Thesis (MScAgric)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The effect of foliar application oftriadimenol (a triazole), Promalin'", or scoring branches on fruit set, fruit size and fruit quality of 'Royal Gala' apples were evaluated. Four treatments were tested, viz., (a) an unsprayed control, (b) triadimenol sprayed on 6 March 1997 (one month after harvest) and then every two weeks for 8 weeks until leaf drop, as well as at mouse ear and full bloom, (c) as treatment b, plus Promalin® two weeks after full bloom, and (d) Promalin® two weeks after full bloom. Four scoring treatments were tested, viz., (a) a control, (b) scoring at full bloom, (c) scoring two weeks after full bloom, and (d) scoring four weeks after full bloom. Promalin® application two weeks after full bloom improved fruit size without any detrimental effects on fruit quality. This application was in addition to the standard commercial applications of Promalin'" as part of the chemical thinning program. The possible negative effect of the G~+7 on return bloom was however not determined. The scoring treatments were not severe enough to influence growth and development significantly and should be investigated again in the future. The influence of bearing position on apple flower and subsequent fruit quality was evaluated. At full bloom in the 1997/98 season, ten flower clusters from the following bearing positions were collected and evaluated: (a) dorsal spurs, (b) ventral spurs, (c) terminal on bourse shoot, (d) terminal on long shoot, and (e) lateral on long shoots. The same bearing positions were used, one week after full bloom, for the 1998/99 season. The flowering pattern was monitored for both seasons and just prior to harvest in both seasons the length and diameter of the fruit were measured as well as the length of the bourse shoot that had developed from the same bud. Fruit thinning by hand was done in 1997 by thinning to the largest fruit per cluster, but no thinning was done in the 1998 season. The results obtained in the morphological analysis of the flower cluster of 'Royal Gala' were not very consistent. In general, the dorsal spurs appeared to be the better quality flowers and the "king" flower is believed to be the best quality flower in the cluster as far as the receptacle dimensions are concerned. When fruit were harvested, no fruit on long shoots, either in the terminal or lateral positions, were found. Even though the percentage of these positions were low at bloom, this indicates a low set potential and possibly poor flower quality of these bearing positions in 'Royal Gala'. The size of the fruit at harvest in 1998/99, did not correlate well with the parameters measured at bloom. The correlation coefficients between bourse shoot length and fruit size were significant, but relatively small. We found a positive correlation between developed seed number and fruit dimensions. Thinning and heading pruning cuts affect fruit size and yield of 'Royal Gala' apple trees. During the 1997 winter trees were pruned as follows: (a) control with no further pruning, (b) thinning cuts of only entire secondary branches (branches that were thicker than half of the trunk diameter were removed at the point of attachment to the trunk), (c) thinning cuts of secondary branches and tertiary fruiting units (positioned on branches), (d) thinning of spurs only, without removal of branches or fruiting units, and (e) thinning cuts of branches and tertiary fruiting units combined with heading back of fruiting units into the spurs leaving four bud on the fruiting units. Treatments (b) through (e), were conducted at light or heavy pruning intensities, i.e., by leaving 300 or 150 reproductive buds/tree, respectively. Pruning was followed up by hand thinning of fruitlets to one fruit per cluster. All pruning treatments increased fruit size, primarily because of a indirect fruit thinning effect except the combined thinning and heading treatments where a direct effect resulted in the largest apples without having a negative effect on yield. In winter 1998 trees were pruned as follows: (a) control with no further pruning, (b) heavy thinning of secondary branches and fruiting units leaving 250 reproductive buds/tree, (c) light thinning of secondary branches and fruiting units leaving 400 reproductive buds/tree, (d) heavy thinning of secondary branches and fruiting units combined with heading