Application Of 1-methylcyclopropene Research Articles

Retention of iceberg lettuce quality by low temperature storage and postharvest application of 1-methylcyclopropene or gibberellic acid.

This study was conducted to evaluate the changes in quality of iceberg lettuce during storage at different temperatures and the effects of postharvest treatments of 1-methylcyclopropene or gibberellic acid at high temperature. The results showed that quality of the lettuce was remarkably retained during storage at 0°C, but significantly declined at 20°C. However, quality of the vegetable at shelf-temperature (20°C, 85 ~ 95% RH) was effectively delayed by the treatment with 1-methylcyclopropene (1-MCP) or gibberellic acid (GA). Browning of the lettuce leaves was significantly inhibited by the storage at low temperature and by treatment with1-MCP and GA. The biochemical analysis further indicated that the reduction of soluble protein and sugar, decrease in activity of polyphenol oxidase (PPO) and peroxidase (POD) and accumulation of free amino acids in the lettuce leaves during storage could be remarkably prevented by low temperature, treatment with1-MCP or GA. Our result suggested that 1-MCP or GA treatment would provide a potential way for controlling quality of the lettuce under suboptimal postharvest temperature conditions.

POSTHARVEST APPLICATION OF 1-METHYLCYCLOPROPENE (1-MCP) EXTENDS SHELF LIFE OF KIWIFRUIT

The role of postharvest application of 1-methylcyclopropene (1-MCP) in the softening of ‘Hayward’ kiwifruit under different cold storage conditions was investigated. 1-MCP treated fruit (0.0, 0.5, 1.0 µl L -1 ) were kept in cold storage (1°C) up to 6 months before ripening. Different 1-MCP application times were also tested in this trial (12 and 24 h). Effect of 1-MCP under ethylene-free atmosphere and under ethylene contaminated atmosphere during storage was investigated. Under both conditions, 1-MCP treatment significantly delayed the rate of fruit softening during cold storage. Firmness out of cold storage was significantly increased by 1MCP treatments. Moreover, the number of days of shelf life at 20°C (after 4 and 6 months of cold storage at 1°C) needed by ‘Hayward’ kiwifruit to reach a flesh firmness ≤10 N was significantly increased by 1-MCP postharvest treatment. These data show that 1-MCP treatment recommendations for an optimal result depend on both the length of cold storage as well as ethylene contamination of the atmosphere during storage.

1-METHYLCYCLOPROPENE (1-MCP) AFFECTS PHYSIOLOGICAL DISORDERS IN 'GRANNY SMITH' APPLES DEPENDING ON MATURITY STAGE

'Granny Smith' apples (Malus domestica Borkh.) are very susceptible to various physiological disorders, superficial scald being the most important. Application of 1-methylcyclopropene (1-MCP) to 'Granny Smith' apples may extend storage life by reducing storage scald, loss of firmness and acidity. However, other skin disorders may be enhanced by 1-MCP. The effect of 1-MCP on the incidence of disorder development and ripening during storage and subsequent shelf life was investigated in 'Granny Smith' apples from different maturity stages (38, 42 and 52% starch degradation). Fruits were exposed to 0 (control) and 0.6 μl·L -1 1-MCP at 1°C during 24 hours. The fruit was evaluated after 120, 180, 210 and 240 days in regular air at 0.5°C, upon removal from storage and after 7 and 14 days at 20°C. Application of 0.6 μl·L -1 1-MCP effectively delayed the ripening rate of the fruit harvested at different times, as indicated by better retention of firmness and titratable acidity. 1-MCP treatment significantly reduced superficial scald. Treated fruit developed scald after 240 days of cold storage, while controls developed scald after 120 days. Core flush incidence was also reduced by 1-MCP treatment, even in the fruit from the latest harvest (52% starch degradation), which was the most affected by this disorder. There was fruit affected by physiological disorders related to calcium deficit, such as bitter pit and lenticel blotch in every evaluation. In early-harvested fruit (38% starch degradation), 1-MCP treated fruit developed less bitter pit and more lenticel blotch, but the incidence of both disorders combined was higher in 1-MCP treated fruit than in control fruit. No significant differences between treatments were detected in optimum- (42% starch degradation) and late-harvested fruit. We conclude that the effect of 1-MCP on different physiological disorders differs with fruit maturity stage. Calcium-related disorders were enhanced in early harvested fruit, especially in the 1-MCP treated fruit and as the length of storage increased.

