Results of our experiments are interpreted according to fertilizing system developed by long-term experiments and investigations. The potassium fertilization and favourable N/K ratio can increase the frost tolerance of generative organs of fruit trees to some extent. The effect of suitable growing site can surpass the effect of fertilizers. Frequently, the increase of phosphorus and potassium levels in the soil and leaves are relatively small comparing to amount of fertilizers, because of the strong fixation in the fertilized soil layer and – in other cases – leaching from root zone. Main soil characters should be taken into consideration to determine the favourable phosphorus, potassium levels in the soil. The excess of lime can be compensated by potassium fertilization to some extent, but on acid soils the NPK fertilization may be more effective – or effective at all – following lime or dolomite application.

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