Thesis (MScAgric)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Internal breakdown (internal browning - IB and gel breakdown - GB), over maturity and immaturity are the main factors adversely affecting the quality of exported South African plums. Maturity problems occur when plums are strip harvested, i.e., all the fruit in a block or orchard are harvested once, when the majority of the fruit are at optimum maturity. This results in both ovennature and immature fruit being harvested and contributes to a high percentage of fruit being rejected for export. In general, internal browning occurs when plums are exported under a single 10\,,, temperature regime and gel breakdown occurs when plums are exported under a dual temperature regime. However, GB can also occur at harvest in fruit that are very ripe and may occur at single low temperatures, where it would be masked by lB. While it is known that some cultivars, like 'Angeleno', can withstand a single temperature regime, others cannot. To the best of our knowledge, the reason for this difference is not understood. Many factors affect the quality of plums, including light incidence in the canopy, mineral nutrition and harvest maturity. Plums that were grown on high density training systems such as 'a V- or spindle system yielded consistently high quality fruit with low incidences of gel breakdown. This was in contrast to earlier findings where low-density training systems produced high levels of GB, especially in the lower part of the tree canopy. Branches that were shaded with 80% shade netting yielded fruit with high levels of GB, indicating that the main effect of improved canopy structure on quality was improved light management. A postharvest boron application on 'Songold' plums prior to storage had no effect on the incidence of intemal breakdown in the fruit, but did damage the cuticle, resulting in severe shrivel. However, internal conductivity and firmness measurements indicated that there was some effect of the boron on cell membranes. A more thorough investigation of pre- and postharvest application of boron is recommended in order to determine whether there could be a positive effect of boron in improving fruit quality in plums. Four cultivars of plums ('Pioneer', 'Sapphire', "Songold ' and 'Angeleno') were harvested throughout, and extending beyond, the commercial harvesting period. In all cultivars, the drop in firmness between harvests was not as great as expected and the later harvested fruit were of a similar, if not superior, quality as compared to the earlier harvested fruit. Later harvested plums tended to have higher TSS and better colour development. Contrary to what was expected, later harvested fruit did not have more internal disorders than earlier harvested fruit. This indicates the importance of harvesting at optimum maturity. 'Angeleno' plums had no internal disorders, even after five weeks of cold storage at a single low temperature. 'Pioneer' and 'Sapphire' plums were classified as climacteric and 'Songold' and 'Angeleno' were classified as suppressed climacteric based on ethylene production. The climacteric plums respired and produced ethylene at a higher rate than the suppressed climacteric plums. Climacteric plums ripened faster during shelf life than suppressed climacteric plums. Furthermore, while climacteric plums did not need a cold storage period prior to ripening, suppressed climacteric plums needed a cold storage period in order to ripen normally. The longer the cold storage period prior to transfer to higher temperatures, the faster the plums ripened and the higher the ethylene production at the higher temperature. The suppressed climacteric genotype could possibly be incorporated into plum breeding programs in order to extend the storage period and shelflife of new plum cultivars. The long storage times required to ship plums from South Africa to the export markets has necessitated research on postharvest physiology and quality of this fruit. The use of the climacteric