back into the spurs of the remaining fruiting units leaving 250 reproductive buds/tree, and (e) light thinning of secondary branches and fruiting units combined with heading back into the spurs of the remaining fruiting units leaving 400 reproductive buds/tree. In 1998/99 season the advantage of pruning on fruit size were not observed. Lastly, the effect of artificial extinction (removal) of flower clusters on fruit size and quality of 'Royal Gala' apples were evaluated. Individual branches were pruned as follows: (a) control, (b) 25 % removal of fruiting spurs, (c) 50 % removal of fruiting spurs, (d) 75 % removal of fruiting spurs to test for any possible enhancements of fruit size. No subsequent hand thinning of fruitlets was done. Thinning by artificial extinction methods of the fruit buds did not influence fruit size, colour, seed set or seed development. No significant differences were found between fruit number, but with 50% and 75% bud removal fewer fruit were counted. In these data the absence of any significant fruit size improvement may be due to the lack of subsequent hand thinning of fruitlets. / AFRIKAANSE OPSOMMING: Die effek van blaarbespuiting van triadimenol en Promalin® asook ringelering op vrugset, vruggrootte en vrugkwaliteit is geëvalueer. Vier behandelings is toegepas nl: (a) onbehandelde kontrole, (b) triadimenol op 6 Maart 1997 en dan elke twee weke tot en met blaarval asook met "muis oor" en volblom, (c) soos behandeling b, plus Promalin® twee weke na volblom, en (d) Promalin® twee weke na volblom. Vier ringelering behandelings is ook toegepas nl: (a) geen ringelering (kontrole), (b) tydens volblom, (c) twee weke na volblom, en (d) vier weke na volblom. Promalin® bespuiting twee weke na volblom verbeter vruggrootte sonder enige nadelige effekte op vrugkwaliteit. Dit moet ingedagte gehou word dat hierdie behandeling van Promalin® was addisioneel toegevoeg tot die standard kommersiele gebruik van Promalin® wat deel vorm van die chemiese uitdun program. Die moontlike negatiewe effek van GA4+7 op blominisiasie is nie bepaal nie. Die ringelering behandelings was nie straf genoeg nie en dit het nie die groei en ontwikkeling betekenisvol beïnvloed nie en sal in die toekoms weer geëvalueer moet word. Verder is die invloed van draposisies op die appel blomkwaliteit en die daaropvolgende vrugkwaliteit geëvalueer. Met vol blom in die 1997/98 seisoen is tien blom trosse van die volgende draposisies versamel en geëvalueer: (a) dorsale spore, (b) ventrale spore, (c) terminaal op beurslote, (d) terminaal op langlote, en (e) lateraalop langlote. Dieselfde draposisies is versamel, een week na volblom, vir die 1998/99 seisoen. Die blompatroon is gemonitor gedurende beide seisoene. Net voor oes is die vruglengte en - deursnee gemeet as ook die lengte van die beurslote wat van dieselfde knop ontwikkel het as die vrugte. Vruguitdinning met die hand tot die grootste vrug per tros was gedoen in die 1997/98 seisoen, maar nie in die 1998/99 seisoen nie. Die resultate wat gekry is met die morfologiese analise van die blom trosse was nie baie konsekwent nie. In die algemeen vertoon die dorsale spore die beste kwaliteit blomme en die "koning" blomme het die grootste blombodems. Met die oes van die vrugte is geen vrugte op lang lote, hetsy in die terminale of laterale posisies gevind nie. Al was die persentasie van die posisies laag met volblom dui dit op lae setpotensiaal en moontlik ook op 'n lae blom kwaliteit van hierdie draposisies vir 'Royal Gala" appels. Die grootte van die vrugte van die 1998/99 oes korreleer nie goed met die parameters wat tydens blom gemeet is nie. Ongelukkig is die vrugte vir die 1998/99 seisoen nie gedurende die na-blom staduim uitgedun nie, wat daartoe bygedra het dat dit moeilik is om afleidings te maak. Die korrelasiekoeffisient tussen die beurslootlengte en vruggrootte was betekenisvol maar redelik klein. 