1-MCP对不同成熟度白凤桃冷害发生的影响

以白凤桃果实为材料,研究了1-甲基环丙烯(1-MCP)对低温冷藏条件下果实成熟生理和冷害发生的影响。实验采用25μL/L1-MCP分别对底色转白期(MG)和成熟期(RR)桃果实进行处理,然后置于(0±1)℃冷库中贮藏24d。结果表明,1-MCP处理都能够延缓MG和RR果实的后熟软化进程,降低乙烯释放量,并抑制了果实快速软化阶段的PG酶活性;1-MCP处理提高了贮藏后期MG果实的硬度,降低了出汁率,加剧了冷害的发生程度,1-MCP处理对RR果实的冷害发生率没有显著影响,表明1-MCP对桃冷害的发生程度与果实成熟度有关。     

The effects of storage temperature and fruit size on firmness,extractable juice,woolliness and browning in two nectarine cultivars

Fruit firmness, extractable juice, woolliness and browning of the mesocarp tissue in ‘Independence’ and ‘Flavortop’ nectarines stored at —0.5°, 3°, 5° and 7°C for four weeks were determined during ripening at 15°C. The firmness of both ‘Independence’ and ‘Flavortop’ during ripening decreased as storage temperatures increased. The percentage extractable juice after cold storage and during ripening varied considerably between cultivars and between the storage temperatures. The extractable juice of fruit stored at higher temperatures tended to increase during ripening, whereas fruit stored at lower temperatures tended to decrease first before increasing. At storage temperatures of —0.5° and 3°C both cultivars passed through a stage of woolliness during ripening, while less woolliness occurred after storage at 5° and 7°C. In both cultivars the percentage extractable juice during ripening was higher on average at storage temperatures of 5° and 7°C. Severe browning of mesocarp tissue in both cultivars occurred during ripening after storage at 3°C. The effect of fruit size on changes in firmness, development of woolliness and mesocarp browning in ‘Flavortop’ nectarines stored at — 0.5°C for four weeks and ripened at 15°C was also determined. Larger nectarines lost firmness more rapidly, woolliness occurred sooner and the mesocarp tissue was more prone to browning than smaller fruit during ripening.     

Effect of temperature manipulation during storage and ripening on firmness,extractable juice and woolliness in nectarines

‘Independence’ nectarines were stored at — 0.5°C for three or four weeks or at 3°C for four weeks or kept at room temperature for 18 h prior to storage for four weeks at -0.5°C. After cold storage, fruit from all treatments was ripened at 10°, 15°or20°C. In all treatments the percentage woolly fruit initially increased to high values and thereafter decreased with further ripening. The rate of increase and decrease in woolliness depended on the ripening temperature. A storage period of four weeks at — 0.5°C resulted more woolliness during subsequent ripening. Woolliness persisted longer after a four-week cold storage period than after a three-week one. When fruit was delayed at room temperature prior to cold storage, woolliness generally developed earlier and to a lesser extent during ripening. At all ripening temperatures initial storage at 3°C resulted in most woolliness extending over the longest period. In addition, browning of the meso- carp tissue occurred only in fruit cold stored at 3°C.-The delay period before cold storage decreased fruit firmness by 15.7 to 17.6 N. Except for fruit subjected to the delay period, the extractable juice in fruit of all treatments first decreased during ripening to low values then increased.     

MaCDPK7, a calcium-dependent protein kinase gene from banana is involved in fruit ripening and temperature stress responses

