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Crop Load, Fruit Thinning and their Effects on Fruit Quality of Apple (Malus domestica Borkh.)
Published October 11, 2006
29-35

Crop load, a quantitative parameter used by industry, is generally defined as the number of fruit per tree. It is often expressed in terms of number of fruit per trunk cross-sectional area (fruit/TCSA). Crop load is the most important of all factors that influence fruit size, and the removing of a part of the crop is the most effective way to i...mprove fruit size.
The potential size of a given pome fruit is determined early in the season and growth proceeds at a relatively uniform rate thereafter. This uniform growth rate permits the accurate prediction of the harvest size of the fruit as early as mid-summer. The growth rate, once established, is not easily altered, and fruit numbers, therefore, can affect fruit size only within definite limits and maximum effectiveness requires adjustment in fruit numbers relatively early in the season. It was established, that „thinning does not change a potentially small fruit into a large fruit, but rather insures that a potentially large fruit will size properly.” Emphasis should be on estimating fruit numbers rather than fruit size.
Fruit thinning can quickly reach the point of diminishing returns. Rather than a high percentage of large fruits, the objectives of thinning should be the elimination of the smallest fruits, improved fruit quality and annual production. Fruit thinning is accomplished by hand or chemical thinning. Chemical thinners are separated into categories as bloom thinners and post-bloom thinners. Early removal of potential fruit (blossom thinning) is currently used in many apple producing areas to enhance flower initiation for next year’s crop and thus, return bloom. It also results in reduced competition for photosynthates. Blossom thinners usually have a caustic effect on floral parts.
The amount of fruit left on a tree should be determined by the vigor and general condition of the tree. Leaf area per fruit affects the number of spurs flowering the following season. It can be difficult to separate timing and fruit number effects in crop loading studies, as abscission rates after hand thinning of retained flowers/fruitlets tend to very with the time of hand thinning.

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Effect of Ozone Exposure on Phytopathogenic Microorganisms on Stored Apples
Published December 14, 2004
9-13

The aim of our study was to clarify the effect of ozone exposure on several phytopathogenic fungi on stored apple fruits under different storage conditions. The study was conducted at Bistrita, Romania, in the storehouse of an experimental apple orchard in 2002 and 2003. Two widely grown apple cultivars (‘Jonathan’ and ‘Golden Delicious...) were used. General microbial examination of the fruits was made during storage in order to identify the most important storage pathogens. Efficacy of six ozone treatments was evaluted on fruit decay caused by phytopathogenic fungi. Monthly observations (January, February, March and April) were made of the degree of decay and three measurements were assessed (disease frequency, disease intensity and degree of attack). Our results showed that the most important phytopathogenic fungi during storage was blue mold, caused by species of Penicillium. Disease frequency of apple fruits was very high on cv. ‘Jonathan’, much higher than on cv. ‘Golden delicious’. Ozone treatments (25 ppm ozone for 0.5 and 1.5 hours in November) caused significantly lower disease incidence on stored apple than all other ozone treatments. For longer storage, it seems that additional ozone treatments in February increased treatment efficacy. Cv. ‘Golden delicious’ seemed to be more resistant to storage diseases than cv. ‘Jonathan’ both on the untreated and treated fruits. The effect of the ozone treatments was also the most effective when 25 ppm ozone was applied for 0.5 and 1.5 hours in November.

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Nutrient Supply Effects on the Fruit Quality of Apple (Malus domestica Borkh.)
Published December 6, 2005
230-235

The aim of our two year study is to research the effect of nutrient supply on apple fruit quality, and to explore the relationships between selected fruit quality parameters.
Observations were made in Kálmánháza (in the eastern part of Hungary), on a commercial apple orchard. In this experiment, we studied the nutrient supply reaction of ...four apple cultivars (Golden Delicious, Granny Smith, Idared and Jonathan Csány) under different N and NPK doses. The following fruit quality parameters were studied: fruit diameter, fruit height, fruit weight, flesh firmness, colour-coverage and we studied the density of foliage.
The research results showed that N fertilization has a great effect on fruit quality. This is shown in the cases of increase of fruit size (fruit diameter, fruit height, fruit weight). The increase is proportional with the N doses, accordingly the highest positive difference was observed by using 100 kg/ha N doses. It is important to note that moderate N doses (75 kg/ha) plus P and K additions also had positive effects. There approached the values of 100 kg/ha N, and even exceeded its values in the cultivar Golden Reinders. The increased N doses enlarged the standard deviation, on the other hand, this parameter was low in the cases of balanced NPK fertilization. The nutrient supply increased the vegetative area (density of foliage) in addition to the generative parts, in particular only N fertilizer. However the denser foliage hindered the growth of fruit weight and colour-coverage, and also decreased the fruit quality and the flesh firmness of cultivars, which have a negative effect on storageability.
A linear correlation was demonstrated between the fruit weight and colour-coverage, or between fruit weight and flesh firmness. The character of their relationship was similar, but the direction differed: high fruit weight was with high colour-coverage, but with low flesh firmness.

