Versuche zur Phasenverschiebung endogener Rhythmen: Blütenblattbewegung von Kalanchoe blossfeldiana

Abstract

Studies on phase shifts of endogenous rhythms: The petal movement of Kalanchoe blossfeldiana. It takes up to 5 cycles until the phase shifts of the diurnal petal movement of Kalanchoe by short light periods are constant. Effects of a second light break are explainable neither by the suggestion of BUNNING and ZIMMER that the behaviour of the oscillator is immediately reflected in the course of the curves of the movement nor by that of PITTENDRIGH that an A-oscillator is immediately phase shifted by light, with several cycles being required for phase control of the B-oscillator. We propose to explain the results, especially those shown in curve 5 of fig. 2, in terms of a coaction of on- and off-rhythms.