Jonathan Spot Research Articles

Effect of Biostimulants on Apple Quality at Harvest and After Storage

Nutritional unbalances, such as calcium deficiency at the fruit level, are generally the causative agent of post-harvest disorders in apples. Foliar application of Ca as calcium chloride is the current solution to increase Ca concentration in apples, even though the effectiveness of this approach is often not satisfactory. In this research, we tested the efficacy of a combined application of Ca with selected biostimulants to improve apple quality and to reduce the incidence of storage disorders. The experiment was conducted in two “Jonathan” apple orchards that differed in management systems and characteristics. Tree canopies were sprayed with calcium chloride alone and in combination with a commercial product containing zinc and silicon or a seaweed extract. The seaweed extract increased apple quality by boosting the reddish coloration (+32% of color index) and by enhancing final anthocyanin concentration of fruit skin. Both biostimulants significantly reduced (by 20%) the incidence of the physiological disorder, known as “Jonathan spot”, after 160 days of storage. Increased concentration of nutrients (Ca, Zn, and Mn) in the skin of apples after biostimulant applications, together with changes of the phenolic profile during the storage, are discussed as the possible causes of the reduced fruit susceptibility to post-harvest disorders.

Use of Biostimulants for Organic Apple Production: Effects on Tree Growth, Yield, and Fruit Quality at Harvest and During Storage.

The experiment was conducted during two consecutive seasons (years 2016 and 2017) in an organic apple orchard of the cultivar Jonathan. Several biostimulants were tested (10 in total), including humic acids, macro and micro seaweed extracts, alfalfa protein hydrolysate, amino acids alone or in combination with zinc, B-group vitamins, chitosan and a commercial product containing silicon. Treatments were performed at weekly intervals, starting from the end of May until mid-August. The macroseaweed extract was effective in stimulate tree growth potential in both years, as shown by a significantly larger leaf area (+20% as compared to control) and by an higher chlorophyll content and leaf photosynthetic rate in year 2016. As for the yield performances and apples quality traits at harvest (average fruit weight, soluble solids content, titratable acidity, and flesh firmness), they were generally affected by the different climatic conditions that characterized the two growing seasons (year 2017 being characterized by higher maximal and average temperatures and by limited rainfalls at the beginning of the season). Treatments with macroseaweed extract, B-group vitamins and alfalfa protein hydrolysate were able to significantly improve the intensity and extension of the red coloration of apples at harvest. Correspondingly, the anthocyanin content in the skin of apples treated with the same biostimulants resulted significantly higher than control, highlighting the potential influence of these substances on the synthesis of secondary metabolites in apple. The incidence of physiological disorders was also monitored during apple storage period. Amino acids plus zinc application was effective in reducing (more than 50%) the incidence of the “Jonathan spot,” the main post-harvest disorder for this cultivar.

The quality and storage efficiency of some apple varieties as a function of picking date, area of production and duration of storage

Numerous apple varieties have been tested parallel with traditional Jonathan varieties during four years, 1990-1994 on three different geographical areas of Hungary. The picking time took place at three different times in a year: ten days before the probably optimal picking time, at close-to-optimal picking time, and ten days after the optimal picking time. The effect of storage on quality of fruits have been tested in February, March, and April under circumstances of a semi-industrial storage experiment.
 The results of experience can contribute to answer numerous current, from point of view of practice important topics:
 
 The stochastic relations between various fruit quality parameters at different varieties
 The change of fruit — quality during storage
 The effect of different picking date on storage losses
 The possibilities of storage — loss predicting by the utilization of multiple regression analysis.
 
 The most important results of experiences are as follows :
 
 The starch — degradation test and Streiff — index are well applicable for practical purposes to determine the optimal harvest-date.
 On base of analysis of various losses and physiological diseases the high importance of mass loss is obvious. In the variety Jonnee the earlier picking date considerably increased the mass loss. The effect of variety on mass loss is rather limited. In the Jonathan varieties the Jonathan spot was a rather important physiological disease. The late picking time increased the frequency of Jonathan - spot. At optimal date of harvest at Jonnee the frequency of Jonathan -spot was lower, than at Jonathan M 41. In the Jonathan M41 and Jonnee the importance of scald was rather limited, but in the Wellspur Delicious and Smoothee this disease occurred relatively frequently. In the Smoothee the earlier picking time considerably increased the probability of scald.
 The multiple regression analysis yielded reliable results, fit for prediction of storage losses and diseases on the base of chemical and physical properties, determined at the time of picking.
 