EFFECTS OF 1-METHYLCYCLOPROPENE ON INTERNAL BROWNING AND QUALITY IN COLD-STORED LOQUAT FRUIT

Internal browning (IB) and flesh leatheriness (mainly manifested as increased fruit firmness and decreased extractable juice rate) are major problems of loquat (Eriobotrya japonica Lindl.) fruit during cold storage. The effects of a postharvest application of 1-methylcyclopropene (1-MCP) on internal browning and quality in loquat fruit during storage at 5°C were investigated. Freshly harvested loquat fruit were exposed to 50 nl/L 1-MCP for 24 h at 20°C, and then stored for six weeks at 5°C. Changes in internal browning, polyphenol oxidase (PPO) activity, fruit firmness, extractable juice rate, total soluble solids (TSS) and total titratable acidity (TA) contents were monitored. The results showed that fruit internal browning was effectively controlled by 1-MCP for up to five weeks during storage at 5°C. Treatment with I-MCP inhibited PPO activity, which may account for inhibited internal browning. Increase in fruit firmness and decrease in extractable juice rate were significantly inhibited by 1-MCP treatment. Treatment with 1-MCP also arrested the decline in both TSS and TA contents. Thus, a postharvest application of I-MCP effectively reduced internal browning and maintained quality in cold-stored loquat fruit. These results suggest that 1-MCP may of commercial use to control internal browning and flesh leatheriness in loquat fruit during cold storage.

Preharvest Application of 1-Methylcyclopropene Influences Fruit Drop and Storage Potential of ‘Bartlett’ Pears

Preharvest applications of 1-methylcyclopropene (1-MCP) were tested on California ‘Bartlett’ pears at 80 N maturity and at rates of 0, 28, and 56 mg·L−1 in 2006 and 0, 50, and 100 mg·L−1 in 2007. In 2007, a parallel experiment was conducted to compare 50 mg·L−1 1-MCP with 96 g a.i./ha 1-naphthaleneacetic acid (NAA) used commercially to control or decrease premature fruit drop. Premature fruit drop, maturity, firmness at harvest, color, softening, and ethylene production during ripening and physiological disorders were studied in fruit harvested between 7 and 21 days after 1-MCP application and either ripened at 20 °C immediately after harvest or after 3.5 to 6 months storage at –1 °C. Overall, 50 mg·L−1 1-MCP reduced the incidence of premature fruit drop when compared with the untreated fruit and fruit drop was similar to adjuvant-treated fruit and NAA-treated fruit, especially 28 days or longer after the treatment. 1-MCP was more effective in retarding color, softening, and ethylene production during ripening than delaying fruit maturation on the tree (loss of firmness), and both rates of 1-MCP tested each season yielded similar fruit responses on most evaluation times. 1-MCP's effect on ripening was lost if fruit remained on the tree 21 days or after the fruit were stored for 3.5 months in cold storage regardless of treatment concentration. A reduction of internal breakdown incidence was observed in 1-MCP-treated fruit.

1-METHYLCYCLOPROPENE APPLICATION SUPPRESSES LIPID PEROXIDATION AND INCREASES ANTIOXIDANT ENZYME ACTIVITY IN COLD-STORED 'SEKAKI' PAPAYAS

The effects of postharvest application of 1-methylcyclopropene (1-MCP) at 270 ppb for 12h on lipid peroxidation and activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) in papayas (Carica papaya 'Sekaki') stored at 10°C for four weeks were studied. Papaya fruit treated with 1-MCP exhibited lower malondialdehyde (MDA) content when transferred to ambient temperatures (28°C) for ripening as compared to the non-MCP treated fruit suggesting that lipid peroxidation was suppressed by 1-MCP. In addition, the activities of SOD, APX and CAT were also elevated by the treatment. Chilling injury (CI) incidence was slightly alleviated; however, loss of tissue firmness was greatly arrested. These results suggest that 1-MCP being an antagonist of ethylene action may reduce cellular disintegration that involves development of oxidative stress through the enhancement of some antioxidant enzyme activity and prevent ethylene-associated degradation of cell wall components that leads to tissue softening.

