The influence of harvest maturity, calcium concentration and storage conditions on the keeping quality of Spartan apples grown in England

Spartan apples from several commercial orchards were stored in three successive years. The principal physiological disorders that developed were scald and core rowning. These disorders were minimised by picking at the end of September and storing in either 2% O₂ or 2% CO₂+ 2% O₂ at 1.5°C. Fruit calcium concentrations were usually high enough to avoid flesh breakdown but could be increased without risk of skin damage by dipping in a 2% solution of calcium chloride. It was concluded that storage of Spartan for up to 9 months is possible provided that fruit calcium concentrations are adequate and that picking date and storage conditions are optimised.     

Changes during low-oxygen storage in the effects of ethylene on induction of ethylene synthesis and stimulation of respiration of 'Gloster 69' apples

The ability of ethylene to stimulate respiration and advance the onset of rapid ethylene production was investigated at different times during storage of 'Gloster 69' apples in 2 kPa O₂ at 1.5–3.5°C. Ethylene stimulated respiration in apples at 15°C immediately after harvest; maximal rates were recorded at 10–1000 μl I⁻¹ but attainment of these rates was delayed after low O₂ storage until day 3 of treatment at 15°C. The onset of rapid ethylene production at 15°C occurred later in non-ethylene-treated apples after storage than after harvest. Ethylene production was induced in some apples during ethylene treatment for 3 or 6 days; in others it was induced about 20 days after treatment, but a proportion of the fruit showed no induction in the 45-day duration of experiments. An ethylene treatment at 10 μl I⁻¹ led to a near maximal increase in the frequency of induction of ethylene production at all times. After storage apples were mainly induced during treatment or not induced, whereas after harvest induction after treatment was more frequent. The presence of 2000 μl l⁻¹ norbornadiene during ethylene treatment inhibited the stimulation of respiration and the induction of ethylene production; this inhibition was only partly reversed by ethylene at 1000 μl l⁻¹ the experiments suggest that receptors for ethylene were present at all stages but that response capacity changed during storage.     

Post-harvest chemical treatments for the control of storage disorders of apples

Immersion of apples of the varieties Cox's Orange Pippin and James Grieve for 1 min in solutions of calcium chloride or nitrate reduced the incidence of bitter pit and senescent breakdown that developed during air storage at 3 °C. Calcium nitrate treatments decreased the severity of superficial scald in both Bramley's Seedling and Cox apples probably by slightly delaying the rate of senescence. Calcium chloride caused unacceptable levels of damage when applied to Cox and Grieve at concentrations above 0.125 M; this injury was enhanced in Cox when benomyl was added to this strength of solution. Bramley's Seedling apples were more sensitive to calcium injury than Cox, especially in the presence of benomyl and the scald inhibitor, ethoxyquin; diphenylamine did not increase calcium injury. Calcium nitrate caused more damage to Cox than equimolar concentrations of the chloride without improving the control of bitter pit. Virtually no damage occurred when Cox and Grieve apples were immersed for 10 min in 0.125 M calcium nitrate at 45 °C. The incorporation of calcium in warm water treatments to control rotting and scald may delay sensecent breakdown in heat-treated apples.     

Abscisic acid and the development of storage breakdown in apples

(±)-ABA injected into the calyx of mature fruit increased the incidence of storage breakdown in Jonathan apples. The increase in disorder was greater when ABA was added early in the storage period and was proportional to the amount of ABA added. Most of the added ABA was converted into ‘bound’ ADA which remained at high concentrations throughout storage; however, the amount of ‘free’ ABA was also always higher than that in a control fruit. GA₃ decreased and geraniol increased the amount of ‘free’ ABA in the fruit on injection into the calyx. This could explain the ability of these compounds to respectively decrease and increase the incidence of breakdown.     

