Light-induced Germination and Endogenous Ion Currents in Turions of Spirodela polyrhiza

Non-dormant turions of the duckweed Spirodela polyrhiza (L.) Schleiden were used to investigate endogenous ion currents in light-induced germination and early growth of higher plants. Before light treatment, a small outward current was measured at the ventral side of the turions near the pocket containing the most developed sprout primordium. After a light pulse the direction of the endogenous current changed from outward to inward. Dormant turions showed no significant light-induced endogenous current. After germination, young sprouts of Spirodela showed highest inward current near the sprout base where cells grew rapidly and divide frequently. Ageing of sprouts resulted in a fast decrease of endogenous current.