|
All current shoots of one-year-old, container-grown ´Fuji´/M.26/seedling apple trees (Malus domestica Borkh.) were headed back to 1/2 of their length in summer pruning treatment on May 30. Seven weeks after summer pruning increment of stem diameter, total shoot length and dry weight per tree in the summer pruned tress were significantly less than the unpruned trees. Leaf, bark and root tissues were sequentially fractionated using hot water, sodium nitrate, acetic acid and hydrochloric acid to extract Ca in various forms. During 7 weeks after summer pruning total Ca concentrations in the leaf and bark tissues of summer pruned trees were higher than the unpruned trees, whereas the concentration was much less in the root tissues of summer pruned trees. Of the total Ca concentration, distribution of water-soluble and sodium nitrate-exchangeable Ca, which were considered to be the physiologically active forms, was higher in the bark and old root tissues except for leaf of summer pruned trees than unpruned trees during 7 weeks after summer pruning. These facts suggest that Ca mobility from the root to the upper parts may be enhanced by summer pruning treatment.
|