Storage of 'Gloster 69' apples in the preclimacteric state for up to 200 days after harvest

'Gloster 69' apples are unusual because they do not accumulate ethylene during storage at 2 kPa O₂ at 1.5–3.5°C with continuous ethylene removal. Their ethylene physiology and the extent of various ripening processes in storage were investigated. Ethylene production and l-aminocyclopropane-l-carboxylic acid (ACC) remained low for up to 200 days, and both increased on transfer of fruit to 15°C. The increase in ACC could be stimulated by ethylene treatment of apples after storage. In spite of this evidence that fruit remained preclimacteric, some softening and production of soluble pectin and volatile esters occurred at 3.5°C. These processes were suppressed at 1.5°C, but chlorophyll, starch, malate and sucrose losses and increases in glucose and fructose occurred at both temperatures.     

An investigation of persistent infection of stored apples by Gloeosporium spp.

Orchards of Cox's Orange Pippin apples with a history of persistent Gloeosporium infection were examined for wood infections and fruit susceptibility. The amount of wood infection on the trees was not excessively high and the conidia from wood and fruit infections were not resistant to captan. Extensive rotting developed following the application of conidia of G. perennans to the surface of the fruit after harvest. Mineral analysis indicated low calcium and high nitrogen content and it is suggested that fruit susceptibility associated with mineral imbalance is responsible for much of the rotting encountered in the past.     

Calcium in plant senescence and fruit ripening

Abstract. Calcium has long been associated with regulation of the ripening process of fruit and post-harvest storage life. Specifically, maintenance of relatively high calcium concentrations in fruit tissue results in a slower rate of ripening, as seen in lower respiration rates, reduced ethylene production, and slower softening of fruit flesh. There are also some specific fruit disorders such as bitter pit, which can be prevented if sufficient calcium is present. Senescence of other plant tissues such as leaves and flowers has also been shown to be retarded by the application of calcium.
Work leading to the above information is reviewed and discussed in the context of what is currently known of cellular regulation of calcium in plants. The major sites for the action of calcium in senescence and ripening are suggested to be in membrane structure and function, and in cell wall structure. Although high external concentrations of calcium are an advantage in reducing the rate of senescence or ripening, it is emphasized that normal cell function requires the maintenance of low concentrations of free calcium in the cell cytosol. It is suggested that one possible feature of senescence is a breakdown in such cellular regulation.     

Effect of orchard and postharvest application of daminozide on ethylene synthesis by apple fruit

The effects of daminozide (butanedioic acid-2,2-dimethylhydrazide) on ethylene synthesis by apple fruits were investigated. The objective was to determine the effects of postharvest applications as compared to the standard application of diaminozide in the orchard. Immersion in a solution containing 4.25 g L^?1 active ingredient for 5 min delayed the rise in ethylene production in individual “Cox” apples at 15°C by about 2 days, whereas orchard application of 0.85 g L^?1 caused delays of about 3 days. Both modes of application depressed the maximal rate of ethylene production attained by ripe apples by about 30%. Daminozide did not affect the stimulation of respiration by ethylene treatment of “Gloster” apples, but it delayed the increase in ethylene synthesis. Daminozide applied immediately after harvest delayed the rise in ethylene synthesis in “Golden Delicious” held at 15°C, but it was less effective when applied 48 h after harvest or when apples were held at 5°C. Exposure to 1–2 μl L^?1 ethylene for 48 h was less effective in promoting the rise in ethylene in daminozidetreated “Cox” and “Gloster” apples than in untreated fruit. High (100–1000 μl L^?1) concentrations of ethylene more or less overcame the daminozide effect. Apples absorbed about 40% of surface-applied [¹⁴C]daminozide in 48 h, but more than 90% of the radioactivity in the fruit was recovered from the peel and outer 1 cm of the cortex. Daminozide was partly converted to carbon dioxide and other metabolites.     