Calcium-dependent protein kinase (CDPK) is an important Ca²⁺ sensor in plant development and responses to stress stimuli. Banana fruit is a typical climacteric- and chilling-sensitive fruit. The roles of CDPK genes in the ripening and chilling response of banana fruit are unclear. We isolated a cDNA fragment with full-length coding MaCDPK7 (HM061075) from fruit peel tissue. Induction of MaCDPK7 expression in fruit peel was observed 0.5 h after phytohormone ethylene treatment, earlier than the up-regulation of MaACO1 and MaACS1, coding a 1-aminocyclopropane-1-carboxylate oxidase and 1-aminocyclopropane-1-carboxylate synthase, respectively. Penetration of calcium signaling blockers, EGTA, or LaCl₃ inhibited the ripening and gene expression of MaCDPK7, MaACO1, and MaACS1 in the in vitro cultured peel pieces, but Ca²⁺ application removed the inhibitory effect of EGTA and LaCl₃. This suggested that MaCDPK7 might be a positive regulator involved in the calcium signaling in banana fruit ripening. Under temperature stresses, we found that MaCDPK7 gene expression increased 3 h after hot water dipping (HWD). The HWD-treated fruits exhibited markedly less chilling injury (CI) than control fruits in cold storage. Stored at 7°C (CI temperature) dramatically increased MaCDPK7 gene expression, while pre-treatment of HWD repressed the induction in cold storage. These results show that the MaCDPK7 gene is involved in regulating banana fruit ripening and chilling resistance induced by heat treatment.     

Effect of low temperatures on pulp browning and endogenous abscisic acid and ethylene concentrations in peach (Prunus persica L.) fruit during post-harvest storage

Summary

Changes in the severity of pulp browning, endogenous abscisic acid (ABA) and ethylene concentrations, and related gene expression in peach (Prunus persica L. ‘Bayuecui’) fruit stored at the biological freezing-point temperature (BFT; 1ºC), at 4ºC, or at room temperature (20ºC; as a control) were investigated.The results showed that fruit stored at room temperature showed climacteric changes in ethylene and ABA concentrations and in levels of expression of the corresponding ethylene synthetase genes (PpACS1, PpACO1) and the gene for a key enzyme of ABA synthesis (PpNCED), concomitant with a significant decrease in fruit firmness and an increase in juice yield. Meanwhile, two sucrose synthase genes (PpSUS1 and PpSUS2) were expressed at relatively low levels. However, fruit firmness decreased slightly and chilling injury (CI) increased significantly 40 d after storage (DAS) at 4ºC, with a significant accumulation of proline [from 8.33 µg g^–1 (at t = 0 d) to 9.125 µg g^–1 (at t = 40 d)]. In contrast, fruit firmness decreased slowly and pulp browning increased slightly 80 DAS at the BFT ( 1ºC), with a lower accumulation of proline than in fruit stored at 4ºC. The concentrations of soluble sugars and titratable acidity decreased during storage at 1ºC, 4ºC, or 20ºC, but there was a peak of soluble sugars at a late stage of storage at the BFT ( 1ºC). The fruit browning index was significantly and positively correlated (R ² = 0.967) with ABA concentration. The decrease in ABA concentration in cold-stored fruit (at both 1ºC and 4ºC) inhibited ethylene production. Moreover, there was no significant correlation between CI in fruit and ethylene production. In conclusion, the decrease in ABA concentration reduced ethylene concentrations and inhibited the development of pulp browning, which resulted in an improved taste, but crisper fruit, when fruit were stored at the BFT (–1ºC).     

Changes in ripening behavior of ‘d'Anjou’ pears (Pyrus communis L.) after cold storage

‘d'Anjou’ pear fruit, harvested at optimum maturity with flesh firmness of 6.8 kg, were stored at ?1.1°C. Fruit were ripened at 20°C for 15 days following storage for 1–8 months. Dessert qualities were evaluated organoleptically on Day 10 of each ripening period. Changes in fruit firmness, extractable juice, titratable acids, solubl solids, respiration, ethylene production and internal ethylene were determined daily during each ripening period. Fruit firmness declined continually from 6.8 kg at harvest to 4.5 kg after 8 months of storage. Fruit stored for 2–8 months softened with a similar pattern during a 15-day ripening period at 20°C, while fruit stored for 1 month softened at a slower rate during ripening to 3.2 kg, with a coarse and dry texture after 15 days at 20°C. Fruit stored for 2–4 months ripened with the desirable buttery and juicy texture, while those stored for more than 5 months ripened with a coarse or mealy and dry texture. The buttery and juicy texture was highly correlated with a lower extractable juice, which could be used for quantitative determination of storage life based on ripened fruit quality. Changes in titratable acids and soluble solids during each ripening period were not associated with changes in dessert qualities of the ripened pears. Rates of respiration, ethylene production and internal ethylene during ripening at 20°C varied with duration of storage, but were not associated with changes in dessert qualities of the ripened fruit.     

