Incidence Of Scald Research Articles

Effects of hydrogen peroxide accumulation, lipid peroxidation, and polyphenol oxidation during superficial scald development in ‘Fuji’ apples

Hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels and polyphenol oxidase (PPO) activity were measured in ‘Fuji’ apples with different susceptibilities to the development of superficial scald during storage at 0 and 20°C. Both scald incidence and severity increased gradually in the cold and the symptoms became apparent in the fruits with an early, middle, and late harvest after 12, 15, and 21 weeks storage, respectively. Early harvest fruits had the highest scald incidence and severity as well as H2O2 and MDA contents, while late harvest had the lowest. The H2O2 and MDA levels increased, while PPO activity remained constant during storage at 0°C. All fruits showed a rapid increase in scald incidence and severity after warming, especially at the first 4 days, when H2O2 and MDA levels and PPO activities also increased. The H2O2 and MDA levels in scald-free tissues in late harvest fruits were lower initially but became higher in the scald tissues after warming for 4 days. The PPO activities were equal in both tissues. These results indicated that mature fruits were relatively resistant to scald, and that scald symptom development was highly dependent on the accumulations of H2O2 and MDA during cold storage, but PPO activity was less important.

Ethylene synthesis, ripening capacity, and superficial scald inhibition in 1-MCP treated ‘d’Anjou’ pears are affected by storage temperature

A continuing challenge for commercializing 1-methylcyclopropene (1-MCP) to extend the storage life and control superficial scald of ‘d’Anjou’ pear (Pyrus communis L.) is how to initiate ripening in 1-MCP treated fruit. ‘D’Anjou’ pears harvested at commercial and late maturity were treated with 1-MCP at 0.15μLL−1 and stored either at the commercial storage temperature −1.1°C (1-MCP@−1.1°C), or at 1.1°C (1-MCP@1.1°C) or 2.2°C (1-MCP@2.2°C) for 8 months. Control fruit stored at −1.1°C ripened and developed significant scald within 7 d at 20°C following 3–5 months of storage. While 1-MCP@−1.1°C fruit did not develop ripening capacity due to extremely low internal ethylene concentration (IEC) and ethylene production rate for 8 months, 1-MCP@1.1°C fruit produced significant amounts of IEC during storage and developed ripening capacity with relatively low levels of scald within 7 d at 20°C following 6–8 months of storage. 1-MCP@2.2°C fruit lost quality quickly during storage. Compared to the control, the expression of ethylene synthesis (PcACS1, PcACO1) and signal (PcETR1, PcETR2) genes was stable at extremely low levels in 1-MCP@−1.1°C fruit. In contrast, they increased expression after 4 or 5 months of storage in 1-MCP@1.1°C fruit. Other genes (PcCTR1, PcACS2, PcACS4 and PcACS5) remained at very low expression regardless of fruit capacity to ripen. A storage temperature of 1.1°C can facilitate initiation of ripening capacity in 1-MCP treated ‘d’Anjou’ pears with relatively low scald incidence following 6–8 months storage through recovering the expression of certain ethylene synthesis and signal genes.

Podridão apical e escaldadura em frutos de pimentão submetidos a estresse hídrico e doses de silício

As respostas da planta de pimentão submetida ao estresse hídrico são pouco conhecidas. A busca por indutores de resistência ao estresse hídrico (como a adubação silicatada) pode ser uma importante medida para reduzir os efeitos negativos desse estresse abiótico. Dessa forma, o objetivo desse estudo foi testar a hipótese de que a adubação silicatada aplicada via foliar pode atenuar a incidência de anomalias causadas pelo estresse hídrico na qualidade dos frutos de pimentão. O experimento foi conduzido em ambiente protegido na área experimental de olericultura do Instituto Federal Goiano, câmpus Urutaí-GO. O delineamento utilizado foi em blocos casualizados, com parcela subdividida no espaço, em esquema fatorial 3x4, sendo três doses de silício (0,0, 4,3, 8,6 kg ha-1) na forma de silicato de potássio (K2SiO3) e quatro tensões de água no solo de aproximadamente -15, -25, -35 e -45 kPa, totalizando 12 tratamentos, com quatro repetições. Os níveis de água no solo para a produção do pimentão, cultivar híbrido Magali-R, variaram desde a suficiente oferta de água até o déficit hídrico e, também, valores intermediários. Vinte e uma aplicações foliares de silicato de potássio foram efetuadas semanalmente ao longo do experimento. O aumento da tensão de água no solo e a ausência do silicato de potássio estiveram correlacionados com a incidência da podridão apical nos frutos. Nenhum dos dois fatores estudados influenciou a incidência de escaldadura nos frutos de pimentão. No total foram 129 frutos de pimentão com podridão apical e 70 com escaldadura, representando 2,14% e 1,16% do total de frutos colhidos.