and suppressed climacteric system to classify fruit is expected to assist in understanding the different physiological responses of the cultivars and assist in developing handling protocols. Preharvest factors, particularly light and nutrition, also playa role in postharvest quality. / AFRIKAANSE OPSOMMING: Interne verval (interne verbruining en gelverval), oorrypheid en onryp vrugte, is die hoof faktore wat die uitvoer van Suid Afrikaanse pruime negatief beïnvloed. Rypheidsprobleme ontstaan wanneer pruime gestroop-oes word, met ander woorde, al die vrugte in 'n blok of boord word geoes wanneer die meerderheid vrugte optimum rypheid bereik het. As gevolg hiervan word 'n groot persentasie vrugte vir uitvoer afgekeur, omdat hulle te ryp of nie ryp genoeg is nie. Oor die algemeen vind interne verbruining plaas wanneer vrugte onder 'n enkel lae temperatuur uitgevoer word en gelvervel vind plaas wanneer vrugte onder 'n dubbele temperatuur regime vervoer word. Gel verval kan egter in baie ryp vrugte by oes voorkom en mag by enkel lae temperature voorkom .waar dit deur interne verbruining gemaskeer sal word. Kultivars soos 'Angeleno' kan onder enkel lae temperatuur uitgevoer word sonder interne probleme, terwyl ander pruimkultivars me so uitgevoer kan word nie. So ver ons weet, word die rede hiervoor nie goed verstaan nie. Daar is baie faktore wat die kwaliteit van pruime beïnvloed, onder meer lighuishouding, minerale voeding en die rypheid waarby die pruime geoes word. Pruime wat in hoë-digtheid sisteme soos 'n V- of "spindle" groei het goeie kwaliteit vrugte met 'n lae persentasie gelverval gelewer. Dit is in teenstelling met vroeër bevindinge, waar vrugte van lae digtheid boorde hoë persentasies geverval gelewer het, veral in die onderste gedeeltes van die boom. Takke wat met 80% skadunet bedek is het hoër persentasies gelverval as die kontrole gelewer, wat aandui dat die hoof effek van die verbeterde boom struktuur op kwaliteit, verbeterde lighuishouding was. 'n Na-oes aanwending van boor op 'Songold' pruime het geen effek op die voorkoms van gelverval gehad nie, maar het die kutikula beskadig en tot hoë persentasies verrimpeling gelei. Fermheid en inteme weerstand lesings het egter getoon dat daar wel 'n effek van die boor op die selmembrane en selwande was. 'n Meer omvattende ondersoek van voor- en na-oes aanwending van boor word aanbeveel om vas te stelof daar wel 'n positiewe effek van boor in die verbetering van pruim kwaliteit is. Vier pruim kultivars, ('Pioneer', 'Sapphire', 'Songold' en 'Angeleno'), is gedurende, sowel as later as die kommersiële oesperiode geoes. In al die kultivars was die afname in fermheid kleiner as wat verwag is, en vrugte wat later geoes is het dieselfde, en soms beter, kwaliteit as die vrugte wat vroeër geoes is gehad. Pruime wat later geoes is het beter kleur en gewoonlik hoër suikers gehad. In teenstelling met wat verwag is, het pruime wat later geoes is nie meer interne verval gehad as die pruime wat vroeër geoes is nie. Dit dui die belangrikheid van optimale oesrypheid aan. 'Angeleno' het geen interne verval gehad nie, selfs na vyfweke opberging by -0.5°C. 'Pioneer' en 'Sapphire' pruirne is as klimakteries en 'Songold' en 'Angeleno' as onderdrukte klimakteries geklassifiseer, gebaseer op etileen produksie. Die klimakteriese pruime het teen 'n hoër tempo gerespireer en etileen geproduseer as die onderdrukte klimakteriese pruime. Gedurende raklewe het klimakteriese vrugte vinniger as onderdrukte klimakteriese vrugte ryp geword. Verder, terwyl klimakteriese pruime nie opbgerging by 'n lae temperatuur nodig gehad het nie, het onderdrukte klimakteriese vrugte welopberging by 'n lae temperatuur nodig gehad om normaal ryp te word. Hoe langer die koel opbergingsperiode was, hoe vinniger het die pruime ryp geword by raklewe en hoe hoër was hulle etileen produksie. Die onderdrukte klimakteriese genotipe kan moontlik in teelprogramme geïnkorporeer word om kultivars met verlengde opbergings- en raklewe te teel. Die lang vervoer tye wat benodig word om Suid Afrikaanse pruime by die uitvoer markte te kry het dit nodig gemaak om navorsing oor die na-oes fisiologie en kwaliteit van pruime te doen. Die klassifisering van pruime as klimakteries of onderdrukte klimakteries kan ons in staat stelom die verskillende fisiologiese reaksies van die kultivars te verstaan en om hanterings prosedures te ontwikkel. Voor-oes faktore, veral lighuishouding en mineraalvoecling speelook 'n rol in na-oes kwaliteit van pruime.