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Genotype-by-environment interaction analysis on bud break dynamics, yield potential and fruit quality of diverse apple (Malus domestica) trees in contrasting environments
Thesis (MScAgric)--Stellenbosch University, 2024.
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| Language: | English |
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613909508161536 |
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| access_status_str | Open Access |
| author | Du Toit, Cara |
| author2 | Louw, Esme D.
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| author_browse | Du Toit, Cara Louw, Esme D. |
| author_facet | Louw, Esme D.
Du Toit, Cara |
| author_sort | Du Toit, Cara |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/131649 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:43:38.086Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/131649 Genotype-by-environment interaction analysis on bud break dynamics, yield potential and fruit quality of diverse apple (Malus domestica) trees in contrasting environments Du Toit, Cara Louw, Esme D. Labuschagne, Iwan Stellenbosch University. Faculty of AgriSciences. Dept. of Horticultural Science. Apples (Malus domestica) -- Breeding Genotype-environment interaction Buds Fruit trees -- Effect of temperature on Apples -- Quality Apples -- Seasonal variations Orchards -- Management UCTD Thesis (MScAgric)--Stellenbosch University, 2024. Du Toit, Cara. 2024. Genotype-by-environment interaction analysis on bud break dynamics, yield potential and fruit quality of diverse apple (Malus domestica) trees in contrasting environments. Unpublished masters dissertation. Stellenbosch : Stellenbosch University [online]. Available: https://scholar.sun.ac.za/handle/10019.1/131649 ENGLISH ABSTRACT: The apple industry plays a pivotal role in the global economy and holds a noticeable position in South Africa’s economic landscape. This thesis includes three research papers that explore the influence of environmental conditions as well as inherent genetics of different genotypes on their bud break patterns, thinning requirements, yield potential, fruit size and fruit quality. A multi-environmental trail (MET) was conducted which consisted of three climatically contrasting environments. Each environment included a complete randomised block design which consisted of ten genotypes (3rd and 4th leaf) with varying chilling requirements (low, medium and high). The impact of a rest-breaking agent (RBA) treatment was assessed using a split-plot design. The trees were trained to a central leader system with M7 rootstocks. Data was collected for an abundant number of traits with the focus on vegetative and reproductive bud break dynamics across two seasons and yield potential and fruit quality for a single season. The data was analysed using an ANOVA, DA, AMMI, and GGE biplot analysis to assess adaptability (performance and stability) across different environments and RBA treatment. Many interactions were present, however the main contributors towards the observed variability for most of the traits were either the inherent genetics of the genotypes and/or the environment. RBA treatment had some effect, but to a lesser extent. Patterns of adaptability were observed amongst the genotypes, where the medium and high chill genotypes had a higher amount of bud break and shorter bud break period in the cold and intermediate environments. An environmental effect was observed where the number of vegetative buds decreased, and reproductive buds increased with increasing winter temperatures. The low chill genotypes showed broad adaptability, with prolonged bud break periods in cooler environments due to an ecodormancy effect. RBA treatment resulted in accelerated bud break periods and higher bud break for some genotypes in the warmer environments. The thinning traits were mainly determined by the genotype; however, the high chill genotypes required more thinning in the cooler environment and larger variation in fruitlet size was observed in the warmer environment. The low chill genotypes again showed broader adaptability. Fruit size at harvest, yield and yield efficiency were greatly influenced by the environment, where a higher number of smaller fruit was harvested for both low- and high chill genotypes in the warmer environment, and a higher yield efficiency observed in the cooler environments. The fruit quality and storability traits showed that many of the internal characteristics such as TA and TSS were largely related to genotype genetics, however it was also influenced by the environment and RBA. Fruit firmness was also determined by genetics, but smaller fruits tended to have higher fruit firmness. The high chill genotypes showed good storability, whereas the low chill genotypes did not. This study emphasised the importance of selecting well adapted genotypes during orchard establishment to suit specific micro-climates and illustrated the effect of both the inherent genetics of the genotypes as well as the environment and RBA application on genotype adaptability. AFRIKAANSE OPSOMMING: Die appelbedryf speel 'n kern rol in Suid-Afrika, asook die wêreldekonomie. Hierdie tesis sluit drie navorsings artikels in waarin die invloed van omgewingstoestande en genetika van verskillende genotipes op hul knopbreekpatrone, uitdunningsvereistes, opbrengspotensiaal, vruggrootte en vrugkwaliteit ondersoek word. 