'n Positiewe korrelasie tussen die aantal goed ontwikkelde sade en vrugdimensie is gevind. Die effek van uitdun en terugsnysnitte op vruggrootte eh opbrengs van 'Royal Gala' is ook geëvalueer. Gedurende die 1997 winter is die bome op die volgende manier gesnoei: (a) geen snoei (kontrole), (b) uitdunsnitte van hele sekondêre takke (takke wat dikker was as die helfde van die stam se deursnee by die punt van aanhegting aan die stam), (c) uitdunsnitte van sekondêre takke en tersiêre vrugdraende takke, (d) uitdun van spore alleen sonder om enige takke te verwyder, en (e) uitdunsnitte van sekondêre takke en tersiêre vrugdraende takke gekombineerd met terugsnysnitte van vrugdraende takke in die spoor sisteem in tot net vier spore per tak oorbly. Vir behandelings (b) tot (e) was die behandelings opgedeel in 'n ligte en 'n strawwe uitduning van knoppe deur onderskeidelik uit te dun tot 300 en 150 reproduktiewe knoppelboom. Die snoei was opgevolg deur handuitdunning tot een vrug per tros. Alle snoeibehandelings verbeter vruggrootte, primêr as gevolg van 'n indirekte vruguitdunnings, effek behalwe die behandeling met uitdunsnitte van sekondere takke en tersiêre vrugdraende takke gekombineerd met terugsnysnitte van vrugdraende takke. In hierdie behandeling is daar 'n direkte effek op vruggrootte sonder om 'n negatiewe effek op die oes opbrengs te he. In die winter van 1998 is die bome soos volg gesnoei: (a) geen snoei (kontrole), (b) strawwe uitdun snitte van hele sekondêre takke en vrugdraende takke tot op 250 reproduktiewe knoppe/boom, (c) ligteuitdun snitte van hele sekondêre takke en vrugdraende takke tot op 400 reproduktiewe knoppe/boom, (d) strawwe uitdunsnitte van sekondêre takke en tersiêre vrugdraende takke gekombineerd met terugsnysnitte van vrugdraende takke tot in die spoorsisteem tot op 250 reproduktiewe knoppelboom, en (e) ligte uitdunsnitte van sekondêre takke en tersiêre vrugdraende takke gekombineerd met terugsnysnitte van vrugdraende takke tot in die spoorsisteem tot op 400 reproduktiewe knoppelboom. Geen handuitdunning is gedurende die' seisoen gedoen nie, In die 1998/99 seisoen is geen voordeel van snoei op vruggrootte waargeneem nie. Snoei moet dus opgevolg word deur handuitdunning van vruggies. Laastens is daar na die effek van kunsmatige uitdun van blomtrosse op vruggrootte van 'Royal Gala' appels gekyk. Individuele takke is soos volg gesnoei: (a) kontrole, (b) 25 % verwydering van spore, (c) 50 % verwydering van spore, en (d) 75 % verwydering van spore. Geen opvolg handuitdunning is gedoen nie. Die uitdun tegniek het nie die vruggrootte, - kleur of die hoeveelheid en ontwikkeling van saad beïnvloed nie. Met die 50 % en 75 % verwydering is daar soos verwag minder vrugte geoes. Die rede dat geen vruggrootte verbetering gevind is nie kan moontlik daaraan toegeskryf word dat geen opvolg handuitdunning toegepas is nie.

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: We aimed to determine how canopy microclimate influences fruit quality and consumer preference in apples. Our postulate was that consumer preference would be higher for the taste, but not necessarily for the appearance of outer canopy fruit. Outer canopy fruit, exposed to higher irradiance and temperatures, accumulated more phenolics and ascorbic acid, and had higher antioxidant capacities in their peel compared to inner canopy fruit. Phenolic levels and antioxidant capacity were also higher in the flesh of outer canopy fruit while ascorbic acid was higher in the flesh of outer canopy ‘Granny Smith’. From a marketing perspective, outer canopy fruit can be seen as possessing greater potential health benefits. Outer canopy fruit were higher in dry matter content (DMC), sugars and TSS, but lower in TA in the first season of the study. The sweeter and less sour taste of outer canopy fruit was preferred in all three cultivars over two years of study. Sunburnt fruit were higher in DMC, TSS:TA ratio, lower in TA and were perceived to be the sweetest, least sour and lowest in apple flavour and textural attributes. The effect of canopy position on apple flavour and textural attributes was inconsistent. The redder outer canopy ‘Starking’ fruit were preferred by consumers because this cultivar is marketed with full red colour. The appearance of blushed, outer canopy ‘Granny Smith’ and ‘Golden Delicious’, and sunburnt ‘Golden Delicious’ were not preferred by consumers. Consumers are not familiar with such fruit. Blushed ‘Granny Smith’ is downgraded and sometimes sold at a lower price while sunburnt apples are processed or dumped depending on sunburn severity. The consistency of these results was investigated in one season for ‘Golden Delicious’ from five locations. The consumer taste preference differential for inner and outer canopy fruit diminished as canopy size decreased. This indicates that there generally would be no benefit in harvesting and marketing outer and inner canopy ‘Golden Delicious’ separately. We investigated the effect of familiarity on consumer preference by utilising an “experienced” consumer group of farm labourers from Ceres who are familiar with all fruit on a tree compared to an “inexperienced” consumer group of Stellenbosch consumers who are only exposed to fruit on the commercial market and eat apples less frequently. Both groups preferred the taste and appearance of outer canopy ‘Starking’. The taste of sunburnt fruit was preferred by a substantial segment of both consumer groups, but the appearance was preferred by only some Ceres consumers. A small segment of Ceres consumers preferred the taste and appearance of the blushed outer canopy ‘Granny Smith’ and ‘Golden Delicious’ while some Stellenbosch consumers preferred the taste of outer canopy ‘Golden Delicious’, but not ‘Granny Smith’. Therefore, Ceres consumers who are more familiar with the taste attributes of sunburnt and blushed fruit of green cultivars have a higher preference for the appearance of these fruit. Based on our results, fruit marketers may be able to develop niche markets for outer canopy and sunburnt ‘Golden Delicious’ fruit. / AFRIKAANSE OPSOMMING: Ons het ondersoek hoe vrugkwaliteit en verbruikersvoorkeur in appels deur die blarekoepel mikroklimaat beïnvloed word. Ons vermoede was dat verbruikersvoorkeur hoër sou wees vir die smaak, maar nie noodwendig vir die voorkoms van vrugte aan die buitekant van die boom (buitevrugte) nie. Buitevrugte was blootgestel aan hoër ligstraling en temperature en hul skil het meer fenole en askorbiensuur geakkumuleer asook hoër antioksidantkapasiteit gehad vergeleke met binnevrugte. Fenole en die antioksidantkapasiteit was ook hoër in die vleis van buitevrugte terwyl askorbiensuur hoër was in die vleis van ‘Granny Smith’ buitevrugte. Vanuit bemarkingsperspektief kan buitevrugte gesien word as vrugte met hoër potensiële gesondheidsvoordele. Buitevrugte was hoër in droë materiaal inhoud (DMC), suikers en TSS, maar laer in TA, laasgenoemde slegs in die eerste seisoen van die studie. Verbruikers het die soeter en minder suur smaak van buitevrugte verkies in beide jare van die studie. Vrugte met sonbrand was hoër in DMC, TSS:TA verhouding, laer in TA en was die soetste, minste suur en laagste in appelgeur en tekstuureienskappe. Die effek van blaredakposisie op appelgeur en tekstuureienskappe was variërend. Verbruikers het die rooier buitevrugte van ‘Starking’ verkies. Ons reken dit is omdat hierdie kultivar as ‘n volrooiappel bemark word. Verbruikers het minder van die voorkoms van rooiblos ‘Granny Smith’ en ‘Golden Delicious’ asook van ‘Golden Delicious’ met sonbrand gehou. Verbruikers is nie vertroud met sulke vrugte nie. Rooiblos ‘Granny Smith’ appels word afgradeer en word soms teen laer pryse verkoop terwyl sonbrand appels geprosesseer of uitgeskot word afhangend van die graad van sonbrand. Die konsekwentheid van ons resultate is ondersoek met ‘Golden Delicious’ van vyf lokaliteite. Die smaakvoorkeur differensiaal tussen binne- en buitevrugte het afgeneem met afname in boomgrootte. Oor die algemeen sou daar dus geen voordeel wees om ‘Golden Delicious’ binne- en buitevrugte apart te oes en te bemark nie. Ons het die effek van vertroudheid op verbruikervoorkeur ondersoek deur gebruik te maak van “ervare” verbruikergroep bestaande uit plaasarbeiders in Ceres en “onervare” verbruikersgroep van Stellenbosch. Die Ceres verbruikers is vertroud met al die appels op die boom vergeleke met die Stellenbosch verbruikers wat net blootstelling het aan vrugte op die kommersiële mark en ook minder gereeld appels eet. Beide verbruikersgroepe het die voorkoms en smaak van ‘Starking’ buitevrugte verkies. Substansiële segment van beide verbruikersgroepe het die smaak van sonbrand vrugte verkies, maar die voorkoms van hierdie vrugte is slegs deur sommige Ceres verbruikers verkies. Klein segment Ceres verbruikers het die smaak en voorkoms van ‘Granny Smith’ en ‘Golden Delicious’ buitevrugte verkies terwyl sommige Stellenbosch verbruikers die smaak van ‘Golden Delicious’, maar nie ‘Granny Smith’ buitevrugte verkies het nie. Ceres verbruikers is meer vertroud met die smaakeienskappe van sonbrand en blosvrugte van groen kultivars en het gevolglik hoër voorkeur vir die voorkoms van hierdie vrugte. Gebaseer op ons resultate kan bemarkers moontlik nismark vir gebloste en sonbrand ‘Golden Delicious’ vrugte ontwikkel.

