Movement of Calcium 



391 



Table 1 . The effect of various growth inhibitors and decap- 

 itation upon the translocation of foliarly-appHed Ca''^ from the 

 terminal to the fifth leaf in 6-year-old apricot trees. 



Treatment 



Control 



TIBA 



MTPA 



Decapitation 



Counts Per Minute, 2, 4, and 7 

 Days After Treatment 



5,055 



20,307 



7,191 



799 



12,345 



27.683 



21,888 



848 



15,560 



48,775 



3,830 



695 



Table 2. Time course of the distribution of radioactivity 

 from^Ca''^ along MTPA-treated branches of 6-year-old apricot 

 trees. 



In view of the activity of TIBA on the movement of calcium, the 

 effect of different concentrations of this substance was tested. From 

 Figure 4 it can be seen that the optimal concentration of TIBA was 

 about 50 p.p.m. while higher concentrations were less effective. 



DISCUSSION 



The experimental results reported in this paper suggest that cal- 

 cium is able to move in a downward direction in apricot trees, to 

 some extent. The translocation of calcium in white pine trees has 

 already been demonstrated by Ferrell and Johnson (7). But this 

 movement is very different in various tree species and in trees of dif- 

 ferent ages of the same variety. It was previously found that there is 

 no downward movement of calcium in one-year-old apple trees (12), 

 a finding which is in conformity with the generally held opinion that 

 little or no basipetal movement of calcium occurs within the plant. 

 Comparing the movements of calcium in apple and apricot trees, it 



