The effect of calcium foliar fertilizers on cv. Ligol apples

The effects of calcium fertilizers on cv. Ligol apples were studied in the experiment conducted at the Lithuanian Institute of Horticulture in 2007-2009. Fertilizers were applied four or eight times from June to September on the 8th-9th leaf of apple trees on P 22 rootstock. Calcium nitrate or liquid calcium fertilizers were used. The results differed over the years of experiment. During the first year, four applications of liquid calcium fertilizers significantly reduced the Mg/Ca ratio in fruit, whereas in 2008 the tendency of decrease in the ratios of K/Ca and Mg/Ca at both fertilizers was observed. The bitter pit incidence rate on stored apples of the 2007 yield was 1.5-3.0%. The eight applications of liquid calcium fertilizers significantly reduced the incidence of bitter pit after storage. In 2008, higher fruit calcium content and lower ratios of N/Ca, K/Ca, and Mg/Ca were detected. Moreover, these apples were not affected by bitter pit. The worse fruit quality of the 2007 yield could be linked to the abundant rainfall during 2007 vegetation season. However, the application of fertilizers had a positive effect on natural weight loss and fruit flesh firmness after storage.