INFLUENŢA SISTEMULUI DE ÎNTREŢINERE A SOLULUI ŞI A FERTILIZĂRII CU AZOT ASUPRA UNOR COMPONENTE CHIMICE DIN FRUNZELE ŞI FRUCTELE SOIULUI DE PIERSIC SPRINGCREST THE INFLUENCE OF MANAGEMENT SYSTEM AND NITROGEN FERTILIZATION ON LEAF AND FRUIT CHEMICAL COMPONENTS IN 'SPRINGCREST' PEACH VARIETY

The knowledge of the soil management system (SMS) effect and of the nitrogen doses application on the main chemical components from peach leaves and fruit has an particular importance both for fruit tree nutrition level measurement and fruit quality. During 2002-2006 a study was achieved in order to quantify these effects in Dobrogea - the optimum area for peach culture. Dobrogea is a region characterised as having rich soils with optimum values of chemical elements, but high water deficits. The experiment was carried out in a peach orchard at the Research Station for Fruit Growing Constanta on a calcareous chernozem showing high fertility. The orchard was established in 1991 in a 4m x 2m planting scheme. The peach tree orchard was planted in 1991 with Springcrest cultivar grafted on wild peach rootstock. The following layout was studied according to the subplot method in four replications and five trees were used within a replicate plot: SMS between tree rows (factor A with 2 graduations), SMS on the tree rows (factor B with 2 graduations) and N amount (kg active substance/ha) with 3 graduations. The mowed sod versus the clean cultivation system between the tree rows determined a significant increase in dry matter by 2% and in ash by 16% after four years of study. The values of other studied chemical components of the fruit (sugar content, total acidity, phosphorus, potassium and pH) were not significantly influenced by the SMS between tree rows. The mulch treatment on the tree rows determined a significant increase in leaves nitrogen by 4%, in fruit total acidity by 10%, in phosphorus by 15% and in potassium by 19% versus clean cultivation. Under similar treatment conditions the values of other analyzed chemical components of the fruit were not significant. Versus 60 kg N a.s/ha the fertilization by 90 kg N a.s./ha determined an increase in fruit nitrogen content by 7% and in phosphorus content by 6%, respectively. Also, the fertilization with 30 kg N a.s/ha showed a significant increase in fruit dry matter by 5% and in total nitrogen content by 11.6% versus 90 kg N a.s/ha. The values of other six analyzed chemical fruit components did not indicate significant differences in relation with the applied nitrogen doses.