Abstract
The surface of leaves, fruits and twigs from 5-year old Ralls tree grown in minus Ca water culture solution was treated in summer of 1966 either with 0.018M 45CaCl2 or 45Ca(OH)2 solutions to elucidate the distribution of applied 45Ca between different parts of the tree.
The results showed that 45Ca applied to either upper or lower surface of the leaves penetrated into tissues regardless of the form of salts, and that the distribution of 45Ca was greater in younger leaves (leaves on the apex position) than older (basal leaves of the same shoot).
The autoradiographs showed that there was no apparent translocation of 45Ca from the treated leaf of mid-shoot position to the adjacent upper or lower leaves. However, slight radioactivity was detected in the fruit when fruit spur leaves were treated with 45Ca salts.
45Ca applied to the fruit surface by dipping, penetrated to flesh through vascular systems, but radioactivity was greater in skin and core than in flesh.
45Ca applied in a cloth tape around 1-year or 3-year twigs was detected 34 or more days in the phloem and xylem under the site of application, and translocated to the extent of 8cm upper and lower directions from the site of application though its radioactivity was rather slight.
Although the 45CaCl2 treatment usually showed greater activity than 45Ca(OH)2, attempts to compare the nature of the two salts were not successful because of the formation of slight precipitation in Ca(OH)2 solution by addition of wetting agent.
On the basis of these data, it seemed reasonable to assume that the Bordeaux mixture, which contain an excess of lime, may act as a Ca source for the trees, consequently the Ca levels of leaves, branches and fruits increase to some extent by replicated Bordeaux sprays.