Dynamic changes in conjugated trienols during storage may be employed to predict superficial scald in ‘Granny Smith’ apples

In order to predict scald disorders in ‘Granny Smith’ apples, fruit were harvested from three different orchards and stored in controlled storage regimes of 2.5 kPa O2/2.5 kPa CO2 (CA) and 0.7 kPa O2/0.5 kPa CO2 (Ultra low oxygen; ULO) or in air after treatment with 1-MCP. Relationships between different oxidative markers (hydrogen peroxide, antioxidant potential, malondialdehyde), compounds related to α-farnesene metabolism (α-farnesene, conjugated trienols (CTols) including CTol258 and CTol281) and scald incidence were established. Our results showed that neither changes in fruit antioxidant potential, malondialdehyde nor the generation of hydrogen peroxide during storage were associated to scald and hence were not able to predict scald incidence. The ratio between conjugated trienols (CTol258/CTol281) failed to predict scald susceptibility on a short- or mid-term basis. In contrast, a novel and accurate model based on CTols accumulation dynamics (dCTols/dt) during early stages of storage (<50 days) is proposed. After validation of the model, a threshold value of δCTols/δt ≥ 5.5 is defined to predict scald occurrence in ‘Granny Smith’ apples.

Relationships among postharvest ripening attributes and storage disorders in ‘Honeycrisp’ apple

Introduction . The objective of this study was to examine the relationships among the ripening attributes of ‘Honeycrisp’ apples at harvest and after storage, and the direct and indirect contributions of these attributes to peel greasiness and the incidence of soft scald and soggy breakdown during storage using correlation and path-coefficient analyses. Materials and methods . Fruit were harvested from a commercial orchard at least five times throughout the commercial harvest period during four subsequent years (2008 to 2011). In two of the years, fruit were stored in air for 3 months at 3 °C and/or in a controlled atmosphere (1–2 kPa O2 + 1–2 kPa CO2) for 6 months at 3 °C. Fruit were analyzed at harvest and after storage. Results and discussion . Negative correlations were detected between internal ethylene concentration (IEC) and soluble solids concentration (SSC) or titratable acidity (TA) (the higher the IEC, the lower the SSC and TA) and a positive correlation between firmness and TA (the higher the firmness, the higher the TA). More peel greasiness and higher incidence of soggy breakdown during storage were associated with lower firmness, SSC and TA. Negative correlations were also detected between the incidence of soft scald and IEC or peel greasiness. The results of the path-coefficient analyses suggest that, in ‘Honeycrisp’, interrelationships among postharvest ripening indices and each individual disorder differ. Three possible path models for the interrelationships among ripening attributes (independent variables) and the incidence of peel greasiness, soft scald and soggy breakdown (dependent variables) are presented.

Modeling the effect of preharvest weather conditions on the incidence of soft scald in ‘Honeycrisp’ apples

‘Honeycrisp’ apples show a high susceptibility to physiological disorders such as soft scald. The objective of this study was to identify weather parameters during fruit development that influence soft scald development in ‘Honeycrisp’ apples. Soft scald susceptibility of ‘Honeycrisp’ has been linked to weather conditions during specific periods of the growing season, referenced by given phenological stages. Using weather data and fruit quality analysis data from three sites in Ontario, two sites in Quebec and one site in Nova Scotia for three seasons (2009–2011) and four additional sites in Ontario from 2002–2006, a model for soft scald incidence (SSI) was built to predict the susceptibility of ‘Honeycrisp’ apples prior to storage. This model used primarily two weather variables during three sub-periods of fruit development to accumulate a SSI index (%) during the growing season, from full bloom to harvest time. Relatively wet conditions during phenological stages from full bloom until 10mm diameter (precipitation>0.5mm) and from 10mm until 50% of final caliber (precipitation>6.0mm), cool conditions (temperature<15°C) from full bloom until 10mm diameter, and warm conditions (temperature>20°C) from 50 to 80% of final size are conditions that resulted in increased soft scald susceptibility for ‘Honeycrisp’ apples. The SSI model may be used by producers to establish more appropriate marketing and storage strategies depending on levels of susceptibility to soft scald development predicted prior to storage.

