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The study carried out at the Faculty of Agriculture and Life Sciences of the University of Maribor aimed to evaluate the attractiveness of dried persimmon fruit depending on the method of preparing the fruit for drying. The methods varied in terms of the ripeness of the fruit, the thickness and shape of the slices, the presence of seeds (in fertilised fruits) and the presence of peel. Sensory evaluation was performed by students and staff, using a hedonic scale, where evaluators evaluated the appearance (shape and colour) and taste (sugar-acid ratio, texture, tartness, presence of fruit peel, and general impression) of the fruit. Dried unfertilized persimmons, with the presence of peel, cut into 3 mm thick slices, were given the highest score for overall attractiveness. In terms of taste, unfertilised, peeled persimmon slices scored the highest. Considering all parameters, the results showed that unfertilised persimmons were more suitable for drying and that the presence of the peel was not a disturbing factor for consumers.

In this study, we focused on the possibility of forecasting the development of skin color in apples on the basis of weather forecast by using a machine learning methods. We used supervised learning and generated models via the use of six decision trees. The purpose of the research was to build models that would allow for in-practice-acceptable accuracy in the prediction of the development of fruit skin color (especial a colour parameter a*), for three apple varieties. For cv. ‘Gala, Brookfield’, the most accurate models were generated by using decision tree J48 (89.13% accuracy). For late ripening cv. ‘Fuji, Kiku 8’ and cv. ‘Braeburn, Maririred’, the most accurate model was obtained by using decision tree LMT (91.73 and 96.65% accuracy). The data confirm that the applicability of predictive models strongly depends on the accuracy of weather forecasts. In regard to the seven-day weather forecast, which was used for expert models, the accuracy of the models was, on average, reduced by 10.73%.

Size is an important property of all fruit as it determines, together with crop load, fruit yield. The aim of this study is to model the increase in fruit size during cell expansion based on diameter or length and to predict fruit size and volume, including the variation in size and volume, at harvest. The size of individual fruit during growth of fruit (four apple, two tomato and six pepper cultivars) was measured from early fruit set until harvest at several seasons. Size data were evaluated as diameter and length using the von Bertalanffy growth model, adapted to include the variation in size between individuals and the effect of growing temperature. The adapted von Bertalanffy model describes the increase in diameter and length and their variation. For any fruit type, size increased along the same generic growth model. A single stochastic variable, the biological shift factor, was sufficient to describe the variation in development time, initial size and maximum size. For all batches the percentage variation explained for were well over 93% with growth rate constants similar per species and only a minor effect of growing temperature. Prediction of the maximum size distribution based on measurements half way the cell expansion period is explored and discussed. Size and its distribution can be predicted based on a single measuring point in time but with two or three points in time the prediction system becomes more robust.

Anti-hail nets for the production of apples has become a normally action for a new or update an old apple orchard. In 2007 and 2008, the development of quality and maturity parameters of cv. 'Gala Brookfield' and ‘Fuji Kiku 8' apples grafted on M9 were studied in the Fruit growing centre Maribor-Gačnik as a factor of being grown under a blackhail net. The results showed that when grown under the black hail net fruit of both cultivars reach a higher mean mass, lower soluble solids content (0.6 to 1 ° Brix), and lower starch index, while no effect of the black hail net was detected on fruit flesh firmness and yield.

Size increase (expressed as diameter) of four apple cultivars in five seasons during about 130 days before harvest, was analysed with a simple first order production mechanism. All variation in diameter among individual fruit could be attributed to the same origin (development stage or biological age), with explained parts (R2 adj) of more than 98%. The same general behaviour of diameter development was observed in two tomato cultivars whose fruits where grown at two different temperatures. These data were also analysed using the same model with explained parts (R2 adj) of about 90%. Converting diameter into volume (assuming a perfect sphere), the usually observed asymmetrical sigmoidal behaviour was obtained, frequently described in growth modelling with the Richard's curve. A similar sigmoidal behaviour was also observed in the accumulation of dry matter (DM), as measured with NIR technology in growing mangoes. The cubic root of these data on DM could be analysed using the same model formulation, including the variation between individual fruit, with R2 adj well over 90%. Accumulation of DM ends at harvest, so the mechanism of DM production can very well define the final level of DM obtained in harvested fruit. Since sugars and DM are strongly related (e.g., conversion of starch into sugars, Brix values), a very similar mechanism could govern the accumulation of sugars. Destructively measured data on sugars were collected in nectarines, showing indeed a very similar overall behaviour and variation. This indicates that growth (diameter, mass) and quality increase (DM, sugars) could be described by a very similar mechanism, providing the first tools in the quest to harvest quality.

