Incidence Of Physiological Disorders Research Articles

Physiological disorders in cold-stored ‘Autumn Sense’ hardy kiwifruit depend on the storage temperature and the modulation of targeted metabolites

This study aimed to elucidate the effects of storage temperature on various fruit quality attributes, physiological disorders, and associated metabolites in the 0.5, 3, or 10 °C stored hardy kiwifruit. Peel pitting, which was highest in the 0.5 °C stored fruit, was identified as a chilling injury symptom of hardy kiwifruit. Proline and branched-chain amino acid contents showed higher values at 0.5 °C stored fruit as chilling responses. On the other hand, fruit shriveling and decay were highest in the 10 °C after 5 weeks of storage. The 10 °C storage induced fruit ripening during 3 weeks, but fruit shriveling and decay were severe after 5 weeks of storage. Therefore, storing the ‘Autumn Sense’ hardy kiwifruit at proper temperatures would be more beneficial, as it alters targeted metabolites and helps reduce the incidence of physiological disorders during cold storage.

Short-term storage of ‘Honeycrisp’ apples at 0.5 oC does not improve control of bitter pit without increasing low temperature-induced physiological disorders

‘Honeycrisp’ apples are conditioned at 10 °C for 7 d before storage at 3 °C to reduce development of low temperature disorders such as soft scald. Conditioning, however, can result in greater risk of bitter pit development. A strategy to compromise between two types of disorder by storing fruit for short periods at 0.5 °C before being transferred to 3 °C showed promise in earlier research. Here, this strategy has been investigated over three years. Fruit were conditioned or not conditioned for 1 week at 10 °C before being stored at 0.5 or 3 °C. Fruit stored at 0.5 °C were moved to 3 °C after 1, 2, 3, 4, or 6 weeks in year 1; 5 weeks in year 2; and 1, 2, 3, 4, 6, or 8 weeks in year 3. Fruit quality and incidence of physiological disorders assessed after 16 weeks in years 1 and 2, and 20 weeks in year 3, plus 4 d at 20 °C. Internal ethylene concentration (IEC) and concentrations of acetaldehyde, ethanol and ethyl acetate of the fruit were measured during storage in year 3. Storage at 0.5 °C for different durations before transferring fruit to 3 °C in different years did not inhibit bitter pit or soft scald development compared with 0.5 or 3 °C with or without conditioning for 1 week at 10 °C. Fruit quality was not affected by storage temperature manipulation in any year. Bitter pit incidence correlated negatively with that of soft scald, and positively with IEC. Acetaldehyde, ethanol and ethyl acetate concentrations reached a maximum at 6–8 weeks of storage, but were not consistently related to treatment differences on soft scald incidence. However, volatile accumulations were associated with increasing severity ratings when fruit were categorized by disorder severity. Cavities and vascular browning of fruit were increased by short-term periods at 0.5 °C in year 3. Previous research suggesting that temperature manipulations could be used to manage soft scald and bitter pit incidence was not supported by this study.

Pre-storage temperature conditioning reduces cortex browning and cavity and alters organic, amino, and fatty acid metabolism in cold-stored ‘Chuhwangbae’ pears

‘Chuhwangbae’ pears are susceptible to internal disorders thought to be related to abiotic physiological chilling stress during cold storage. For this cultivar, pre-storage warm temperature conditioning (e.g. gradual or step-down of fruit temperatures) after harvest is highly recommended to control the development of postharvest storage disorders during cold storage. This pre-storage temperature conditioning at relatively warm temperatures relative to final storage temperature is also called “ambient temperature” conditioning by fruit packinghouse personnel. This study evaluated the influence of pre-storage ambient temperature conditioning duration (holding fruit at 22 °C) on ‘Chuhwangbae’ pear fruit quality including the incidence of physiological disorders and metabolic responses related to these disorders during cold storage. Postharvest pre-storage temperature conditioning (1, 2, 3, or 4 weeks at 22 °C) reduced cortex lightness and flesh firmness, and increased fruit weight loss and shrivelling during cold storage. The incidence and severity of cortex browning and cavity were reduced by pre-storage temperature conditioning. Pre-storage temperature conditioning reduced glucose, sorbitol, and fumaric acid contents after cold storage. Phenylalanine, isoleucine, and valine contents decreased with pre-storage temperature conditioning, but methionine, glutamine, and proline contents were higher in conditioned fruit than in unconditioned fruit. In addition, oleic acid content and the ratio of unsaturated fatty acid to saturated fatty acid were reduced by pre-storage temperature conditioning during cold storage. Results indicate that pre-storage temperature conditioning reduces incidence of cortex browning and cavity in part by altering cell wall metabolism during cold storage. Concurrently, pre-storage temperature conditioning reduces metabolites that are substrates for primary metabolism (glucose, sorbitol, and fumaric acid) and for volatile metabolism (isoleucine and valine), which corresponded to other aspects of fruit quality negatively affected by pre-storage temperature conditioning.