Peanut (Arachis hypogaea L.) Response to the Ethylene Binding Inhibitor 1-Methylcyclopropene

Abstract Senescence and abscission of mature peanut pods is controlled by the ethylene cascade. Reducing senescence and abscission could involve inhibiting the ethylene cascade and allow greater harvest flexibility in peanut. Application of 1-methylcyclopropene (1-MCP), the ethylene binding inhibitor, may reduce senescence and abscission of mature peanut pods. Research was conducted from 2005 through 2008 in North Carolina to determine the effects of 1-MCP on pod yield and percentages of sound mature kernels (%SMK), sound splits (%SS), total sound mature kernels (%TSMK), other kernels (%OK), extra large kernels (%ELK), fancy pods (%FP), and pod retention. Treatments of 1-MCP were applied at 26 g ai/ha plus a crop oil concentrate at 7, 10, or 14 d prior to digging peanut at the projected optimum digging date. Peanut was dug at the projected optimum digging date or at 7 or 20 d after projected optimum digging date. The cultivars NC-V 11 (2005 and 2007), Phillips (2006 and 2007), and Perry (2008) were evaluated in separate experiments. Pod yield, %SMK, %TSMK, %SS, %OK, %ELK, and %FP were not affected by 1-MCP regardless of application timing when NC-V 11 and Phillips were evaluated. Only %SMK and %TSMK were affected by 1-MCP when applied to the cultivar Perry. Digging date affected pod yield and market grade characteristics. When digging of Phillips and Perry was delayed by 7 or 20 d past the optimum digging date, %SMK and %TSMK increased. Pod retention, determined by comparing the number and mass of pods/plant following digging, was affected by digging date and location but not 1-MCP treatment. These data suggest that 1-MCP will have little activity on peanut pod yield, market grade characteristics, or pod retention.

Amadurecimento de kiwis 'bruno' submetidos ao dano mecânico de impacto e ao tratamento com 1-metilciclopropeno

O objetivo do presente trabalho foi avaliar o efeito do dano mecânico por impacto e da aplicação de 1-MCP sobre o amadurecimento de kiwi 'Bruno'. Os tratamentos avaliados foram: (T1) controle (sem dano mecânico); (T2) dano mecânico com queda de 60 cm; (T3) dano mecânico com queda de 120 cm; (T4) 1-MCP (1µL L-1); e (T5) 1-MCP (1µL L-1) + dano mecânico com queda de 120 cm. Após a aplicação dos tratamentos, os frutos foram armazenados a 20±2 ÚC e 65±5% UR. O tratamento T3 ocasionou o aumento na atividade respiratória e da produção de etileno e reduziu a firmeza da polpa e a textura. O tratamento com 1-MCP ocasionou menor produção de etileno e na atividade respiratória e maior retenção de firmeza da polpa e da textura. A aplicação de 1-MCP em frutos submetidos ao dano mecânico por impacto proporcionou firmeza de polpa, textura e atividade respiratória e produção de etileno semelhantes ao tratamento controle. Pelos resultados constata-se que o tratamento com 1-MCP pode evitar a indução do amadurecimento ocasionado pelo dano mecânico em kiwis 'Bruno'.

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.

Integrated application of 1-methylcyclopropene and modified atmosphere packaging to improve quality retention of litchi cultivars during storage

The effect of 1-MCP application on overall quality retention of ‘Mauritius’ and ‘McLean's Red’ litchi under modified atmosphere packaging (MAP) was investigated. Fruit was packed in biorientated polypropylene bags and exposed to different concentrations of 1-MCP (300, 500 and 1000 nL L −1) within the packaging, heat sealed and stored at 2 °C for 14 and 21 d. Of the three concentrations, 300 nL L −1 was most effective in preventing browning and retention of colour in both cultivars after 14 and 21 d cold storage. The effect of 1-MCP (300 nL L −1) was more promising on ‘McLean's Red’ than ‘Mauritius’. 1-MCP (300 nL L −1) significantly reduced the polyphenol oxidase (PPO) and peroxidase (POD) activity, retained membrane integrity, anthocyanin content and prevented the decline of pericarp colour values, L*, a* and b* during storage. At higher concentrations, 1-MCP showed negative effects on membrane integrity, pericarp browning, PPO and POD activity in both cultivars. 1-MCP (1000 nL L −1) significantly suppressed fruit respiration and retained the SSC/TA and firmness. Thus, application of 1-MCP in combination with the use of MAP can extend the storage life of ‘McLean's Red’ up to 21 d.