Selection of a proper cultivar is one of the most important management decisions when investing into apple orchard. This paper presents a methodology for evaluation of suitability for cultivation of some apple cultivars by using a multi-criteria model based on analytical hierarchy process. The software tool Expert Choice was used to support growers in making decisions about which new apple cultivar to grow. The model was applied to 13 cultivars with data derived from questionnaires completed by group of experts of different fields (orchardists, experts for fruit production economics and fruit marketing, cultivar breeders, experts of state service and commission for introduction of new cultivars, experts for fruit storage and fruit quality assessment, plant protection and fruit growing advisers). The results are shown as priority for individual cultivar. The potential of the model for assessing apple cultivar is demonstrated with the aim of providing a comprehensive explanation and justification of the assessment technique. It also indicates strong and weak points (in market potential, fruit estimation, production demands and tree estimation) of each assessed cultivar.

Summary The orientation of this research was to evaluate the classic parameters regarding the external and internal quality of tomato fruits cv. 'Brilliant' at different stages of maturity and to define the dynamics of their changes during the ripening in storage at 18 C. Principal component analysis (PCA) and multivariate canonical discriminant analysis (DA) were used to classify tomato samples according to quality (internal and external) and nutritional value based on fruit mass, fruit skin colour, contents of soluble solids (SS), total titratable acids (TTA), ascorbic acid (AA), and total antioxidant potential (TAP). Several methods are usedfor determining AA content and TAP in plant samples. A simple routine method, direct redox titration with iodate solution and spectrophotometric determination of TAPSP, as described by Singleton and Rossi, also called total phenols, were used respectively. The results show that the stage of maturity (based on fruit skin colour) strongly determines the quality and nutritional value of the tomato fruit. Tomatoes harvested at table maturity (red colour, index a*/b* ≥ 0.85) have a significantly higher nutritional value (in terms of antioxidants - TAPSP and AA content) and overall quality than those harvested at an earlier maturity stage and then ripened in storage. This brings out the importance of short food supply chains and, from the viewpoint of overall fruit quality, it raises doubt about harvesting before reaching table maturity. On the other hand, it is necessary to be extremely attentive when determining optimal maturity, because when the plant becomes over-ripe or when stored, the nutritional value and overall quality decrease drastically. Besides the colour parameters, AA content is the most important chemical marker for a simple quality control. By using a simple and reliable analytical method for determining AA content, such as direct redox titratiation, the monitoring of tomato fruit quality could also be easily performed in situ.

Traditionally, crop load and fruit yield from previous seasons are used as indicators for prediction of fruit size. Disregarding the inevitable biological variation between fruit, von Bertalanffy (1938) described the growth, expressed as length, of virtually any living organism. The model is here extended to include the variation between individuals in a batch. Using this extended model, fruit size and its variation can be predicted, using measurements of a large number of fruit at a single point during early development. The diameter of 200 tomatoes was measured 15 days after full bloom (DAFB). Using the density function derived from the extended von Bertalanffy model, and applying prior knowledge of some of the model parameters, the variation in size at harvest could be predicted. Validation of the results was obtained by comparing the predicted sizes with the diameters of the same tomatoes at harvest.

