Two types of high frequency oscillations in Glycine max (L.) Merr.

Movements of the first trifoliolated leaf of Glycine max (L.) Merr. plants were monitored continuously for several weeks in a study that included 14 individual plants. Two types of high frequency oscillations that had periods of 1 hr or less were superimposed on the circadian profile of eight of the 14 plants. The first type of leaf movement was found to be an ultradian oscillation having periods that ranged from 45 to 62 min. These oscillations started 2 to 5 hr after the beginning of the 15-hr light span. Analysis by double complex demodulation revealed a progressive period elongation during the light span. The second type of leaf movement had a more complicated pattern with fast and irregular amplitude variations and appeared in the last 5-hr portion of the light span.