Effects of Rapid Consecutive Postharvest 1-Methylcyclopropene Treatments on Fruit Quality and Storage Disorders in Apples

The objective of this study was to investigate the effects of rapid consecutive 1-methylcyclopropene (1-MCP) treatments on apple quality and disorders in storage. ‘McIntosh’ and ‘Spartan’ apples were harvested twice from commercial orchards and 1-MCP (1 μL·L−1) was applied postharvest either 1 day after harvest or 1 and 2 days after harvest. Similar fruit from both cultivars were also not treated with 1-MCP, plus an additional treatment of 2 μL·L−1 (double rate) 1-MCP was used on ‘McIntosh’. Fruit were held in either air storage at 0.5 °C for three or six months or in controlled-atmosphere (CA) storage for six or nine months. Overall, 1-MCP treatment improved firmness and acidity retention and reduced internal ethylene in both cultivars. However, ‘Spartan’ stored in CA often maintained these attributes without 1-MCP. ‘McIntosh’ apples treated twice with 1-MCP were often firmer than those treated just once. All 1-MCP treatments substantially reduced superficial scald and there was no difference in scald incidence among the treatments. Core browning was generally reduced by 1-MCP, but fruit treated once with 2 μL·L−1 or twice with 1 μL·L−1 1-MCP sometimes had higher incidence than fruit treated only once with 1 μL·L−1. ‘Spartan’ treated twice with 1-MCP also had higher incidence of internal browning after nine months. 1-MCP increased the incidence of external CO2 injury in ‘McIntosh’ from the first harvest, with fruit treated with 2 μL·L−1 having the highest incidence after six months of CA storage and those treated once with 1 μL·L−1 having the highest incidence after nine months. Storage rots were greatest after six months of air storage and 1-MCP treatments usually reduced the incidence, regardless of treatment. These results suggest that using more than the traditional single application of 1 μL·L−1 1-MCP may improve firmness retention, but there is also some risk associated with increased disorders, especially when storing apples long-term, such as for six months in air or nine months in CA storage.

Interactions of α-farnesene, conjugated trienols, and anti-oxidant activity during the development of superficial scald in ‘Fuji’ apple

SummaryThe effects of harvest maturity and post-harvest treatment with ethephon or 1-methylcyclopropene (1-MCP) on the development of superficial scald in ‘Fuji’ apple (Malus × domestica Borkh.) have been investigated. The concentrations of α-farnesene, conjugated trienols (CTols), and hydrogen peroxide (H2O2), total anti-oxidant activity (TAA), and the activities of superoxide dismutase (SOD), guaiacol peroxidase (POX), and catalase (CAT) in the peel were measured during 24 weeks of storage of fruit harvested 3 weeks before (H1), or at (H2) commercial maturity. Fruit from H2 had a lower incidence and severity of superficial scald than fruit from H1. Scald development was further inhibited by the treatment of fruit with 1-MCP on either harvest date; however, treatment with ethephon inhibited the development of scald at H1, but increased it at H2. Fruit from H2 had lower concentrations of α-farnesene, CTols, and H2O2, but higher TAA and anti-oxidant enzyme activities than fruit from H1. 1-MCP treatment diminished the increases in the concentrations of α-farnesene, CTols, and H2O2 in fruit after both harvest dates. Compared with untreatd control fruit, the TAA in 1-MCP-treated fruit was higher at H2, but lower at H1. The effects of 1-MCP on anti-oxidant enzymes activities were only detected late during storage, with higher SOD, but lower CAT and POX activities in H1 fruit, and lower activities of all anti-oxidant enzymes in H2 fruit. Ethephon stimulated the accumulation of α-farnesene in fruit from both harvest dates, while the concentrations of CTols and H2O2 decreased following ethephon treatment at H1, but increased at H2. Pre-storage treatment with ethephon resulted in higher TAA and SOD activities in fruit from H1 at late storage, but had no effect on H2 fruit. Based on the data from all time-points, ethephon-treated fruit had higher CAT and POX activities at H2, but lower CAT and POX activities at H1 compared to untreated fruit. These results suggest that oxidative stress, leading to the development of superficial scald, depends on a combination of the production and scavenging of free radicals related to the interactions of α-farnesene, CTols, and anti-oxidant components.

