The Fate of 14C(2-Chloroethyl)phosphonic Acid in Summer Squash, Cucumber, and Tomato1,2

Abstract

Abstract Radioactive (2–chloroethyl)phosphonic acid (ethephon) was applied to leaves and fruits of ‘Tiny Tim’ tomato and ‘Pioneer’ cucumber and to seedlings of ‘Yellow Crookneck’ summer squash. During the first day, slightly over 21% of the applied 14 C-ethephon was converted to 14 C-ethylene by the squash plants, and 10 to 15% was converted by the tomato plants. A week after treatment the rate of 14 C-ethylene production decreased rapidly to less than 1% per day. Increases in rates of production of total ethylene following treatment were attributed to the decomposition of ethephon. Radioactive CO 2 production was small, amounting to about 0.1% of the 14 C applied. Seven days following treatment of tomato leaves, about 15% of the 14 C was translocated to developing fruits and lesser amounts to other parts of the plant. In the squash seedling, from 3 to 9% was translocated after 2 days from the site of application to other tissues. Twenty–five days after application to cucumber leaves, the fruits containted only 0.3% of the applied 14 C–ethephon. In the tomato tissue the radioactivity was present as 14 C–ethephon, but in the squash seedling tissue much of the radioactivity was present in a new compound.