Possible control of gibberellin-induced release of temperature-dependent primary dormancy in seeds of celery (Apium graveolens L.) by transmembrane ion fluxes

The temperature-dependent primary dormancy of cv Florida 683 celery seeds in darkness was broken by GA_4/7 (2 × 10^-4 M) alone but other growth regulators such as BA, ethephon or daminozide were necessary to break dormancy of cv Lathom Blanching seeds in the presence of GA_4/7 at this concentration. Although AgNO₃ partially inhibited both the ethephon- and BA- induced germination of cv Lathom Blanching seeds in the presence of GA_4/7 in the dark it did not affect the promotive action of daminozide. Ethephon did not overcome the inhibitory action of high concentrations of AgNO₃ in the light. The ethylene synthesis inhibitor aminoethoxyvinylglycine (AVG) did not inhibit the germination of cv Lathom Blanching seeds induced by growth regulators in the dark or in the absence of growth regulators in the light. Fusicoccin (FC) did not break celery seed dormancy unless applied in the presence of GA_4/7. Germination of cv Lathom Blanching celery seeds treated with GA_4/7 at 16°C in the dark was inhibited by the K⁺ ionophore benzo-18-crown-C-6 (18-C-6) and in the presence of Ca²⁺ by the Ca²⁺ ionophore A23187; the 18-C-6 inhibition was reversed by BA.It is concluded that the involvement of gibberellin in celery seed dormancy is not dependent on endogenous ethylene and is directly or indirectly controlled through the action of other hormones on transmembrane ion fluxes.