The response of growth and circadian rhythm to cycle length and photoperiod
- 34 Downloads
The growth of bean plants (Phaseolus vulgaris L., cv Red Kidney) is inhibited by cycle lengths of 36 and 48 hours. Maximal inhibition occurs when the length of the light period is equal to or shorter than 3/6 of the cycle length. The inhibition does not occur when the photofraction is 5/6 or longer. The rhythmic leaf movement in beans can be entrained to a 30-hour cycle with a photofraction of 3/6 or less. No entrainment occurs to 36-or 48-hour cycles, but such cycles with photofraction of 3/6 or less cause an irregular course of the rhythm. When the photofraction is 5/6 or greater, the leaf movement proceeds as in continuous light, independent of cycle length. In continuous light the rhythm persists for at least 12 days. The parallel response of growth and circadian rhythm to cycle length and photoperiod suggests that a circadian oscillation is involved in the growth process. It further indicates that the response of these phenomena to cycle length and photoperiod involves the same basic timing mechanism.
KeywordsCircadian Rhythm Growth Process Cycle Length Light Period Continuous Light
Unable to display preview. Download preview PDF.
- Aschoff, J.: Exogenous and endogenous components in circadian rhythms. Cold Spr. Harb. Symp. quant. Biol.25, 11–27 (1960).Google Scholar
- Bruce, V. G.: Environmental entrainment of circadian rhythms. Cold Spr. Harb. Symp. quant. Biol.25, 29–48 (1960).Google Scholar
- Bünning, E.: The physiological clock, 2nd ed. (English transl.). Berlin-Göttingen-Heidelberg: Springer 1964.Google Scholar
- Hastings, J. W.: The role of light in persistent daily rhythms In:A. Giese, Photophysiology, vol. 1. New York: Academic Press 1964.Google Scholar
- Ketellapper, H. J.: Interaction of endogenous and environmental periods in plant growth. Plant Physiol.35, 238–241 (1960).Google Scholar
- Ketellapper, H. J.: Interaction of photoperiod and cycle length in plant growth. Physiol. Plantarum (in press).Google Scholar
- Kleinhoonte, A.: Über die durch das Licht regulierten autonomen Bewegungen der Canavalia-Blätter. Arch. néerl. Sci.IIIb,5, 1–110 (1929).Google Scholar
- Pittendrigh, C. S.: Circadian rhythms and the circadian organization of living systems. Cold Spr. Harb. Symp. quant. Biol.25, 159–184 (1960).Google Scholar
- Tukey Jr. H. B., andH. J. Ketellapper: Length of the light-dark cycle and plant growth. Amer. J. Bot.50, 110–115 (1963).Google Scholar
- Went, F. W.: The experimental control of plant growth. Waltham: Chronica Botanica Co. 1957.Google Scholar