Thesis (MSc)--Stellenbosch University, 2004. / Full text to be digitised and attached to bibliographic record. / ENGLISH ABSTRACT: The control of excessive vegetative growth is important in deciduous fruit orchards.
Currently the plant growth regulator prohexadione-calcium (p-Ca) is used to control
apple shoot growth in the Untited States of America and some European countries.
The effect of P-Ca on the shoot and fruit growth of apples (Malus domestica B.),
pears (Pyrus cummunis L.), plums (Prunus sa/icina L.) and nectarines (Prunus
persica L.) was evaluated. Inhibition of shoot growth can effect fruit growth.
Therefore I did a literature review on the fruit growth of pome- and stone fruit. Split
pit, a physiological disorder associated with an increased fruit growth rate in stone
fruit, was also investigated.
During the course of the 2001 / 2002 season two trials were conducted in the
Villiersdorp area of the Western Cape on 'Golden Delicious' and 'Granny Smith'
apple trees. Single and multiple applications of P-Ca at different rates, with and
without the surfactant Dash®, were applied. One of these trials was continued during
the 2002 / 2003 season.
In the 2001 / 2002 season, P-Ca reduced shoot growth in both trials on 'Golden
Delicious'. The shoot growth of 'Granny Smith' was reduced in both trials where PCa
was applied three or four times. There was an improvement in the fruit size of
'Golden Delicious' in both trials, but there was no improvement in the fruit size of
'Granny Smith'. In the 2002 / 2003 season, the single P-Ca application did not reduce
shoot growth. Unfortunately 'Golden Delicious' was harvested before any data were
obtained. Once again P-Ca had no effect on the fruit size of 'Granny Smith'. Dash®
did not improve the effect ofP-Ca.
In the 2002 / 2003 season we replicated one trial on five different pear cultivars in the
Wolsely area of the Western Cape. Single and multiple applications of P-Ca at
different rates were compared to a girdling treatment (2 weeks after full bloom).
'Early Bon Chretien', 'Rosemarie', 'Flamingo', 'Forelle' and 'Packham's Triumph'
pear trees were used and Dash®was added to all 0f the treatments. P-Ca reduced shoot growth in all of the pear cultivars. Girdling reduced shoot growth
only in 'Forelle'. P-Ca increased fruit set of 'Early Bon Chretien', 'Rosemarie' and
'Forelle', however, this was associated with a reduced fruit size of 'Early Bon
Chretien' and 'Rosemarie'. Girdling did not increase fruit set, but increased fruit size
of 'Flamingo' and 'Early Bon Chretien'. P-Ca reduced return bloom of 'Packham's
Triumph' and 'Forelle', whereas girdling increased return bloom in all the cultivars
except 'Packham's Triumph'.
In the 2002 / 2003 season, trials were also conducted on 'Pioneer' and 'Songold'
plums and 'May Glo' nectarine in the Wemmershoek and Stellenbosch area of the
Western Cape. Single applications at different rates of P-Ca were applied. Dash®
was added to all of the treatments.
The higher rates of P-Ca reduced the shoot growth of 'Pioneer'. P-Ca only reduced
shoot growth of 'Songold' initially and but did not reduce shoot growth of 'May Glo'.
P-Ca had no influence on fruit size of 'Pioneer', 'Songold' or 'May Glo'. P-Ca did
not aggravate the occurrence of split pit.
In conclusion, P-Ca reduced shoot growth in apples and pears when applied at the
appropriate rates. Although P-Ca reduced shoot growth of 'Pioneer' plum, more
research needs to be done on stone fruit to optimise timing and rate of P-Ca
applications. / AFRIKAANSE OPSOMMING: Die beheer van oormatige lootgroei is van kardinale belang in vrugtebome. Tans
word die plantgroeireguleerder proheksadioon-kalsium (P-Ca) gebruik om die
lootgroei van appels te beheer in die Verenigde State van Amerika en sekere lande in
Europa. Die effek van P-Ca op lootgroei en vruggrootte is in proewe op appels
(Malus domestica B.), pere (Pyrus cummunis L.), pruime (Prunus salicina L.) en
nekatriens (Prunus persica L.) geëvalueer. Aangesien lootgroei inhibisie moontlik
vruggroei kan vesnel, is 'n literatuurstudie oor die vruggroei van kern-en steenvrugte
gedoen. Die ontwikkelling van gesplete pit by steenvrugte ('n fisiologiese defek
geassosieer met versnelde vruggroei) is ook ondersoek.
