Influence of foliar application of calcium on physiological disorders in two apple cultivars
Bitter pit and soft scald are physiological disorders often observed in apple fruits during storage. These disorders influence both the appearance and taste of fruits, and therefore cause economical losses for fruit growers. During two consecutive seasons, apple trees Antei and Rubin grafted on B.396 rootstock were investigated in an orchard with a tree density of 1,666 trees ha-1 (1.5×4.0 m). The soil of the experimental orchard was Haplic Luvisol (Hypereutric), sandy loam, with an organic matter content of 17 g kg-1 and pHKCl 6.8. Plant available phosphorus was 113 mg kg-1 and potassium was 211 mg kg-1. The orchard was irrigated and grass grown in the alleys was mowed regularly. A foliar calcium application was performed 6 times per season with Ca(NO3)2 and CaCl2 (3 times each product), with 6 kg ha-1 doses. Rubin apples were harvested earlier and stored at 10-12°C for two weeks. The control trees were not treated with foliar fertilizers and their harvested apples were directly placed in cold storage after harvest. Foliar Ca applications reduced the occurrence of bitter pit in Antei fruits. At the same time the effectiveness was not satisfied due to high K/Ca ratio in fruits at the conditions of biennial yielding. Some positive tendency of premature fruit ripening temperature regime was observed for Rubin. Calcium application had only minor effects in delaying soft scald in Rubin fruits.
Pole, V., Rubauskis, E. and Missa, I. (2018). Influence of foliar application of calcium on physiological disorders in two apple cultivars. Acta Hortic. 1217, 385-390
fruit quality, bitter pit, soft scald, foliar spray, K/Ca ratio