Call number: LD2668 .T4 1985 E27 / Master of Science

Thesis (MScAgric (Horticulture))--University of Stellenbosch, 2007. / The production of high quality fruit that meet international standards is of vital importance to the South African fruit industry. Detrimental climatic conditions are forcing producers to examine alternate production methods. In this study the effect of protective netting on apple tree (Malus domestica) physiology, microclimate and fruit quality was investigated to determine the potential of apple production under netting in the Western Cape Province of South Africa. The influence of 20% black shade netting on the photosynthetically photon flux density, leaf and fruit surface as well as air temperature was measured on four blush apple cultivars over a two year period in the Koue Bokkeveld area, in the Western Cape, South Africa. Measurements were also taken on leaf gas exchange, including net CO2 assimilation rate under ambient and saturating CO2 conditions, stomatal conductance, and transpiration rate. A decrease in light conditions of 22 - 31% was measured under black netting thus reducing the amount of light available to the plant significantly. Leaves under the netting were cooler by 1.7 – 3.9°C on a milder day (11 January 2005) and by 4.3 – 6.2°C on a hot day (28 February 2005) than control leaves. Fruit surface temperature under the netting was cooler by 0.7 - 2.9°C on milder days, and by 4.0 - 5.3°C on a hot day (28 February 2005) than control fruit. Significant increases in CO2 assimilation, stomatal conductance and transpiration were found under the netting. Netted treatments also showed a lower leaf vapour pressure deficit and tended to be less water stressed having higher leaf water potential than the control treatments. Differences in leaf nitrogen were not significant between treatments except for ‘Cripps’ Pink’ where non netted treatments had higher leaf nitrogen levels than the netted treatments during the 2004 season. Heat tolerance and the ability to recover after exposure to different temperatures for different lengths of time, was evaluated for the same four blush apple cultivars grown under protective netting. The results showed that fruit taken from the netted treatments had a higher incidence of injury based on chlorophyll fluorescence measurements, and did not recover well at temperatures higher than 45°C. The higher tolerance of the non-netted fruit at 45°C could be due to better acclimation to high light and heat levels than the fruit from the netted treatment. Fruit quality of ‘Royal Gala’, ‘Fuji’, Cripps’ Pink’ and ‘Braeburn’ was evaluated for netted and non-netted treatments as well as between five different crop loads as sun-treatments. It was found that cultivars reacted differently to the altered microclimate under the netting. Significant interaction between net and crop load treatments was found for fruit mass of ‘Royal Gala’ and ‘Fuji’. Fruit mass declined more rapidly with increased crop load under nets than in the open. The net treatment reduced sunburn significantly in all the cultivars except ‘Cripps’ Pink’. Ground colour was found to be positively influenced by netting on ‘Braeburn’ and during 2005 on ‘Royal Gala’. Blush colour was reduced under the netting for ‘Braeburn’ and ‘Fuji’ and unaffected for ‘Royal Gala’ and ‘Cripps’ Pink’. Fruit firmness, total soluble solids and titratable acidity, were reduced under nets for most of the cultivars. Netting thus seems to have a positive effect in reducing sunburn damage but a varying effect on other fruit quality parameters, which seem to be cultivar specific. The influence of black protective netting on vegetative growth was determined by measuring total prunings and trunk circumference. Reproductive bud development analysis was also done. An increase was found in summer prunings for ‘Fuji’ and ‘Cripps’ Pink’ which was most likely due to the topping of the trees to prevent them from growing into the netting. Seasonal trunk growth was affected significantly for ‘Braeburn’ with a higher percentage recorded under the netting. Reproductive bud development was higher for the netted treatments and on trees with lower crop loads. Photosynthetic photon flux density was reduced significantly in a ‘Granny Smith’ orchard at harvest by black, blue and grey type netting. Sunburn was significantly reduced under the black and blue netting. Fruit mass was higher under the netted treatments during the second season of measurements. Firmness and total soluble solids were lower under the netting. Blush colour was found to be significantly lower under the black netting. Seed viability, ground colour, titratable acidity, starch breakdown, stem end russet and the occurrence of Fusicladium pyrorum damage was unaffected by the netting.

