Jivan C., Sala F., 2014. Relationship between tree nutritional status and apple quality. Hort. Sci. (Prague), 41: 1-9.Development of prediction models for the quality of apples is useful in guiding fruit tree nutrition and in optimising fruit management. The interrelationships between the leaf nutrient contents and some fruit quality indices were studied in five apple cultivars -Generos, Florina, Delicios de Voinesti, Jonathan and Pionier. Highly significant relationships between N and Fe contents (R 2 = 0.734; P < 0.01) and between Cu and K (R 2 = 0.702; P < 0.01) were found. Acidity was negatively correlated with soluble solids content in the cvs Generos, Delicios de Voinesti and Jonathan, whereas the respective correlation in the apple cv. Pionier was positive. In cv. Florina fruits no significant correlation was found between acidity and soluble solids content. Among macroelements, nitrogen had a considerable contribution to fruit acidity and this allows to predict this index with a high degree of safety (R 2 = 0.690; RMSEP N = 0.105). Microelements have a lower contribution to acidity and a higher one to the sugar accumulation; in case of Zn are R 2 = 0.809; RMSEP Zn = 4.250.

The studies the production quality of three varieties of apples, Generos , Florina and Delicios de Voinesti  under the influence of differential nutrition based on macroelements. The nutritive elements came from complex fertilizers (NPK) 120 and 240 kg s.a./ha. The size of the fruits was directly influenced by mineral fertilization and it was established by taking into account two evaluating factors like diameter and average weight. The spore of average diameter apples was between 7.82 - 14.58 mm in Florina variety, 9.4 - 24.02 mm in Delicios de Voinesti variety and 29 - 33.4 mm in Generos variety. The average spore of weight varied according to variety and doses from 1.2 to 1.9 g in Florina variety, 1.5 - 3.2 g in Delicios de Voinesti variety and 3.7 - 5.3 g in Generos variety . The sugar content was between 16.90±0.41 % in Generos variety and 22.10±0.56 % in Delicios de Voinesti variety  . The total acidity is in reverse raport with the sugar content and has the following values: 0.26 % in Delicios de Voinesti variety and 0.58 % in Generos variety.