During the 2008–2010 growing seasons, an alternative ‘zero residue apple production system’ was compared with integrated apple production with cvs ‘Idared’, ‘Golden Delicious’, ‘Jonagold’ and ‘Gala’ in commercial orchards at several locations throughout Slovenia, using data envelopment analysis (DEA), and multi criteria assessment by an analytical hierarchical process (AHP). The principle of the ‘zero residue apple production’ is a combination of integrated (IP) and organic apple production. During the first 3 months of the growing season (1 April–30 June), pesticides used in IP with rapid degradation (8–10 applications) were used to control pests and diseases. During the second part of the season from 1 July to harvest, organic products (6–12 applications) were employed compared with 19–25 applications overall in IP. The goal of the alternative system was to reduce the amount of applied conventional pesticides by 40 % and to minimize pesticide residues in fruits to below the limit of 0.5 % of the legal maximum residue level (MRL) or below the residue concentrations of 0.005–0.01 mg/kg and to retain the high long-term level of yield, fruit quality, and net income per hectare. The number of pesticide residues was reduced from 4.2–5.5 in IP to 1.8–3.4 in zero residue cultivation, while 3 year average yields (class 1 fruit) were 4–9 % lower than in IP. The break even prices ranged from € 0.31 for Idared in IP, € 0.34 for ‘Elstar’ of both production systems to € 0.35/kg for zero residue cultivated ‘Golden Delicious’. Overall, a price increase of just € 0.02/kg for residue free apples would make this new ‘zero residue apple production’ profitable then representing a realistic alternative to the standard integrated apple production system.

Fruit pigmentation in ripening cv. ‘Gala, Schniga’ apples was monitored under the influence of fertigation weekly during 21 July–31 August 2009, i.e. 34 days before and 7 days after the optimal harvest date in Slovenia. The soil was a heavy loam clay with high humus content (2.8 %) and high acidity (low pH 4.9). The spectral indices NDVI (Normalized Difference Vegetation Index) and NAI (Normalized Anthocyanin Index) were obtained by a PA 1101 on attached fruit on the transition between the ground and blush colour of the fruit surface. NAI increased slowly from 0.25 to 0.6 two weeks prior to optimum maturity. NDVI values fell from 0.9 to 0.2 before and during ripening, with significant changes starting ca. 3 weeks before and during the week after the optimum harvest date. Fertigation delayed fruit ripening viz harvest date by ca. 4 days. Fertigation delayed changes in the intensity of the fruit’s epidermal pigments, expressed as NDVI for 1 week and NAI for 4 weeks, respectively, but had no significant effect on fruit colour or NDVI and NAI values at the optimal harvest date. At this time, those fruits from the fertigated trees were firmer with a lower starch index compared with the un-fertigated control. Statistically, highly significant correlations were found (p ≤ 0.01) (r = 0.35 to r = 0.91, R2 = 0.11–0.83) between all the studied spectral and standard parameters i.e. fruit fresh firmness, soluble solids content and starch index.

Colour and taste are important attributes of apple fruit quality and have therefore been widely studied. Nevertheless, because of the destructive sampling methods commonly used to obtain the data, and of the subsequent traditional analyses, ignoring the effects of biological variation, the knowledge on the kinetic mechanisms of synthesis and degradation of individual quality components during fruit development and growth is still lacking. Spatio-temporal changes of taste components (sugars: fructose, sucrose, glucose, organic acids: malic, citric, shikimic and fumaric acid) and colour aspects (a) in individual apple fruits were monitored to assess the dynamics and mechanisms of change during development and ripening with respect to location within fruit as a factor and the variation between individual apples. Data were analysed with non-linear indexed regression based on either a logistic or an exponential process oriented model assessing the technical variation simultaneously. The rate constants for colour or taste component were roughly similar between cultivars, suggesting a similar mechanism of development and confirming the generic nature of the model. There was a very large biological variation in individual quality components observed in the raw data (the biological variation), which can be almost exclusively explained by the difference in the maturity stage between individual fruit. The explained parts (R2 adj) were, with one exception, higher than 0.90. The major contribution of this study is the fact that all the herein monitored taste defining components can be analysed and described with the same process-oriented model.

