Effects of 1-methylcyclopropene alone and in combination with polyethylene bags on the postharvest life of mango fruit

Experiments were conducted to determine how 1‐methylcyclopropene (1‐MCP) treatments influence ethylene‐stimulated ripening of harvested mango cv. Zihua fruit at 20°C. The ripening response of fungicide (prochloraz) treated fruit was characterised following various 1‐MCP treatments in sealed jars followed by storage in polyethylene bags and/or subsequent ethephon (ethylene) exposure. Exposure of fruit to increasing concentrations of 1‐MCP for 12 h resulted in the reduced softening of produce when subsequently held in air for 7 days after ethephon treatment. Application levels of between 1 and 100 μl litre^?1 1‐MCP had increasing impact, while 200 μl litre^?1 1‐MCP apparently began to approach response saturation. Exposure of fruit to 50 or 100 μl litre^?1 concentrations of 1‐MCP for periods from 1 to 24 h subsequently resulted in reduced softening of produce when held in air for 7 days after ethephon treatment. Increasing periods of exposure from 1 to 12 h had increasing impact, while exposure times greater that 12 h appeared to reach saturation. In the absence of ethephon‐stimulation, the natural ripening of mangoes held in polyethylene bags was delayed by prior exposure to 100 μl litre^?1 1‐MCP for 12 h. Extended holding of 1‐MCP treated and non‐1‐MCP treated control fruit in polyethyene bags encouraged physiological and pathological deterioration. Following exposure to 100 μl litre^?1 1‐MCP for 12 h, mango fruit held for 10 days in polyethylene bags showed a delay in the onset of ripening relative to bagged but non‐1‐MCP treated control fruit. Treatment with 1‐MCP allowed storage of mango fruit in plastic bags at 20°C for 30 days. Observations suggest that 1‐MCP treatments do not adversely influence the quality of the post‐storage ethephon‐ripened fruit. Thus, application of 1‐MCP in combination with the use of polyethylene bags can extend the postharvest life of mango fruit at ambient temperature. Treatments that extend postharvest life are important in developing countries, such as China, where the cold chain infrastructure is often lacking.     

1-MCP对香蕉果实货架期的影响

香蕉果实经乙烯利处理后当天和1d分别用1-甲基环丙烯(1-MCP)处理,果实色泽转变、软化及淀粉降解均受到明显抑制,货架期延长5d以上;而乙烯利处理后贮放2d或3d再用1-MCP处理已失去对果实后熟的抑制作用。香蕉果实经1-MCP处理后在常温下贮藏11d完全恢复对乙烯敏感。     

Softening response of banana fruit treated with 1-methylcyclopropene to high temperature exposure

Elevated temperatures experienced by harvested fruit can modulate theirripening. Moreover, heat treatments can be applied to reduce susceptibility tolow temperature disorders and to help control pests and diseases. Theethylene-binding inhibitor 1-methylcyclopropene (1-MCP) was used to investigatethe ethylene-mediated softening response of banana fruit exposed to elevatedtemperatures. A preliminary experiment was conducted to determine levels ofhightemperature (30–50°C) imposed for a short periodof time that did not cause skin scald. The softening response of Williamsbananafruit treated with 1-MCP at various temperatures and durations wascharacterisedin subsequent experiments. Exposure of fruit to hot air for 60 minat 45°C or for 30 min at50°Ccaused 30–40% peel scald. The peel was not visibly damaged forfruit treated at 40°C for up to 60 min.Softening of fruit treated with 1-MCP for 12 h at25°Cand then held for 7 days at 30, 35 or 40°C wasinhibited in proportion to increasing concentration over the range 0.01–1l/l 1-MCP. However, softening was progressively enhanced withincreasing holding temperatures from 30–40°Cand/or time from 1–7 days, although fruit treated with the higher 1-MCPconcentrations of 1 and 10 l/l were comparatively lessresponsive to heat. Although banana fruit held at30–40°Cdid not de-green, their increased softening at elevated temperatures andinhibition of this response by 1-MCP suggest that heat enhances synthesis ofnewethylene sites which mediated banana fruit softening.     