Nitrogen and calcium nutrition and fruit quality of commercial apple cultivars grown in Finland

During 1994–1995, field experiments were conducted in six apple orchards located in the southwest of Finland (the mainland and the Åland Islands). The cultivars were ‘Melba’, ‘Raike’, ‘Red Atlas’, ‘Lobo’, ‘Aroma’, and ‘Åkero’. Fruit samples were picked at about one week before commercial maturity and stored for three to six months at 2 to 4°C and 85–95% relative humidity. During storage the percentage of physiological disorders was visually recorded. Fruit nitrogen (N) and calcium (Ca), firmness, diameter, juice titratable acidity (TA), and soluble solids concentrations (SSC) were determined at harvest. Nitrogen and Ca in the soil and leaves collected during fruit development were determined. The ranges in fruit N were 296–624 and Ca 27–68 mg kg‐1 fresh weight, and in the leaves N 15–23 and Ca 9–19 g kg‐1 dry matter. The N/Ca ratio was 5 and 16 and 0.9 and 2.3 in fruit and leaves, respectively. There was more variation between years in N and Ca contents of leaves than that of fruit. Other fruit quality characteristics varied between seasons and cultivars. Leaf N correlated positively with fruit diameter and negatively with fruit dry matter. The incidence of physiological disorders on apples after three month storage was 2 to 13% and after six months 10 to 95%. Fruit with Ca content below 45 mg kg‐1 fresh weight were susceptible to bitter pit ('Aroma’ and ‘Åkero') and Jonathan spot ('Red Atlas'). The cultivar ‘Melba’ was susceptible to bruising damages and ‘Raike’ and ‘Red Atlas’ were affected more with internal breakdown and core browning.

The effects of storage atmosphere on the keeping quality of ‘Idared’ apples

SummaryThe response of ‘Idared’ apples to storage in atmospheres containing less carbon dioxide than the recommended 8% was investigated after it was found that core flush could develop in 8% CO2 + 13% O2 at 3.5°C. Storage in <1 % CO2 and 1 or 2% O2 resulted in less core flush than storage in 5% CO2 + 3% O2, but apples from 2% O2 were softer, as determined by both a sensory panel and a penetrometer, than those from 5% CO2 + 3% O2. Jonathan spot developed in both low oxygen regimes. A pre-harvest application of daminozide increased the surface area coloured red, increased firmness at harvest and reduced the incidence of core flush in samples stored in 8% CO2 + 13% O2. It was concluded that to minimize losses from physiological disorders, ‘Idared’ grown in UK should be picked no later than the beginning of November and stored in <1% CO2 +1% O2 for no more than three months.

The effects of a summer spray of succinic acid-2, 2-dimethylhydrazide on the incidence of physiological disorders and quality of Jonathan and Delicious apples after cool storage

A foliar spray of succinic acid-2, 2-dimethylhydrazide (daminozide) applied in late summer to Delicious and Jonathan apples delayed fruit maturity and softening in subsequent storage. This difference was usually retained throughout storage especially with Jonathan. Development of superficial scald was effectively delayed in stored Delicious. Jonathan spot, and, to a lesser extent, low temperature breakdown, were reduced in Jonathan. After three consecutive years of application at 1000 p.p.m. there was no reduction in effects on firmness or breakdown in Delicious. There was also a carryover effect into the third season when daminozide at 1500 p.p.m. was applied in the first two years but not used in the third.