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: In order to export South African plums to overseas markets strict quality standards must be maintained. Among these quality classifications are specifications about the presence of cavities and pieces of broken stone/pit within the flesh of the fruit. If more than 10% of the fruit in a carton are affected by severely broken stones or large flesh cavities, the fruit have to be marketed as Class 2. A substantial amount of plums destined for export from South Africa is affected by broken stones and thus have to be marketed as Class 2. Lower prices are attained for Class 2 fruit, therefore, the presence of broken stones has a detrimental effect on the income generated from these fruit. The main aim of this study was to gain a better understanding of broken stone development and compare the growth characteristics of Japanese plum cultivars differing in their susceptibility to broken stones. Stone breakage in ‘Laetitia’ was observed as soon as stone hardening was initiated. At the start of stone hardening the parts of the stone that are still ‘soft’ are not strong enough to resist the pulling forces of the growing mesocarp and the stone is subsequently pulled apart. Regression analysis indicated that lengthwise growth of the fruit, fresh weight of the endo- and mesocarp, minimum orchard temperature and orchard night temperature, and relative humidity (RH) early in the growing season could possibly be used to predict the incidence of broken stones at harvest. Differences in the incidence of broken stones were observed between ‘Laetitia’, ‘Sapphire’ and ‘Songold’ plums and between seasons. Furthermore, significant differences were observed in the density of the endocarp in different parts of the stone. For ‘Laetitia’ and ‘Songold’, stone breakage was observed when rapid increases in stone density coincided with rapid increases in fruit growth. The stones broke in positions where an interface exists between high and low density parts in the stone and when rapid radial growth takes place in the direction where the stone is least dense. In contrast, in ‘Sapphire’, stone breakage was observed before the stones had started to lignify, indicating that the endocarp was pulled apart by the expanding flesh because it was too soft to withstand the strong pulling forces created by the flesh. The incidence of broken stones was influenced by environmental factors, as higher temperatures during the stone development and hardening period could lead to more complete endocarp formation (more stone cells are formed under such conditions). Such fruit would thus have higher endocarp density, which, if coupled with rapid radial growth, could lead to a higher incidence of broken stones. Foliar and/or root applications of calcium nitrate and potassium silicate were applied to ‘Laetitia’ plums to determine whether the incidence of broken stones could be reduced by increasing the strength of the endocarp cell walls. However, no such effect was observed. Hence, neither calcium nor silicate treatments can be recommended for reducing broken stones in plums. / AFRIKAANSE OPSOMMING: Om Suid-Afrikaanse pruime na oorsese markte uit te voer moet vrugte aan streng kwaliteitstandaarde voldoen. Daar is ondermeer spesifikasies in verband met die teenwoordigheid van holtes en stukkies gebreekte pit binne die vrug. Indien meer as 10% van die vrugte in ʼn karton deur ernstige gebreekte pit of groot vrugholtes geaffekteer word, moet die vrugte as Klas 2 bemark word. Aangesien ʼn