Modified atmosphere packaging alleviates chilling injury in cucumbers

Cucumbers (Cucumis sativus L.) packaged in perforated or sealed 31.75 μm (1.25 mil) low density polyethylene (LDPE) bags were found to have less severe chilling injury than nonwrapped fruit in storage at 5 °C and 90–95% relative humidity. The onset of chilling injury was also delayed by the LDPE packaging compared to the nonpackaged control. The concentrations of CO₂ increased to 3% while O₂ levels decreased to 16% in the sealed bags. Fruit in the sealed bags had the least decay. The O₂ and CO₂ concentrations inside the perforated bags changed very little from the ambient atmosphere. However, there was a marked difference in the weight loss between nonwrapped cucumbers and fruit from perforated or sealed bags. The weight loss of nonwrapped fruit reached 9% in 18 days while perforated and sealed samples lost less than 1% during the same period. Chilling stress induced increases in putrescine levels in all treatments but the sealed fruit had the highest levels of putrescine. Sealed fruit and perforated fruit also had higher content of spermidine than non-wrapped fruit. These high levels of polyamines may have contributed to the increase of chilling tolerance in fruit from perforated and sealed packages.     

Assessment of chilling injury during storage: chlorophyll fluorescence characteristics of chilling-susceptible and triazole-induced chilling tolerant basil leaves

Chlorophyll (Chl) fluorescence analysis by pulse-amplitude modulation (PAM) measurements was performed to assess the extent of chilling injury (CI) in stored sweet basil (Ocimum basilicum L.) leaves. Changes in three photosynthetic characteristics, in relation to visible CI rating, were monitored in leaves following modification of their chilling susceptibility by varying storage temperature and duration in two basil cultivars, or by soil application of triazole. Basil leaves developed severe or moderate visible symptoms of CI after 4 days of storage at 4 or 8 °C, respectively, but remained undamaged when stored at 12 °C. The chilling-dependent changes obtained in the ratios of variable to maximal fluorescence (F_v/F_m), represented chilling sensitivity rather than membrane damage. The photochemical quenching coefficient (qP) was unaffected by low temperatures and did not seem to be correlated with CI. On the other hand, changes in the non-photochemical quenching coefficient (qNP) were positively correlated with the appearance of visual CI symptoms in leaves of the two cultivars at all storage temperatures and durations. Similarly, the chilling-alleviating effect of triazole was accompanied by a corresponding reduction in the chilling-induced decrease of qNP. Therefore, qNP may be associated with an irreversible transition step in the CI process, which precedes the appearance of visual symptoms. As such, changes in qNP may provide a suitable, rapid and non-destructive criterion for estimation of chilling damage in green tissues.     

缓慢降温对石榴果实冷害发生及生理变化的影响

对缓慢降温处理后石榴果实在冷害温度下的生理反应进行了研究,旨在为石榴果实采后保鲜提供理论依据。以新疆大籽石榴为试材,研究了0℃低温胁迫及缓慢降温对石榴果实采后生理的影响结果表明,与0℃的低温相比,缓慢降温处理减缓石榴果皮细胞膜透性的升高以及膜脂质过氧化物丙二醛的积累,抑制了多酚氧化酶活性的增加及减少了酚类物质的氧化,明显推迟和减轻石榴果实冷害症状的发生,减轻了果皮的褐变,保持果实品质。     

Postharvest nitric oxide fumigation delays fruit ripening and alleviates chilling injury during cold storage of Japanese plums (Prunus salicina Lindell)