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The effect of sunburn damage on the fruit quality parameters of apple (Malus domestica cv. Idared)
Published September 14, 2005
55-64

In the present study the authors investigated the effect of sunburn injury on fruit quality parameters (cover colour, depth of tissue damage, fruit flesh firmness, dry matter content) of apple.
The symptoms of sunburn injury appeared as concentric rings, differing in colour from each other and the cover colour. This can be connected with the... ratio of the injury. The authors observed the following colours on the fruit surface (from the epicentre of spots on the surface of the fruit) dark brown (strongly damaged), light brown (moderately damaged), pale red transition (weakly damaged), red surface cover colour (not damaged).
Sunburn of apple fruits is a surface injury caused by solar radiation, heat and low relative humidity. In the initial phase, a light corky layer, golden or bronze discolouration and injuries of the epidermal tissue appear on the surface exposed to radiation. Thus, it detracts from the fruit’s appearance, but in most of the cases it would not cause serious damages in the epidermal tissue. The depth of tissue damage is not considerable, its values are between 1.5-2.0 mm in general. It is commonly known, that tissue structure of the apple fruit is not homogeneous. Accordingly, the degree of injury shows some differences under the different parts of the fruit surface.
On the basis of the flesh firmness studies, it can be stated that the flesh firmness of the damaged parts increases due to the sunburn effect. This is due to the fact that the damaged plant cells die, the water content of the tissue decreases and it hardens. However, due to this reduction in the water content the dry matter content will increase.

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The effect of rootstocks on the fruit quality parameters of apple (Malus domestica Borkh.)
Published September 14, 2005
39-43

The authors studied the effect of rootstocks with different growing vigour on fruit quality of different cultivars. Research results shows that best fruit diamter and fruit weight of all cultivars are for M9 rootstock. Similar tendency was found in skin colour, but in the case of Granny Smith, MM106 rootstock is more favourable because the gree...n skin colour is necessary for the consumers’ acceptance. Seedling rootstok has some unfavourable effects on fruit quality, thus its usage is not expedient.

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N-Phenyl-Phthalamic Acid and Fertilization Effects on Flowering, Fruit Set and Fruit Quality of Apple (Malus domestica Borkh.)
Published October 11, 2006
24-28

On seven apple cultivars (Gala Must, Gloster, Granny Smith, Idared, Jonagold, Jonathan Csány 1, Mutsu), the authors studied the influence of N-phenyl-phthalamic (PPA) acid and fertilization on flowering, fruit set and fruit quality in the years 2003-2004. The research results showed that PPA application extended the flowering time of the most ...cultivars. Fruit set of apple cultivars increased in many cases when regulator was applied. The additional nutrient supply could increase the fruit set too. The increase of fruit set increased the number of fruit per tree. Quality parameters determined by fertilization and fruit number per tree. For example, when N-phenyl-phthalamic acid was applied without fertilization the fruit number per tree increased considerably however, it caused a considerable frittering away. The reason for this is that fruit set was high and fruit received not enough nutrition for growing up. The skin colour of fruits was decreased in several cases by the treatments. In one respect the enlarged fruit number was shaded the others and the fertilization increased the vegetative shading leaf area.

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Early evaluation of use of fermented chicken manure products in practice of apple nutrient management
Published May 26, 2022
195-198

According to the Green Deal efforts, the importance and relevance of organic fertilization will increase in the near future. Therefore, the investigation of the effects of different organic fertilizers on soil productivity and nutrient supply is a priority area of agricultural research. Organic fertilizer experiment was conducted in an eigh...t-year-old apple (Malus domestica Borkh.) orchard at Debrecen-Pallag. In the trial Pinova cultivar was used. In this study, two different fermented chicken manure products were added to the soil (in 20 cm depth) to test their effects on soil nutrient status, plant uptake and fruit quality. It was found that the applied treatments slightly increased the pH and nutrient levels in almost all cases, but significant effect was not observed in all treatments compared to the control. Leaf nutrient contents (N, P, K, Ca and Mg) were measured in the experiment. Leaf nutrient status was not affected by the fermented chicken manure treatments. However, used treatments had strong effects on the fruit characteristics and inner parameters, such as fruit diameter and Brix value. Moreover, it was established that the applied organic fertilizers increased the yield significantly.

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