groot hoeveelheid van die pruime wat vir uitvoer bestem is, geaffekteer word deur gebreekte pit en gevolglik as Klas 2 bemark moet word, word aansienlike finansiële verliese gelei. Laer pryse word behaal vir Klas 2 vrugte, en dus het die teenwoordigheid van gebreekte pitte ʼn negatiewe effek op die wins wat deur die uitvoer van hierdie vrugte gegenereer kan word. Die hoofdoel van hierdie studie was om die ontwikkeling van gebreekte pit in Japannese pruime te ondersoek en om die groei-patrone van kultivars wat geneig is tot gebreekte pit te vergelyk met ʼn nie-sensitiewe kultivar. Gebreekte pit in ‘Laetitia’ is opgemerk sodra die pit begin verhard het. Met die aanvangs van pit- verharding is die gedeeltes van die pit wat nog nie volkome verhard het nie, nie sterk genoeg om die sterk trekkragte van die groeiende mesokarp te weerstaan nie en die pit word gevolglik uitmekaar- getrek. Regressie-analise het gewys dat lengtegroei van die vrugte, vars massa van die endo- en mesokarp, minimum boordtemperatuur en boord-nagtemperatuur, asook relatiewe humiditeit gedurende die vruggroei-periode moontlik gebruik kan word om die voorkoms van gebreekte pit by oes te voorspel. Verskille in die voorkoms van gebreekte pit is opgemerk tussen ‘Laetitia’, ‘Sapphire’ en ‘Songold’ pruime, en ook tussen seisoene. Verder is beduidende verskille opgemerk in die digtheid van die endokarp in verskillende dele van die pit. By beide ‘Laetitia’ en ‘Songold’ is gebreekte pit opgemerk wanneer vinnige toename in pit-digtheid saamgeval het met ʼn vinnige toename in vruggroei. Die pitte breek veral in die oorgang tussen dele van die pit met hoë en lae digtheid en as dit gekombineer is met vinnige radiale vruggroei in die rigting waar die pit die minste dig is. In teenstelling hiermee is gebreekte pit in ‘Sapphire’ opgemerk selfs voordat die pitte begin verhard het. Dit dui daarop dat die endokarp uitmekaargetrek is deur die vinnig groeiende mesokarp, omdat dit te sag was om die trekkragte van die groeiende vrugvlees te weerstaan. Die voorkoms van gebreekte pit word ook deur weerstoestande beïnvloed, want hoër temperature gedurende die pit-ontwikkeling en verhardingsperiode, kan lei tot die ontwikkeling van endokarpe met meer steenselle. Hierdie vrugte sal dus ʼn hoër digtheid hê, en as dit saamval met vinnige radiale groei, kan dit lei tot ʼn groter voorkoms van gebreekte pit. Blaar- en/of worteltoedienings van kalsiumnitraat en kaliumsilikaat is gemaak om te bepaal of die voorkoms van gebreekte pit in ‘Laetitia’ verminder kon word deur die versterking van die endokarp-selwande. Geen van hierdie behandelings het tot ʼn vermindering in gebreekte pit gelei nie en nie kalsiumnitraat of kaliumsilikaat kan dus aanbeveel word om gebreekte pit in pruime te verminder nie.

Der Verzehr von Pflaumen ist derzeit sehr gering. Häufig wird unbefriedigende Fruchtqualität aufgrund unreif geernteter Früchte als Ursache genannt. Um eine hohe Fruchtqualität zu erzeugen ist es nötig, Vorerntebedingungen wie Fruchtbehang und Bodeneigenschaften optimal zu gestalten und die Früchte im richtigen Reifestadium zu ernten. Die Ziele dieses Projektes waren daher 1. die Untersuchung des Einflusses und interaktiver Effekte von Bodeneigenschaften, Fruchtbehang und Baumwasserzustand auf die Qualität von ''Jojo'' und ''Tophit plus'' Pflaumen. 2. den Effekt unterschiedlicher Pflücktermine auf die innere und äußere Fruchtqualität zu bewerten. 