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Response of Jonagold apples to various doses of nitrogen fertilizers in the orchard. I. Effect of increasing N doses on the concentration of mineral constituents and the susceptibility of apples to some physiological disorders

Jan Błaszczyk, Jan Ben

Department of Pomology
Faculty of Horticulture, Agricultural University
29 Listopada 54, 31-425 Kraków, Poland

A 3-year study concerned the effect of various doses of nitrogen fertilizers on the concentration of nitrogen in apples, the accumulation of different mineral constituents in the fruit, and the health of yields. In the first and second year of the experiments the concentration of nitrogen significantly increased with doses of 60 and 120 kg N ha-1. In the third year this effect was only obtained with the higher dose. The concentration of calcium was not uniform and changed in the different years of the study. Increasing doses of nitrogen significantly reduced the content of phosphorus in the fruit, particularly in years of low yield.

The coefficient of linear r correlation between bitter pit and K/Ca ratio showed a highly significant positive correlation. The increased nitrogen concentration in the apples intensified their susceptibility to internal breakdown, especially in years of poorer yields and low Ca concentration in the fruit. Moreover, a high positive correlation occurred between the internal breakdown of apples and the accumulation of potassium in them.

Błaszczyk J., Ben J., 1996. Response of Jonagold apples to varius doses of nitrogen fertilizers in the orchard. I. Effect of increasing N doses on the concentration of mineral constituents and the susceptibility of apples to some physiological disorders. Folia Horticulturae 8/2: 21-30.