We investigated the effects of nitric oxide (NO) fumigation on fruit ripening, chilling injury, and quality of Japanese plums cv. ‘Amber Jewel’. Commercially mature fruit were fumigated with 0, 5, 10, and 20 μL L⁻¹ NO gas at 20 °C for 2 h. Post-fumigation, fruit were either allowed to ripen at 21 ± 1 °C or were stored at 0 °C for 5, 6, and 7 weeks followed by ripening for 5 d at 21 ± 1 °C. NO-fumigation, irrespective of concentration applied, significantly (P ≤ 0.5) suppressed respiration and ethylene production rates during ripening at 21 ± 1 °C. At 21 ± 1 °C, the delay in ripening caused by NO-fumigation was evident from the restricted skin colour changes and retarded softening in fumigated fruit. NO treatments (10 and 20 μL L⁻¹) delayed the decrease in titratable acidity (TA) without a significant (P ≤ 0.5) effect on soluble solids concentration (SSC) during ripening. During 5, 6, and 7 weeks of storage at 0 °C, NO-fumigation was effective towards restricting changes in the ripening related parameters, skin colour, firmness, and TA. The individual sugar (fructose, glucose, sucrose, and sorbitol) profiles of NO-fumigated fruit were significantly different from those of non-fumigated fruit after cold storage and ripening at 21 ± 1 °C. CI symptoms, manifest in the form of flesh browning and translucency, were significantly lower in NO-fumigated fruit than in non-fumigated fruit after 5, 6, and 7 weeks storage followed by ripening for 5 d at 21 ± 1 °C. NO-fumigation was effective in reducing decay incidence in plums during ripening without storage and after cold storage at 0 °C for 5, 6, and 7 weeks. In conclusion, the postharvest exposure of ‘Amber Jewel’ plums to NO gas (10 μL L⁻¹) delayed ripening by 3–4 d at 21 ± 1 °C, and also alleviated chilling injury symptoms during cold storage at 0 °C for 6 weeks.     

东北主推玉米品种种子形态及贮藏物质与萌发期耐冷性的关系

种子萌发是作物形态建成的起始阶段,由其自身属性和环境因素共同决定。低温是影响种子萌发的重要因素之一,探讨低温环境下种子自身属性与其萌发的关系对东北春播玉米生产具有重要意义。本研究选用东北主推的36个玉米品种以6℃为低温胁迫, 15℃适温为对照,测定了其发芽势、发芽率、种子形态和内含物等指标。通过主成分分析、耐冷性综合评价值(CL值)、隶属函数值(R值),对36个玉米品种进行耐冷性评价,分析了种子形态(粒长、粒宽、粒厚度、长宽比、百粒体积和百粒重)、贮藏物质(淀粉、蛋白质和脂肪)与其耐冷性的关系。结果表明,在低温胁迫下,36个玉米品种的发芽势和发芽率均受到不同程度的抑制,相对发芽势冷害率和相对发芽冷害率的变异最大。7个表征耐冷性的单项指标之间显著相关,主成分分析可将7个单项指标转化为2个独立的综合指标,其中相对发芽势和相对发芽率的正向贡献率最大,可作为玉米品种耐冷性评价的关键指标。聚类分析将36个品种划为强耐冷型(19.4%)、耐冷型(30.6%)、一般型(33.3%)和敏感型(16.7%)4种类型,其中,吉单56、垦吉267、绥玉23、吉单953、垦吉268、吉单96和吉单95为强耐冷...     

油菜素内酯诱导番茄幼苗抗冷效果的影响

试验采用油菜素内酯（BR）诱导二叶一心期和五叶一心期番茄幼苗,研究BR诱导后低温胁迫对番茄幼苗抗冷性相关生理指标的影响。在5℃～10℃低温胁迫条件下,不同浓度BR处理,可降低幼苗叶片细胞膜透性,减少叶片中丙二醛的含量,可溶性糖和脯氨酸的含量明显升高,同时增加了幼苗的根系活力,提高幼苗抗冷性。研究表明,低温条件下,五叶一心期对番茄幼苗喷施0.1mg/LBR,其冷害指数可比对照降低32.7%,电导率比对照降低58.4%,丙二醛含量最少,仅为25.5649nmol/g,溶性糖含量最高,达到137.27umol/g,脯氨酸含量最高,为542.3ug/g,同时幼苗的根系活力变化较平稳,变化幅度仅为20.9%。     

