Extractability of Calcium from Apple Fruit and Apple Leaf Tissue and the Occurrence of Bitter Pit

Water-soluble Cation Contents of ‘Jonathan’ Apple Fruit Pulp as an Estimation of Total Content

“…The 6) warned that aqueous extracts might be of little value in studying Ca fractionation because of the differing extractabilities in different plant tissues (apple fruit and leaf, kiwifruit). However, our results regarding Ca extractability in water are similar to those of van Lune and van Goor (17), in spite of differences in cultivar, location, and state of tissue used for Ca extraction by each investigator (fresh and freeze-dried powder, respectively).…”

“…The latter finding is in agreement with previous reports on changes in mineral levels during fruit maturation (2). The uniform percentage of water-soluble Ca, extracted at harvest from the pulp of 'Jonathan' apples grown in various regions of Israel, is in close agreement with the 54% to 65% of total Ca extracted in water from the pulp of 'Cox's Orange Pippin' apples from 16 different orchards in the Netherlands (17). The 6) warned that aqueous extracts might be of little value in studying Ca fractionation because of the differing extractabilities in different plant tissues (apple fruit and leaf, kiwifruit).…”

“…The application of the suggested method appears justified, since a) in apple pulp most of the total mineral content is extractable in water; b) it might be of importance to measure the Ca content of fruit as close to harvest as possible, considering the fact that its concentration declines during maturation at or shortly before harvest (2); c) in 'Cox's Orange Pippin' watersoluble Ca at harvest correlated with bitter pit as did total Ca (17); and d) the method is simple, time-saving and efficient, and results are reproducible.…”

Senescent Breakdown of `Jonathan' Apples in Relation to the Water-soluble Calcium Content of the Fruit Pulp before and after Storage

“…One possible explanation for this apparent inconsistency with regard to Ca is that the physiological disorder is related only to a certain fraction of the cell Ca, which is not always directly correlated with total content. This possibility was suggested previously in relation to bitter pit, another storage disorder (van Lune and van Goor, 1979). However, it still remains to be determined which Ca fraction might correlate satisfactorily with senescent breakdown.…”

Seasonal Trends of Calcium, Magnesium, and Potassium Fractions in Apple Leaf and Fruit Tissues1

“…Lastly, the percent of total Ca extracted by N aN 03 increased continually from 24% early in the season to 55% at the end. The (Mg + K)/Ca or K/Ca ratio has been suggested as a more accurate predictor of physiological disorders in apples than the Ca concentration alone (6,15,16). We plotted ratios of PA concentrations which might be more indicative of nutritional status and susceptibility to physiological disorders than total concentrations (Fig.…”