In 1992, branches on ‘Triple Red Delicious’/M.7 were girdled. A factorial arrangement of girdling treatments (control, 9-mm girdle + uncovered, 9-mm girdle + electric tape, 9-mm girdle + TreeKote), and timings (0, 15, 30, 60, 90 days after full bloom (DAFB)) was used. With ‘Golden Delicious’/M.7, branch treatments were control, scored, and 6-mm, 9-mm, 12-mm electric-tape-covered girdles, each applied at 0, 15, 30, and 60 DAFB. In 1993, treatments on both cultivars were control, 9-mm uncovered girdle, and pruning saw wound. Each was applied at 0, 7, 14, and 21 DAFB. Each girdle was a complete ring of bark; pruning saw wound was removal of bark using a pruning saw; scoring was a knife cut through the bark. In 1992, the two cultivars responded similarly to girdling. Effects were greatest with treatments at 0 to 30 DAFB and included increased fruit set or retention, temporary suppression of vegetative growth (except watersprouts), and increased levels of soluble solids in the fruit. Treatments affected starch levels in the fruit and flesh firmness, but these effects were variable. In 1993, the two cultivars responded similarly to the main effects of girdling, which caused increased crop density and yield efficiency. Girdling increased mean apple diameter, weight, and soluble solids on ‘Triple Red Delicious’/M.7 branches. Fruit diameter was reduced on ‘Golden Delicious’/M.7 branches. Girdling affected flesh firmness in both cultivars, but these results were variable. / Master of Science

Thesis (MscAgric (Horticulture))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Experiments were conducted to increase the percentage class one ‘Granny Smith’ and ‘Cripps’ Pink’ apples. ‘Granny Smith’ is the most widely grown apple cultivar in South Africa, but its profitability is compromised by the high incidence of sunburn, red blush and poor green colour development. ‘Cripps’ Pink’ is a very lucrative cultivar and producers are striving to maximise the production of fruit that qualify for export. Fruit technologists and growers are debating whether it is best to maximise class one fruit in ‘Cripps’ Pink’ by increasing total yield or by increasing fruit quality. The relationship between ‘Granny Smith’ canopy position and external fruit quality was investigated. Light exposure, peel temperature, green colour development, sunburn and red blush development was followed for individual fruit from the outer, intermediate and inner canopy. Dark green fruit were exposed to moderate to high light levels (25-50% full sun) during the first half of fruit development, similar to fruit that eventually developed sunburn and red blush. The difference came in during the latter half of fruit development when dark green fruit became shaded (3% full sun). Pale green fruit contained less chlorophyll due to consistent low light levels (2% full sun). Fruit at partially shaded canopy positions had a lower occurrence of sunburn and red blush than outside fruit and better green colour development than fruit from the heavily shaded inner canopy. Based on these data, pruning strategies and mulching were evaluated to alter canopy vigour and the light environment in such a way that green colour development is promoted and the occurrence of sunburn and red blush is reduced. In an older, vigorous orchard with a dense canopy, pruning was done to increase light distribution for green colour development and to induce more growth on the side of the trees that are prone to sunburn and red blush. Pruning improved green colour development without affecting sunburn or red blush. In a younger, non-vigorous orchard, pruning and mulching were used to invigorate the canopy to increase shading of fruit and thereby decrease sunburn and red blush. However, these treatments were not effective. Further research should focus on the use of shade nets, accompanied by rigorous pruning, to reduce sunburn and red blush while not decreasing green colour. Five different crop loads were established in an exceptionally high yielding (averaging over 100 ton·ha1) ‘Cripps’ Pink’ orchard by first the thinning of clusters, then