Growth Regulators in Agriculture 811 



Dr. Gowing: "In my Father's house there are many mansions." 



Dr. Thimann: There are some rather striking differences between 

 the effectiveness of growth substances in simple growth tests and their 

 effectiveness in the production of parthenocarpic fruits. An impor- 

 tant point to bear in mind is that in different types of tests like these, 

 there is a very wide difference in timing. After the substance is ap- 

 plied to the pineapple, how many weeks or months later. Dr. Gowing, 

 is it that the flower initials appear? 



Dr. Gowing: It varies from 50 to 120 days. 



Dr. Thimann: In contrast, a growth test is usually done in 24 hrs. 

 So one must consider that the determining factors for activity in a 

 long time test are going to include not only activity per se, but the 

 ability of the substance to be adsorbed or combined on other constitu- 

 ents of the plant and its ability to be metabolized or destroyed, or at 

 least made inactive. In considering those different phenomena that 

 can intervene between application and finally getting the effect, we 

 will probably get the explanation of these differences. 