Variability of responses to 1-methylcyclopropene by banana: influence of time of year at harvest and fruit position in the bunch

To examine the effect of early‐climacteric (postripening) 1‐methylcyclopropene (1‐MCP) exposure on the shelf‐life and quality of green Cavendish bananas (Musa acuminata cv. Williams) from the middle section of the bunch, bananas were harvested bimonthly and treated with 100 μL L^?1 ethylene for 2 consecutive days prior to exposure to 0, 100, 300, 1000, 3000 or 10 000 nL L^?1 1‐MCP for 24 h prior to storage at 22°C. 1‐MCP treatment at a concentration of 300 nL L^?1 or above increased banana shelf‐life significantly compared with the control, regardless of the month in which fruit were harvested except March where a higher concentration was needed (3000 nL L^?1). Fruit harvested in May were the most responsive with a greater than twofold increase in shelf‐life. To examine the effect of fruit position in the bunch on 1‐MCP efficacy, green fruit from the top or bottom of bunches were treated with 100 μL L^?1 ethylene for 2 consecutive days prior to early‐climacteric 1‐MCP (300 nL L^?1) exposure for 24 h at 22°C. In spring and autumn but not in summer, application of 1‐MCP to early‐climacteric fruit was more effective in fruit from the top than in those treated from the bottom of the bunch, increasing shelf‐life. Firmness of 1‐MCP‐treated fruit was up to 19% greater than that of the control across the year, except in fruit from the bottom of the bunch. Given that 1‐MCP is less effective in extending the shelf‐life of summer‐harvested fruit (particularly those from the bottom of the bunch), we conclude that preharvest conditions and fruit position in the bunch affect their responsiveness to ethylene and their behaviour during the ripening process.     

Comparison of cyclopropene, 1-methylcyclopropene, and 3,3-dimethylcyclopropene as ethylene antagonists in plants

A comparison has been made of cyclopropene (CP), 1-methylcyclopropene (1-MCP), and 3,3-dimethyl-cyclopropene (3,3-DMCP) in their ability to protect plants against ethylene. In bananas, both CP and 1-MCP are effective around 0.5 nL L^–1, and 3,3-DMCP was effective at 1 L L^–1. Bananas treated with CP and 1-MCP again become sensitive to ethylene at 12 days and those treated with 3,3-DMCP at 7 days. Mature green tomatoes are protected by 5–7 nL L^–1 of 1-MPC for 8 days at 25°C and tomatoes treated with 3,3-DMCP at 5–10 L L^–1 are protected for 5 days. Carnation flowers are protected with CP or 1-MCP after exposure to 0.5 nL L^–1 for 24 hours and by 1 L L^–1 of 3,3-DMCP. The display life of Campanula flowers is increased from 3.3 to 5.4 days by 10 L L^–1 of 3,3-DMCP and to 9 days by 20 nL L^–1 of 1-MCP. Ethylene inhibition of pea seedlings is reduced by treatment with 1-MCP at 10 L L^–1 of ethylene but as ethylene is increased to 3000 L L^–1 growth inhibition increases. 3,3-DMCP treatment causes very little reduction of the ethylene effect even at very low concentrations.     

Inhibition of ethylene responses by 1-Methylcyclopropene and 3-Methylcyclopropene

3-Methylcyclopropene (3-MCP) binds to the ethylene receptor and blocks it for several days, but concentrationswise is less effective than 1-methylcyclopropene (1-MCP). In diverse ethylene-responsive systems, including ripening of mature-green bananas (Musa sapientum L.), inhibition of growth in etiolated pea (Pisum sativum L.) seedlings, abscission of orange (Citrus sinensis L.) leaf explants and mung bean (Vigna radiata L.) leaves, and wilting of campanula (Campanula carpatica) and kalanchoe (Kalanchoë blossfeldiana) florets, full inhibition of the ethylene response required higher concentrations of 3-MCP. Depending on the experimental system, the effective concentration of 3-MCP was from 5 to 10 times higher than that required for 1-MCP.     

