l82 



PLANT GROWTH SUBSTANCES 



For example, the rooting response after treatment with indolebutyric 

 acid is conditioned by the age of the experimental species, the environ- 

 mental growing conditions, and the storage of material in the treated 

 tissue. 



Repeated experiments with tomato plants verify the earlier reports 

 (15) that 2,3,5-triiodobenzoic acid and 2-chloro-3,5-diiodobenzoic acid 

 cause axillary buds to develop flower clusters instead of leafy shoots. 

 Branches and main tomato shoots were caused to terminate in flower 

 clusters appearing to supplant a shoot growing point. Treated tomato 



TABLE 4 



Molecular configuration and comparative activity of derivatives of benzoic 



acid involving the tomato plant as test object 



Substances 



Cell 

 elongation 



Formative 



EFFECTS 



Benzoic acid 

 2Todobenzoic acid 

 3-Iodobenzoic acid 

 4-Iodobenzoic acid 

 2,4-Diiodobenzoic acid 

 2,3,5-Triiodobenzoic acid 

 3,5-Diiodobenzoic acid 

 2-Iodo-3,5-dibromobenzoic acid 

 2-Chloro-5-nitrobenzoic acid 

 2-Amino-5-chlorobenzoic acid 

 2-Bromo-3-nitrobenzoic acid 

 2-Chloro-3,5-diiodobenzoic acid 

 2,3,6-Trichlorobenzoic acid 



plants also developed flower clusters in the usual places along the stem, 

 but they frequently had fewer or more than the normal number of 

 flower buds. In fact, internodal, axillary, and terminal flower clusters 

 were similar and were characterized by extremes from short to long, 

 heavy peduncles, and fasciated flowers mixed with small buds. Upon 

 recovering from the chemical influence plants often produced abnormally 

 large flowers (Fig. 3D). Some of the fasciated flowers when pollinated 

 produced a circular ovary resembling a doughnut (Fig. 3C). Such ovaries 

 had sepals both within and around the ovary. Under certain conditions 

 the axillary peduncles had only yellowish cells at the tip, indicating 

 unorganized flower cells. 



