Thesis (MScAgric)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Ineffective pollination of the main cultivar with the pollinator cultivar is due to either an
incompatibility problem between the main and pollinator cultivar, or because the
flowering times of the main and pollinator cultivars do not overlap adequately. Three
trials were conducted to try and find a more effective way to determine cultivar
compatibility and to group cultivars together according to their budburst reaction to
chilling.
Most apple cultivars are self-incompatible and need cross-pollination for fruit set. Due to
differences in the genetically defined fertilisation compatibility between the pollen from
the male parent (pollinator) and the egg cell of the female parent, various apple
pollinators differ in their ability to set fruit with viable seed. Fruit weight and size are
positively correlated with seed set although it has been found that the pollinator can have
a direct influence on fruit quality. 'African Red' apple trees on M7 rootstock in an
evaluation block on a commercial farm in the Koue Bokkeveld region (32°55'N 19°27'E,
Mediterranean climate, ;::::1060Utah chill units, and ;::::530mm rainfall annually; altitude
966 m) were used to assess the influence of 5 pollinators ('Granny Smith', 'Winter
Banana', 'Cripps' Pink', 'Cripps' Red' and 'Simpson Crab') on fruit set, fruit weight and
length and diameter. The degree to which 'African Red' is self-compatible was also
assessed and the effect of flowering position ("king" vs. lateral) on fruit quality was
determined. None of the pollinators showed a significantly higher fruit set. No differences in fruit set were found between the "king" and lateral flowering positions. No
significant differences were found in the average number or weight of well developed
seeds between pollinators. In both years fruit weight was significantly correlated to seed
number for all five pollinator cultivars. In 1998 'Simpson crab' gave fruit that were
significantly more elongated than those of 'Cripps' Pink'. 'African Red' is highly self
incompatible.
Compatibility assessments that are based on the number of fruit that develop after the
flowers ofthe main cultivar had been hand pollinated in field trials are a time-consuming
process. Allele-specific PCR amplification for some of the known S-alleles of the
incompatibility S-gene (S2, S3, S5, S7 and S9) was carried out to successfully predict the
compatibility of genotypes. The results compared well with that found in literature. For
all the Malus domestica cultivars tested at least one, but in some instances both alleles of
the S-gene were determined. 'Simpson crab' (Malus baccata) did, however, not possess
any of the tested S-alleles.
One-year-old, ca. 40 mm long shoots of various apple cultivars were selected from
commercial orchards in both the Elgin [34°S, 305 m, ca. 750 chill units (CU) (Richardson
et al., 1974)] and Koue Bokkeveld (33°S, 945 m, ca. 1300 CU) regions of the Western
Cape, South Africa in two consecutive years (1998 and 1999). Shoots were forced at a
constant 25°C with continuous illumination after receiving their allocated chill units. The
effect of chilling period on the budburst of each cultivar in both regions was estimated by
determining, 1) the total proportion of budburst (%Bb), 2) the proportion of shoots with terminal budburst (%TBb), and 3) the rate of budburst [lI(days to 25% budburst)]. It was
found that these indices differed significantly between cultivars, and within cultivars
between areas, as far as budburst patterns, in reaction to chilling, were concerned. The
rate of budburst was the most consistent in describing the reaction of buds to different
chilling periods and could be used to group cultivars together according to their budburst
reaction to chilling. / AFRIKAANSE OPSOMMING: KRUISBESTUIWINGSBIOLOGIE VAN APPELS MET
SPESIALE VERWYSING NA 'AFRICAN RED'.
Oneffektiewe kruisbestuiwing III die boord kan toegeskryf word aan Of
onverenigbaarheid tussen die hoof- en bestuiwingskultivar Of as gevolg van die blomtyd
van die kruisbestuiwer wat nie genoegsaam oorvleuel met die van die hoofkultivar nie.
Drie proewe is uitgevoer om 'n meer effektiewe proses daar te stel vir die toets van
kultivarverenigbaarheid en om kultivars te probeer groepeer na gelang van hul reaksie op
bepaalde hoeveelhede koue.