The response of apples cv. Cox's Orange Pippin to different concentrations of oxygen in the storage atmosphere

The response of apples cv. Cox's Orange Pippin to storage in flowing streams of air and nitrogen mixed to generate atmospheres ranging from 0.5% to 2% oxygen was examined in two seasons. The benefits of reducing store oxygen concentrations below 1.25% were small but storage in 0.75% may be advantageous for Cox's Orange Pippin apples in seasons when flesh firmness is low at harvest. Ethanol-induced flesh breakdown was recorded in samples stored in 0.5% O₂ in one season and the risk of low temperature breakdown was increased in oxygen levels below 1.25%. Ethylene production was reduced by lowering the oxygen concentration.     

Effects of Treatment with a Composite Preparation (2-Chloroethylphosphonic Acid and Methacide) or Butylated Hydroxyanisole on Ethylene Release in Apples

We studied the effect of a Russian composite preparation (2-chloroethylphosphonic acid and methacide) and butylated hydroxyanisole on ethylene release in whole fruit and peel disks of two apple cultivars, Antonovka obyknovennaya (Antonovka) and Simirenko's rennet (Simirenko). Treatment with the composite preparation was followed by an increase in ethylene release from both the whole apples and peel disks. The development of microbial infection (fruit rot) in the whole apples became less pronounced after the treatment. Treatment of whole apples with the antioxidant butylated hydroxyanisole (BHA) increased the intensity of ethylene release during the first subsequent days; thereafter, ethylene release decreased and was 10–15% lower than in the control on days 10–12. In model experiments, BHA decreased ethylene release from apple peel disks below control levels as early as on the first day after treatment. Antonovka apples gave quick responses to the treatment. In the late-ripening Simirenko apples, the response persisted for a longer period. Our results suggest that treatment with physiologically active preparations affects the ethylene release, ripening, and preservation of apples in storage.     

Electron-energy-loss spectroscopic imaging of calcium and nitrogen in the cell walls of apple fruits

Changes in texture are an integral part of ripening in most fleshy fruits and these changes are thought to be determined, primarily, by alterations in cell wall structure. Electron energy loss spectroscopy (EELS) imaging was used to obtain quantitative information on the levels of calcium and nitrogen in the cell walls of apple (Malus domestica Borkh. cv. Cox's Orange Pippin) fruits. Samples of fruit cortex were prepared for EELS by high-pressure freezing and molecular distillation drying to minimize loss and redistribution of soluble cell wall components such as calcium. The EELS imaging successfully resolved calcium and nitrogen levels in the middle lamella and primary cell wall. When the elemental compositions of the cell walls of Cox's apples from two sites in the UK were compared at harvest or after 6 months storage, the orchard which always produced consistently firmer fruit had significantly lower levels of cell wall calcium and higher levels of cell wall nitrogen. This result was unexpected since firm texture in apples and other fruits has been commonly associated with elevated levels of fruit calcium. The nitrogen-rich material in the sections used for EELS was insoluble in acidified methanol, indicating that it represented a high-molecular-weight component in the cell wall. Furthermore, total tissue hydroxyproline levels were greatest in material with elevated cell wall nitrogen, suggesting enhanced levels of wall structural proteins in the tissue. These data indicate a correlation between increased amounts of cell wall nitrogen and firm fruit texture. The possible role of cell wall proteins in determining the textural properties of fruit tissue is discussed. Received: 19 November 1998 / Accepted: 28 January 1999     

