Improvement of Growth Regulator Formulation 



795 



as contrasted with rapid uptake and movement in the symplast (Fig- 

 ure 2). Calcium also moves in this way when applied to the leaf 

 surface. Monuron and simazin applied to leaves move in this way. 

 Figure 3 shows contrasting symplastic and apoplastic movement in 

 potato tuber tissue. 



Recent studies by Clor (1) have shown that not only MH, but 

 amitrol, urea, and 2,4-D are all subject to accelerated uptake and 



Fig. 4. Urea translocation in cotton; autoradiograms, top and mounted plants, 

 bottom. The plant on the left of each pair was unringed, the one on the right was 

 steamringed below the cotyledons. The left pair of plants were covered with 

 a polyethylene bag and developed a saturated atmosphere soon after treating. The 

 right pair of plants were left in the greenhouse in a fairly dry atmosphere. 

 Phloem movement to the roots was prevented by the ring in each environment. 

 In the saturated atmosphere the urea moved via the xylem to the opposite cotyledon 

 and into the top leaves. 