Methyl jasmonate plays a role in fruit ripening of ‘Pajaro’ strawberry through stimulation of ethylene biosynthesis

The role of methyl jasmonate (MJ) in strawberry (Fragaria × ananassa Duch. cv Pajaro) fruit ripening was investigated by monitoring its endogenous concentrations in fruit at various stages of development and the effects of exogenously applied MJ at these stages on ethylene biosynthesis. The concentration of endogenous trans-MJ was significantly higher in the white fruit (31.7–162.2 ng g⁻¹) and decreased sharply in half and fully ripe fruit. Higher concentrations of endogenous trans-MJ at the white stage of strawberry fruit development followed by a decline during fruit ripening indicate that MJ may play an important role in modulating fruit ripening. Significantly increased ethylene production was measured in the fruit when MJ was applied at white, half ripe and at fully ripe stage. The application of MJ (50 μM) resulted in significantly highest ethylene production and increased activities of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase as compared to all other treatments. The effect of exogenously applied MJ on ethylene production, ACC synthase and ACC oxidase activities was dependent on concentration of MJ applied and on fruit developmental stage. In conclusion, MJ in strawberry modulates fruit ripening, as its concentration is higher in white fruit and is declined with the progression of ripening and exogenous application of MJ increases ethylene production, activities of ACC oxidase and ACC synthase depending upon the concentration of MJ applied and fruit developmental stage.     

Low-oxygen treatment for inhibition of decay and ripening in organic bananas

Summary

Application of a low-O₂ atmosphere for several days prior to storing organic banana clusters was effective in preventing decay development on the crown cuts, and in delaying ripening. Preclimacteric banana clusters (Musa spp. AAA group cultivar Ziv) were treated with a low-oxygen atmosphere (2%) at 208C for 24, 48 and 72.h immediately after harvest. After removal from low-O₂ stress, the bananas were stored at 128C for 21.d, and were then treated with ethylene at 188C for 24.h and transferred to shelf life at 208C for an additional 4.d. The low-O₂ treatments were compared with the commercial treatment of dipping the crown cuts in 0.2% thiabendazole (TBZ). The low-O₂ stress for 48 or 72.h was effective in preventing decay after shelf life, but less so than the TBZ treatment. Low-O₂ for 24.h was not effective enough, and the 72.h treatment markedly impaired colour development after ripening with ethylene. The 48.h low-O₂ treatment which resulted in the best decay prevention also retarded ripening processes (colour, ®rmness, respiration and ethylene production) and reduced chilling injury symptoms, without impairing the taste. The level of reducing sugars in the 48.h-treated fruit was similar to that in the control fruit after ripening and shelf life. The endogenous levels of acetaldehyde (AA) and ethanol produced by the treated fruit were lower than those in the control fruit during shelf life. It seems that there is a high potential for this physical treatment of low-O₂ stress to replace chemical treatments, as means of maintaining the quality of organic bananas.     