Modifying Walk-In Tunnels through Solar Energy, Fogging, and Evaporative Cooling to Mitigate Heat Stress on Tomato

Global warming is by far the most significant issue caused by climate change. Over the past few decades, heat stress has intensified into a serious issue that has a negative impact on crop production. Hence, it is crucial to modify cultivation systems to cope with this kind of stress, particularly in arid dry regions. In comparison to open-field cultivation, tomato production under protected cultivation techniques in walk-in tunnels that are suited for different farmers’ financial abilities was evaluated during the late summer season. The studied tunnels included a shaded net tunnel with natural ventilation, net tunnel with a fogging system and plastic tunnel with evaporative cooling (wet pad and fans). For the operation of fogging and evaporative cooling systems, solar energy was used as a sustainable, eco-friendly energy source. The results indicated that the solar energy system successfully operated the studied cooling systems. All studied protective cultivation techniques mitigated heat stress on tomato plant and improved the microclimate under walk-in tunnels. Moreover, evaporative cooling and fogging systems significantly increased plant leaf area, cell membrane efficiency and the contents of chlorophyll, relative water and proline compared to the net tunnel with natural ventilation. Furthermore, a marked reduction in physiological disorders was noticed. Improved physiological and biochemical parameters and limited physiological diseases led to higher fruit set, marketable fruit yield and total productivity. The percentage of marketable fruit yield increased by around 31.5% with an evaporative cooling system, 28.8% with a fogging system and 17% with a shaded net tunnel with no positive cooling as compared to an open field. However, the plants grown in open-field cultivation without protection significantly deteriorated from heat stress and had a high incidence of physiological disorders. The most incident physiological disorders were blossom-end rot, cracking, internal white tissues, sunscald, puffiness, blotchy ripening, cat face and exserted stigma. It is recommended to use a solar energy system to modify microclimate conditions through fogging or evaporative cooling under walk-in tunnels to ameliorate heat stress on grown tomato in the late summer season for higher fruit yield and fewer physiological disorders.

Effect of ICM Practices on Yield and Economics in Tomato (Lycopersicon esculentum Mill.)

The present investigation was carried out to study the effect of integrated crop management practices on yield and economics of tomato at farmer’s field of Mancherial district, Telangana state during the year from 2019-20, 2020-21 and 2021-22. The farming area available for the production of tomato across India during the financial year 2022 is estimated to have amounted to 841 thousand hectares. The treatments consist of farmer practice (T1) with application of RDF (180: 100: 60 kg NPK ha-1) and direct sowing in the field and T2 consists of raising of seedlings by nursery, installation of yellow sticky traps @ 25 ha-1, staking of plants, marigold grown as trap crop (tomato 16 rows: marigold 1 row) and spraying of need-based chemicals along with application of RDF (180: 100: 60 kg NPK ha-1). The results revealed that the total percent yield gap between potential yield and actual yield of tomato was 52.94 percent, in which 10.38 percent of yield gap between demonstration plot and actual farmers plot yield and 42.56 percent of technological gap. The data (T2) showed that highest yield recorded (34.46 t ha-1) in comparison to farmer practice (25.54 t ha-1) (T1), high net prot (T2) over (T1) with BC Ratio 1.56 (T2) and 1.42 (T1). The experiment showed that the number of fruits, fruit weight and marketable yield were highest in T2 (ICM practices) over T1 (application of RDF: 180: 100: 60 kg NPK ha-1). The adoption of ICM practices shows positive impact on yield (34.46 t ha-1) and economics of tomato through adoption of ICM practices and also decreased the incidence of physiological disorders (blotchy ripening, sun-scalding) and pest-disease incidence (fruit borer and blight infestation).