Field trials were carried out from 2008 to 2011 at Maribor, Slovenia to determine the effect of new copper fungicide formulations on the copper content in apple fruits, separated in peel and flesh, of seven cultivars at harvest. Apple trees were treated 12–18 times per season with formulations based on copper oxychloride or sulphate (trial standards), copper hydroxide and their complexes or chelates with amino acids, peptides, EDTA, urea, and octanoic or gluconic acids at the same rate of 200 g of pure copper ions (Cu2+) per hectare irrespetive of the product. Copper formulations were applied with Teejet 800067 flat fan nozzles mounted on a vertical boom of the sprayer, which gave a droplet volume median diameter (VMD) of 120 microns and 130–180 droplet impacts per square centimeter, as determined on water sensitive papers. The new formulations of copper in the form of salts of fatty acids or organic complexes or chelates had a higher penetration rate into apple fruit tissue than the traditional formulations based on Cu-hydroxide, Cu-oxychloride and Cu-sulphate. The copper content in the fruit depended on the ratio between copper solubility in the formulation, rate of penetration into the fruit and stability of the copper fungicide deposit on the fruit surface. Despite being applied at lower hectare rates, frequent applications led to the exceeding of the permitted EC maximum residue level of 5 mg/kg fresh mass (FM). MRL was most often exceeded with the application of formulations based on Cu-octanoate and Cu-gluconate and less often in case of the application of complexes of copper with amino acids, peptides or urea. A comparison of the copper content between different cultivars showed that cv. ‘Jonagold’, ‘Golden Delicious’ and ‘Elstar’ accumulated more cooper than other cultivars. Copper concentrations in the peel exceeded that of the flesh at least twice. The potential effects of accumulation of copper in woody tissue of bearing shoots after long-term application of highly systemic copper formulations on growth and blooming of apples are discussed too. Some apple growers may not be aware of much higher penetration rate of these new copper products (fungicides, fertilisers or plant strengtheners) and should be warned about the necessity to adapt their spraying schedules despite applications of a low hectare rates of copper, i.e. the number of treatments and proper seasonal timing, to avoid exceeding of EU MRL of copper in fruit.

Streuobst stands, i.e., tall fruit trees on vigorous rootstock on traditional grassland, represent an important source of raw material for the processing industry and for traditional fruit processing on family-run farms. Apart from production aspects, the high-stem orchards also play a role in the conservation of the traditional landscape, and indirectly in maintenance of the viability of rural areas. In this paper, a qualitative multi-attribute model for the assessment of Streuobst stands with respect to their multifunctional characteristics is presented. The assessment is based on four groups of attributes: (1) production criteria (percentage of missing trees), (2) biodiversity (fruit species and varieties, artificial human intervention), (3) landscape diversity (visual appearance, eco-diversity and erosion protection), and (4) function of the stand (row or individual trees, countryside appearance). The assessment is based on the aggregation of input attribute values to an overall assessment through user-defined decision rules. The model was applied to 85 sample stands in NE Slovenia. The assessment shows that most of the stands (48) were rated as “very poor” or “poor”, mainly as a result of poor cultivation and lack of maintenance.

BACKGROUND: In managing apple orchards, crop load and rate of nitrogen (N) fertilisation are two factors with a significant influence on fruit quantity and quality, because they affect all physiological processes in the tree. Both factors are strongly related to external and internal fruit quality, especially to skin colour, sugar and acid contents and mineral composition, and consequently to the keeping quality of fruits. The aim of this study was to assess the effects of both factors (three crop load levels and two N fertilisation levels) on the colour development of Golden Delicious apples during the last month on the tree in two consecutive seasons. Data on skin colour (L*, a*, b* values) were analysed using nonlinear mixed effects modelling to extract information on the variation in biological shift factor for colour and to link this variation to the different strategies used concerning N fertilisation and crop load. RESULTS: The major source of information is contained in the a* value. The behaviour of the a* value could be described by a logistic or an exponential model depending on the season and the experimental set-up. Nonlinear mixed effects analysis estimating the biological shift factor (maturity) for each individual fruit (random effect) while estimating the rate constant of the decolouration process in common (fixed effect) resulted in explained parts well over 95%. CONCLUSION: The variation in maturity stage between individual fruits is large. Season has the most profound effect on the estimated values, far more important than that of crop load or fertilisation level. The magnitude of variation in colour due to crop load and N fertilisation is not too large. Its effect on the maturity stage of fruits is more profound: the higher the crop load, the higher the variation. The effect of fertilisation seems to be opposite: the higher the fertilisation level, the lower the variation.