Temporal Patterns in Appearance of Sooty Blotch and Flyspeck Fungi on Apples

Sooty blotch and flyspeck (SBFS) is a complex of about 80 fungal species that blemish the surface of apple fruit in humid regions worldwide. The dark colonies become visible in mid- to late summer, reducing the value of fresh fruit. Although many SBFS species can co-occur in the same orchard and even on the same apple, little is known about temporal patterns of these species, including the timing of colony appearance. To test the hypothesis that colonies of SBFS species appear on apples at characteristic times during the growing season, 50 apples were monitored weekly at three Iowa orchards in 2006 and six orchards in 2007 and 2008. However, a mean of 24.3 apples per orchard was assessed at harvest because of apple drop throughout the season. Colonies were marked with colored pens as they appeared. After harvest and after storage of apples at 2?°C for 3?months, SBFS colonies on each fruit were counted and classified by morphology, and a representative subset of colonies was excised from the fruit and preserved on dried peels for species identification using rDNA. Seventeen species were identified. Stomiopeltis spp. RS1 and RS2 appeared on apples 10 to 14?days before other SBFS taxa. Dissoconium aciculare was generally the last species to appear on apple fruit, and it continued to appear during postharvest storage. The most prevalent taxa in Iowa orchards were also the most abundant. Diversity of SBFS fungi in an orchard was positively correlated with cumulative hours of surface wetness hours due to rainfall or dew, which is believed to favor growth of SBFS fungi. Species-specific information about temporal patterns of appearance on apple fruit may lead to improved SBFS management strategies.     

Effects of Chilling Temperatures on Ethylene Binding by Banana Fruit

Banana fruit are highly susceptible to chilling injury during low temperature storage. Experiments were conducted to compare ethylene binding during storage at chilling (3 and 8 °C) versus optimum (13 °C) temperatures. The skins of fruit stored at 3 and 8 °C gradually darkened as storage duration increased. This chilling effect was reflected in increasing membrane permeability as shown by increased relative electrolyte leakage from skin tissue. In contrast, banana fruit stored for 8 days at 13 °C showed no chilling injury symptoms. Exposure of banana fruit to the ethylene binding inhibitor 1-methylcyclopropene (1 l l^-1 1-MCP) prevented ripening. However, this treatment also enhanced the chilling injury accelerated the occurrence of chilling injury-associated increased membrane permeability. ¹⁴C-ethylene release assay showed that ethylene binding by banana fruit stored at low temperature decreased with reduced storage temperature and/or prolonged storage time. Fruit exposed to 1-MCP for 12 h and then stored at 3 or 8 °C exhibited lower ethylene binding than those stored at 13 °C. Thus, chilling injury of banana fruit stored at low temperature is associated with a decrease in ethylene binding. The ability of tissue to respond to ethylene is evidently reduced, thereby resulting in failure to ripen.     

不同品种苹果采后后熟软化过程中细胞壁多糖的降解

以2种苹果为试材,提取了不同贮藏时期果实的细胞壁物质和8种细胞壁多糖组分,并采用气相色谱法分析了细胞壁多糖组分的单糖组成。结果表明,在贮藏过程中,‘金星’苹果果肉的硬度下降明显,在贮藏第10天前后出现明显的乙烯释放量高峰,而耐贮藏性‘富士’苹果在贮藏期间只释放极少量的乙烯。‘金星’苹果的Na2CO3-1溶性果胶多糖组分的减少尤为显著。这些结果表明,苹果果实Na2CO3-1溶性果胶多糖组分侧链成分的酶降解,是引起苹果细胞壁多糖网络结构的变化,进而导致果实软化的重要原因之一。     

Effects of treatment with a composite preparation (2-chloroethylphosphonic acid and methacide) or butylated hydroxyanisole on ethylene release in apples

We studied the effect of a Russian composite preparation (2-chloroethylphosphonic acid and methacide) and butylated hydroxyanisole on ethylene release in whole fruit and peel disks of two apple cultivars, Antonovka obyknovennaya (Antonovka) and Simirenko's rennet (Simirenko). Treatment with the composite preparation was followed by an increase in ethylene release from whole apples and peel disks. The development of microbial infection (fruit rot) in whole apples became less pronounced after the treatment. Treatment of whole apples with the antioxidant butylated hydroxyanisole (BHA) increased the intensity of ethylene release during the first subsequent days; thereafter, ethylene release decreased and was 10-15% lower than in the control on days 10-12. In model experiments, BHA decreased ethylene release from apple peel disks below control levels as early as on day 1 after the treatment. Antonovka apples gave quick responses to the treatment. In the late-ripening Simirenko apples, the response persisted for a longer period. Our results suggest that treatment with physiologically active preparations affects ethylene release, ripening, and preservation of apples in storage.     

