EFFECTS OF DIFFERENT DOSES OF MINERAL FERTILIZATION ON YIELD AND FRUIT QUALITY OF 26-YEAR-OLD APPLE TREES.

The experiment was set up at the Experiment Station Dabrowice near Skierniewice on a sandy loam grey-brown podsolic soil in 1956. McIntosh Bancroft, Jonathan and Boiken apple trees on Antonovka seedling rootstock were planted at the spacing of 8 × 6 m.
Doses of fertilizers employed have been changed in the course of the experiment and they ranged from 30 to 180 kg of N, from 15 to 60 kg of P₂O₅ and from 45 to 270 kg of K₂O/ha/year.
Lime was applied in a dose of 1500 kg of Ca0 once in every four years.
Until 1971 soil in the orchard was clean cultivated and since 1972 alleyways have been grassed down and herbicides have been applied along tree rows.

Mean fruit weight increased with increasing fertilizer doses.
Fruit coloration was evaluated in representative samples and it was expressed as a percentage of fruits showing more than 50 or more than 75% of red skin surface in McIntosh, Jonathan and Bancroft fruits and more than 25 or more than 50% of coloured surface in Boiken; in samples of fruits of the cultivar Boiken a percentage of completely green fruits was additionally recorded.

The highest percentage of intensely coloured fruits was found in the treatment without any mineral fertilization and the lowest one in the treatment with the highest fertilizer doses, including in the last period 300 kg of N per ha.

It has be concluded that application of N fertilizers in doses higher than 120 kg per ha does not result in an increase of yield but it causes a decrease of fruit coloration and has an adverse effect on fruit storage quality.

International Symposium on Diagnosis of Nutritional Status of Deciduous Fruit Orchards

M.G. Piatkowski, W. Klossowski, J. Mochecki

https://doi.org/10.17660/ActaHortic.1990.274.49