Effects of maturity and 1-MCP treatment on postharvest quality and antioxidant properties of ‘Fuji’ apples during long-term cold storage

‘Fuji’ apple fruit harvested 10 days before normal harvest (H1) and at normal harvest (H2) were untreated or treated with 1 L L−1 1-methylcyclopropene (1-MCP) and stored at 0 for up to 30 weeks. Fruits from H1 were firmer and had higher titratable acidity (TA) but lower soluble solids concentrations than those from H2. 1-MCP treatment delayed loss of firmness and TA in fruit from both harvests during storage. Superficial scald incidence was decreased by 1-MCP treatment, but flesh browning was unaffected. H2 fruit had higher total phenolics, flavonoid, and glutathione content as well as total antioxidant activity than H1 fruit at harvest and throughout storage. 1-MCP treated fruit tended to have higher levels of these constituents than untreated fruit in peel, but not in flesh tissues. These results suggest that fruit harvested at the mature stage have better integral quality with 1-MCP treatment.

Concentração e época de aplicação de aminoetoxivinilglicine (AVG) na maturação de macieiras 'Fuji Suprema'

O efeito de aminoetoxivinilglicine (AVG), comercialmente disponível com o nome de Retain®, foi avaliado em macieiras da cultivar Fuji Suprema durante quatro ciclos agrícolas. Foram estudadas a época de aplicação e a concentração em uma ou em múltiplas aplicações, visando a avaliar o efeito no retardamento da maturação dos frutos, queda pré-colheita dos frutos, produção de frutos, massa média de frutos, resistência da polpa, conteúdo de sólidos solúveis, acidez titulável, índice de iodo-amido, cor da epiderme dos frutos, incidência de pingo-de-mel, incidência de rachadura peduncular e danos de sol. O AVG foi aplicado uma, duas, quatro semanas antes do ponto de colheita e no ponto de colheita, em concentrações variando de 60 a 120 g ha-1. Todos os tratamentos retardaram a maturação dos frutos, sendo que aplicados duas e uma semana antes do ponto de colheita concentraram a mesma na última data de colheita. O atraso da maturação foi acompanhado da manutenção da resistência da polpa e degradação do amido. A massa média dos frutos aumentou significativamente em comparação ao tratamento-testemunha. O desenvolvimento da coloração vermelha dos frutos foi retardado proporcionalmente ao atraso da maturação. As aplicações de AVG com diferentes concentrações e épocas de aplicação em uma ou duas vezes não diferiram entre si quanto à queda de frutos em pré-colheita na cultivar Fuji, contudo todos os tratamentos com AVG foram significativamente inferiores ao tratamento-testemunha.

Development of Barley Cultivars with Resistance to Scald (Rhynchosporium secalis (Oud.) Davis) in Japan

Hokuriku district in Japan is a major producing area of six-rowed barley, which is mainly consumed as pearled grain. However, the barley cultivated in this region has been damaged by scald, and commercial scald-resistant cultivars need to be developed. The influence of scald on yield reduction (previously addressed in many reports) and on pearled-grain quality was investigated. The whiteness of pearled grain, which is the most important quality in pearled barley, was not affected, but the pearling time tended to increase with the incidence of disease. Appropriate methods to evaluate resistance or susceptibility of cultivars in breeding programs were considered. Artificial inoculation in seedlings is not adequate to determine the resistance of cultivars because an outbreak of the disease has at times occurred after the heading stage. A field test with a source of infection, i.e., scattering leaves that were badly infected by prior inoculation of scald, accelerated the incidence and prevalence of the disease. When the source of infection was applied before the winter snows, it was especially effective in spreading the disease. The field test helped to determine resistant cultivars and breeding lines that inhibited the incidence of scald after the heading stage, although the occurrence of scald fluctuated according to weather conditions. Most Japanese commercial cultivars are highly susceptible in the field, whereas some foreign cultivars exhibit resistance to the dominant race of scald in Hokuriku district. We analyzed the resistance of “Brier” and showed that it was possibly controlled by one dominant gene at the heading stage, an observation that was in agreement with previous reports. On the other hand, three recessive genes are expected to confer resistance at the grain-filling stage. The heritability of resistance at the grainfilling stage was high, which means it is relatively easy to select resistant individuals in a breeding program even if it is controlled by several genes.

