Determination of Total and Ionic Calcium in Apple Leaf and Fruit Tissues1

Abstract

Apple ( Malus domestica Borkh.) leaf, peel, and flesh tissues were sequentially fractionated using hot water, sodium nitrate, acetic acid and hydrochloric acid to extract Ca in various forms. Water soluble and sodium nitrate exchangeable Ca, which were considered to be the physiologically active forms, composed 53%, 78 %, and 73 % of the total Ca present in apple leaf, peel, and flesh tissues, respectively. Ionic Ca was determined in each of the fractions using an ion-selective electrode. Eleven to 42% of the total Ca concentration in each of the fractions was found to be in the free ionic form. Bound and exchangeable Ca in each of the fractions was also measured by an ion exchange resin in a batch method, and exchangeable Ca was 19 to 87% of the total.