Armazenabilidade de maçã 'SCS417 Monalisa' conforme maturação na colheita, tratamento com 1-metilciclopropeno e atmosfera de armazenagem

Abstract The objective of this work was to determine the storability of 'SCS417 Monalisa' apple fruit in response to harvest maturity, 1-methylcyclopropene (1-MCP) treatment, and storage atmospheres. Fruit quality was evaluated after two, four, six, and eight months plus one day or seven days in shelf life at 22°C. The controlled atmosphere (CA) and 1-MCP (1.0 μL L-1) treatments reduce fruit ethylene production and respiration, prevent rapid softening, and inhibit the incidence of scald-like symptoms, flesh browning, cracking, and fungal decay, in comparison with air storage . The combination of 1-MCP and CA provides additive benefits in firmness retention and in the reduction of the incidence of physiological disorders. CA and/or 1-MCP increase the risk of fruit developing wrinkly skin disorder. The loss of flesh firmness and acidity and the development of all physiological disorders and decay are higher in late-harvested fruit. The storage life of 'SCS417 Monalisa' apple is about two months in cold air and from six to eight months in cold CA, considering the time necessary to reach a flesh firmness of 53 N. The limiting factor for the long-term storage of 'SCS417 Monalisa' apple fruit under CA without 1-MCP is the development of physiological disorders and fungal decay.

Evaluating the Efficacy of Gum Arabic-Zinc Oxide Nanoparticles Composite Coating on Shelf-Life Extension of Mandarins (cv. Kinnow).

Restricted postharvest application of synthetic fungicides in maintaining the quality of citrus fruits has led to a search for alternative postharvest treatments. This study evaluated the efficacy of gum arabic (GA) enriched with green synthesized zinc oxide nanoparticles (ZnO-NPs) in maintaining the postharvest quality of mandarin (cv. Kinnow). ZnO-NPs were synthesized using Bidens pilosa leaf extract and incorporated into GA (2% w/v) at 0, 0.25, 0.5, and 1% to form composite coatings: GA, GA + ZnO-NP 0.25%, GA + ZnO-NP 0.5% and GA + ZnO-NP 1%, respectively. Fruit were dipped for 3 min in the respective coatings, with untreated fruit used as control. Fruit were air-dried, packed in commercial cartons, and stored at 5 ± 1°C and 90 ± 5% relative humidity (RH) for 40 days and observed at 10 days intervals, plus 5 days at 20 ± 5°C and 65 ± 5% RH to determine the incidence of physiological disorders. GA + ZnO-NP showed promise as an alternative postharvest treatment for controlling postharvest physiological disorders associated with ‘Kinnow’ mandarin. For instance, GA + ZnO-NP 0.5% markedly minimized weight loss (9.2%), electrolyte leakage (43.8%) and chilling injury incidence (5.4%) compared to control (weight loss; 33.3%, electrolyte leakage; 90.3% and chilling injury incidence; 41.5%) at the end of the storage. GA + ZnO-NP 1% significantly alleviated rind pitting, with 13.2% incidence compared to 45.2% rind pitting incidence in the control fruit. This was due to significantly higher phytochemical and antioxidant capacity and reduced antioxidant enzyme degradation in coated fruit than in control. In conclusion, gum arabic coating enriched with ZnO-NPs at concentrations between 0.5 and 1% is recommended as a viable option to maintain the quality of ‘Kinnow’ mandarin fruit during cold storage.

