392 



Kessler, Moscicki, and Bak 



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 TIBA, PRM. 



Fig. 4. The efEect of different concentrations of TIBA upon the basipetal move- 

 raent of Ca" in 1 -year-old apricot trees. 



is of interest that apricot trees branch more easily than do apple trees 

 and so do older trees in comparison to young ones. The phenomena 

 are usually attributed to a stronger polarity (or apical dominance) 

 inherent in the apple trees, as well as in young trees in general. This 

 difference between apple and apricot trees and between young and 

 old apricot trees may be reflected in the movement of foliarly-applied 

 calcium (12), since in apricot trees there is some translocation. The 

 relative translocation of calcium in young apricot trees is lower than 

 in older trees. Thus, it appears that the translocation of Ca-*^ might 

 be related to polarity. This suggestion has been made by Bukovac 

 ct al. (4), who were led to this hypothesis by the effects of an anesthe- 

 tizing agent (diethyl ether) upon the movement of calcium. These in- 

 vestigators also found little or no transport of Ca^^ through graft 

 union involving reversed polarity (3). The inverse relation between 

 the degree of apical dominance and the translocation of Ca^s raises 

 the possibility that the movement of calcium might be somehow con- 

 nected with the transport of auxin. The assumption that the move- 

 ment of calcium is related to the transport of auxin is supported by 

 the fact that 2,4-dinitrophenol, which alters the polar transport of 

 auxin (14, 15), also stimulated the uptake of calcium (5). 