Combination of 1-Methylcyclopropene and Ethoxyquin to Control Superficial Scald of ‘Anjou’ Pears

Superficial scald of ‘Anjou’ pears (Pyrus communis) usually develops after cold storage of ≥3 months. Ethoxyquin has been used to control scald commercially. However, only a small amount of fruit can be treated within 7 days after harvest as recommended, and sometimes ethoxyquin causes phytotoxicity. Application of 1-methylcyclopropene (1-MCP) showed excellent scald control potential, with rapid and mass treatment feasible. However, fruit may lose normal ripening ability at a dosage of 1-MCP as low as 30 nL·L−1, whereas a dosage of ≤20 nL·L−1 is not enough to control scald. In this investigation, ‘Anjou’ pears treated with 25 nL·L−1 1-MCP immediately after harvest were stored at −1 °C for up to 5 months. After 1, 7, 30, or 60 days of cold storage, part of the fruit were treated with 1000 μL·L−1 ethoxyquin and the remainder was left untreated as nonethoxyquin controls. The incidence of superficial scald, the concentrations of α-farnesene and its conjugated triene (CT) oxidation products, and the ripening ability of fruit were measured after 3-, 4-, and 5-month storages. All fruit ripened properly within 7 days of shelf life at 20 °C regardless of treatment. 1-MCP treatment at harvest or ethoxyquin alone applied within 7 days adequately controlled scald for only 3 months. By contrast, 1-MCP + ethoxyquin controlled scald for 5 months, regardless of when ethoxyquin was applied from 1 to 60 days after the start of cold storage. Thus, a combination of 25 nL·L−1 1-MCP, which is easily applied and does not influence ripening ability, and a delayed application (up to 60 days) of 1000 μL·L−1 ethoxyquin, which is a low dosage that does not cause phytotoxicity on fruit, controlled scald sufficiently. Scald is linked with accumulation of CT oxidation products of α-farnesene. 1-MCP and ethoxyquin inhibited accumulation of CT in fruit peel by different mechanisms. 1-MCP inhibited the production by reducing α-farnesene synthesis and the oxidation to CT, whereas ethoxyquin worked by inhibiting the latter.

Combination of 1-Methylcyclopropene and Ethoxyquin to Control Superficial Scald of ‘Anjou’ Pears

Superficial scald of ‘Anjou’ pears (Pyrus communis) usually develops after cold storage of ≥3 months. Ethoxyquin has been used to control scald commercially. However, only a small amount of fruit can be treated within 7 days after harvest as recommended, and sometimes ethoxyquin causes phytotoxicity. Application of 1-methylcyclopropene (1-MCP) showed excellent scald control potential, with rapid and mass treatment feasible. However, fruit may lose normal ripening ability at a dosage of 1-MCP as low as 30 nL·L−1, whereas a dosage of ≤20 nL·L−1 is not enough to control scald. In this investigation, ‘Anjou’ pears treated with 25 nL·L−1 1-MCP immediately after harvest were stored at −1 °C for up to 5 months. After 1, 7, 30, or 60 days of cold storage, part of the fruit were treated with 1000 μL·L−1 ethoxyquin and the remainder was left untreated as nonethoxyquin controls. The incidence of superficial scald, the concentrations of α-farnesene and its conjugated triene (CT) oxidation products, and the ripening ability of fruit were measured after 3-, 4-, and 5-month storages. All fruit ripened properly within 7 days of shelf life at 20 °C regardless of treatment. 1-MCP treatment at harvest or ethoxyquin alone applied within 7 days adequately controlled scald for only 3 months. By contrast, 1-MCP + ethoxyquin controlled scald for 5 months, regardless of when ethoxyquin was applied from 1 to 60 days after the start of cold storage. Thus, a combination of 25 nL·L−1 1-MCP, which is easily applied and does not influence ripening ability, and a delayed application (up to 60 days) of 1000 μL·L−1 ethoxyquin, which is a low dosage that does not cause phytotoxicity on fruit, controlled scald sufficiently. Scald is linked with accumulation of CT oxidation products of α-farnesene. 1-MCP and ethoxyquin inhibited accumulation of CT in fruit peel by different mechanisms. 1-MCP inhibited the production by reducing α-farnesene synthesis and the oxidation to CT, whereas ethoxyquin worked by inhibiting the latter.

