B. KESSLER 



Z. W. MOSCICKI 



R. BAK 



National and University Institute of Agriculture 

 Rehovot, Israel 



The Effects of Decapitation and Growth 

 Regulators on the Movement of Calcium. 



in Apricot Trees' 



The movement of calcium in plants is very limited or negligible 

 (1,4) once it has reached certain organs, particularly leaves and fruits. 

 Calcium is not withdrawn from leaves prior to leaf fall in the autumn, 

 and is regarded as being immobile in the phloem. Bledsoe et al. (2) 

 showed that Csl*'^, supplied to the root environment of peanut plants, 

 moved directly to the stems and foliage, but could not move through 

 the phloem to reach the developing fruits in any significant quantity. 

 The latter findings have been confirmed by several authors (8), based 

 on the immobility of radiocalcium applied as a foliar spray (4, 12, 19). 

 Bukovac et al. (4) reported that there was little movement of 

 radiocalcium in the plants, but that after the plants had been anes- 

 thetized with diethyl ether, considerable quantities of Ca^^ moved 

 from the site of application to other parts of the plants. A similar 

 effect upon the movement of Ca^'^ was obtained with triiodobenzoic V 

 acid (TIBA) (12), which interferes with auxin transport (14, 15, 16). 

 The effect of TIBA upon the movement of metal ions, in addition to 

 being a problem of translocation, became of interest in the light of 

 suggestions that the activity of plant growth regulators might, in 

 part, be due to their metal-chelating ability (6). This paper describes 

 the effect upon downward translocation of radiocalcium of several 

 growth regulators. 



MATERIALS AND METHODS 



One-year-old apricot seedlings and 6-year-old apricot trees were 

 used for these experiments. Trees of similar performance were se- 

 lected and each experiment was carried out in quadruplicate. The 



•Publication of the Agricultural Research Station, Rehovot, Israel. Series 

 No. 216-E. 



[387] 



