The impact of soil and foliar spraying with calcium on quality of apple fruits (Malus domestica) 'Jonagold'

Abstract

In a two-years trial on the location Ivanjkovci near Ormož we investigated the impact of the soil and different calcium foliar sprays (Kalgan, Caltrac in Calciogreen) on apple fruit quality of ‘Jonagold’. For the parameters of apple fruits quality we observed the calcium (Ca), potassium (K) and magnesium (Mg) content in dry weight and in fresh weight of fruits, the suitable relations among mentioned elements in fruits (Ca/Mg, (K+Mg)/Ca, K/Ca), firmness, weight and diameter of fruits. The soil had very low pH (4,57 in KCl), small share of exchangeable Ca (30 % in cation exchange capacity - CEC) and big share of Mg (11,5 % in CEC). The soil was distric (base saturation level  was 44 %). Correlations between calcium, magnesium and potassium content in soil and in fruits were very weak, what indicated the very complex relationship between the soil and the trees. Weather conditions for calcium accumulation in period of fruit development were favourable in both seasons, because there was no drought. Calcium sprays had no significant impact on calcium content in fruits (except significant effect of Calciogreen in the year 1997). Positive affect of calcium sprays was observed in suitable relations among calcium, magnesium and potassium in fruits, whereas the control fruits showed the worst storage quality. Calcium sprays had no impact on fruit firmness, weight and diameter of fruits. We also observed very weak correlations among some parameters of fruit quality (Ca, Mg and K content in fruits, fruit firmness).