3. das Potenzial der Laserlichtrückstreubildanalyse als neues zerstörungsfreies Verfahren zur Bewertung der Fruchtqualität abzuschätzen. Die Untersuchungen wurden 2011 bis 2013 durchgeführt. Zur Bewertung der Vorernteeinflüsse wurden Früchte dreimal vor sowie am kommerziellen Erntetermin geerntet und im Labor untersucht. Dann wurden sie für 28 Tage bei 2°C und zusätzlich 2 Tage bei 20°C bei 90% rF gelagert. Während dieser Zeit wurden Früchte jeder Behandlungsgruppe nach 0, 7, 14, 21, 28 und 30 Tagen analysiert. Früchte von Bäumen mit geringerem Fruchtbehang von Böden mit geringen ECa Werten wiesen die höchsten SSC und Trockenmassegehalte, solche von Bäumen mit geringem Fruchtbehang und von Böden mit hohem ECa die höchste Frischmasse auf. Gut wasserversorgte Bäume hatten niedrigere Fruchterträge, ihre Früchte transpirierten verstärkt und hatten geringere Zucker- und Trockenmassegehalte als Pflaumen von Bäumen mit schlechter Wasserversorgung. Die späten Ernte von ''Jojo'' Pflaumen, vorzugsweise ca. 137 Tage nach der Vollblüte, ergab die beste Fruchtqualität. Diese Früchte besaßen die höchste Frischmasse und die geringste Transpiration. Laserlichtrückstreumessungen bei 532 und 785 nm zeigten, dass diese zerstörungsfreie Methode für die Analyse von Qualitätsparametern wie Anthocyangehalt und Fruchtfleischfestigkeit gut geeignet ist. / Plum consumption does not meet its potential, most probably because of a non-uniform fruit quality and lack of fully-mature fruit. It is necessary to manage preharvest conditions such as crop load and soil properties optimally in order to obtain high quality plums and to harvest the fruit in ripe stage. In this study, (1) the effects of soil ECa, crop load and maximum daily trunk shrinkage (MDS) on various fruit quality parameters of two European plum cultivars ''Jojo'' und ''Tophit plus'') (2) the internal and external fruit quality as it relates to harvest time were investigated. The investigation of plums was carried out in an experimental orchard in 2011, 2012 and 2013. Fruit of selected trees were sampled and subjected to laboratory measurements three times before and at the commercial harvest. At the commercial harvest, plums were stored at 2 °C and 90% RH for up to 28 days plus 2 days at 20 °C. During storage, fruit of each treatment were sampled after 0, 7, 14, 21, 28 and 30 days in order to analyse the physicochemical quality. In addition, the optical properties of samples were non-destructively evaluated through laser light backscattering imaging (LLBI). Fruit from low crop load trees grown under low ECa had the highest SSC and dry matter content, while those from low crop load trees under high ECa showed the highest fresh mass in 2013. Moreover, low MDS trees had lower total fruit yield, and fruit had higher transpiration, lower SSC, and dry matter content than those grown on trees with high MDS. Fruit quality was best when plums had been harvested late, preferably at the 3rd harvest date (137 DAFB) in this study. These fruit had the highest fresh mass and lowest transpiration. Furthermore, the results of LLBI measured at 532 nm and 785 nm showed an encouraging potential to predict quality parameters of plums such as anthocyanin content and fruit firmness.

Em termos econômicos, a ameixeira já representa a sexta frutífera mais cultivada no Estado de São Paulo. Plantio de ameixeiras foram realizados em regiões novas e desconhecidas quanto à adaptação climática. Aliado a esse fator, ainda apresenta inúmeros problemas relacionados à auto-infertilidade e auto-incompatibilidade polínica, exigência de técnicas de manejo e produtos para quebra de dormência, problemas relacionados à maturação dos frutos e armazenamento. Assim, objetivou-se avaliar o desenvolvimento de cultivares de ameixeira de baixa exigência em frio para regiões subtropicais do estado de São Paulo e o armazenamento refrigerado dos frutos. As plantas do presente experimento foram plantadas num delineamento experimental em blocos ao acaso com quatro repetições e duas plantas por parcela. Para as variáveis referentes aos estádios fenológicos avaliados, período de colheita, porcentagem de fixação de frutos, ciclo, número de frutos e produção, seguiu-se um esquema fatorial 2 x 11, sendo o 1º Fator com dois níveis (com e sem aplicação de cianamida hidrogenada) e o 2º fator com 11 níveis (cultivares: Januária, Kelsey-31, Irati, Reubennel, Golden Talismã, Kelsey Paulista, Gema de Ouro, Gulfblaze, Carmesim, Centenária e Roxa de Itaquera). Para as variáveis características físicas, altura e diâmetro de copa, avaliou-se apenas as plantas tratadas com cianamida