ION EFFLUX AND CHANGES OF EXTERNAL PH IN EARLY RESPONSES OF EXCISED CUCUMBER COTYLEDONS TO KINETIN AND CALMODULIN INHIBITORS

After 6h of treatment, 1-10 mM Ca2+ promoted growth and chlorophyll ac cumulation in the cotyledons. Fluphenazine inhibited these processes, as well as abolished the stimulatory effects of kinetin. After 30 min treatment, both kinetin and fluphenazine enhanced ion efflux from the cotyledons. Kinetin treatment followed by a water bath caused a decrea se in pH of the bathing medium relative to control. Lowering the pH of tile incubation medium (to 4-4.5) resulted in growth promotion of til e cotyledons. The results point to a role of Ca-calmodulin in the gree ning, response and of Ca-calmodulin and lowering of pH of tile cell me dium in the growth response of the cucumber cotyledons to cytokinins.