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The impact of protective netting on reproductive bud development, flowering, fruit set and fruit quality in apple trees
Thesis (MScAgric)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867613987046162432 |
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| access_status_str | Open Access |
| author | Jordaan, Stephen Christiaan |
| author2 | Midgley, S. J. E. |
| author_browse | Jordaan, Stephen Christiaan Midgley, S. J. E. |
| author_facet | Midgley, S. J. E. Jordaan, Stephen Christiaan |
| author_sort | Jordaan, Stephen Christiaan |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/127354 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:52.037Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/127354 The impact of protective netting on reproductive bud development, flowering, fruit set and fruit quality in apple trees Jordaan, Stephen Christiaan Midgley, S. J. E. Lotze, Elmi Stellenbosch University. Faculty of Agrisciences. Dept. of Horticulture. Fruit -- Quality Netting Apples -- Breeding -- Varieties Budding (Plant propagation) Crop load -- Management Apples -- Growth Apples -- Flowering time UCTD Thesis (MScAgric)--Stellenbosch University, 2023. ENGLISH ABSTRACT: The overall objective of this study was to determine how yield, fruit quality and maturity, reproductive bud development, flowering, fruit set and early fruit growth of apple orchards are impacted by two types of protective netting compared to open orchards, in the Western Cape Province of South Africa. The study also aimed to investigate the interactive effects between black draped netting and various levels of crop load on reproductive processes of ‘Golden Delicious’ trees. To achieve these aims, three trials were conducted over two seasons. In the first trial, fixed white (20%) netting over ‘Rosy Glow’ resulted in improved fruit growth rate, increased fruit diameter and mass, lighter green ground colour, less peel red colour, lower viable seed count, and less sunburn and hail damage in two consecutive seasons. The netting did not induce any significant effect on percentage reproductive buds (R-buds), R-bud progression for different shoot types, flower progression, flower quality, and early fruit growth. A small but significant reduction in fruit set percentage under netting was, however, found. In the second trial, black draped netting (end-November to end-February) over ‘Golden Delicious Reinders’ resulted in greener fruit, less sunburn and hail damage, reduced firmness, and reduced ratio of total soluble solids (TSS) to titratable acidity (TA). R-bud percentage was promoted under the netting; however, R-bud progression was delayed after net removal. The latter effect may have culminated in delayed flowering, lowered fruit set (farm data) and reduced early fruit growth. In the third trial, black draped netting (mid-December to early March) over ‘Golden Delicious’ resulted in more stem-end russet, greener ground colour, lower firmness and advanced starch breakdown, fewer viable seed, less sunburn, and lower TSS and TA. Significant interactions between net/control and crop load treatments were found for ground colour, TA and TSS:TA. R-bud percentage was higher and more uniform across all crop loads and shoot types under the netting, while the control treatment displayed an increasing R-bud percentage for decreasing crop load level across most shoot types. After the harvest and net removal, R-bud progression was slightly but significantly delayed. Flower progression was unaffected by the netting. For flower quality, significant interaction between flower type and netting was found for pedicel length, receptacle length and number of locules. In addition, significant interaction between net/control and crop load treatments was found for ovule length. Fruit set percentage improved under netting. The different crop load levels did not have a significant impact on flower progression, flower quality and fruit set. The use of both fixed and draped netting in apple orchards has the potential to improve apple fruit quality. However, caution is required based on the impact of draped netting on flowering and reproductive growth during the following season in ‘Golden Delicious’ and its strains. Crop load adjustments are recommended in ‘Golden Delicious’ and its strains to minimise the impact of netting on reproductive growth during the current and following season. AFRIKAANSE OPSOMMING: Die oorhoofse doel van hierdie studie was om vas te stel hoe opbrengs, vrugkwaliteit en rypheid, reproduktiewe vrugknop-ontwikkeling, blom, vrugset, en vroeë vruggroei van appelboorde beïnvloed word deur twee tipes beskermende nette in vergelyking met oop boorde, in die Wes-Kaap, Suid-Afrika. Die studie het ook ten doel gehad om die