Low temperature breakdown in apples

Low temperature breakdown in apples was increased by geraniol and a number of inhibitors of isoprenoid biosynthesis which were injected into the fruit after harvest. The addition of gibberellic acid reduced breakdown.     

Observations on the infection and rotting of apples var. Bramley's Seedliong by Diaporthe perniciosa

In N. Ireland Diaporthe perniciosa March is a common inhabitant of the dead wood of Bramley's Seedling apple trees, and its pycnospores, extruded throughout the growing season, are responsible for fruit infections which result in stalk-end rots during storage.
Pycnidia were produced in culture only after exposure to light, near-UV radiation being particularly favourable. The carbon source in the medium influenced pycnidia production: high yields were obtained where mannitol was used. Only a -spores germinated under the conditions tested, giving optimum germination at 25 C. in a water film. No germination occurred at less than 98% R.H. Germ tubes and hyphae developed appressoria after germination on artificial surfaces but on apple skin most spores produced only a protuberance from which penetration hyphae developed directly. The cuticle and epidermal cells of apples of all ages were penetrated within a few days of inoculation. Intact surfaces and lenticels were penetrated equally. Susceptibility to further rotting increased with age of the fruit. Apples loaded with spores early in the season rotted later than similar apples loaded just before picking. Polygalacturonase was detected in sap expressed from rotted apples of various ages, the level of activity being correlated with the susceptibility of the fruit.     

The effect of a post-harvest heat-treatment on the storage behaviour of Cox's Orange Pippin apple fruits

Samples from a wide range of commercially grown Cox's Orange Pippin apple fruits were immersed in water at 45° C. for 10 min. to control rotting due to Gloeosporium spp. In two seasons the incidence of rotting following storage for 19 weeks at 3·3° C. (38° F.) was reduced to about 40% of the level in the untreated samples. However, there was a marked increase in the incidence of breakdown and core flush in the treated fruit, particularly when stored in a controlled atmosphere of 5% CO₂, 3 % O₂. A similar but less severe increase in the incidence of breakdown was also recorded in the second season in treated fruit stored in 2% O₂ (with continuous removal of CO₂). The treated fruit tended to develop a more yellow ground colour and softened more rapidly during storage in 5% CO₂, 3% O₂. It is concluded that the treatment advances fruit senescence and that the increased incidence of physiological disorders is likely to limit the use of this method for the control of Gloeosporium rotting in English-grown Cox apples.     

Occurrence of a Temperature-induced Phase Transition in Mitochondria Isolated from Apple Fruit

Mitochondria were isolated from fruit of six cultivars of apples differing in susceptibility to the physiological disorder, low temperature breakdown. The state 3 rate of succinate-dependent oxygen uptake and the motion of a spin label were measured at from 0 to 25 C. Arrhenius plots of the data showed that the apparent energy of activation of both respiration and motion of the spin label increased abruptly at low temperatures indicative of a temperature-induced phase change in the membrane lipids. The changes were detected with mitochondria from all of the cultivars, but the temperature at which the changes occurred did not correlate with the susceptibility of the cultivars to low temperature breakdown.     

The infection of apples by Phytophthora syringae

Contamination with infected soil has led to high wastage of apples in storage due to rotting by Phytophthora syringae. At 3-3 ^oC lesions formed 3–4 wk after inoculation with zoospores; the percentage infection fell if the suspensions dried after 48 h at this temperature and after 22 h at 15 ^oC. Infected soil rotted fruit only if kept moist; at 3-3 ^oC a 3-day period of wetness resulted in 37-5% rotting after 8 wk. Fruit dipped in soil slurry remained wet in some parts of a 4361(12 bushel) bin for at least 3 wk. There was a 10-fold increase in rotting by contact between sound and rotting fruit after 11 wk at 3-3 ^oC. Captan gave effective protection against rotting derived from zoospores or infected soil; it had no eradicant action.