Gedurende die 2001 / 2002 seisoen is P-Ca in twee afsonderlike proewe in die
Villiersdorp area van die Wes Kaap geëvalueer. Enkel en veelvuldige toedienings van
verskeie konsentrasies P-Ca, met en sonder die benatter Dash", is op 'Golden
Delicious' en 'Granny Smith' bome toegedien. Een proef is herhaal gedurende die
2002 / 2003 seisoen.
In die 2001 /2002 seisoen het die P-Ca behandelings in beide proewe die lootgroei
van 'Golden Delicious' verminder. Die lootgroei van 'Granny Smith' is in beide
proewe verminder waar P-Ca 3 of 4 keer toegedien is. Die vruggrootte van 'Golden
Delicious', maar nie 'Granny Smith' nie, is in beide proewe deur die P-Ca verbeter.
In die 2002 / 2003 seisoen kon die enkeltoedienings van P-Ca nie die lootgroei
verminder van 'Golden Delicious' of 'Granny Smith' nie. 'Golden Delicious' is
geoes voor enige inligting oor die vruggrootte ingesamel kon word. Weereens het PCa
geen invloed op die vruggrootte van 'Granny Smith' gehad nie. Dash® het nie die
effek van P-Ca verbeter nie.In die 2002 / 2003 seisoen is proewe met P-Ca gedoen op 5 verskillende peer kultivars
in die Wolsely area van die Wes Kaap. P-Ca is teen verskillende konsentrasies, met
enkel en veelvuldige bespuitings toegedien en vergelyk met 'n ringelerings
behandeling (2 weke na volblom). 'Early Bon Chretien', 'Rosemarie', 'Flamingo',
'Forelle' en 'Packham's Triumph' bome is gebruik en die benatter Dash® is by al die
behandelings gevoeg
P-Ca toedienings het lootgroei verminder in 'Early Bon Chretien', 'Rosemarie',
'Flamingo', 'Forelle' en 'Packham's Triumph'. Ringelering kon slegs die lootgroei
van 'Forelle' verminder. P-Ca het die vrugset van 'Early Bon Chretien',
'Rosemarie'en 'Forelle' verhoog. Die toename in vrugset het gelei tot 'n afname in
die vruggrootte van 'Early Bon Chretien' en 'Rosemarie'. Ringelering het die
vruggrootte van 'Flamingo' en 'Early Bon Chretien' verbeter. P-Ca het 'n afname in
die hoeveelheid reproduktiewe knoppe in die volgende seisoen, van 'Packham's
Triumph' en 'Forelle' veroorsaak. Ringelering het 'n toename in die hoeveelheid
vegetatiewe knoppe in die volgende seisoen gehad vir al die kultivars, behalwe
'Packham's Triumph'.
Geduerende dieselfde seisoen is daar ook proewe gedoen op 'Pioneer' en 'Songold'
pruime en 'May Glo' nektarienbome in onderskeidelik die Wemmershoek en
Stellenbosch areas van die Wes Kaap. Bome is met enkel toedienings van
verskillende konsentrasies P-Ca behandel en die benatter Dash® is by al die
behandelings bygevoeg.
Die hoër dosisse P-Ca het die lootgroei van 'Pioneer' verminder. P-Ca kon slegs die
aanvanklike lootgroei op 'Songold' verminder en kon nie lootgroei van 'May Glo'
beperk nie. P-Ca het geen invloed op die vruggrootte van 'Pioneer', 'Songold' of
'May Glo' gehad nie. P-Ca het nie die voorkoms van gesplete-pit vererger nie.
Om saam te vat kan gesê word dat P-Ca lootgroei op appels en pere goed beperk teen
die regte konsentrasies. Alhoewel P-Ca lootgroei suksesvol beheer het op 'Pioneer',
moet daar meer werk gedoen word op steenvrugte.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/49827 |
| Date | 03 1900 |
| Creators | Meintjes, Jacobus Johannes |
| Contributors | Theron, K. I., Stassen, P. J. 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 | English |
| Type | Thesis |
| Format | 85 pages : illustrations |
| Rights | Stellenbosch University |
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