冻藏温度对牡蛎蛋白质变性速率的影响

研究在三个不同冻藏温度（-10±1℃、-15±1℃、-20±1℃）下,牡蛎Ca2+-ATPase活性和盐溶性蛋白质含量的变化,并在此基础上研究蛋白质变性动力学模型,将蛋白质品质变化速率与贮藏温度和贮藏时间相关联,建立牡蛎在冻藏期间蛋白质品质变化规律的方程。结果表明：在冻藏期间牡蛎Ca2+-ATPase活性和盐溶性蛋白质含量的变化符合一级反应动力学模型,蛋白质变性与冻藏的温度和时间有关,Ca2+-ATPase活性和盐溶性蛋白质含量变化趋势一致,都随冻藏温度和冻藏时间的增加而下降,温度越低蛋白质变性越缓慢;蛋白质品质变化方程在试验范围内可有效描述冻藏牡蛎蛋白质品质的变化。     

Variation in the storage proteins of peas in relation to sulphur amino-acid content

Summary A cellulose acetate electrophoretic technique has been used to characterise the storage proteins present in pea seeds in order to try and determine the proportions of proteins present which are enriched in sulphur amino-acids. Some of the eight varieties examined were shown to differ in their proportions of the various storage proteins. When the proteins were separated and estimated quantitatively and also characterised by their sub-unit composition, it was shown that cellulose acetate electrophoresis of crude protein extracts or of whole globulins did not give the degree of resolution required. The procedures which have to be undertaken in order to obtain this information are considered, and the difficulties of incorporating them into a plant breeding programme discussed.     

Reproductive development response to high daytime temperature in field pea

Flowering plants are highly sensitive to heat stress during reproductive phase, which covers development from floral initiation to seed maturity. The objectives of this study were to diagnose high temperature effects on pollen production and morphology, production of reactive oxygen species (ROS) in pollen grains and ovules in pea cultivar “CDC Golden.” This study also investigated timing and duration of heat exposure at specific developmental stages of floral buds, open flowers and early set pods on flower and pod abortion, seed development and seed yield in “CDC Golden” and a second cultivar “CDC Sage.” The experiments were conducted in growth chambers with two temperature regimes (24/18°C and 35/18°C day/night temperature for 4–14 days) during reproductive development. Heat stress reduced the number of pollen grains per anther, induced smaller pollen grains and increased ROS production in pollen grains, but it did not affect ROS accumulation in ovules and ovule number per ovary. Heat exposure when young floral buds were visible at the first reproductive node was more detrimental to flower retention, seed set, pod development and seed yield compared to heat exposure started later when flowers at the second reproductive node were fully open.     

Bruise susceptibility of banana peel in relation to genotype and post-climacteric storage conditions

The aim of this study was to understand the genotypic factors and post-climacteric storage conditions that affect bruise susceptibility of banana peel. Putative physicochemical indicators of bruise susceptibility, including peel electrolyte leakage (PEL), total polyphenolic content, hardness, water content, and peel thickness, were investigated. Bruise susceptibility is the lowest impact energy needed to produce visible bruising by an object dropped on post-climacteric banana fruit from a pre-determined height, converted into impact energy (20–200 mJ with a 20 mJ increment). The bananas were stored either at 18 °C throughout ripening or at 13 °C between the 2nd and 6th day after ethylene induction. Five cultivars with contrasting susceptibility to impact bruises were used. Neither Grande Naine nor hybrid Flhorban925 bruised at the maximum impact energy (200 mJ) during ripening whatever the storage conditions. A gradient in bruise susceptibility was observed among the other cultivars: French Corne > Fougamou > hybrid Flhorban916. Bruise susceptibility increased during ripening and was higher in bananas stored at 18 °C. The lower ripening temperature resulted in a two-day delay to fruit maturity as well as in bruise susceptibility. Bruise susceptibility was positively correlated with PEL (R = 0.78) and to a lesser extent negatively correlated with hardness (R = −0.45), and was not correlated with polyphenolic content. In conclusion, membrane permeability provides the first clue to understanding bruise susceptibility.     