hidrogenada. Para a realização da curva de maturação, foram colhidas amostras semanalmente, logo após o início da mudança de coloração dos frutos. Para avaliação dos efeitos do armazenamento refrigerado sobre os atributos físico-químicos, os frutos foram divididos em 3 lotes, sendo que um dos lotes foi armazenado a 25±1°C, outro a 1±1°C e o terceiro a 4±1°C. A umidade relativa nas três temperaturas de armazenamento foi de 90%±5. Os frutos mantidos a 25°C foram avaliados no quarto e sexto dia e os submetidos à refrigeração ficaram estocados por 21, 28 e 35 dias seguidos da comercialização simulada, por dois dias a 25°C. As cultivares de ameixas que melhor se adaptam na região são: Roxa de Itaquera, Kelsey 31, Centenária, Gema de Ouro e Gulfblaze. As cultivares Januária, Reubennel e Kelsey Paulista são mais exigentes em frio, sendo necessário o uso de regulador vegetal para estimular a brotação. O uso de cianamida hidrogenada é eficiente na antecipação e uniformidade do florescimento para todas as cultivares. As ameixas Centenária e Kelsey 31 podem ser armazenadas a 1oC até 21 + 2 dias, enquanto que os frutos da ameixa Gulfblaze se conservam até 28 +2 dias. As ameixas Carmesim podem ser armazenadas a 1oC ou 4oC mantendo a qualidade dos frutos até 21 + 2 dias. / I n economic terms, the plum is the sixth most common fruit cultivated in Sao Paulo State. Plums were planted in regions where this crop has not been climate adapted. In this factor, the plum cultivation still has several difficulties related to selfinfertility and self-incompatibility polinic. Improvement in management and development of products for dormancy broken are points to be upgraded. Other difficulties faced to plum cultivation are questions related to fruit maturity and storage. The objective was to evaluate the plum cultivars with low cooling demand in subtropical regions of the Sao Paulo State and refrigerated storage of these fruits. The plants in this experiment field were planted in an experimental randomized blocks design with four replicates and two plants per plot. The variables harvest time, percentage of fruit-setting, production cycle, number of fruits and production, was evaluated in every phenological stages. The experimental plots were arranged by a factorial 2 x 11, where the first factor had 2 levels (with and without application of hydrogen cyanamide) and the second factor had 11 levels (cultivars: Januária, Kelsey-31, Irati, Reubennel, Golden Talismã, Kelsey Paulista, Gema de Ouro, Gulfblaze, Carmesim, Centenária and Roxa de Itaquera). The variables related to physical characteristics such as height and diameter of tree, the experimental evaluation regarded just plants treated with hydrogen cyanamide. Samples of fruits were harvested weekly as soon as the color of the fruit has changed in order to carry out the curve of maturation. The evaluation effects of cold storage on the physical and chemical attributes were made with the fruits divided in 3 lots. The first lot was stored at 25±1°C, the second at 1±1°C and last one at 4±1ºC. The relative humidity in the three storage temperatures was 90% ± 5. The fruits storage at 25°C were evaluated in the fourth and sixth days and the fruits in refrigeration were stored for 21, 28 and 35 days followed by marketing simulation for two days at 25°C. The cultivars Roxa de Itaquera, Kelsey 31, Centenária, Gema de Ouro and Gulfblaze have shown the best adaptation to these climate conditions. The cultivars Januária, Reubennel and Kelsey Paulista need higher cooling to be able to flowering. In this way, the growth regulator application may stimulate the flowering. Application of hydrogen cyanamide is efficient in anticipating and uniformity of flowering for the cultivars. The plum cultivars Centenária and Kelsey 31 can be stored at 1oC during 21 + 2 days. In the other hand, the Gulfblaze cultivar can be stored during 28 + 2 days. The Carmesim cultivar can be well stored at 1oC or 4oC keeping the same fruits qualities until 21 + 2 days.

