Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Investigating plant growth dynamics of selected southern highbush blueberry (V. corymbosum L. interspecific hybrids) cultivars under South African growing conditions
Thesis (MScAgric)--Stellenbosch University, 2022.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2022
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614025661022208 |
|---|---|
| access_status_str | Open Access |
| author | Steyn, Juan |
| author2 | Lotze, Elmi |
| author_browse | Lotze, Elmi Steyn, Juan |
| author_facet | Lotze, Elmi Steyn, Juan |
| author_sort | Steyn, Juan |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2022. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/126145 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:45:28.762Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2022 |
| publishDateRange | 2022 |
| publishDateSort | 2022 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/126145 Investigating plant growth dynamics of selected southern highbush blueberry (V. corymbosum L. interspecific hybrids) cultivars under South African growing conditions Steyn, Juan Lotze, Elmi Hoffman, L. (Lynn) (Horticulturalist) Stellenbosch University. Faculty of Agrisciences. Dept. of Horticulture. Blueberries -- Breeding -- South Africa Highbush blueberry (SHB) -- Effect of climatic changes on Bud swell Petal fall Blueberries -- Harvesting Plant growth dynamics Highbush blueberry -- Environmental aspects -- South Africa UCTD Thesis (MScAgric)--Stellenbosch University, 2022. ENGLISH ABSTRACT: In South Africa, southern highbush blueberry (SHB) cultivars exhibit an evergreen growth habit, due to the generally warmer climatic conditions. Two SHB cultivars, 8- 42 and 9-02, were selected based on their observed differences in their aboveground characteristics. Cultivar 9-02 has a more vigorous growth habit than 8-42, but yields are considerably lower in 9-02 than in 8-42, regardless of the larger plant structure. Therefore, the aim of the study was to quantify the above- and belowground phenology of these cultivars, along with non-structural carbohydrate allocation patterns to provide deeper insights into the observed difference in yield between the cultivars. In the first trial, the timing, duration and intensity of selected flower bud stages in ‘8-42’ and ‘9-02’ were determined at two production sites (Hex River and Wolseley) in the Western Cape, South Africa. Cultivar 8-42 flowered from April to mid-October and reached a peak during early August, while cultivar 9-02 flowered from April to late October but also reached a peak during early August at the Wolseley site. However, at the Hex River site, peak flowering occurred a month later, in September, thus indicating a possible genetic and climate-related interaction response. Fruit harvesting commenced in early August in ‘8-42’, at both sites, and at the Hex River site for ‘9-02’; however, harvest was advanced to the end of July, at the Wolseley site. Despite these early harvesting times, more than 90% of the crop was concentrated between late- September and mid-November, for both cultivars, at both sites. Furthermore, the study confirmed the challenges encountered when attempting phenological predictions for SHB grown in an evergreen production system, as flowering and harvest stages can occur continuously, across several weeks, within a single plant. In the second trial, the number and length of new root production were quantified in ‘8-42’ and ‘9-02’ at the Hex River site to describe the seasonal timing of new root production and root distribution patterns. New root production (number of additional roots recorded on consecutive evaluation dates) was evident throughout the study, with increased root production rates occurring at similar times, for both cultivars. A first root production peak occurred at the onset of early winter and coincided with flowering. New root production continued until increased fruit maturation and harvesting that commenced in early spring. A second root production peak coincided with mid-summer, approximately one month after fruit harvest. New root formation occurred simultaneous with active shoot growth, until shoot activity declined with the termination of shoot elongation during early May. In the third trial, non-structural carbohydrate allocation patterns were determined in bearing and non-bearing ‘8-42’ and ‘9-02’ plants, at selected phenological stages at the Hex River site, to gain a better understanding of the underlying causes of the reported differences in yield between the cultivars. Leaves were the major source of carbohydrates to support, not only reproductive development between 50% and 90% flowering in both cultivars, but also root growth, which was evident during this period. Thereafter, reproductive growth and new vegetative growth were sustained by all evaluated plant organs in ‘8-42’, during both seasons, whereas distinctly different results between seasons occurred during this period, in ‘9-02’. Leaf carbohydrates decreased between 90% flowering and peak harvest in the 2020 season, whereas it increased sharply in the 2021 season. It was suggested that this could indicate that ‘9-02’ had excess carbohydrates in the 2021 season which were not utilized to enhance reproductive growth and development. AFRIKAANSE OPSOMMING: In Suid-Afrika, volg “southern highbush” bloubessie (SHB) kultivars ‘n immergroen groeiwyse as gevolg van die algemene warmer klimaatstoestande. Twee SHB kultivars, 8-4’ en 9-02, is geselekteer op grond van hul waarneembare verskille in bogrondse eienskappe. Kultivar 9-02 het ‘n meer groeikragtige voorkoms as 8-4, maar opbrengs is laer in 9-02 as in 8-42, ongeag die groter plantstruktuur. Die doel