Effect of 1-MCP on quality and antioxidant capacity of in vitro digests from ‘Sunrise’ apples stored at different temperatures

Abstract The antioxidant capacities of phenolic and non-phenolic fractions for in vitro digestates from ‘Sunrise’ apple were assessed after postharvest application of 1-methylcyclopropene (1-MCP), a ripening inhibitor, and three weeks storage at 5, 13, 15, 18 and 22 °C. An in vitro digestion system was used to generate the soluble bioaccessable digestate which was then fractionated into phenolic and non-phenolic fractions. The two fractions were assayed for Folin-Ciocalteu Reaction (FCR) reducing capacity and peroxyl radical scavenging capacity. Quality retention of the fruit was assessed by measuring internal ethylene concentration, firmness and titratable acidity. Treatment with 1-MCP inhibited internal ethylene concentration and better maintained the firmness and titratable acidity of ‘Sunrise’ summer apples as compared with untreated control apples at storage temperatures of 15 °C and above. The FCR reducing capacity of the phenolic fraction of the in vitro , simulated gastrointestinal digestates showed similar response as did the quality measures, with significantly higher activity in the 1-MCP treated fruit at higher storage temperatures. However, no consistent differences were found between 1-MCP and control treatments for the FCR reducing capacity of the non-phenolic fraction or for the peroxyl radical scavenging capacity of either fraction. The non-phenolic fractions consistently had higher levels of both types of antioxidant capacities. Treatment and storage of ‘Sunrise’ apples at elevated temperatures (> 13 °C) resulted in improved fruit quality and retention of reducing capacity in simulated gastrointestinal digestates.

Flavour volatile production and regulation in fruit

Consumption of fresh fruits is increasing as consumers become more aware of their nutritional value and role in disease prevention. Improving the flavour properties of fresh fruit reaching the consumer would add value, increase consumption, and create new markets for these commodities. One of the important characteristics of fruit ripening is volatile aroma production. Using apples (Malus domestica), strawberries (Fragaria ananassa Duch.) and melons (Cucumis melo L. var. reticulatus Naud; C. melo L. inodorus; C. melo L. cantalupensis) fruit as examples, this review focuses on recent developments in fruit aroma research. Both sensory studies and instrumental analysis confirm the importance of volatile production in fruit and its contribution to eating quality. Sensory analysis should further define the contribution of individual volatile compounds to total flavour quality. Volatile biosynthesis and its contribution to fruit eating quality is very complex, and is influenced by many factors, such as genome, harvest maturity, and postharvest handling and storage. Application of 1-methylcyclopropene (1-MCP) and transgenic lines suppressing ethylene action and biosynthesis demonstrate ethylene involvement in volatile formation and provide useful research tools to elucidate the volatile production process during fruit ripening. Cloning of genes and characterization of enzymes responsible for volatile production helps us to understand the biochemical pathways and control mechanisms. Despite the exciting developments in flavour research, several challenges still remain to be solved. An understanding of the fundamental mechanisms controlling changes in flavour quality is limited, and most biochemical pathways determining this quality trait are still unknown. As part of secondary metabolism, volatile production in fruit is a complex process with tightly controlled systems involving substrates, enzymes and energy from many pathways. It is our hope that the biochemical pathways regulating the synthesis of volatile compounds in fruit will be determined using integrated approaches, including biochemical, genomic, proteomic and microscopy tools to determine fundamental metabolism and its localization. Combining these efforts with direct measurement of sensory properties will lead us to new methods to optimize and retain fruit flavour in the market place. Key words: aroma, fruit ripening, volatile analysis, sensory, apple, strawberry, muskmelon

Application of 1-methylcyclopropene, calcium chloride and calcium amino acid chelate on fresh-cut cantaloupe muskmelon

The objective of this work was to determine the effects of postharvest application of 1-methylcyclopropene (1-MCP) and two calcium salts, applied individually or combined, on firmness and visual quality of fresh-cut muskmelon stored in air, for 18 days. Two sets of fruits, one of them exposed to 1-MCP at 300 nL L-1, were cut into cubes, dipped in deionized water, or in 1% Ca solutions as CaCl2, or in calcium amino acid chelate (Ca-chelate), placed in clamshell containers, and stored in air at 5±1ºC and 90±5% RH, for 18 days. The assay was conducted using an entirely randomized design, with three replications, in a split plot array. Evaluation of visual appearance, color, flesh firmness, total soluble solids, titratable acidity, and pH was performed right after treatments, and every period of three days, up to eighteen days. Application of 1-MCP at 300 nL L-1, calcium chloride or Ca-chelate, or the combination 1-MCP and calcium, preserved initial freshness and reduced softening of the samples. Ca-chelate synergistically enhanced the effect of 1-MCP on firmness after nine days of storage, while calcium chloride improved firmness of the samples throughout storage. Ca-chelate may serve as an alternative for shelf life extension of cantaloupe fresh-cut muskmelon.