Effect of Calcium Sprays on Physiological Disorders of Jonathan Apples

To determine the effect of calcium sprays on the occurrence of Jonathan spot and the related spotting disorders, CaCl2, lime water or Ca(NO3)2 were sprayed to Jonathan apple trees 4 times in July and August or 2 times in September (CaCl2 only). The concentration of each chemical applied was; CaCl2…0.38%, lime water…1.2% as CaO, and Ca (NO3)2…0.5%. Details of treatments were shown in Part I of this series of report.The incidence of Jonathan spot was reduced by the sprays of CaCl2, lime water and Ca(NO3)2 as shown in Table 1 and 2. Lime water was the most effective in controlling the disorder, CaCl2 was next, and Ca(NO3)2 was least effective.The calcium content of the peel of fruits from the lime treatment was not higher than that of the CaCl2 treatment (Fig. 2). Generally, the incidence of Jonathan spot was relatively low in fruits where the calcium content of the peel was high. However, disorder incidence did not always increase as the calcium content decreased (Figs. 2 and 3). These results suggest that Jonathan spot is not a simple calcium deficiency disorder. The incidence of Jonathan spot in M orchard was exceptionally severe as compared with other orchards (Table 2). In M orchard, K/Ca ratios of the leaves, fruitlets and mature fruits tended to be higher than in any other orchard (Table 5).We classified the spotting disorders of the surface of Jonathan apples into two main types; Jonathan spot and Jonathan freckle according to Heald (6). Additional spotting disorders other than these two main types were found in this experiment, and were also controlled by the sprays of calcium chemicals (Tables 3 and 4). As in the case of Jonathan spot, lime water tended to be the most effective for these disorders. The results of Jonathan freckle were not shown, as this disorder scarcely occurred one month after harvest, the period of this experiment.Fruit spot caused by a fungus (Mycosphaerella pomi) were also reduced by the sprays of lime water and CaCl2 (Table 6).

Effect of Calcium Sprays on Physiological Disorders of Jonathan Apples

It has been proposed that use of Bordeaux mixture for disease control in Japanese apple orchards be discontinued in order to reduce labor costs. However, it was found that, without Bordeaux mixture, Jonathan apples were severely affected with several kinds of physiological disorders such as Jonathan breakdown and Jonathan spot. A preliminary experiment in 1965 showed that calcium element of Bordeaux mixture had the effect on control of these disorders. In the 1966 and 1967 growing seasons, experiment were made in commercial orchards (M, S and T) and our research station′s orchard (J) to confirm these results. In this paper, the effect of calcium chemicals applied as CaCl2, lime water (Ca component of Bordeaux mixture), or Ca(NO3)2 on the occurrence of Jonathan breakdown was examined.Each calcium chemical was sprayed to whole trees with a gun sprayer in July and August or in September. Details of treatments were shown in Table 1.Two kinds of flesh browning disorders were found during this experiment on Jonathan fruits; Jonathan breakdown (Fig. 1) and an unknown flesh browning disorder (Fig. 2). Neither disorder was typical of low temperature breakdown.The incidence of Jonathan breakdown was reduced by all calcium sprays. However, the effect of lime water varried among orchards more than that of CaCl2 (Table 2). In common storage, breakdown increased rapidly until January. The disorder occurred slowly during this time in fruits treated with any of the calcium sprays, but after January, it occurred at the same rate in all treatments (Fig. 3).The incidence of the unknown flesh browning disorder was not reduced by calcium sprays applied in July and August, but was reduced by the CaCl2 sprays in September (Table 4).Sprays of calcium chemicals, including lime water, increased the calcium content of the peel and flesh of mature fruits (Table 5). Fruits affected with Jonathan breakdown were significantly lower in calcium than normal fruits. Phosphorus, potassium and magnesium tended to accumulate in the flesh of affected fruits (Table 6).

Distinguishing Characteristics of the Jonathan Spot and Lenticel Spot Disorders in the ‘Jonathan’ Apple Fruit1

Abstract The disorder known as Jonathan spot commonly observed on ‘Jonathan’ apples actually consists of 2 spot types which must be distinguished in order to define the affecting factors and to resolve the confusing and contradictory evidence in the literature. The spots which occur in the epidermal tissues without definite relation to lenticels are considered as Jonathan spot. Those which occur directly around the lenticels are defined as lenticel spots. Histologically, the epidermal tissues afflicted with Jonathan spot showed a significant radial compression of the collenchyma cells in the 4 to 7 subepidermal tiers; whereas, such modification was not always apparent in tissues affected with lenticel spot. For the latter, some degree of rupture of the epidermis and the 3 to 5 subepidermal collenchyma tiers was usually noted. Jonathan spot development was inhibited by high temperature (70°F). It was favored by delayed harvest, yet none was observed until the fruit was stored at low temperature for several months. Conversely, lenticel spot often was present at harvest time and its development was accelerated at high temperature and inhibited at low temperature. High relative humidity (90%) enhanced lenticel spot development, whereas, humidity level had no effect on Jonathan spot.