'n Multi-omgewingsproef is uitgevoer wat uit drie klimaatskontrasterende omgewings bestaan. Elke omgewing sluit 'n volledige gerandomiseerde blok ontwerp met tien verskillende appel genotipes met verskillende koue behoeftes (lae, medium en hoog) in. Die impak van 'n rusbreekmiddel (RBA) behandeling is geëvalueer deur middel van 'n split-plot ontwerp. M7 EMLA onderstamme is gebruik en die bome is opgelei en manipuleer as sentrale leiersisteme. Data is ingesamel vir 'n groot aantal eienskappe met die fokus op vegetatiewe en reproduktiewe knopbreek patrone oor twee seisoene, asook opbrengspotensiaal en vrugkwaliteit vir een seisoen. Die data is ontleed deur middel van ANOVA, DA, AMMI en GGE biplot ontledings om die aanpasbaarheid (prestasie en stabiliteit) oor verskillende omgewings en RBA-behandeling te evalueer. Alhoewel baie interaksies sigbaar was, was die hoof bydraers tot die waargenome variasie vir meeste van die eienskappe die genetika van die genotipes en/of die omgewing. RBA-behandeling het 'n effek gehad, maar tot 'n mindere mate. Die medium en hoë koue behoefte genotipes het 'n hoër hoeveelheid knopbreek en 'n korter knopbreekperiode in die kouer en intermediêre omgewings gehad. 'n Omgewingseffek is waargeneem waar die aantal vegetatiewe knoppe afgeneem en reproduktiewe knoppe toegeneem het met toename in wintertemperature. Die lae kouebehoefte genotipes het breë aanpasbaarheid getoon, met verlengde knopbreekperiodes in kouer omgewings. RBA-behandeling het gelei tot 'n versnelde knopbreekperiode en hoër knopbreek vir sommige genotipes in die warmer omgewings. Die uitdunningseienskappe is hoofsaaklik deur die genotipe bepaal; alhoewel die hoë kouebehoefte genotipes meer uitdunning vereis het in die kouer omgewing en 'n groter variasie in vruggrootte is waargeneem in die warmer omgewing. Die lae kouebehoefte genotipes het meer breër aanpasbaarheid getoon. Vruggrootte by oes, opbrengs en opbrengsdoeltreffendheid is sterk deur die omgewing beïnvloed, waar 'n groter aantal kleiner vrugte geoes is vir beide lae- en hoë kouebehoefte genotipes in die warmer omgewing, en 'n hoër opbrengsdoeltreffendheid in die kouer omgewings waargeneem is. Die vrugkwaliteit en opberging eienskappe het getoon dat baie van die interne eienskappe soos totale sure en totale opgeloste suikers grootliks verwant is aan die genetika van die genotipe. Vrugfermheid is ook deur genetika bepaal, alhoewel kleiner vrugte geneig was om 'n hoër vrugfermheid te hê. Die hoë kouebehoefte genotipes het goed opgeberg, terwyl die lae kouebehoefte genotipes meer beperk was. Hierdie studie het die belangrikheid van die seleksie van goed aangepaste genotipes tydens die vestiging van appelboorde beklemtoon en het die effek van beide die genetika van die genotipes sowel as die omgewing en RBA-toediening op genotipe-aanpasbaarheid geïllustreer. Masters 2025-02-03T11:42:58Z 2025-02-03T11:42:58Z 2024-12 Thesis https://scholar.sun.ac.za/handle/10019.1/131649 en Stellenbosch University 306 pages : ill. vii, 299 pages : illustrations (some color), maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Apples (Malus domestica) -- Breeding Genotype-environment interaction Buds Fruit trees -- Effect of temperature on Apples -- Quality Apples -- Seasonal variations Orchards -- Management UCTD Du Toit, Cara Genotype-by-environment interaction analysis on bud break dynamics, yield potential and fruit quality of diverse apple (Malus domestica) trees in contrasting environments |
| title | Genotype-by-environment interaction analysis on bud break dynamics, yield potential and fruit quality of diverse apple (Malus domestica) trees in contrasting environments |
| title_full | Genotype-by-environment interaction analysis on bud break dynamics, yield potential and fruit quality of diverse apple (Malus domestica) trees in contrasting environments |
| title_fullStr | Genotype-by-environment interaction analysis on bud break dynamics, yield potential and fruit quality of diverse apple (Malus domestica) trees in contrasting environments |
| title_full_unstemmed | Genotype-by-environment interaction analysis on bud break dynamics, yield potential and fruit quality of diverse apple (Malus domestica) trees in contrasting environments |
| title_short | Genotype-by-environment interaction analysis on bud break dynamics, yield potential and fruit quality of diverse apple (Malus domestica) trees in contrasting environments |
| title_sort | genotype by environment interaction analysis on bud break dynamics yield potential and fruit quality of diverse apple malus domestica trees in contrasting environments |
| topic | Apples (Malus domestica) -- Breeding Genotype-environment interaction Buds Fruit trees -- Effect of temperature on Apples -- Quality Apples -- Seasonal variations Orchards -- Management UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/131649 |
| work_keys_str_mv | AT dutoitcara genotypebyenvironmentinteractionanalysisonbudbreakdynamicsyieldpotentialandfruitqualityofdiverseapplemalusdomesticatreesincontrastingenvironments |