Chilling induced ethylene biosynthesis in ‘Hayward’ kiwifruit following storage

‘Hayward’ kiwifruit were stored at 0, 5, 10, 15 and 20°C for 5, 12 and 17 days before rewarming to 20°C for 10 more days. Ethylene and CO₂ production, ACC, ACC synthase (ACS) and ACC oxidase (ACO) activities, flesh and core firmness, soluble solids content (SSC) and flesh colour were measured. Kiwifruit stored at 0, 5, 10 and 15°C did not ripen, produce ethylene or show increases in ACS or ACO activity. Fruit stored for 5 days at the above temperatures, then rewarmed to 20°C, did not show any change during the following 10 days. Rewarmed fruit, pre-stored at 0–10°C for 12 days, started autocatalytic ethylene production within 24 h, followed by fruit ripening. Fruit stored at 15°C for 12 days needed 72 h to start ethylene autocatalyse and did not fully ripen during 10 days at 20°C. After 17 days storage at 0–15°C kiwifruit started autocatalytic ethylene production with no delay upon exposure to 20°C. Autocatalytic ethylene production correlated with increased ACC content, and increased activities of ACS and ACO. Fruit held continuously at 20°C started autocatalytic ethylene production after 19 days, with concomitant increases in ACC content, ACS and ACO activities and ripening. Respiration increased after rewarming, concomitantly with the increase in ethylene production.We concluded that exposing kiwifruit to chilling temperatures (0–10°C) for 12 days advanced ethylene biosynthesis and ripening when compared with fruit held continuously at 20°C. The advanced ethylene biosynthesis was due to increase ACS and ACO activities immediately upon rewarming of the fruit.     

Preventing cold storage disorders in nectarines

A storage experiment was aimed at preventing low temperature storage disorders in nectarine fruits, of cvs July Red and Autumn Grand. Fruit was either cooled immediately after harvest or kept at 20°C for 48 h, before transfer to controlled atmosphere (CA) conditions at 0°C. Combinations of 0, 10, 15 and 20% C02 with 8 and 16% 02 were assayed. The fruit was evaluated following cold storage, 31 days after harvest, and after four and eight days under ‘shelf conditions’ (ripening at 15-18 °C). Warming of the fruit at 20°C before cold storage prevented woolliness in the absence of elevated C02 levels but did not affect internal browning and increased reddish discoloration; further, it enhanced water loss and ripening, increasing fruit softening markedly. Conversely, high C02 delayed fruit ripening in CA storage, keeping the fruit firmer, and preventing the development of woolliness, internal browning and reddish discoloration during ripening, the best results being mostly obtained with 20% C02. 02 levels assayed did not show clear effects, but decreased 02 concentration in absence of high C02 showed some benefit in ‘July Red’. No deleterious effect of C02 concentrations even as high as 20% could be detected. Thus, even though high C02 in CA conditions showed promise for controlling disorders and preventing over-ripening, further work is needed on other cultivars, and lower 02 concentrations should be investigated before making a general recommendation.     

Differential propylene induced ethylene production in ‘Anjou’ pears during storage at chilling and non-chilling temperatures

Summary

‘Anjou’ pears were harvested from the Mid-Columbia Experiment Station, Hood River, Oregon, at 67 N firmness, stored at –1° or 20°C for 85 d and periodically tested for sensitivity to 0 or 500 µl l^?1 propylene for at least 14 d at 20°C. Climacteric ethylene of pears stored at 20°C remained at low levels and started rising on the 90th day. Pears chilled at –1°C required 70 d to ripen and produced climacteric ethylene immediately upon transfer to 20°C. The sensitivity of the fruit to exogenous propylene increased progressively with storage time at –1°C. However, the non-chilled fruit responded to propylene similarly to freshly harvested fruit during the first 55 d of storage, then similarly to –1°C-stored fruit up to 85 d. Anjou pear ripening events and the sensitivity of the fruit to exogenous propylene developed differently in storage at non-chilling temperature compared with chilling temperature.     

Polyphenoloxidase activity during ripening and chilling stress in ‘Manila’ mangoes

Summary

‘Manila’ mangoes were stored at 6 or 12°C, while a control lot was ripened at 258C. Polyphenoloxidase activity was measured in pulp and peel of mangoes during normal ripening and chilling-stress conditions. Compositional parameters (textural hardness, pH, acidity, and soluble solids) were monitored during ripening and chilling injury (CI) was assessed by visual inspection. PPO activity increased in refrigerated mangoes but fruit stored at 6°C displayed greater activity than those stored at 12°C. Both temperatures produced a peak in enzyme activity at day 16 of storage. Peel browning and acidity correlated with PPO activity (r.=.0.9073 and 0.9818) at 6°C. After the PPO peak was observed at day 16, refrigerated mangoes showed lower enzyme activities; however external browning became more pronounced.     