Em termos econômicos, a ameixeira já representa a sexta frutífera mais cultivada no Estado de São Paulo. Plantio de ameixeiras foram realizados em regiões novas e desconhecidas quanto à adaptação climática. Aliado a esse fator, ainda apresenta inúmeros problemas relacionados à auto-infertilidade e auto-incompatibilidade polínica, exigência de técnicas de manejo e produtos para quebra de dormência, problemas relacionados à maturação dos frutos e armazenamento. Assim, objetivou-se avaliar o desenvolvimento de cultivares de ameixeira de baixa exigência em frio para regiões subtropicais do estado de São Paulo e o armazenamento refrigerado dos frutos. As plantas do presente experimento foram plantadas num delineamento experimental em blocos ao acaso com quatro repetições e duas plantas por parcela. Para as variáveis referentes aos estádios fenológicos avaliados, período de colheita, porcentagem de fixação de frutos, ciclo, número de frutos e produção, seguiu-se um esquema fatorial 2 x 11, sendo o 1º Fator com dois níveis (com e sem aplicação de cianamida hidrogenada) e o 2º fator com 11 níveis (cultivares: Januária, Kelsey-31, Irati, Reubennel, Golden Talismã, Kelsey Paulista, Gema de Ouro, Gulfblaze, Carmesim, Centenária e Roxa de Itaquera). Para as variáveis características físicas, altura e diâmetro de copa, avaliou-se apenas as plantas tratadas com cianamida hidrogenada. Para a realização da curva de maturação, foram colhidas amostras semanalmente, logo após o início da mudança de coloração dos frutos. Para avaliação dos efeitos do armazenamento refrigerado sobre os atributos físico-químicos, os frutos foram divididos em 3 lotes, sendo que um dos lotes foi armazenado a 25±1°C, outro a 1±1°C e o terceiro a 4±1°C. A umidade relativa nas três temperaturas de armazenamento foi de 90%±5. Os frutos mantidos a 25°C foram avaliados no quarto e sexto dia e os submetidos à refrigeração ficaram estocados por 21, 28 e 35 dias seguidos da comercialização simulada, por dois dias a 25°C. As cultivares de ameixas que melhor se adaptam na região são: Roxa de Itaquera, Kelsey 31, Centenária, Gema de Ouro e Gulfblaze. As cultivares Januária, Reubennel e Kelsey Paulista são mais exigentes em frio, sendo necessário o uso de regulador vegetal para estimular a brotação. O uso de cianamida hidrogenada é eficiente na antecipação e uniformidade do florescimento para todas as cultivares. As ameixas Centenária e Kelsey 31 podem ser armazenadas a 1oC até 21 + 2 dias, enquanto que os frutos da ameixa Gulfblaze se conservam até 28 +2 dias. As ameixas Carmesim podem ser armazenadas a 1oC ou 4oC mantendo a qualidade dos frutos até 21 + 2 dias. / I n economic terms, the plum is the sixth most common fruit cultivated in Sao Paulo State. Plums were planted in regions where this crop has not been climate adapted. In this factor, the plum cultivation still has several difficulties related to selfinfertility and self-incompatibility polinic. Improvement in management and development of products for dormancy broken are points to be upgraded. Other difficulties faced to plum cultivation are questions related to fruit maturity and storage. The objective was to evaluate the plum cultivars with low cooling demand in subtropical regions of the Sao Paulo State and refrigerated storage of these fruits. The plants in this experiment field were planted in an experimental randomized blocks design with four replicates and two plants per plot. The variables harvest time, percentage of fruit-setting, production cycle, number of fruits and production, was evaluated in every phenological stages. The experimental plots were arranged by a factorial 2 x 11, where the first factor had 2 levels (with and without application of hydrogen cyanamide) and the second factor had 11 levels (cultivars: Januária, Kelsey-31, Irati, Reubennel, Golden Talismã, Kelsey Paulista, Gema de Ouro, Gulfblaze, Carmesim, Centenária and Roxa de Itaquera). The variables related to physical characteristics such as height and diameter of tree, the experimental evaluation regarded just plants treated with hydrogen cyanamide. Samples of fruits were harvested weekly as soon as the color of the fruit has changed in order to carry out the curve of maturation. The evaluation effects of cold storage on the physical and chemical attributes were made with the fruits divided in 3 lots. The first lot was stored at 25±1°C, the second at 1±1°C and last one at 4±1ºC. The relative humidity in the three storage temperatures was 90% ± 5. The fruits storage at 25°C were evaluated in the fourth and sixth days and the fruits in refrigeration were stored for 21, 28 and 35 days followed by marketing simulation for two days at 25°C. The cultivars Roxa de Itaquera, Kelsey 31, Centenária, Gema de Ouro and Gulfblaze have shown the best adaptation to these climate conditions. The cultivars Januária, Reubennel and Kelsey Paulista need higher cooling to be able to flowering. In this way, the growth regulator application may stimulate the flowering. Application of hydrogen cyanamide is efficient in anticipating and uniformity of flowering for the cultivars. The plum cultivars Centenária and Kelsey 31 can be stored at 1oC during 21 + 2 days. In the other hand, the Gulfblaze cultivar can be stored during 28 + 2 days. The Carmesim cultivar can be well stored at 1oC or 4oC keeping the same fruits qualities until 21 + 2 days.