Calcium transport in apple trees.
(45)Ca, applied to roots of apple seedlings, moved readily to the developing leaves. Kinetin, benzyladenine, and B sprays increased movement. NO(3) (-) as the source of N increased movement and accumulation of Ca into mature leaves; NH(4) (+) increased movement into new leaves. Translocation in the stem is effected by a nonspecific ion exchange. Any divalent cation can free Ca for ascent. The exchange may be a property of lignin. Genetic differences in the uptake and translocation of Ca exist among apple seedlings. Those which show juvenile leaf characteristics translocate Ca into mature leaves more readily. Translocation of Ca in woody species appears to be similar to that reported for herbaceous plants.
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Crop Research Division Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland 20705.
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