Auxin- and carbon dioxide-sensitive effects of mercury and iodine vapors in plant senescence

Vapors of mercury and iodine induce abscission in Coleus explantsand color-ripening in immature bananas. Their effects on abscissionare antagonized by an auxin, anaphthaleneacetic acid, and bycarbon dioxide. Alkyl derivatives of mercury and iodine areless active than the parent element, a situation parallel tothe reduced activity of the homologs (alkyl derivatives) ofethylene and acetylene. Chemical differences between the elements and olefins precludea direct ethylenelike effect. Hence it is suggested that theiractivities are mediated by endogenous ethylene, and that theirprimary action leads to increased biosynthesis. (Received November 18, 1974; )