Quality of lemons sealed in high-density polyethylene film during long-term storage at different temperatures with intermittent warming

Storage of lemons is designed to extend the marketing of fruit throughout the year, from the main harvest season in the winter until late summer, which is a period of short supply in the market. This work was concerned with physiological and chemical attributes of stored lemons either seal-packaged in high-density polyethylene plastic film (HDPE), or left unwrapped, during storage at 13, 8 and 2°C. Intermittent warming (IW) was used to prevent chilling injury at the lower temperatures. Differences between fruit subjected to the two treatments which produced longest storage (sealed at 13°C and non-sealed at 2°C with IW) are discussed. Both treatments are recommended for adoption in commercial practice.     

Leatheriness and mealiness of peaches in relation to fruit maturity and storage temperature

Summary

`Huangjin' peaches (Prunus persica Batsch) were harvested at commercial harvest time (commercial) and 20 d before (early) or after (later) commercial harvest. Fruit from each harvest were stored at three temperature regimes (0, 5 and 10°C) at 95% r.h. After four weeks of storage at 0 or 5°C, early harvested fruit developed more leatheriness but less mealiness and later harvested fruit did not develop leatheriness but developed more mealiness comparedwith fruit from commercial harvest. Overall, fruit stored at 5°C developed more mealiness but less leatheriness than fruitat 0°C for the same period of storage. When stored at 10°C for two weeks, after which fruit were senescent, fruit did not develop any leatheriness or mealiness regardless of harvest times. Fruit with leatheriness were firmer (>30 N) thanjuicy or mealy fruit (<10 N) after the same period of cold storage and 4 d at 20°C. Mealy fruit were as soft as juicy fruit. 1-Aminocyclopropane-1-carboxylate oxidase (ACO) activity, 1-aminocyclopropane-1-carboxylic acid (ACC) content, and polygalacturonase (PG) and galactosidase (GAL) activities were lower, and insoluble pectin content was higher in leathery fruit than that in juicy or mealy fruit. ACO, PG and GAL activity, ACC, and insoluble pectin content were similar between mealy and juicy fruit.     

Postharvest UV-C treatment combined with 1-methylcyclopropene (1-MCP), followed by storage in continuous low-level ethylene atmosphere,improves the quality of tomatoes

Mature green tomatoes (Solanum lycopersicum L. cv Neang Pich) were exposed to 13.6 kJ m^?2 UV-C or 0.5 μL L^?1 1-MCP or combination of 13.6 kJ m^?2 UV-C and 0.5 μL L^?1 1-MCP, with appropriate untreated controls. After treatment, tomatoes were stored in air containing 0.1 μL L^?1 ethylene at 20°C and 100% RH. The untreated fruit ripened significantly faster than those of all other treatments. UV-C treatment alone was able to delay fruit ripening by up to 5 days longer compared to untreated fruits whilst the additional of 1-MCP further delayed fruit ripening. UV-C and 1-MCP treatments alone or in combination had significantly slower ethylene production rates throughout the storage period. The fruit treated with the combination of 1-MCP and UV-C was significantly firmer and had higher total phenolic content compared to that of the other treatments. However, there was no difference between treatments in soluble solids content/titratable acids ratio, chlorophyll content, lycopene content and total antioxidant activity. These results show that UV-C and 1-MCP treatment delay ripening and improve the quality of tomatoes in the presence of low-level ethylene during storage. This new treatment could be used to extend the shelf-life of mature green tomatoes through the supply chain without the use of refrigeration.     

