit maturity and further strategies should be investigated to enhance rind thickness to reduce creasing incidence. These findings emphasize that improving citrus fruit quality does not merely depend on standardised nutrient applications, but physiological and environmental factors should also be considered. Masters 2026-04-08T06:50:17Z 2026-04-08T06:50:17Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/135689 en Stellenbosch University 74 pages : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Claassen, Jean Pierre Practices used to reduce the incidence of creasing and improve citrus fruit quality |
| title | Practices used to reduce the incidence of creasing and improve citrus fruit quality |
| title_full | Practices used to reduce the incidence of creasing and improve citrus fruit quality |
| title_fullStr | Practices used to reduce the incidence of creasing and improve citrus fruit quality |
| title_full_unstemmed | Practices used to reduce the incidence of creasing and improve citrus fruit quality |
| title_short | Practices used to reduce the incidence of creasing and improve citrus fruit quality |
| title_sort | practices used to reduce the incidence of creasing and improve citrus fruit quality |
| url | https://scholar.sun.ac.za/handle/10019.1/135689 |
| work_keys_str_mv | AT claassenjeanpierre practicesusedtoreducetheincidenceofcreasingandimprovecitrusfruitquality |