ETHYLENE INVOLVEMENT IN LEAF ABSCISSION, CHLOROSIS, AND ROOTING OF CODIAEUM-VARIEGATUM VAR. PICTUM (LODD) MUELL AUCUBAEFOLIA

Cuttings of Codiaeum variegatum var. pictum 'Aucubaefolia' (croton) sh ow leaf drop and yellowing of leaves directly after transport. To solv e the problem the ethylene sensitivity of pot plants and cuttings was investigated. Storage under 3.5 mu l.l(-1) ethylene for 7 days also re sulted in severe leaf drop and yellowing, both in cuttings and intact plants. 1-methylcyclopropene (1-MCP) and silver thiosulfate (STS) redu ced both abscission and chlorosis of Leaves, suggesting involvement of ethylene in promoting senescence. Both inhibitors of ethylene action significantly decreased the percentage of rooted cuttings, number of r oots, root dry weight, and partly of total root length per cutting. Be cause inhibitors of ethylene action reduce rooting a practical use of these compounds as prestorage treatment of cuttings is questionable. T he consequences of the ethylene sensitivity of C. variegatum var, pict um 'Aucubaefolia' for further investigations are discussed.