interaktiewe uitwerking tussen swart drapeernette en verskillende oesladingsvlakke op die reproduktiewe prosesse van ‘Golden Delicious’ bome te ondersoek. Om hierdie doelwitte te bereik, is drie navorsingsproewe oor twee seisoene gedoen. In die eerste proef het wit vaste (20%) nette oor ‘Rosy Glow’ (RG) verbeterde vruggroeitempo, ‘n toename in vrugdeursnee en -massa, ligter groen grondkleur, minder rooi skilkleur, laer lewensvatbare saadtelling, en minder sonbrand en haelskade in twee opeenvolgende seisoene tot gevolg gehad. Die nette het geen betekenisvolle effek op reproduktiewe vrug knop persentasie, reproduktiewe vrug knop progressie vir verskillende loottipes, blomfenologie, blomkwaliteit, en vroeë vruggroei gehad nie. ’n Geringe maar beduidende afname in vrugset-persentasie onder nette, is nietemin gevind. In die tweede proef het swart drapeernette (einde November tot einde Februarie) oor ‘Golden Delicious Reinders’ groener vrugte, minder sonbrand en haelskade, ‘n vermindering in fermheid, en ’n verminderde verhouding tussen totale oplosbare vastestowwe (TSS) en titreerbare suurheid (TA) tot gevolg gehad. Reproduktiewe vrug knop persentasie is verhoog onder die nette, terwyl reproduktiewe vrug knop ontwikkeling vertraag is na verwydering van nette. Laasgenoemde effek mag gelei het tot die vertraagde blom, verlaagde vrugset (plaasdata) en verminderde vroeë vruggroei. In die derde proef het swart drapeernette (middel Desember tot vroeg-Maart) oor ‘Gotlden Delicious’ meer stingelentverruwing, groener grondkleur, laer fermheid en gevorderde styselafbreek, minder lewensvatbare sade, minder sonbrand, en laer TSS en TA ot gevolg gehad. Beduidende interaksies tussen net/kontrole en oeslading-behandelings is gevind vir grondkleur, TA en TSS:TA. Reproduktiewe vrug knop persentasie was hoër en meer eenvormig oor alle oesladings en loottipes onder nette, terwyl die kontrole-behandeling ‘n toenemende reproduktiewe knop presentasie vir laer oesladingsvlakke oor die meeste loottipes getoon het. Na afloop van die oes en die verwydering van nette, is reproduktiewe vrugknopontwikkeling effens maar beduidend vertraag. Blomontwikkeling is nie geaffekteer onder die nette nie. Blomkwaliteit het wel betekenisvolle interaksie tussen blomtipe en die nette getoon wat blomsteellengte, blombodem-lengte en aantal vrughokke betref. Daarbenewens is ‘n beduidende interaksie tussen net/kontrole en oeslading-behandelings gevind t.o.v. saadknoplengtes. Vrugsetpersentasie onder nette het verbeter. Die onderskeie oesladingsvlakke het nie ‘n betekenisvolle impak op blomfenologie, blomkwaliteit and vrugset gehad nie. Die gebruik van vaste nette, sowel as drapeernette, in appelboorde het die potensiaal om appelvrugkwaliteit te verbeter. Nietemin moet omsigtigheid aan die dag gelê word op grond van die impak van drapeernette op blom- en reproduktiewe groei tydens die daaropvolgende seisoen, op ‘Golden Delicious’ en variteite daarvan. Aanpassings t.o.v. oeslading word aanbeveel vir laasgenoemde kultivars, om die impak van nette op reproduktiewe groei, gedurende die huidige sowel as die daaropvolgende seisoen, te verminder. Masters 2023-03-06T08:10:01Z 2023-05-18T07:17:46Z 2023-03-06T08:10:01Z 2023-05-18T07:17:46Z 2023-03 Thesis http://hdl.handle.net/10019.1/127354 en_ZA Stellenbosch University xii, 149 pages : illustrations (some color) application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Fruit -- Quality Netting Apples -- Breeding -- Varieties Budding (Plant propagation) Crop load -- Management Apples -- Growth Apples -- Flowering time UCTD Jordaan, Stephen Christiaan The impact of protective netting on reproductive bud development, flowering, fruit set and fruit quality in apple trees |
| title | The impact of protective netting on reproductive bud development, flowering, fruit set and fruit quality in apple trees |
| title_full | The impact of protective netting on reproductive bud development, flowering, fruit set and fruit quality in apple trees |
| title_fullStr | The impact of protective netting on reproductive bud development, flowering, fruit set and fruit quality in apple trees |
| title_full_unstemmed | The impact of protective netting on reproductive bud development, flowering, fruit set and fruit quality in apple trees |
| title_short | The impact of protective netting on reproductive bud development, flowering, fruit set and fruit quality in apple trees |
| title_sort | impact of protective netting on reproductive bud development flowering fruit set and fruit quality in apple trees |
| topic | Fruit -- Quality Netting Apples -- Breeding -- Varieties Budding (Plant propagation) Crop load -- Management Apples -- Growth Apples -- Flowering time UCTD |
| url | http://hdl.handle.net/10019.1/127354 |
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