Effects of NIR Reflective Film as a High Tunnel-Covering Material on Fruit Cracking and Biomass Production of Tomatoes

Tomatoes require higher irradiance, although the incidence of physiological disorders in fruit increases at high temperatures. Near-infrared (800–2500 nm) (NIR) reflective materials are effective tools to suppress rising air temperatures in greenhouses. We examined the physiological and morphological changes in tomato growth and fruit quality when grown in a high tunnel covered with NIR reflective film (NR) and in another covered with polyolefin film (PO; control). There was no relationship between the fruit cracking rate and mean daytime temperature under NR. The fruit temperature at the same truss was lower and the increase in air temperature was slow under NR. Fruit dry matter (DM) content under NR was also significantly decreased. These findings suggest that the reduction in fruit cracking under NR results from a decrease in fruit DM content as a consequence of lower fruit temperature and a decrease in total DM (TDM). Total fruit yield did not differ, whereas TDM was significantly decreased under NR. This was considered to result from a lower transmitted photosynthetic photon flux density (400–700 nm) (PPFD) and LAI, and lower photosynthetic capacity in single leaves because of a decrease in both total nitrogen and chlorophyll content. We conclude that NR film reduces fruit cracking in exchange for a slight reduction in TDM.

Calcium applications on ‘Fuji Suprema’ and ‘Maxi Gala’ apple trees: fruit quality at harvest and after cold storage

The aim of this study was to evaluate the effect of new Ca sources sprayed on ‘Fuji Suprema’ and ‘Maxi Gala’ apple trees on nutrient levels in leaves and fruit, as well as on fruit ripening features and quality at harvest time and after cold storage. Experiments were carried out in a commercial orchard planted with ‘Fuji Suprema’ and ‘Maxi Gala’ apple trees in Caçador, Santa Catarina state, Brazil. Application of different Ca sources and untreated trees were evaluated in each experiment. Fruit were harvested at two different ripening stages and analyzed based on the following variables: fruit ripening at harvest time, as well as fruit quality and incidence of physiological disorders after 210-day storage at 1 °C. Calcium applications did not change Ca levels in the leaves and of the whole fruit. Calcium levels in fruit peel increased in cultivars Maxi Gala and Fuji Suprema due to leaf Ca applications. ‘Maxi Gala’ apples recorded higher postharvest incidence of physiological disorders, such as greater loss of fruit firmness than ‘Fuji Suprema’ apples (Due to 1-methylcyclopropene [1-MCP] application on ‘Fuji Suprema’ apples). Calcium applications did not change fruit maturation (starch index and pulp firmness) or apple pulp firmness preservation in both cultivars, although they reduced the incidence of bitter pit disorder in ‘Maxi Gala’ apples. The new sources of Ca tested did not increase Ca contents, nor did they reduced the risk for physiological disorder compared to the standard CaCl2 treatment that has been commercially used for decades as the main Ca fertilizer.

The efficacy of acetylsalicylic acid, spermidine and calcium preharvest foliar spray applications on yield efficiency, incidence of physiological disorders and shelf-life performance of loquat fruit

The effect of preharvest foliar spray applications at fruit colour breaker stage with acetylsalicylic acid (synthetic salicylate), spermidine (polyamine), their combination and a commercial calcium supplement on loquat (Eriobotrya japonica Lindl cv. ‘Karantoki’) fruit at successive harvests and subsequently during maintenance at room temperature (shelf-life) for 3 and 6 days respectively, were investigated. Yield efficiency, qualitative attributes, textural properties and the incidence of physiological disorders, namely purple spot and fruit cracking, were determined. Loquat fruit quality parameters were affected by spraying treatments, harvesting day and shelf-life periods applied. Acetylsalicylic acid is recommended as an efficient and cost-effective treatment that needs to be further explored towards production of loquat fruit with enhanced quality properties. However, spermidine application alone, or in combination with acetylsalicylic acid, did not show any beneficial and/or synergistic effect on loquat fruit quality parameters to justify its application. All foliar applications did not affect fruit growth and yield efficiency. The current study shed some light on the potential use of foliar spraying with acetylsalicylic acid, alone or in combination with a calcium supplement, towards enhancement of fruit quality properties of an added value product as loquat. To this aim, further studies need to be implemented to test their efficacy under different environmental conditions that may accelerate the incidence of physiological disorders and/or multiple applications over the growing season.