The trial was conducted in a ‘Gala’/M9 orchard and the experiment was designed as a randomized block comprising four treatments (application of Prohexadione-Ca: 125 mg-l, 250 mg-l, 2 x 125 mg-l, and control - without growth regulator). Experiments have been carried out for 2 years (2003, 2004). Application of Regalis reduced trunk cross-sectional area increment, and cumulative extension shoot growth. The effect increasing with concentration, and a greater inhibition was obtained when the trees were sprayed two times. Compared to control, return bloom of Regalis-treated trees was not affected. No negative effects of treatment with Regalis on yield per tree were observed, but some reduction of average fruit weight was found.

The trial was conducted in 'Fuji'/M9 orchard in Slovenia with 5100 trees ha-1. The experimental design was as split-block comprising three rates of nitrogen (N) as broadcast fertilizer application with 60, 90 or 120 kg N ha-1, and three crop load (5.0, 3.5 or 1.5 fruits cm-2 trunk cross sectional area (TCSA)). Treatments with different N rates lasted two years beginning in the fourth year after planting. In the 4th growing season, crop load was adjusted by hand thinning whereas in the next year fruits were not thinned (control year). The major effect of excessive crop load on 'Fuji' apple was reduced return bloom. A positive relationship was found between N rates and TCSA in year of applied treatments and return bloom in control year. Results showed no significant effect of N treatment on size and internal fruit quality.

BACKGROUND: Homogeneity in appearance is one of the quality aspects asked for in the supply chain. Decreasing the biological variation in batches of harvested apples (cultivars Braeburn, Fuji and Gala) becomes increasingly important. Skin colour is one of the aspects that determine both optimal harvest and stage of development. Skin colour is affected by location in the canopy. The rules of development of biological variation are now established and will be used on skin colour data. RESULTS: The Minolta colour aspects a*, b* and L* measured before commercial harvest change in a sigmoidal fashion and can be analysed including the biological variation, with a logistic model in indexed nonlinear regression, obtaining explained parts of above 90%. The mechanism of colour change is not affected by state of development or location in the canopy. The location in the canopy affects the intensity of both red and green colouring compounds. The variation in colouration is not affected by the location in the canopy. CONCLUSION: The red-coloured apple cultivar (Gala) depends more on the location in the canopy than the less-coloured cultivars (Fuji and Braeburn). The colour development in Fuji apples is considerably slower, with a much larger variation in stage of development. The location in the canopy affects all aspects of biological variation (biological shift factor and asymptotic starting level of colouration) for all three colour aspects L*, a* and b*, but only the mean value, not the standard deviation. The biological shift factors per colour aspects are linearly related. Once induced, variation remains constant during development.

A trial was conducted over two years in a 'Topaz'/M9 orchard (4000 trees/ha) using a randomized block design comprised of five fertilizer treatments: 400 kg/ha Compo Guano (11% N), 880 kg/ha Maltaflor Special (5% N), 880 kg/ha Agrovit (5% N), 550 kg/ha Biosol (8% N) and an unfertilized control, and two types of orchard floor management: tree row clean-cultivated and grass within the tree row mowed. The treatments began in the third year after orchard establishment. Trunk cross sectional area (TCSA), the number of flower clusters per tree, fruit set, yield and average fruit weight were determined. The tree growth (TCSA increment) was significantly higher following treatments with Maltaflor Special and Agrovit than with Biosol. The cumulative yield per tree was higher following application of Agrovit than Biosol or Maltaflor Special, but no treatments significantly increased cumulative yield compared with the control. No significant differences were found for growth, yield and external fruit quality parameters for the other fertilizers and vegetation management methods, compared with the control.

In central Europe there are many backyard fruit growers who receive no proper education about fruit tree care. Their knowledge is mostly based on various handbooks and learning through trial and error. Such learning is slow and can even result in damage to the tree. To shorten the learning time, a new interactive teaching tool EduAPPLE has been developed based on the basic laws of apple tree (Malus ×domestica) growth and training. Pruning, weighting, tying, and spreading can be interactively practiced over and over again without any danger to the actual trees. Training responses are immediately seen and are analogous to those of real trees. They are not only predetermined by a set of rules, but also calculated based on the changes the actions cause to the light interception of the tree. EduAPPLE enables high-quality views of trees and their light interception from all angles in real time and is designed for education regarding free-standing apple tree training (spindle). It can, therefore, be used in schools, universities, and other educational organizations, as well as by tree growers, including the large number of growers having only a few fruit trees.