Effect of spraying with calcium chloride at difTerent water rates on 'Jonagold' apple calcium concentration

The aim of the study was to examine the effect of calcium chloride (CaCl2) spraying at different rates of water on apple (Malus domestica Borkh.) calcium concentration. The examination was carried out in 1997-1998 on 'Jonagold' apple trees grafted on M.26 rootstock and planted in 1990 on sandy-loam soil at a distance of 4 x 2.5 m.The trees were trained as a spindle at 2,4 m and 2 m of height and canopy width, respectively. In the experiment apple trees were sprayed with CaCl2 at a rate of 7 kg ha-1 using 250, 500, 1000 and 1500 L of water volumes which gives : 2.8, 1,4, 0,7 and 0.5% CaCl2 solutions, respectively. Sprays with CaCl2 solutions were applied 6, 4 and 2 weeks before commercial fruit harvest. The trees unsprayed with Ca served as a control. The study showed that sprays with CaCl2 at all studied water volumes had not effect on leaf and fruit damages. Regardless of the applied water rates, apples from the middle and the bottom of the canopy had higher calcium concentrations as a result of CaCl2 sprays whereas this treatment had not effect on fruit calcium concentration from the top of the canopy. However, the laboratory study showed that 'Jonagold' apples from the canopy top had ability to take up exogenous calcium. It was found that efficacy of CaCl2 sprays at studied water rates in increasing fruit calcium concentration was similar. The study showed as well that young 'Jonagold' fruitlets took up clearly less exogenous calcium compared to mature fruit which suggests that sprays of this cultivar with calcium salts should be applied mainly at late apple development stages