Application of Dynamic Controlled Atmosphere Technologies to Reduce Incidence of Physiological Disorders and Maintain Quality of ‘Granny Smith’ Apples

The efficacy of dynamic controlled atmosphere technologies; repeated low oxygen stress (RLOS) and dynamic controlled atmosphere-chlorophyll fluorescence (DCA-CF) to control superficial scald development on ‘Granny Smith’ apples during long-term storage was studied. Fruit were stored for 2, 4, 6, 8, and 10 months at 0 °C in DCA-CF (0.6% O2 and 0.8% CO2), regular atmosphere (RA)(≈21% O2 and 90–95% RH), and RLOS treatments: (1) 0.5% O2 for 10 d followed by ultra-low oxygen (ULO) (0.9% O2 and 0.8% CO2) for 21 d and 0.5% O2 for 7 d or (2) 0.5% O2 for 10 d followed by controlled atmosphere (CA) (1.5% O2 and 1% CO2) for 21 d and 0.5% O2 for 7 d. Development of superficial scald was inhibited for up to 10 months and 7 d shelf life (20 °C) under RLOS + ULO and DCA-CF treatments. Apples stored in RLOS + ULO, RLOS + CA, and DCA-CF had significantly (p < 0.05) higher flesh firmness and total soluble solids. The RLOS phases applied with CA or ULO and DCA-CF storage reduced the development of superficial scald by possibly suppressing the oxidation of volatiles implicated in superficial scald development.

Effects of 1-methylcyclopropene and aminoethoxyvinylglycine treatments on fruit quality and antioxidant metabolites in cold-stored ‘Sangjudungsi’ persimmons

After harvest, ‘Sangjudungsi’ persimmon (Diospyros kaki Thunb.) fruit quickly soften and develop physiological disorders during cold storage. The objective of this study was to evaluate the effectiveness of 1-methylcyclopropene (1-MCP) and aminoethoxyvinylglycine (AVG) treatments on fruit quality attributes and antioxidant metabolites in ‘Sangjudungsi’ persimmon fruit stored at 0.5 °C and 95% relative humidity over a 3-month period. The treatments caused a reduction in weight loss; in the middle of the cold storage, the soluble solids content was higher with the AVG treatment than with the 1-MCP treatment. Both treatments reduced the incidence and severity of peel blackening and fruit softening, whereas fruit decay was only affected by AVG. The content of total phenolic compounds was lower with AVG than with 1-MCP or in the untreated control during the same period. At the end of cold storage, the AVG treatment resulted in a greater total flavonoid and total antioxidant activity and a higher reduced glutathione level than with 1-MCP or in the untreated control. AVG likely evoked the least physiological and biochemical responses in persimmons, according to the results of a normalized heatmap matrix system. Correlation coefficient networking results showed that 1-MCP and AVG caused differential correlation responses between the fruit quality variables and targeted metabolites during cold storage. Overall, the results indicated that treatment of cold-stored persimmons with 1-MCP and AVG likely reduced the incidence of physiological disorders, although antioxidant metabolites were relatively less affected by both regulators.

Differential effects of preharvest sprayable 1-methylcyclopropene application on fruit quality attributes and major targeted metabolites in cold-stored ‘Chuhwangbae’ pears

The effect of preharvest sprayable 1-methylcyclopropene (1-MCP) on fruit quality and certain targeted major metabolites was investigated in ‘Chuhwangbae’ pears during short-term cold storage and shelf life. Preharvest 1-MCP application affected methionine, sucrose, and total flavonoid content and fruit decay. During cold storage and shelf life, numerous fruit quality attributes and specific targeted metabolites were affected not by preharvest 1-MCP application but by the storage duration. Overall responses in the normalized heatmap matrix and principal component analysis (PCA) loading plot showed that preharvest sprayable 1-MCP treatment enhanced the incidence of physiological disorders and suppressed the responses of targeted metabolites compared with that in untreated fruit. The results obtained using the PCA score plot showed that physiological and biochemical parameters of the fruit after preharvest 1-MCP treatment were highly separated and diverged based on the storage duration. Nevertheless, preharvest 1-MCP treatment did not significantly affect the physiological and biochemical responses associated with fruit parameters or soluble carbohydrates and free amino acids contents in cold-stored pears. Therefore, the results suggest that preharvest sprayable 1-MCP application may not have strong positive effects on the postharvest quality attributes of ‘Chuhwangbae’ pears during cold storage and shelf life.