Application of 1-Methylcyclopropene in Fresh-cut/Minimal Processing Systems

The application of 1-methylcyclopropene (1-MCP) in fresh-cut processing systems has been approached in three ways: 1) treatment of freshly harvested crop before longer-term storage after which the product is processed, 2) treatment of whole product just before processing, or 3) treatment of fresh-cut product immediately after processing. Results in the literature to date are quite variable in terms of whether 1-MCP treatment provides a benefit, no effect, or a negative effect on shelf life and quality retention of fresh-cut product. There are a number factors that impact the nature and extent of response to 1-MCP by fresh product and these include, but are not limited to, temperature of storage for fresh-cut product, condition of raw product, type of fruit or vegetable, cultivar, harvest maturity, duration of storage before cutting, and the 1-MCP treatment approach. A critical analysis, using existing published and unpublished data, provides a preliminary assessment of the impact of some of these factors. This analysis is intended to provide some insight into important considerations on the use of 1-MCP in fresh-cut processing systems and will guide researchers in considering experimental parameters for future work.

Suppression of Ethylene Responses Through Application of 1-Methylcyclopropene: A Powerful Tool for Elucidating Ripening and Senescence Mechanisms in Climacteric and Nonclimacteric Fruits and Vegetables

The discovery of 1-methylcyclopropene (1-MCP) as an inhibitor of ethylene action has provided yet another effective tool for understanding the role of this hormone in the development of higher plants. In the nearly 12 years since the description of the effects of this growth regulator on ethylene action, the subsequent introduction of stable formulations has resulted in an explosive increase in 1-MCP-targeted research, particularly, although not exclusively, in the discipline of postharvest science. The vicinal relationship between 1-MCP and postharvest biology is understandable in view of the established roles of ethylene, both beneficial and detrimental, in the handling and storage behaviors of a vast majority of harvested fruit and vegetative organs. The use of 1-MCP is proving to be supplemental to molecular approaches for identifying and understanding the spectrum of senescence and ripening processes under the direct control of ethylene perception. Climacteric fruits have served as the predominant target for investigations of 1-MCP, and the responses of these fruits have confirmed that the antagonist operates in opposition to ethylene. Studies of nonclimacteric fruits challenged with 1-MCP and other ethylene action inhibitors have identified both ethylene-dependent and ethylene-independent ripening processes and have posed interesting questions regarding the canonical distinctions between climacteric and nonclimacteric fruits.

Effect of Time of Harvest on Postharvest Leaf Abscission in Lantana (Lantana camara L. ‘Dallas Red’) Unrooted Cuttings

This study investigated the preharvest carbohydrate status and postharvest ethylene action of unrooted shoot-tip cuttings of lantana ‘Dallas Red’ harvested at three times during the day (0800, 1200, and 1600 hr) in relation to subsequent leaf abscission, shoot apices blackening, and adventitious root formation. The cuttings harvested at various times during the day were stored in darkness at 20 ± 1 °C for 4 days in sealed polyethylene bags. The cuttings harvested at 0800 hr had lowest total nonstructural carbohydrate concentrations; however, the amount of ethylene production during postharvest storage was similar among harvest times and increased during the storage period. After 4 days of storage, 69% of the leaves of cuttings harvested at 0800 hr abscised, but only 22% and 8% of the leaves abscised in cuttings harvested at 1200 and 1600 hr, respectively. Application of 1-methylcyclopropene (1-MCP) increased ethylene production and suppressed leaf abscission regardless of the harvest time, but cuttings harvested at 0800 hr developed blackened shoot apices. Leaf abscission was negatively correlated with total nonstructural carbohydrate concentration in the leaves, but no relationship was found with ethylene production. These results indicate that a high endogenous carbohydrate status decreases the postharvest ethylene sensitivity in unrooted shoot-tip cuttings of lantana. Time of harvest influenced subsequent rooting response; however, 1-MCP application did not inhibit rooting. Among various storage treatments, the best rooting response was observed in cuttings harvested at 1600 hr and treated with 1-MCP. Therefore, significant improvement of postharvest storage quality in vegetative lantana cuttings could be achieved by harvesting cuttings late in the day and treating with 1-MCP.