α-Farnesene and antioxidative enzyme systems in Asian pear ( Pyrus serotina Rehd.) fruit

The effects of 1-methylcyclopropene (1-MCP) on ripening, superficial scald and concentrations of α-farnesene, conjugated trienols (CTols) and antioxidant enzyme activity of ‘KS 6’ Asian pear ( Pyrus serotina Rehd.) were studied. 1-MCP treated (2 μL L −1) or untreated control fruit were stored at 1 °C and 90–95% RH for up to 120 days. 1-MCP treated fruit were firmer than untreated fruit. Application of 1-MCP delayed skin color change. Scald appeared after shorter storage duration and was reduced, but not entirely controlled, with 1-MCP. Accumulation of α-farnesene and oxidation were slower in skin of 1-MCP treated fruit compared with controls. Catalase and peroxidase activities in untreated fruit either increased while activities decreased in 1-MCP treated fruit. Superoxide dismutase activity remained stable. The treatment of Asian pears with 1-MCP followed by cold storage maintained textural characteristics with less scald incidence.

POSTHARVEST AMINOETHOXYVINYLGLYCINE (AVG) DIPS ON STORAGE CHARACTERISTICS OF 'GOLDEN DELICIOUS' AND 'RED DELICIOUS' APPLES

'Golden Delicious' and 'Red Delicious' apple fruits were dipped in Aminoethoxyvinylglycine (ReTain ® ) solutions at the concentrations 0, 250, 500 and 1000 mg.L -1 for one minute and stored in a cool room at 0±1°C and 85-90% relative humidity for 3 or 6 months to study the effect of treatments on fruit storage characteristics. 'Golden Delicious' and 'Red Delicious' apples dipped in 500 or 1000 mg.l -1 AVG solutions maintained firmness and acidity, and the percent of superficial scald incidence was lower than that of untreated fruits. By 6 months fruit had softened, lost acidity and superficial scald incidence had increased, but to a lesser degree than in untreated fruit. AVG, especially at 1000 mg.L -1 decreased the development of fruit peel colour (carotene and anthocyanin), as well as decreased the rate of respiration of fruits after 6 months storage.

ETHYLENE PRODUCTION AND QUALITY IN 1-METHYLCYCLOPROPENE TREATED 'ABBÉ FÉTEL' PEARS AFTER STORAGE IN DYNAMICALLY CONTROLLED ATMOSPHERE

This research studies the ethylene production rate (EP) and quality in 1-MCP treated 'Abbe Fetel' pears after storage in DCA compared to NA and CA. 1-MCP treated (300 ppb) and control fruit were stored at -0.5°C in NA, CA (2 kPa O 2 + 0.7 kPa CO 2 ) and DCA (0.7 kPa O 2 + 0.3 kPa CO 2 ). After 4 and 6 months storage, fruit were held up to 7 d at 20°C. Skin colour, firmness and EP were measured during shelf life and the incidence of disorders after 7 d. I-MCP treatment drastically reduced EP, which began to recover after 7 d at 20°C, except for DCA stored pears. In control fruit, NA stored pears showed the highest EP. I-MCP treated fruit were the greenest at the end of shelf-life, especially after CA and DCA. Control fruit stored in DCA and in CA were greener than NA both at 1 d and 7 d of shelf life. Pears treated with 1-MCP did not soften during shelf life, while in control fruit firmness decreased from about 40 N to about 15-20 N, whatever the storage atmosphere. 1-MCP treatment prevented soft and superficial scald and internal breakdown, independently of storage atmosphere. DCA prevented superficial scald in control fruit, while it increased internal browning and breakdown in control and 1-MCP treated pears. No differences were found for soft scald incidence between control DCA and CA stored fruit. The highest percentage of sound fruit was found in NA stored 1-MCP treated pears, and the lowest in control fruit stored in DCA.

