IN SEARCH OF ALLELOPATHY IN THE FLORIDA SCRUB - THE ROLE OF TERPENOIDS

The hypothesis was tested that allelopathic agents released from fire- sensitive plants of the Florida scrub community deter the invasion of fire-prone sandhill grasses. The structures of the constituents of fou r endemic scrub species, Conradina canescens, Calamintha ashei, Chryso ma pauciflosculosa, culosa, and Ceratiola ericiodes, were established and their phytotoxic activity against two grasses of the sandhill was examined. Effects of the secondary metabolites from the above scrub sp ecies and their degradation products upon the germination and radicle growth of little bluestem (Schizachyrium scoparium) and green sprangle top (Leptochloa dubia), two native grasses of the Florida sandhill com munity, were determined. The studies included determination of the wat er solubility and release mechanism of terpenes and other allelopathic agents from the source plants and their aqueous transport to the targ et species. Some of the natural products were nontoxic until activated by light and/or oxidation after release from the source plant into th e environment.