(182) Comparison of Aqueous and Gaseous Application of 1-Methylcyclopropene on Ripening of Tomato Fruit Harvested at Two Stages of Maturation

This study was performed to characterize the physiological responses of tomato (Lycopersicon esculentum L.) fruit harvested at either 10% to 30% or 30% to 60% color change and treated with two forms of 1-methylcyclopropene (1-MCP). Tomato fruit were treated either by submersion for 1 min in 1-MCP aqueous solution at the ambient temperature or by exposure for 12 h at 20 °C in air with 1-MCP gas, then stored at 20 °C. The concentrations (1.0, 5.0, or 10.0 μL·L-1) in 1-MCP aqueous solution were achieved through addition of 0.5, 2.5, or 5.0 g of AFxRD-300 powder (2.0% formulation, Agro-Fresh, Inc.) to 10 L of the de-ionized water, following manufacturer's instructions. 1-MCP (0.5 μL·L-1) gas in a 174-L container was achieved through addition of 0.22 g of SmartFresh® powder (0.14% formulation, Agro-Fresh, Inc.) to 100 mL of tap water. Both forms of 1-MCP significantly delayed ripening of fruit at the two initial ripeness stages, as noted by a significant delay in fruit softening and peel color change. The firmness of 30% to 60% color change tomatoes was significantly retained in response to gaseous or aqueous 1-MCP. Control fruit softened rapidly and reached the minimum marketable firmness value (about 5 N) within 8 days of storage at 20 °C, whereas fruit treated with gaseous 1-MCP (0.5 μL·L-1) or aqueous 1-MCP (1.0 or 5.0 μL·L-1) reached the same stage after 16, 20, or 24 days, respectively. Firmness retention was also highly significant for 10% to 30% color change tomatoes treated with both forms of 1-MCP. The highest concentration of aqueous 1-MCP (10.0 μL·L-1) did not result in a further delay in ripening compared with treatment at 5.0 or 1.0 μL·L-1 1-MCP.

EFFICIENCY OF 1-MCP IN NEUTRALIZING ETHYLENE EFFECTS IN CUT FLOWERS AND POTTED PLANTS FOLLOWING SIMULTANEOUS OR SEQUENTIAL APPLICATION

We studied application of 1-methylcyclopropene (1-MCP) in various ornamentals, with the aim of finding optimum application temperature, dose, and duration. We also studied its competition with ethylene, and its synergistic effect with silver thiosulfate (STS). Ethylene (5 µl l -1 ) was simultaneously applied with 1MCP (15 or 150 nl l -1 ) at 4, 12 or 20oC to carnation (Dianthus caryophyllus cv. ‘Yellow Candy’). At these application temperatures ethylene negatively affected flower quality. 1-MCP applied at 15 nl l -1 neutralized the adverse ethylene effects when applied at 4oC, but not at 12 or 20oC. However, when applied at 150 nl, l -1 1MCP successfully eliminated ethylene effects at all temperatures. It seems, therefore, that 1-MCP is a better competitor with ethylene at low temperatures. 1-MCP pre-treatment (0.2-1 µl l -1 /2-20 h), followed by a subsequent exposure to ethylene (1-5 µl l -1 /24 h/20oC or 0.5 µl l -1 /12 days/12oC), significantly improved the quality of cut flowers (carnations cv. ‘Yellow Goldy’, Cymbidium orchids) and potted plants (Ficus ‘Green island’), respectively. In Limonium hybrid ‘Beltlaard’ cut flowers the combined use of 1-MCP and STS resulted in highest quality. This combined treatment also enabled storage under sea transport conditions (8 days at 2oC). When applied alone, 1-MCP (0.4 µ µ µ µl l -1 /4 h) was also very effective in improving flower opening and the length of vase life in several rose cultivars. The results suggest that 1-MCP may be very useful in preserving quality of various ornamentals and that it protects against ethylene effects.