Responses of strawberry fruit to 1-Methylcyclopropene (1-MCP) and ethylene

1-Methylcyclopropene (1-MCP), a competitive inhibitorof ethylene action, binds to the ethylene receptor toregulate tissue responses to ethylene. In this work,we investigated the effects of 1-MCP and exogenousethylene on ripening, respiration rate, ionicconductivity and peroxidase activity in strawberryfruit. Strawberry fruit can ripen without exogenousethylene treatment, but exogenous ethylene inducessecondary ripening processes. Results indicated thatstimulation of respiration by ethylene wasdose-dependent. Fruit colour development and softeningwere slightly accelerated by ethylene, but changes insoluble solid content were not. 1-MCP may/may notaffect the respiratory rise induced by exogenousethylene dependent on fruit maturity. Cycloheximide(CHI) reduced the ethylene-induced respiratoryincrease. Combinations of 1-MCP and CHI reducedrespiration more than CHI alone. 1-MCP and CHI did notinfluence the primary respiratory change in nonethylene-treated fruit. This indicates that ethyleneinduced respiratory increase may involve an ethylenereceptor in early harvested fruit, but not in laterharvested fruit. Exogenous ethylene stimulatedrespiration by regulating new respiratory enzyme(s)synthesis in strawberry fruit. Ethylene induced anionic leakage increase, and this was positivelycorrelated to fruit water loss and peroxidaseactivity. These results suggest that non-climactericfruit, such as strawberry, may have different ethylenereceptor(s) and/or ethylene receptor(s) may havedifferent regulatory functions. It may be thesecondary effect of ethylene to stimulate respirationin strawberry. Non-climacteric fruit ripening may berelated to the development of active oxygen species(AOS) induced by postharvest stress.     

Inhibition of ethylene-induced cellular senescence symptoms by 1-methylcyclopropene, a new inhibitor of ethylene action

Ethylene is known to accelerate flower senescence, but the sequence of events that links its interaction with the tissue and the final senescence symptoms is still obscure. Recently, 1-methylcyclopropene (1-MCP) was found to inhibit ethylene-induced wilting in flowers. This work was carried out in order to investigate the effects of 1-MCP on cellular senescence symptoms in petunia flowers following expossure to ethylene. Cut petunia ( Petunia hybrida ) flowers that were exposed to ethylene for 12 h at concentrations of 1–12 ppm wilted sooner than their untreated counterparts. This effect was abolished by a 6-h pre-treatment with 1-MCP. Immediately following the ethylene treatment, decreases in petal fresh weight and total protein content were measured, along with higher electrolyte leakage, and lower membrane lipid fluidity and protein content. When applied alone, 1-MCP had relatively little impact on these parameters. However, when the flowers were treated with 1-MCP prior to the ethylene treatment, ethylene had no effect. These results indicate that while ethylenes effects on wilting were obvious 3 days after the treatment, cellular parameters were affected already at the end of the treatment. Since 1-MCP repressed these early ethylene effects, it was concluded that it interferes with ethylene action in petunia flowers at a rather early stage, long before apparent wilting.     

1—MCP处理对油桃果实硬度、呼吸及乙烯合成的影响

研究了1-MCP处理对“秦光”油桃果实硬度,呼吸,乙烯,EFE活性的影响。结果表明：1-MCP处理可抑制油桃果实乙烯的合成,显著地降低了乙烯峰值,仅为对照的一半,推迟了乙烯峰和呼吸峰的出现,但提高了呼吸峰值,延缓了果实硬度的下降,介对EFE活性无明显影响。     

Softening response of 1-methylcyclopropene-treated banana fruit to high oxygen atmospheres

Exposure to high O₂ concentrations may stimulate, have no effect or retard fruit ripening depending upon the commodity, O₂ concentration and storage time among other variables. The ethylene-binding inhibitor 1-methylcyclopropene (1-MCP) was used to investigate ethylene-mediated softening responses of Williams banana fruit exposed to elevated O₂ for various periods of time. Fruit softening was measured at 25 °C and 90% relative humidity. Exposure to high O₂ concentrations for 5 days resulted in accelerated softening. Softening of fruit treated with 1-MCP for 12 h followed by 5 days of storage in high O₂ atmospheres at 25 °C was enhanced with increasing O₂ concentration between 21 and 100%. However, overall softening was much less compared to non-1-MCP-treated fruit. Softening of 1-MCP-treated fruit was progressively enhanced with increasing holding time from 5 to 20 days. Fruit treated with 1-MCP and then held for 10 days in high O₂ atmospheres followed by exposure to ethylene for 24 h and subsequent storage for 5 days at 25 °C softened more rapidly than those held in air for 10 days. 1-MCP-treated fruit held in various high O₂ atmospheres can regain gradually the sensitivity to ethylene and finally ripen over time. Enhanced softening of fruit exposed to elevated O₂ concentrations suggests that high O₂ treatments enhance synthesis of new ethylene binding sites.     

Isolation of invertase from banana fruit (Musa cavendishii)

A soluble form of invertase (β-d-fructofuranoside fructohydrolase, EC 3.2.1.26) has been purified from ripe banana fruit (Musa cavendishii). The enzyme has a high specific activity and an apparent MW of 220 000 daltons; it appears to be glycoprotein containing 12.5% mannose and 12% glucosamine.     