The role of ethylene and 1-MCP in early-season sweet cherry ‘Burlat’ storage life

Sweet cherries (Prunus avium L.) are highly appreciated because of their bioactive compound content and attractive organoleptic characteristics; however, they are very perishable. The aim of this work was to investigate whether ethylene and its antagonist 1-MCP affect the postharvest quality of an early-season sweet cherry cultivar, allowing storage life extension. ‘Burlat’ sweet cherries were subjected to three treatments at 1 °C for one month: i) control (air); ii) continuous ethylene supplementation (10 μL L−1); and iii) 1-Methylcyclopropene (1-MCP; 1 μL L−1 for 24 h) followed by air. The incidence of postharvest physiological disorders, the evolution of physical and functional quality traits, and fruit senescence were evaluated at 0, 7, 14, 21, and 30 days. Results showed that sweet cherries were sensitive to both ethylene and 1-MCP treatments. Continuous ethylene exposure reduced abscisic acid accumulation, resulting in higher weight and firmness loss. Moreover, ethylene application decreased titratable acidity through storage, indicating an effect on sweet cherry senescence. No significant differences among treatments were found for soluble solids content and individual sugars. Conversely, 1-MCP preserved firmness during the first 7 days of storage, while reduced the incidence of physiological disorders at the end of storage life. Furthermore, 1-MCP delayed the accumulation of cyanidin-3-O-glucoside for 7 days compared to control and ethylene treated cherries. Taken together these results highlight the potential use of 1-MCP to extend the postharevst life of early season sweet cherry fruit

Effects of Preharvest and Postharvest Applications of 1-Methylcyclopropene on Fruit Quality and Physiological Disorders of ‘Fuji’ Apples during Storage at Warm and Cold Temperatures

The effects of preharvest and postharvest treatments of 1-methylcyclopropene (1-MCP) in combination or alone on fruit quality and the incidence of physiological disorders during storage of ‘Fuji’ apples [Malus sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] at 20 and 0.5 °C were investigated. Preharvest 1-MCP (Harvista) treatments were applied 4 or 10 days before harvest (DBH), and then fruit were either untreated or treated with 1-MCP (SmartFresh) postharvest. Fruit were stored at 20 °C for up to 4 weeks or at 0.5 °C for up to 36 weeks. At harvest, starch pattern indices and watercore incidence and severity were lower in fruit with preharvest 1-MCP treatment applied 10 DBH than in untreated fruit and in fruit treated 4 DBH. At 20 °C, the combination of preharvest and postharvest 1-MCP treatments reduced the internal ethylene concentration (IEC) more than preharvest 1-MCP treatment alone, but not to a greater extent than postharvest 1-MCP treatment alone. Greasiness and watercore were reduced more by the combination of preharvest and postharvest 1-MCP treatments than by either treatment alone. However, preharvest and postharvest 1-MCP treatments, in combination or alone, did not consistently affect flesh firmness, titratable acidity (TA), soluble solids concentration, color a* values, or incidences of flesh browning, core browning, and stem-end flesh browning. At 0.5 °C, the combination of preharvest and postharvest 1-MCP treatments inhibited IECs and maintained firmness and TA more than no treatment or preharvest 1-MCP treatment alone. However, there was a lesser extent of differences than there was with postharvest 1-MCP treatment alone. Incidences of physiological disorders were not consistently affected by the preharvest and postharvest 1-MCP treatments. Overall, the results suggested that the preharvest 1-MCP treatment positively affected fruit quality attributes compared with no treatment during shelf life and long-term cold storage, but not as effectively as a combination of preharvest and postharvest 1-MCP treatments.

Early season ‘Wonhwang’ pear fruit quality following international transport and storage is negatively impacted by fruitlet stage gibberellic acid4+7 (GA4+7) application but improved by postharvest 1-methylcyclopropene (1-MCP)

