COPPER REVERSES SILVER INHIBITION OF FLOWER SENESCENCE IN PETUNIA-HYBRIDA

The action of metal ions on detached flowers of Petunia hybrida was in vestigated to determine how they affected ethylene-promoted senescence . Salts of various metals were applied singly or in combination by 5 s immersion of excised flowers which were then incubated in 1 mu l l(-1 ) ethylene for 24 h. Of the metals tested, only Ag+ prevented ethylene -induced senescence. Cu2+ and Cd2+ completely, and Hg2+ and Fe2+ parti ally reversed the effect of Ag+. K+, Na+, Ca2+, Mg2+, Al3+, Co2+, Mn2 and Zn2+ were ineffective. Cu2+ promoted senescence even when applied after Ag+ and a 24-h ethylene treatment. Cu2+ promoted ethylene synth esis, so that senescence was not affected by ethylene treatment unless flowers had been pre-treated with aminoethoxyvinyl-glycine. Ag+ inhib ited the promotion of respiration and ethylene production by ethylene treatment of corolla tissue. Cu2+ treatment restored these ethylene ef fects in Ag+-treated tissue. The action of Cu2+ suggests that ethylene signal perception occurred in Ag+-treated corolla tissue.