Cation, Organic Acid, and pH Relationships in Peel Tissue of Apple Fruits Affected with Jonathan Spot

Cation, Organic Acid, and pH Relationships in Peel Tissue of Apple Fruits Affected with Jonathan Spot

Jonathon spot &amp;ndash; Three factors related to incidence, fruit size, breakdown, and seed numbers

Observations are reported which show that: (1) There is an interaction between the disorders Jonathan spot and breakdown. There is a negative correlation between them, but the same fruits tend to be susceptible to both disorders. (2) In the absence of other disorders there is a positive intercorrelation between percentage Jonathan spot, mean fruit size, and mean seed number both within and between trees. (3) In the one fruit size group on a tree, fruits with Jonathan spot have a higher mean seed number per fruit than sound fruit, and the seeds have a greater tendency to germinate. (4) Within trees, a thinning treatment which produces fruit of differing sizes but with the same seed number does not alter the percentage Jonathan spot. Between trees, a thinning treatment which produces fruit of the same size but a differing seed number results in differing levels of Jonathan spot.

Histological and physiological studies on the cause of the Jonathan spot in apples. II

Histological and physiological studies on the cause of the Jonathan spot in apples. II

Effect of Apple and pear box liners on fruit in Cool-Storage

Summary Waxed paper and polyethylene case-liners partially reduced wilting and sometimes restricted weight loss of both apples and pears during cool storage. Polyethylene bag liners, both sealed and unsealed, eliminated wilting and further restricted weight loss. Jonathan Spot was controlled by storing apples in polyethylene bags. Advantages in these respects were offset by increased losses due to other physiological disorders, and, in some instances, by “off” odours and flavours. The use of polyethylene sheet- or bag-liners is not recommended.

Histological and physiological studies on the cause of the Jonathan spot in apples. I

1. Many investigators published their findings on the cause of the Jonathan spots which develop on the skin of apples. However, no definite conclu-sion nor established method of prevention have been published to this date. Therefore since 1956 the author has tried to solve this problem from the histological and physiological viewpoint, experimen-ting with such varieties as Jonathan, McIntosh, Ralls and Indo apples. This paper contains the results of these experiments on the spot develop-ment as influenced by the varietal difference in the structure of apple skin. 2. In the Jonathan apple, which seems to be most susceptible variety, cuticula formation on the skin was very slow as compared to the other varieties of apple, and the arrangement of epidermal cells remained brick wall like until about the middle of August. In the spot resistant variety, namely, Rails and Indo apples, cutin sediments were found on the side walls of epidermal cells early in June, and except for the bottom wall which touches the hypodermal cells, cuticule was formed on the walls of the epidermal cells about the middle of July. In McIntosh, a medium resistant variety, the struc-ture of the fruit skin, at first, seemed to change almost like that of Jonathan, but then became like those of Ralls and Indo. 3. In every variety, as the fruit grew some of the stomata showed signs of cracking in the middle of June, and the stomata gradually collapsed, dis-coloring their surrounding tissue and finally develop-ed into the lenticels. The Jonathan apple skin was very slow in this process, so that many stomata were still normal even late in August, when Mc-Intosh and Ralls already had well-developed lenti-cels. 4. In order to clarify the morphological property of the lenticels, some ripe fruits were separately treated with sudan III solution, methylene blue solution and formalin gas, and six hours later the reaction was observed. In Ralls and Indo, dye-sediments were detected only on the surface of the projected lenticels, showing no trace of dye-infiltra-tion in the inner tissue, while in Jonathan some of lenticels allowed dyes to infiltrate into the inner tissues. With formalin gas, the inner tissues of the skin of all varieties tested were damaged more or less through lenticels. 5. When the Jonathan spots were observed under the microscope, it became clear that the lenticels located in the center of the spot were either 1) those in which cork cambium had developed poorly, 2) or the stomata of which were still at the early stage of crack, 3) or in which the skin tissue around the stomata was about to crack. There fore, the author gave these lenticels the name of “openlenticels” 6. In the storage of the fruits which were treated with dye solution, Jonathan spots developed only on the fruits which allowed dyes to infiltrate. The fruits which suffered from Jonathan spots, afterward, were found to have transpired more water than the healthy apples. This fact suggested to us that for the development of Jonathan spots the existence of open lenticels should be considered as an important causal factor. 7. In addition, it was noticeable that when the fruits were stored at different temperatures and hu-midities after harvesting, Jonathan spots developed more rapidly on the fruits kept in a moist block than on those in a dry block, regardless of the stor-age temperature, and also they developed more rapidly on the fruits stored at a temperature of 20°C±5°C than on those at a constant temperature of 35°C or 0°C.