The popularity and demand of early season ‘Wonhwang’ pear fruit are getting increased due to premium fruit quality. However, numerous physiological disorders can be developed after harvest and during short-term storage. The objective of the study was aimed to evaluate the effectiveness of gibberellic acid4+7 (GA4+7) at fruitlet stage, 1-methylcylcopropene (1-MCP), pre-conditioning, or 1-MCP + pre-conditioning on fruit quality attributes and incidence of physiological disorders in ‘Wonhwang’ pears stored at commercial storage facility and then shipped to Taiwan from South Korea. GA4+7 treatment reduced fresh weight loss but was lowered flesh firmness compared with the other treatments. 1-MCP treatment maintained superior fruit firmness during shelf life relative to other treatments. Soluble solids concentration (SSC) did not differ among treatments. Titratable acidity (TA) was lowest in GA4+7 treatment but relatively retained in 1-MCP treatment, compared with the other treatments. Lightness (L*) was not affected by treatments among tissues during shelf life but was higher in 1-MCP treatment than in pre-conditioning or GA4+7 treatments. Peel staining was only detected in GA4+7 treated fruit. 1-MCP treatment reduced the severity of flesh browning, core browning, water soaking and cavity, compared with the other treatments. Overall, the results suggested that 1-MCP treatment to early season ‘Wonhwang’ Asian pears enables the retention of fruit firmness and reduces the severity of physiological disorders for international trading, compared with GA4+7 or pre-conditioning treatments.

High Storage Humidity Affects Fruit Quality Attributes and Incidence of Fruit Cracking in Cold-stored ‘Royal Gala’ Apples

‘Royal Gala’ apples can be susceptible to the incidence of fruit cracking and senescent flesh breakdown during cold storage. Because the development of these physiological disorders in other cultivars can be influenced by humidity during storage, the objective of this study was to evaluate the effect of high storage humidity on fruit quality attributes and incidence of physiological disorders in cold-stored ‘Royal Gala’ apples. Fruit obtained from a commercial orchard were kept in cardboard boxes with or without a perforated polyethylene liner during and after cold storage. High storage humidity induced by the perforated polyethylene liner reduced fresh weight loss but enhanced the change of fruit circumference after cold storage. High storage humidity contributed the most reduction of cortex lightness (L*) and hue angle (ho) in stem-end cortex tissues during shelf life. Fruit stored with liners had reduced internal ethylene concentration (IEC) and outer cortex firmness after removal from storage compared with control fruit. Furthermore, high storage humidity prevented shriveling but provoked fruit cracking. The incidence and severity of flesh breakdown were further aggravated during shelf life, compared with cold storage, regardless of a liner application. Overall, maintaining high storage humidity by applying a perforated polyethylene liner can contribute to delaying fresh weight loss, reducing IEC, and preventing fruit shriveling but can enhance cortex tissue browning, loss of flesh firmness, and incidence of fruit cracking during cold storage and shelf life.

Prestorage Temperature and Ultra-low Oxygen Treatments Affect Incidence of Physiological Disorders in Organic ‘Granny Smith’ Apples

The physiological disorders superficial scald, bitter pit, and lenticel blotch pit severely compromise the commercial value of ‘Granny Smith’ apples. A number of chemical treatments are available to alleviate these disorders but they are unacceptable in the expanding organic market. The objective of this research was to study the effectiveness of prestorage treatments—delayed cooling and elevated temperature under ultra-low oxygen (ULO) atmospheres—as organic-friendly strategies to control these disorders. ‘Granny Smith’ apples were exposed to four different treatments: 1) conditioning temperature treatments (CTemp): 10 days at 3 °C or 30 days at 3 °C or 10 days at 20 °C, in air; 2) the same conditioning temperature treatments combined with an ultra-low oxygen (ULO) conditioning treatment of 0.2–0.5 kPa O2 and <0.5 kPa CO2; 3) 1-methylcyclopropene (1-MCP) treatment as a commercial control; and 4) untreated control fruit. After the prestorage treatment, fruit were stored for 90 or 150 days at 0 °C, and then held poststorage for 8 days at 20 °C before quality analysis. A combination treatment of temperature conditioning and ULO for 30 days at 3 °C achieved the best control of superficial scald, bitter pit, and lenticel blotch pit. The use of ULO with CTemp for 10 days at 20 °C offered the same control but induced high concentrations of ethanol and acetaldehyde that affected the organoleptic acceptability of the fruit and reduced its commercial value. The use of 1-MCP offered 100% control of superficial scald but bitter pit and lenticel blotch pit disorder incidences were similar or higher than in the control fruit. All ULO conditioning treatments resulted in high ethanol and acetaldehyde concentrations during the first 90 days of storage, but fruit exposed to ULO conditioning treatment for 30 days at 3 °C showed similar organoleptic acceptability to control fruit after 150 days. Therefore, ULO conditioning is a potentially useful treatment for the organic apple industry.

