AUXIN OF TOMATO FRUIT AT DIFFERENT STAGES OF ITS DEVELOPMENT WITH A SPECIAL REFERENCE TO HIGH TEMPERATURE INJURIES

Acidic auxin in tomato fruit at various developmental stageswas examined by paper chromatography and Avena curvature test. Auxin activity of the fruit extracts was detected only in thesame R_f zone as that of authentic IAA with four solvent systems,i.e., isopropanol-ammonium hydroxide-water 10:1:1 v/v, n-butanol-ammoniumhydroxide-water 25:1:5 v/v, ethanol-water 7:3 v/v and n-butanol-aceticacid-water 4:1:1 v/v. Auxin content of fruit was the highest on the seventh day afteranthesis, when the two-celled proembryo began to grow rapidlyand the endosperm consisted of multi-cells. The second peakof auxin activity occurred on the 30th day, when the embryo,which consisted of the cotyledons, hypocotyl, and radicle, finishedits most rapid growth. No auxin activity was detected in theripe fruit. Auxin contents in fruit on the fifth, seventh, and tenth daysafter anthesis were lowered by a 4 hr high temperature treatmentat 40 given 0–3 days after anthesis. The nature of tomato auxin and its possible role in the fruitdevelopment were discussed. (Received June 30, 1966; )