Short-period oscillation of starch levels in Lemna under light and darkness.

In Lemna gibba G1 and L. paucicostata 6746 a short-period oscillation of starch content was found during the last hours of the daily light period and subsequent hours of the dark period. The transition from light to darkness was without effect on this oscillation. Starch degradation or synthesis continued after darkening, corresponding to the running phase of the cycle.Amplitude and frequency of oscillation were dependent on the amount of starch that was present within the plants. Under the experimental conditions used, the length of one cycle was normally 60-120 min. After addition of 0.1% sucrose to the medium, or after prolonged preculture of plants (both treatments leading to an elevated starch content), the cycle length was shortened to 40-60 min.