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Chilling injury of lemon fruit (Citrus Limon (L.) Osbeck)
Thesis (MScAgric)--Stellenbosch University, 2019.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2019
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| _version_ | 1867613923764600832 |
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| access_status_str | Open Access |
| author | Kirsten, Nicola |
| author2 | Cronje, Paul |
| author_browse | Cronje, Paul Kirsten, Nicola |
| author_facet | Cronje, Paul Kirsten, Nicola |
| author_sort | Kirsten, Nicola |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2019. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/106967 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:43:51.865Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2019 |
| publishDateRange | 2019 |
| publishDateSort | 2019 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/106967 Chilling injury of lemon fruit (Citrus Limon (L.) Osbeck) Kirsten, Nicola Cronje, Paul Hoffman, Lynn Zacarias, Lorenzo Stellenbosch University. Faculty of AgriSciences. Dept. of Horticultural Science. Citrus fruit industry -- South Africa Lemons -- Postharvest diseases and injuries Citrus fruits -- Storage -- Climatic factors Lemons -- Effect of temperature on Lemons -- Postharvest losses -- Prevention Citrus fruits -- Climatic factors UCTD Thesis (MScAgric)--Stellenbosch University, 2019. ENGLISH ABSTRACT: The export-driven South African citrus industry requires sustainable production of high-quality, to meet existing market demands and to expand to new markets. Various countries require citrus fruit to be cold stored at suboptimal low temperatures (<2°C) during export, frequently for >22 days, reducing fruit quality. Low postharvest temperatures lead to the physiological rinddisorder, chilling injury (CI), which develops as sunken, necrotic spots that coalesce and covers the entire fruit rind in brown, sunken lesions, leading to market rejection. This study aimed to investigate pre-harvest factors, including production areas, canopy position, harvest dates and cultivars, that may contribute to a more chilling injury (CI) tolerant lemon fruit rind. In addition, various postharvest technologies were evaluated for its efficacy to counteract CI development, whilst biochemical factors such as pigments and rind sugars influence the rind physiological condition was quantified. Results indicated that CI depends on climate and harvesting period, as shown by the different levels of CI developed by fruit harvested from various climatic areas and over different harvesting periods but within the same area. Higher temperatures at harvest were shown to result in increased CI whereas a rapid drop in temperature during the 60 days before harvest led to the production of a more CI tolerant fruit. Storage temperature and duration affected CI incidence, while higher temperatures and a shorter storage duration resulted in less injury. Fruit stored at -1 °C for 12 days was similar concerning CI development as when stored at 7 °C for >30 days. A commercially effective postharvest method to prevent the development of CI is the application of a higher solid wax coating. This offers protection under cold storage conditions, while it reduces moisture loss, which contributes to CI symptom development. However, an increased volume of high solid wax application resulted in slower rind colour development, leading to paler fruit compared to fruit that received a lower solid wax volume. Caution should thus be taken not to over-wax fruit. This study provides insight into the effect of pre-harvest factors on lemon fruit susceptibility to CI, intending to assist the industry to predict better the likeliness of CI occurring, thus allowing to take timeously, preventive actions. The study also provides the industry with practical and effective postharvest guidelines for the development of strategies to counteract the incidence and severity of CI in cold-sensitive lemon fruit following long-term cold storage, such as during sea