Effect of maturity and cold storage on ethylene biosynthesis and ripening in ‘Bartlett’ pears treated after harvest with 1-MCP

To further our understanding of the response of ‘Bartlett’ pear fruit to 1-methylcyclopropene (1-MCP) and their ability to recover the capacity to ripen, ‘Bartlett’ pears were treated with 0.3 μL L −1 1-MCP for 12 h at 20 °C immediately after harvest in two seasons and to pear fruit of four maturities. 1-MCP decreased rates of softening, ethylene production, respiration, and yellow color development, and reduced incidence of scald and internal breakdown. Ripening recovery induced by cold storage of 1-MCP treated fruit depended on maturity and season and was associated with stimulated ethylene production, including 1-aminocyclopropene carboxylic acid synthase (ACS) activity, 1-aminocyclopropene carboxylic acid oxidase (ACO) activity, and transcript levels of genes associated with these enzymes.

EFFECT OF DPA REAPPLICATION BY THERMOFOGGING ON SCALD CONTROL IN APPLES

Trials were conducted during three seasons (2001-2004) to determine optimal timing for a second DPA application, for control of superficial scald on apples (Malus × domestica Borkh.) and to evaluate the use of thermofogging for this purpose. 'Granny Smith', 'Fuji' and 'Braeburn' apples from commercial orchards were treated with DPA at harvest and after 2, 3, 4 or 6 months of storage in either regular air (RA, 0°C) or controlled atmosphere (CA, 1.8-2% O 2 and 1.3-1.5% CO 2 ) storage. Initial DPA treatment was applied immediately after harvest by drenching, thermofogging or dipping. DPA reapplications were done by thermofogging (in refrigerated trailers and commercial CA storerooms) or dipping. Scald incidence (%) and severity was evaluated, at 6 or 8 months after harvest and plus 10 days at room temperature. Samples were drawn periodically for DPA residue analyses. At harvest and monthly thereafter, evolution of scald related compounds (α-farnesene, conjugated trienes and antioxidant capacity) were analyzed. Reapplication of DPA was consistently effective at reducing scald development, especially in susceptible fruit and when applied after two or three months of storage. Scald incidence on 'Granny Smith' and 'Fuji' apples was associated with α-farnesene and conjugated trienes (mainly those absorbing at 281 nm). Thermofogging was capable of raising DPA residues in the fruit when applied after two or three months of storage, which resulted in reducing final scald. It has the advantages of direct application in storage (feasibility of more than one treatment), a uniform distribution in the fruit, and eliminates environmental problems associated with disposal of chemical wastes.

Coloração do fruto, distúrbios fisiológicos e doenças em maçãs 'Gala' e 'Fuji' pulverizadas com aminoetoxivinilglicina

O objetivo deste trabalho foi avaliar os efeitos da pulverização pré-colheita de macieiras 'Gala' e 'Fuji' com aminoetoxivinilglicina (AVG) sobre a qualidade dos frutos e a ocorrência de distúrbios fisiológicos e doenças. O experimento foi conduzido nos anos de 2005 e 2006, com pulverização de AVG (30 dias antes do início da colheita comercial dos frutos) nas doses de 0; 125 e 250 mg L-1, sendo que, na segunda safra, também foi utilizada a dose de 62,5 mg L-1. Em maçãs 'Gala', o aumento na dose de AVG reduziu o desenvolvimento de coloração vermelha e a permeância à perda de água na casca. Nesta mesma cultivar, em frutos avaliados após armazenamento refrigerado (três meses a 0±0,5ºC/90-95% UR), seguido de uma semana de vida de prateleira (20±4ºC/60-70% UR), o tratamento pré-colheita com AVG aumentou a incidência de "bitter pit", porém reduziu a incidência de escaldadura, rachadura peduncular e podridões. Em maçãs 'Fuji', o aumento na dose de AVG reduziu a incidência e a severidade de pingo-de-mel em frutos colhidos tardiamente. A pulverização com AVG aumentou a severidade de mancha foliar de 'Gala' (Glomerella cingulata).