van die studie was daarom om die bo- en ondergrondse fenologie, asook die nie-strukturele koolhidraat allokasie patrone van hierdie kultivars te kwantifiseer om insig te kry rakende die waarneembare opbrengs verskille tussen die kultivars. In die eerste proef, is die tyd, tydsduur en intensiteit van selektiewe blomknopfases in ‘8-42’ en ‘9-02’ bepaal in twee produksie streke (Hexrivier en Wolseley) in die Weskaap, Suid-Afrika. Kultivar 8-42 het geblom vanaf April tot mid- Oktober en het ‘n piek bereik gedurende vroeë Augustus, terwyl kultivar 9-02 geblom het vanaf April tot laat Oktober en ‘n piek bereik het gedurende vroeë Augustus. Nietemin het piekblom ‘n maand later plaasgevind, in September, by die Hexrivier produksie area en is dus ‘n moontlike aanduiding van ‘n genetiese en klimaat- verwante interaksies. Oes het in vroeë Augustus vir ‘8-42’ by beide streke begin, asook vir ‘9-02’ by die Hexrivier produksie area, alhoewel die oesdatum vervroeg was, tot laat Julie, in die Wolseley produksie area. Ten spyte van hierdie vroeë oestye, is meer as 90% van die totale oes gekonsentreer tussen einde-September en mid- November, vir beide kultvars, in beide produksie streke. Verder het die studie die uitdagings bevestig soos ondervind met fenologiese voorspellings vir SHB wat verbou word in ‘n immergroen produksiesisteem, waar blom- en oes-stadia deurlopend oor verskeie weke op ‘n enkele plant kan voorkom. In die tweede proef, is die aantal en lengte van nuwe wortelproduksie gekwantifiseer in ‘8-42’ en ‘9-02’ in die Hexrivier produksie area, om die seisoenale tydsberekening van nuwe wortelproduksie en wortelverspreidingspatrone te beskryf. Nuwe wortelgroei (aantal bykomende wortels wat by opeenvolgende evalueringsdatums opgeneem is) was deurgans duidelik sigbaar tydens die verloop van die studie, met verhoogde wortelproduksie koerse, wat in ooreenkomstige tye plaasgevind het, vir beide kultivars. ‘n Eerste piek in wortelproduksie het tydens die vroeë winter plaasgevind en saamgeval met die blomperiode. Nuwe wortelproduksie het voort geduur tot en met vrug-volwassewording en oes, wat in vroeë lente in aanvang geneem het. ‘n Tweede piek in wortelproduksie het saamgeval met mid- somer, ongeveer een maand na die finale oes. Nuwe wortelproduksie het gelyktydig met aktiewe lootgroei plaasgevind totdat lootaktiwiteit afgeneem het, met die beëindiging van lootverlenging, gedurende vroeë Mei. In die derde proef, is nie-strukturele koolhidraatallokasie patrone bepaal in draende en nie-draende ‘8-42’ en ‘9-02’ plante vir gepesifiseerde fenologiese stadia in die Hexrivier produksie area om dieper insig te kry rondom die oorsake vir die gerapporteerde verskille in opbrengs tussen die kultivars. Blare is as hoof bron van koolhidrate geïdentifiseer en het nie net reproduktiewe ontwikkeling tussen 50% en 90% blom ondersteun nie, maar ook die opmerklike wortelgroei tydens hierdie periode onderhou. Daarna is beide reproduktiewe- en vegetatiewe groei ondersteun deur alle plant organe wat ondersoek is in ‘8-42’, gedurende beide seisoene, terwyl kenmerkende verskille tussen seisoene voorgekom het in ‘9-02’ gedurende hierdie periode. Blaar koolhidrate het afgeneem gedurende hierdie tydperk in die 2020 seisoen, terwyl dit drasties toegeneem het in die 2021 seisoen. Daar word voorgestel dat hierdie verskynsel ‘n aanduiding kan wees dat ‘9-02’ ‘n oormaat koolhidrate het wat nie aangewend is om addisionele reproduktiewe groei te ondersteun en uit te brei nie. Masters 2022-11-22T13:54:56Z 2023-01-16T12:52:24Z 2022-11-22T13:54:56Z 2023-01-16T12:52:24Z 2022-12 Thesis http://hdl.handle.net/10019.1/126145 en_ZA Stellenbosch University viii, 115 pages : illustrations (some color) application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Blueberries -- Breeding -- South Africa Highbush blueberry (SHB) -- Effect of climatic changes on Bud swell Petal fall Blueberries -- Harvesting Plant growth dynamics Highbush blueberry -- Environmental aspects -- South Africa UCTD Steyn, Juan Investigating plant growth dynamics of selected southern highbush blueberry (V. corymbosum L. interspecific hybrids) cultivars under South African growing conditions |
| title | Investigating plant growth dynamics of selected southern highbush blueberry (V. corymbosum L. interspecific hybrids) cultivars under South African growing conditions |
| title_full | Investigating plant growth dynamics of selected southern highbush blueberry (V. corymbosum L. interspecific hybrids) cultivars under South African growing conditions |
| title_fullStr | Investigating plant growth dynamics of selected southern highbush blueberry (V. corymbosum L. interspecific hybrids) cultivars under South African growing conditions |
| title_full_unstemmed | Investigating plant growth dynamics of selected southern highbush blueberry (V. corymbosum L. interspecific hybrids) cultivars under South African growing conditions |
| title_short | Investigating plant growth dynamics of selected southern highbush blueberry (V. corymbosum L. interspecific hybrids) cultivars under South African growing conditions |
| title_sort | investigating plant growth dynamics of selected southern highbush blueberry v corymbosum l interspecific hybrids cultivars under south african growing conditions |
| topic | Blueberries -- Breeding -- South Africa Highbush blueberry (SHB) -- Effect of climatic changes on Bud swell Petal fall Blueberries -- Harvesting Plant growth dynamics Highbush blueberry -- Environmental aspects -- South Africa UCTD |
| url | http://hdl.handle.net/10019.1/126145 |
| work_keys_str_mv | AT steynjuan investigatingplantgrowthdynamicsofselectedsouthernhighbushblueberryvcorymbosumlinterspecifichybridscultivarsundersouthafricangrowingconditions |