Upsurge of particulate peroxidase in ripening banana fruit

Peroxidase was isolated from the pulp of ripening banana fruit and assayed with o-dianisidine as hydrogen-donor. Cell macerates contained soluble and particle-bound peroxidase. Soluble peroxidase levels did not appreciably differ in pre-climacteric, climacteric and post-climacteric fruit. Particulate peroxidase levels increased 3-fold with the initiation of the respiration climacteric and gradually declined with the onset of senescence. Bound peroxidase was released from cell wall and membrane fractions with washing in 0–8 M CaCl₂.     

1-甲基环丙烯处理对采后杨桃果实软化和细胞壁代谢的影响

为探讨1-甲基环丙烯(1-methylcyclopropene, 1-MCP)延缓采后杨桃果实软化的作用机理,本文研究了0.6 μL/L 1-MCP处理对在(15±1)℃、相对湿度90%下贮藏的‘香蜜’甜杨桃(Averrhoa carambola Linn. cv. Xiangmi)果实软化和细胞壁代谢的影响。结果表明：与对照果实相比,1-MCP处理可保持较高的杨桃果实硬度,有效降低果胶酯酶(pectinesterase, PE)、多聚半乳糖醛酸酶(polygalacturonase, PG)、纤维素酶等细胞壁降解酶活性,延缓原果胶、纤维素、半纤维素含量的下降和水溶性果胶含量的增加。因此认为,0.6 μL/L 1-MCP处理能有效控制采后‘香蜜’甜杨桃果实的软化进程,延长果实保鲜期。     

“信叶”植物营养液对香蕉产量与果实品质的影响

本试验根据香蕉春、秋季种植的物候期,采用2次土施250倍“信叶”根部营养液和4次喷施350倍花果营养液以及土施结合花果载施营养液等不同处理进行对比。两年试验结果表明,经营养液处理的香蕉,均能不同程度地提高产量和改善果实品质。其中尤以根部营养液结合花果营养液处理效果最好。     

The effect of chemical structure on the antagonism by cyclopropenes of ethylene responses in banana

The compounds, cyclopropene, 1-methylcyclopropene, 3-methylcyclopropene, 1,3-dimethylcyclopropene, 3,3-dimethylcyclopropene, 1,3,3-trimethylcyclopropene, 3-methyl-3-vinylcyclopropene, and 3-methyl-3-ethynylcyclopropene, and 1,2-dimethylcyclopropene were tested as antagonists to the ethylene receptor in bananas. All of the compounds inactivated the receptor and the bananas did not respond to ethylene even at 1000 nL L^–1. Large differences were found in the concentration required (0.7–20,000 nL L^–1 for 24h) to inactivate the receptor and in the duration of inactivation (3–12 days at 24C depending on the compound). After this time the bananas responded to ethylene and appeared to ripen normally.     

''嘎拉''苹果对不同浓度1-MCP处理的反应

以'嘎拉'('Kid's Orange'×'Delicious')苹果为试材,研究了0℃贮藏期间及贮藏30、60、90和120 d后转入室温7d货架期间1-MCP(1-甲基环丙烯)对果实呼吸速率、乙烯释放速率、品质和蛋白质变化的影响.结果表明,1-MCP处理显著抑制嘎拉苹果贮藏期间和贮后货架期间呼吸和乙烯释放速率,延缓果实硬度、可滴定酸含量的下降,对可溶性固形物含量无影响.对照果实在贮藏过程中,出现5条明显的特异性蛋白条带,1-MCP处理能抑制特异蛋白表达.300 nL·L-1浓度1-MCP处理与600 nL·L-11-MCP处理作用效果无显著差异.     

1-甲基环丙烯(1-MCP)对油桃果实软化的影响

1-甲基环丙烯(1-MCP)可延缓油桃果实硬度的下降,阻止引起果实软化的细胞物质(淀粉、纤维素、果胶)的降解,抑制与果实软化相关的酶(淀粉酶、纤维素酶、多聚半乳糖醛酸酶)活性。     

Volatile components of banana pseudostem of a cultivar susceptible to the banana weevil

Volatiles from banana (‘githumo’'cultivar) pseudostem were trapped using porapak S. The trapped volatiles were desorbed from porapak columns by elution with dichloromethane and analysed using GC and GC-MS. The volatile compounds identified included -pinene, β-pinene, β-myrcene, limonene, -cubebene, -copaene, -cedrene, β-caryophyllene and -humulene.