the removal of small fruit and, finally, the selective removal of fruit from the shaded inner canopy. Treatments had no effect on iv fruit quality in the first season. The most severe thinning treatment increased the percentage class one fruit in the second season by increasing the number of fruit with adequate red blush. However, seen cumulatively, the higher crop loads yielded more class one fruit per hectare than the lower crop loads, without affecting reproductive and vegetative development or fruit storability. Producers should strive for the highest crop loads allowed by the fruit size limitations in cultivars that are not prone to alternate bearing / AFRIKAANSE OPSOMMING: Eksperimente is uitgevoer om die persentasie uitvoerkwaliteit ‘Granny Smith’ en ‘Cripps Pink’ appels te verhoog. ‘Granny Smith’ maak die grootste deel uit van appel aanplantings in Suid Afrika, maar die winsgewendheid daarvan word beperk deur `n hoë voorkoms van sonbrand, rooi blos en swak groen kleurontwikkeling. ‘Cripps’ Pink’ is `n baie winsgewende kultivar en produsente streef daarna om die persentasie uitvoerkwaliteit vrugte te maksimaliseer. Vrugte tegnoloë en produsente debatteer oor die wenslikheid daarvan om uitvoerkwaliteit vrugte te maksimeer deur totale produksie te verhoog of deur vrugkwaliteit te verbeter. Die verband tussen ‘Granny Smith’ draposisie in die blaredak en eksterne vrugkwaliteit is ondersoek. Ligvlakke, skiltemperatuur, groen kleurontwikkeling, sonbrand en rooi blos ontwikkeling is deur die loop van die seisoen gevolg vir individuele vrugte aan die buitekant, binnekant en intermediêre posisies binne die blaredak. Daar is gevind dat die donkerste groen vrugte, nes vrugte wat uiteindelik sonbrand en rooi blos ontwikkel het, blootgestel was aan matige tot hoë ligvlakke (25-50% vol son) gedurende die eerste helfte van vrugontwikkeling. Donker groen vrugte is egter oorskadu (3% vol son) tydens die tweede helfte van vrugontwikkeling. Vanweë konstante lae beligting (2% vol son) het binne vrugte min chlorofiel geakkumuleer en daarom is hierdie vrugte lig van kleur. Vrugte in gedeeltelike skadu ontwikkel min sonbrand en rooi blos in vergelyking met buite vrugte en toon beter groen kleurontwikkeling as vrugte in diep skadu binne die boom. Gegrond op bogenoemde resultate is die gebruik van snoei strategieë en deklae om die groeikrag en die ligomgewing van die boom te modifiseer, ten einde groen kleur ontwikkeling te bevorder en sonbrand en rooi blos te verminder, geëvalueer. In ‘n ouer, groeikragtige boord met ‘n digte blaredak is snoei gebruik om ligverspreiding te verbeter vir groen ontwikkeling en om meer groei te stimuleer aan die buitekant van die boom wat meer geneig is tot sonbrand en rooiblos. Groen kleur is wel verbeter, maar sonbrand en rooi blos is nie geaffekteer nie. In `n jonger, minder groeikragtige boord is ‘n deklaag aangebring en eenjarige lote getop, sodoende groei te stimuleer om sonbrand en rooi blos te verminder deur oorskaduwing van vrugte. Hierdie behandelings was egter nie effektief nie. Toekomstige navorsing moet fokus op die gebruik van skadunette tesame met ‘n nougesette snoei strategie om sonbrand en rooi blos te verminder sonder om groen kleur te verswak. Vyf verskillende vrugladings is geskep in `n uitermatig produktiewe (gemiddeld meer as 100 ton·ha-1) ‘Cripps’ Pink’ boord deur eers vrugtrosse uit te dun, gevolg deur die verwydering van klein vrugte en, laastens, die selektiewe verwydering van vrugte in die diep skaduwee van die binneste blaredak. Vrugkwaliteit is nie in die eerste seisoen nie deur oeslading geaffekteer nie. Die strafste uitdunbehandeling het wel die persentasie uitvoerbare vrugte in die tweede seisoen verhoog deur die aantal vrugte met voldoende rooi blos te vermeerder. Kumulatief gesien, het die hoër oesladings egter meer klas een vrugte per hektaar opgelewer sonder om die reproduktiewe en vegetatiewe ontwikkeling of die stoorvermoë van vrugte te affekteer. Produsente moet strewe na die hoogste oesladings wat toegelaat word deur vruggrootte beperkings in kultivars wat nie geneig is tot alternerende drag nie