Effects of skin coatings on the behaviour of apples in storage. III. Cool storage investigations.

The effects of skin coatings on several varieties of apples during cool storage were studied in several seasons from 1941 to 1946. Most of the work was done with the Granny Smith and Jonathan varieties and coatings tested included alcoholic solutions of castor oil and shellac (C.O.S.), oil emulsions, and wax emulsions. With most varieties the more successful coatings, under favourable conditions of fruit maturity and of temperature before and after storage, reduced wastage and retarded loss of condition. The most successful coating, a 7-10 per cent. C.O.S. solution, increased commercial cold-storage life of a number of varieties by 25-30 per cent. C.O.S. and some oil coatings controlled superficial scald, but to a less degree than good oiled wraps. Most coatings controlled Jonathan spot and senescent disorders, but only the alcoholic solutions reduced mould wastage. Coatings at times caused direct injury to the fruit, but under favourable conditions this was usually not of commercial significance. Skin blemishes, internal disorders, and off-flavours were often severe in coated apples exposed to temperatures above 700°F either before or after cool storage. Wrapping in either plain or oiled wraps improved the out-turn of coated fruit.

Effects of skin coatings on the behaviour of apples in storage. 2. Common storage investigations.

Apples of several varieties, particularly Granny Smith, were held in common (unrefrigerated) storage after treatment with skin coatings. Under favourable conditions their storage life was increased by about 50 per cent., the greatest increase being with early varieties. Undesirable side effects are described and their relation to storage conditions discussed. The most important factors influencing the storage behaviour of coated apples were temperature and maturity. Temperatures above 70°F, even for comparatively short periods, led to fermentation and alcoholic breakdown. Fruit picked at the optimum stage for cool storage held best after coating; picked either before or after this stage, it developed disorders in storage. The best coating tested was an 8-10 per cent. alcoholic solution of 2 parts of castor oil and 1 part of wax-free shellac (C.O.S.). It was satisfactory with most varieties in cool conditions, but sometimes caused slight spotting at the lenticels. Emulsions of medicinal-grade paraffin oil, alone or mixed with castor oil, were satisfactory on most varieties (e.g. Granny Smith) which develop a copious natural waxy coating. Waxes were also applied as emulsions; the best was a mixture of 2 or 3 parts of paraffin wax with 1 part of carnauba or lac wax. Emulsion coatings were generally improved by adding 25 per cent. of wax-free shellac in 3 per cent. ammonia. C.O.S. was more effective than oil coatings and both were more effective than waxes in retarding ripening and in controlling disorders of senescence. Waxes reduced shrivelling much more than the other coatings. All coatings controlled Jonathan spot and greatly reduced bitter pit. Only the alcoholic solutions reduced mould, which was often increased by emulsions.

Storage of Australian Apples

THE Jonathan apple is the chief variety exported 1 from Victoria, between 600,000 and 700,000 bushels being sent overseas annually. Large quantities are also kept in cool storage for local consumption. Two or three pickings are made at fortnightly intervals, the earlier fruits, which are usually green, immature and acidic being exported. The large portion of the crop is picked in a late stage of maturity and considerable wastage occurs due to physiological breakdowns and moulds. With the object of reducing this wastage, Trout, Tindale and Huelin (Bull. No. 135, Australian Coun. Sci. and Ind. Res., 1940) have carried out an intensive study of the effect of different factors on keeping quality. The most important are maturity at the time of picking, seasonal and growing conditions, size of the fruit and crop, conditions immediately after picking, and conditions during storage. The ground colour of the fruit is a good index of the stage of maturity in a given district. Immature fruit is not very susceptible to storage disorders, but soft scald and breakdown are more frequent the longer the fruit is left on the tree. ‘Jonathan Spot’ develops in both immature and over-mature fruit. Soft scald is greatest between June and July and at 32° F. It can be controlled by storage at 36°-37° F. The most mature fruit is most susceptible to breakdown, which is greatest at 32° F.