Preharvest 1-Methylcyclopropene Treatment Reduces Soft Scald in ‘Honeycrisp’ Apples during Storage

The main objective of this study was to investigate the effectiveness of preharvest 1-methylcyclopropene (1-MCP) treatment on the development of soft scald in ‘Honeycrisp’ apples. In addition, the effects of preharvest 1-MCP on fruit quality at harvest and after storage were examined. For two consecutive years of study, ‘Honeycrisp’ trees were sprayed preharvest with 1-MCP and fruit were harvested twice during each year. Preharvest 1-MCP treatments had little consistent effect on fruit maturity at the time of harvest. In both years of study, preharvest 1-MCP reduced the incidence of soft scald in ‘Honeycrisp’ apples after air storage at 0 or 3 °C for 5 or 6 months. Soggy breakdown developed only in the second year of study and high incidences were reduced by preharvest 1-MCP treatments. Preharvest 1-MCP often reduced flesh firmness loss in ‘Honeycrisp’ during storage, especially during the second year of study, and with 1-MCP application closer to harvest. Malic acid content was often higher in apples with the preharvest 1-MCP spray closer to harvest. Overall, the most important benefit of preharvest 1-MCP treatments on ‘Honeycrisp’ apples was the reduction in soft scald development. Due to the high potential for substantial fruit losses from this disorder, the use of preharvest 1-MCP sprays on ‘Honeycrisp’ apples could be very advantageous.

Effects of Preharvest Precipitation, Air Temperature, and Humidity on the Occurrence of Soft Scald in ‘Honeycrisp’ Apples

The relationship of soft scald incidence (SSI) with precipitation, temperature, and fruit maturity indicators in ‘Honeycrisp’ apples was examined using 7 years of data in Maine and 6 years in Ontario, Canada. Relative humidity was also examined in Maine. Soft scald incidence was highly variable from year to year ranging from 1% to 85% in Maine and from 0% to 76% in Ontario. In Ontario, SSI was negatively related to soluble solids at harvest (partial r2 = 0.50; P = 0.0041) and negatively related to precipitation during 90 to 120 days from bloom (DFB; partial r2 = 0.28; P = 0.0344). In Maine, SSI was most strongly related to precipitation in the 90 to 120 DFB (partial r2 = 0.53; P = 0.0001), maximum air temperature 60 to 90 DFB (partial r2 = 0.21; P = 0.0001), and number of hours when relative humidity was greater than 85% (partial r2 = 0.11; P = 0.0001).

Effect of the Cooling System and 1-MCP on the Incidence of Superficial Scald in ‘Granny Smith’ Apples

A study was carried out to determine the effects of two cooling systems and the application of 1-methylcyclopropene (1-MCP, SmartFresh TM )�ontheincidenceofsuperficialscaldinapples�(Malus domestica Borkh.) cv. Granny Smith. Fruit were collected from a commercial orchard (Colbun, Maule Region, Chile) during 2004-2005 season. A completely randomized design was used in a 2 x 2 factorial arrangement, using cooling systems (normal and step-wise cooling) and application of 1-MCP (0 and 625 nL L -1 i.a.) as the main factors. Fruit from normal cooling were kept at 0 °C throughout the storage period (180 days). Step-wise cooling consisted of storing the fruit at 10 °C for 10 days; 4 °C for the next 20 days and 0 °C for the remaining 150 days. Every month, maturity indices and the chemicals, global antioxidant content (AO), α-farnesene�(AF)�andconjugatedtrienes�(TC),�weremeasured.�Incidenceofsuperficial� scald was determined after 180 days of storage, plus 10 days at 20 °C. The application of 1-MCP with both cooling systemswascapableofmaintainingfirmnessvaluesaround�8.2�kguptotheendofthestorageperiod,�aswellas� decreasingtheconcentrationofAF,�TCandAOduringstorage.�Incidenceofsuperficialscaldonfruitwith�1-MCP� was 0%, regardless of the type of cooling. Among treatments without 1-MCP, step-wise-cooling was more effective inpreventingsuperficialscald,�resultingin�1.3%�incidencecomparedto�75.6%�withthenormalcoolingsystem.� Nevertheless,�fromthefourthmonthonwardsfirmnesswaslowerthanthatrequiredforexport.