Meeste appelkultivars is selfonverenigbaar en benodig kruisbestuiwing vir genoegsame
vrugset. As gevolg van verskille III die geneties gedefinieerde
bevrugtingsverenigbaarheid tussen die stuifmeel van die manlike ouer (bestuiwer) en die
eiersel van die vroulike ouer (hoofkultivar), verskil bestuiwers in hul vermoë om vrugte
met sade te set. Vruggrootte en -massa is positief gekorreleerd met saadset alhoewel dit
al gevind is dat die bestuiwer op sig self ook 'n invloed op vrugkwaliteit kan hê. 'African
Red' appelbome op M7 onderstamme, in 'n evaluasie blok op 'n kommersiële plaas in
die Koue Bokkeveld (32°55'N 19°27'E, Meditereense klimaat, ::::1060 Utah koue
eenhede, en ::::530mmjaarlikse reënval; ligging 966 m), is gebruik om die invloed van 5
bestuiwers ('Granny Smith', 'Winter Banana', 'Cripps' Pink', 'Cripps' Red' and 'Simpson Crab') op vrugset, vrugmassa, -lengte en -deursnee oor twee seisoene te bepaal.
Die mate waartoe 'African Red' self onverenigbaar is en die effek van blomposisie
("king" vs laterale blom) op vrugkwaliteit is ook bepaal. Geen een van die bestuiwers het
vrugset beduidend beïnvloed nie. Ook is daar geen verskille gevind tussen die "king" en
laterale blomposisies t.o.v. vrugset nie. Geen beduidende verskille is tussen bestuiwers
gevind in die gemiddelde aantal of gewig van volsade geset nie .. In albei jare was die
vrugmassa beduidend gekorreleerd met saadset vir al vyf bestuiwerkultivars. In 1998 het
'Simpson Crab' vrugte geset wat beduidend langer was as vrugte wat geset het toe
'Cripps' Pink' as bestuiwer gebruik is. Daar is ook gevind dat 'African Red' hoogs
selfonverenigbaar is.
Verenigbaarheidstoetse wat gebaseer is op die aantal vruggles wat ontwikkel nadat
blomme van die hoofkultivar met die hand bestuif is, is 'n tydsame proses. Allele
spesifieke PCR amplifikasie vir bekende S-allele van die onverenigbaarheids S-geen (S2,
S3, S5 S7en S9) is suksesvol uitgevoer om die verenigbaarheid van genotipes vooraf te
bepaal. Die resultate het goed vergelyk met wat in literatuur gevind is. Vir al die Malus
domestica spesies wat getoets is, is ten minste een, en in sommige gevalle twee, van die
S-allele gevind. Die blomappel 'Simpson' (Malus baccata) het egter nie een van die vyf
S-allele opgelewer nie
Een-jaar-oue, 40 mm lang lote van verskeie appelkultivars, is in twee opeenvolgende jare
(1998 en 1999) vanuit kommersiële boorde in beide die Elgin [34°S, 305 m, ca. 750 koue eenhede (CU) (Richardson et al., 1974)] and Koue Bokkeveld (33°S, 945 m, ca. 1300
CU) areas van die Wes Kaap gsny. Die lote is geforseer om te bot by 'n konstante
temperatuur van 25°C met deurlopende beligting, nadat elke groep lote aan 'n bepaalde
hoeveelheid koue blootgestel is. Die effek van koue op bot van elke kultivar in beide
areas is bepaal deur, 1) die totale persentasie knoppe wat gebot het, 2) die persentasie
terminale knoppe wat gebot het, en 3) die tempo van bot [l/(dae tot 25% bot)] te meet.
Daar is gevind dat bo-genoemde parameters beduidend tussen kultivars, en binne
kultivars tussen areas, verskil. As 'n beskrywing van die reaksie van knoppe op koue het
die tempo van bot die mees konstante resultate oor die twee opeenvolgende seisoene
gelewer en kon hierdie parameter gebruik word om kultivars in groepe, na gelang van hul
reaksie op koue, in te deel.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/51667 |
| Date | 03 1900 |
| Creators | Halgryn, Petrus J. (Petrus Johannes) |
| Contributors | Theron, K. I., Cook, N. C., Stellenbosch University. Faculty of AgriSciences. Dept. of Horticulture. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 118 p. : ill. |
| Rights | Stellenbosch University |
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