Polyamines induced by hot water treatments reduce chilling injury and decay in pepper fruit

Treatment of peppers with hot water (53°C) for 4 min was found to be effective in alleviating chilling injury and reducing decay after 14 and 28 days of storage at 8°C. Treatment at 45°C for 15 min was less effective in maintaining pepper quality during storage. Packaging with low density polyethylene film significantly reduced weight loss and chilling injury during low temperature storage. Lower O₂ and higher CO₂ levels were found in internal and in-package atmospheres of heated fruit than controls. Ethylene was not detected in the in-package atmosphere of treated fruit, but was present in the control. Polyamine levels increased immediately after hot water treatments. Putrescine levels increased during storage at 8°C particularly in heat-treated fruit and in packaged fruit. A significant increase in putrescine was noted in packaged fruit treated at 53°C for 4 min after 14 days of storage. Spermine levels decreased in control fruit during storage. However, heat treatment in combination with film packaging maintained higher levels of spermine in peppers during storage than controls. These results indicated that hot water treatment in conjunction with film packaging may delay chilling injury and decay of bell peppers through a mechanism that involved elevation of polyamine levels.     

1-MCP处理对黄瓜冷藏期间保鲜效果的影响

以“叶三”黄瓜果实为材料,采用10 ppm1-MCP处理24 h后,与对照(CK)同时转入0℃低温冷藏,并对低温贮藏过程中的黄瓜感官品质、组织相对电导率、可滴定酸(TA)、Vc含量和失重率的变化进行了研究,结果表明,1-MCP处理可抑制低温贮藏中黄瓜相对电导率的上升,减缓黄瓜果实冷害症状的发展,同时延缓Vc和可滴定酸的下降速率,维持黄瓜较好品质。     

Interaction of temperature control deficiencies and atmosphere conditions during blueberry storage on quality outcomes

Southern hemisphere blueberry producers often export their products through extended supply chains to Northern hemisphere consumers. During extended storage, small variations in temperature or atmosphere concentrations may generate significant differences in final product quality. In addition, relatively short delays in establishing cool storage temperatures may contribute to quality loss. In these experiments a full factorial analysis was done of the effects of three cooling delays (0, 12 or 24 h at 10 °C), three atmosphere concentrations (air, 10% CO₂ + 2.5% O₂ and 10% CO₂ + 20% O₂) and two storage temperatures (0 °C and 4 °C) which were assessed for their impact on final quality, measured as weight loss, firmness and rot incidence. Two blueberry cultivars were studied: ‘Brigitta’, a highbush cultivar, and ‘Maru’, a rabbiteye. Delays in cooling had a small effect on final product weight, whereas variation in storage temperature and atmosphere during simulated transport influenced both firmness and rot incidence. Atmospheres with 10% CO₂ reduced decay incidence, particularly at low oxygen concentration (2.5% O₂), although the latter conditions tended to soften fruit. In order to achieve optimal postharvest storage for blueberries, minimising temperature variability in the supply chain is important, as is finding the potentially cultivar-specific optimal combination of high CO₂ and low O₂ concentration that results in simultaneously minimising rot incidence and induced softening.     

Salicylic acid alleviates chilling injury in anthurium (Anthurium andraeanum L.) flowers

We tested if salicylic acid (SA) can alleviate chilling injury in anthurium flowers (Anthurium andraeanum). Cut flowers of five cultivars, individually placed in water, were held at 4 °C and 12 °C. Symptoms of chilling injury (CI) were found in the flowers stored at 4 °C. These symptoms included desiccation of the spadix (the compound floral stalk) and a colour change of the spathe (the large floral bract) to pink and then to brown. The time to the CI symptoms depended on the cultivar. CI symptoms were accompanied by an increase in electrolyte leakage, by loss of fresh weight, and by an increase in catalase (CAT) and superoxide dismutase (SOD) activity. SA at 2.0 mM in water was applied as a 15 min dip. It delayed the CI symptoms, as well as the loss of fresh weight, the increase in electrolyte leakage, and the increase CAT and SOD activity. The data suggest that CI in this system is related to an increase in the concentrations of active oxygen species.     