Ethylene treatment of ‘Hayward’ kiwifruits (Actinidia deliciosa) during ripening and its influence on ethylene biosynthesis and antioxidant activity

The aim of this investigation was to assess the influence of ethylene treatment on ethylene biosynthesis and on antioxidant activity in kiwifruits during ripening. Kiwifruits were treated with ethylene of 100 μg ml⁻¹ at 20 °C for 24 h and then the ripening process at the same temperature was observed for 10 additional days. It was found that in treated fruits: (a) the flesh firmness in the early stage of ripening was significantly decreased in treated samples, (b) the contents of free sugars, soluble solids, ethylene, respiration and sensory value were increased and were significantly higher than in untreated fruits, (c) the ethylene biosynthesis was increased simultaneously with increase in 1-aminocyclopropane-1-carboxylic acid (ACC) content, ACC synthase (ACS) and ACC oxidase (ACO) activities, (d) the polyphenols content and the related antioxidant activity were increased significantly higher than in the untreated fruits and (e) the acidity and pH were not influenced by ethylene treatment.     

Subatmospheric pressure storage of mango fruits

Ripening of mango fruit is markedly delayed when the pressure in the storage chamber is reduced below 100 mm Hg, and fruit storage life is thus prolonged. The prolongation of storage life is inversely related to the pressure; control fruit stored at 760 mm Hg started to ripen after 16 days in storage at 13°C, while fruit stored at 100 and 75 mm Hg after 25 and 35 days, respectively. Fruit stored at 50 mm Hg remained unripe for 35 days. No effect on ripening was recorded at pressures above 250 mm Hg, while at pressures below 50 mm Hg the fruit desiccated. All fruits stored at subatmospheric pressure ripened 3–4 days after transfer to shelf life at 25°C. However, green mango fruits of the colored cultivars like ‘Haden’ and ‘Maya’, stored at subatmospheric pressure for a prolonged period, did not develop the proper red or orange color during shelf-life, but turned pale yellow instead. Treatment with ethylene upon removal from storage slightly improved color development in these fruits.     

黄瓜果实不同部位的耐冷性差异

 为了研究黄瓜果实采后的耐冷性,'津优1号'黄瓜（Cucumis sativus L.）果实在2 ℃下贮藏9 d后,转移到20 ℃下放置2 d,分别测定果脐（靠近花萼）、中部、果肩（靠近果梗）三个部位的冷害指数、电导率、磷脂酶D（PLD）和脂氧合酶（LOX）活性、膜结合Ca2+含量。黄瓜果实的冷害最初在脐部出现,再逐渐漫延到中部和肩部。冷藏以后的黄瓜果实冷害指数、电导率、PLD活性、LOX活性均呈现为脐部最高,中部次之,肩部最低。与膜结合的Ca2+含量则从黄瓜脐部到肩部逐渐递增。结果表明,黄瓜果实从果肩到果脐的耐低温能力逐渐降低,果实冷害程度与PLD和LOX活性提高和膜结合钙离子浓度下降显著相关。     

Reduction of chilling injury in ‘Tommy Atkins’ mangoes during ripening

Studies were conducted to investigate how harvest maturity influence fruit ripening processes to alleviate chilling injury (CI) in mangoes (cv. Tommy Atkins). Fruit at three stages of maturity, immature (M1), half-mature (M2) and mature (M3) were stored for 18 days at 5 °C and then at 1 or 3 days at 20 °C. M1 fruit succumbed to CI after 18 days at 5 °C, with symptoms increasing in severity upon warming. Low C₂H₄ production, poor colour development, minor changes to fruit composition, insipid flavour and poor aroma revealed that fruit ripening was insufficient to reduce CI compared to M2 and M3 fruits. M2 and M3 fruits had higher C₂H₄ production rates than M1 fruit and ripened normally with acceptable flavour and aroma after 18 days at 5 °C and 3 days at 20 °C. While M3 fruit had no CI symptoms, they were overripe and fruit decay incidence was 26.6%, compared to M2 fruit which had no decay, a trace of CI symptoms and possessed the best overall quality.