Use of Biostimulants for Organic Apple Production: Effects on Tree Growth, Yield, and Fruit Quality at Harvest and During Storage.

The experiment was conducted during two consecutive seasons (years 2016 and 2017) in an organic apple orchard of the cultivar Jonathan. Several biostimulants were tested (10 in total), including humic acids, macro and micro seaweed extracts, alfalfa protein hydrolysate, amino acids alone or in combination with zinc, B-group vitamins, chitosan and a commercial product containing silicon. Treatments were performed at weekly intervals, starting from the end of May until mid-August. The macroseaweed extract was effective in stimulate tree growth potential in both years, as shown by a significantly larger leaf area (+20% as compared to control) and by an higher chlorophyll content and leaf photosynthetic rate in year 2016. As for the yield performances and apples quality traits at harvest (average fruit weight, soluble solids content, titratable acidity, and flesh firmness), they were generally affected by the different climatic conditions that characterized the two growing seasons (year 2017 being characterized by higher maximal and average temperatures and by limited rainfalls at the beginning of the season). Treatments with macroseaweed extract, B-group vitamins and alfalfa protein hydrolysate were able to significantly improve the intensity and extension of the red coloration of apples at harvest. Correspondingly, the anthocyanin content in the skin of apples treated with the same biostimulants resulted significantly higher than control, highlighting the potential influence of these substances on the synthesis of secondary metabolites in apple. The incidence of physiological disorders was also monitored during apple storage period. Amino acids plus zinc application was effective in reducing (more than 50%) the incidence of the “Jonathan spot,” the main post-harvest disorder for this cultivar.

Postharvest physiology, storage quality and physiological disorders of ‘Gem’ pear (Pyrus communis L.) treated with 1-methylcyclopropene

‘Gem’ is a crisp, juicy European pear (Pyrus communis L.) that can be consumed immediately at harvest or directly from cold storage. Alternatively, ‘Gem’ pears can ripen (5 d of 20 °C) to a soft, buttery, juicy texture once fruit accumulate 30 to 60 d of low temperature chill. In either condition, ‘Gem’ has a relatively short postharvest storage life of 5 months in regular air (RA). The purpose of this work was to evaluate two concentrations of 1-methylcyclopropene (1-MCP), 0.15 and 0.3 μL L−1, to maintain crisp, juicy textural properties and extend the postharvest storage life of ‘Gem’. Fruit were treated with 1-MCP, held in −1.1 °C RA and evaluated monthly (+1 d at 20 °C) for 7 months. Only minor differences were observed between 0.15 and 0.3 μL L−1 1-MCP for any of the response factors assessed. The respiration (Rs) and ethylene production rates of non-treated fruit increased ∼2- and 30-fold, respectively, between 2 and 7 months. Fruit firmness (FF), peel chlorophyll content (IAD), and titratable acidity (TA) all decreased linearly over the 7-month storage period. Treatment with 1-MCP completely inhibited internal ethylene production for the first four months. Ethylene production increased linearly between 5 and 7 months to a maximum value ∼15% of non-treated fruit. 1-MCP similarly suppressed Rs. FF, IAD, and TA were all significantly higher for 1-MCP-treated fruit than non-treated fruit. 1-MCP maintained the crisp and juicy textural properties of non-ripened fruit throughout the entire 7-month experiment by inhibiting ripening, despite a five-day 20 °C ripening treatment. In contrast, non-treated ‘Gem’ ripened after 2 months; however, the eating quality of non-treated fruit decreased after 5 months. Poor eating quality was associated with mealiness and insufficient softening after ripening. Internal browning and scald were first observed in non-treated fruit following five months of RA and reached levels of 26% and 85%, respectively, after seven months. The development of scald was closely associated with the accumulation of α-farnesene and conjugated trienols (CTols) in the fruit skin. 1-MCP significantly reduced the incidence of internal browning and completely inhibited the development of scald. Overall, 0.15 μL L−1 1-MCP maintained texture and fruit quality for 7 months RA and reduced the incidence of physiological disorders.