Characterization of chilling injury in Heliotropium arborescens and Lantana camara cuttings

Simulated low-temperature shipment of Heliotropium arborescens and Lantana camara cuttings inflicted chilling injury, which was manifested in increased ion leakage in both species. Morning-harvested cuttings of both Lantana and Heliotropium were more sensitive to chilling temperatures than noon-harvested cuttings. However, this difference was expressed only during the summer in Lantana, but both in the winter and summer in Heliotropium cuttings. These results suggest that the chilling injury that occurs during shipment might be alleviated in both species by avoidance of early morning picking of cuttings.

Chilling injury in Lantana was associated with increases in reactive oxygen species (ROS) levels and ethylene production rate. On the other hand, in Heliotropium cuttings ROS levels were increased and the ethylene production rate was reduced after storage at all simulated shipment temperatures. Our results may indicate that different mechanisms of chilling injury exist in Lantana and Heliotropium.     

Thiabendazole residue loading in dip,drench and wax coating applications to control green mould and chilling injury on citrus fruit

Green mould (caused by Penicillium digitatum) is a major cause of postharvest losses in citrus. Residue loading of thiabendazole (TBZ) with application methods typically used in South African packhouses and green mould control was studied. TBZ was applied curatively and protectively in dip, drench and wax coating treatments and fruit were inoculated with a TBZ-sensitive or a TBZ-resistant isolate of P. digitatum. The dip treatments consisted of TBZ concentrations of 0–2000 μg mL⁻¹; fruit were dipped for 60 s at 22 °C at a pH of 7. Residues differed between fruit batches and ranged from 0.5 to 1.7 μg g⁻¹ at 1000 μg mL⁻¹ TBZ. Curative dip treatments almost completely controlled green mould (>96% at 1000 μg mL⁻¹ TBZ). The residue level needed for 75% curative control ranged from 0.06 to 0.22 μg g⁻¹, depending on citrus type. Protective treatments were unreliable and control varied from 17% to 97.9% at 1000 μg mL⁻¹ TBZ between fruit batches. Drench treatments consisted of exposure times of 30, 60 and 90 s with 1000 or 2000 μg mL⁻¹ TBZ. Average TBZ residues were 2.14 μg g⁻¹ for Clementine mandarin fruit and 3.50 μg g⁻¹ for navel orange fruit. Green mould control on navel orange fruit resulted in 66–92%, 34–90% and 9–38% control for curative treatments after 6 and 24 h and protective treatments, respectively, depending on fruit batch. Wax with 4000 μg mL⁻¹ TBZ was applied at 0.6, 1.2 and 1.8 L wax ton⁻¹ fruit. Chilling injury was evaluated after fruit storage at −0.5 °C for 40 days. Average TBZ residues loaded was 1.3, 1.3 and 2.7 μg g⁻¹ at the recommended 1.2 L ton⁻¹ for Satsuma mandarin, Clementine mandarin and Valencia orange fruit, respectively. Protective treatments showed lower infection levels (14–20%) than curative treatments (27–40%) for Valencia orange fruit. The same trend was observed with Satsuma (92–95% curative; 87–90% protective) and Clementine mandarin fruit (82–90% curative; 59–88% protective), but control was relatively poor. TBZ application in wax exceeded 5 μg g⁻¹ at higher wax loads (1.2 and 1.8 L ton⁻¹). Wax treatments showed a significant reduction in chilling injury; TBZ had an additive effect. TBZ resistant isolates could not be controlled.