260 Teubner, Wittwer, and Shen 



substituted AT-arylphthalamic acids as related to their biological ac- 

 tivity in tomato flower formation, and as auxins in the stimulation 

 of tomato parthenocarpy and elongation of Avena coleoptile sections. 



MATERIALS AND METHODS 



Chemical^ 



Most of the substituted AT-arylphthalamic acids used in these in- 

 vestigations were prepared by reacting equal molar amounts of 

 phthalic anhydride and the appropriate aromatic amine in benzene 

 at 30 to 80° C. The products were dissolved in dilute base, reprecipi- 

 tated with hydrochloric acid, washed thoroughly with water, and 

 dried. The sterically hindered 2,6- and 2,4,6-substituted phenyl de- 

 rivatives were prepared by heating the amine and phthalic anhydride 

 together without solvent at 150 to 200° C. to form the imide, then 

 hydrolyzing to the phthalamic acid with one equivalent of sodium 

 hydroxide. Purity of the preparation was checked by titration to ob- 

 tain the equivalent weight, and good agreement with theoretical val- 

 ues was found. Neutral equivalents were a better criterion of purity 

 than melting points since most of the N^-arylphthalamic acids decom- 

 posed as they melted, liberating water and forming the imide. 



Tomato flower formation. The procedure was essentially that de- 

 veloped by Teubner and Wittwer (24) and was based on the observa- 

 tion that the first inflorescence of the tomato (Lycopersicon esculen- 

 tum, 'Michigan-Ohio Hybrid') is initiated 9 days after cotyledon 

 expansion (21). The inflorescence is most susceptible to modification 

 by chemical treatment when the first flower primordium is differen- 

 tiating, which, in the test variety, corresponded to plants having two 

 plumule leaves and a third leaf one-half to one inch in length (24, 33) . 

 Plants treated with the N-arylphthalamic acids at this stage developed 

 branched flower clusters with five to seven flowers on each branch. 

 Over a limited concentration range, which varied for each active 

 chemical, the flowering response was directly proportional to concen- 

 tration. The maximum responses obtained with this method have 

 been clusters consisting of three to four branches and 28 flowers. 

 Higher concentrations either reduced branch and flower numbers or 

 produced severe formative effects. 



Solutions of the various N-arylphthalamic acids were prepared just 

 prior to treatment by dissolving weighed amounts of each chemical 

 in a small quantity of acetone and diluting to the appropriate volume 

 with water. No deleterious effects were observed for concentrations of 

 acetone up to 5 per cent, the maximum employed in the studies. The 



* Personal communication from Dr. A. E. Smith, Agricultural Chemicals, Nauga- 

 luck Clhemical Division, United States Rubber Company. 



