Effects of static magnetic field on the ultradian lateral leaflet movementrhythm in Desmodium gyrans

The rhythmic leaflet movements of the plant Desmodium gyrans (L.t) DC slow down in the presence of a static magnetic field. The leaner positions were digitally retrieved from sequential CCD camera images of the moving leaflet s. The experiments were performed under constant light (ca. 500 lux) and te mperature (about 20 degrees C) conditions. The period of the leaflet was th en around 5 min. Leaflets moving up and down in a magnetic field of approxi mately 50 mT flux density increased the period by about 10% due to a slower motion in the "up" position. Since during this position a rapid change of the extracellular potentials of the pulvinus occurs, it is proposed that th e effects are mediated via the electric processes in the pulvinus tissue.