freighting to export markets. AFRIKAANSE OPSOMMING: Die uitvoergedrewe sitrusindustrie van Suid-Afrika steun op die volhoubare produksie van hoë gehalte, letselvrye vrugte, om aan bestaande markvereistes te voldoen en om uitbreiding na nuwe markte te bewerkstellig. Verskeie lande vereis egter dat sitrusvrugte vir meer as 22 dae gedurende uitvoer teen suboptimale temperature (<2°C) verskeep word, wat vrugkwaliteit kan verlaag. Lae na-oes temperature lei tot ʼn fisiologiese skildefek bekend as koueskade, wat aanvanklik ontwikkel as nekrotiese vlekke, maar wat later aaneen vloei en ewekansig vergroot totdat die hele vrugskil bedek is met gesonke kolle, sodat dit onbemarkbaar is. Die betrokke studie het ten doel om verskeie voor-oes faktore, wat insluit produksie areas, vrugposisie in die boom, oesdatums en kultivars, te identifiseer as moontlik bydraend tot die ontwikkeling van ᾽n meer vatbare suurlemoen vrugskil. Verder is bestaande na-oes tegnologie geëvalueer vir hul doeltreffendheid om koueskade in vrugte doeltreffend te bekamp, terwyl biochemiese faktore, bepalend vir die fisiologiese toestand van die vrugskil, soos pigmente en skilsuikers, gekwantifiseer was. Resultate dui daarop dat koueskade meestal afhanklik is van klimaat asook spesifieke oestye binne ‘n area, soos gesien in die wisselende vlakke van koueskade in vrugte vanuit verskillende klimaatstreke. Daar is bevind dat hoër temperature tydens oes tot meer koueskade gelei het, maar dat ᾽n vinniger daling in temperatuur in die periode van 60 dae voor oes, vrugte geproduseer het met groter weerstand teen koueskade. Opbergingstemperature en tydsduur van opberging is bevind om ‘n direkte invloed op die ontwikkeling van koueskade te hê waar hoër temperature en korter opbergingstye tot minder letsels gelei het. Vrugte wat teen -1°C gestoor is vir 12 dae, het ongeveer dieselfde skade getoon as vrugte wat opgeberg is by 7°C vir >30 dae. Die aanwending van ᾽n waslaag met hoër aantal vastestowwe is bevind as ‘n geskikte kommersiële na-oes strategie vir die voorkoming of beperking van koueskade maar ook om vogverlies in vrugte, wat bydra tot simptoomontwikkeling, te verminder. Aanwending van ʼn verhoogte hoeveelhede waks het egter veroorsaak dat die skil stadiger verkleur, in vergelyking met vrugte van ᾽n laer hoeveelheid waks ontvang het. Vrugte moet dus nie oorbehandel word met waks nie. Samevattend, bied hierdie studie insigte aan die Suid-Afrikaanse sitrus bedryf oor die effek van voor-oes faktore op koueskadesensitiwiteit van suurlemoenvrugte, maar bespreek ook effektiewe, praktiese na-oes strategieë om voorkoming van koueskade in sitrusvrugte beter te bestuur en te bekamp. Masters 2019-11-26T08:19:54Z 2019-12-11T06:40:50Z 2023-01-04T03:00:11Z 2019-12 Thesis http://hdl.handle.net/10019.1/106967 en Stellenbosch University 173 pages : illustrations (some color) application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Citrus fruit industry -- South Africa Lemons -- Postharvest diseases and injuries Citrus fruits -- Storage -- Climatic factors Lemons -- Effect of temperature on Lemons -- Postharvest losses -- Prevention Citrus fruits -- Climatic factors UCTD Kirsten, Nicola Chilling injury of lemon fruit (Citrus Limon (L.) Osbeck) |
| title | Chilling injury of lemon fruit (Citrus Limon (L.) Osbeck) |
| title_full | Chilling injury of lemon fruit (Citrus Limon (L.) Osbeck) |
| title_fullStr | Chilling injury of lemon fruit (Citrus Limon (L.) Osbeck) |
| title_full_unstemmed | Chilling injury of lemon fruit (Citrus Limon (L.) Osbeck) |
| title_short | Chilling injury of lemon fruit (Citrus Limon (L.) Osbeck) |
| title_sort | chilling injury of lemon fruit citrus limon l osbeck |
| topic | Citrus fruit industry -- South Africa Lemons -- Postharvest diseases and injuries Citrus fruits -- Storage -- Climatic factors Lemons -- Effect of temperature on Lemons -- Postharvest losses -- Prevention Citrus fruits -- Climatic factors UCTD |
| url | http://hdl.handle.net/10019.1/106967 |
| work_keys_str_mv | AT kirstennicola chillinginjuryoflemonfruitcitruslimonlosbeck |