Daily rhythm of circumnutation

Under a cyclic light/dark photoperiod, sunflower plants exhibit a daily rhythm of circumnutations manifesting itself as daily changes in the length, period, shape, and angle of circumnutations and daily changes in electrical activity.

Film 28 Circumnutation movements of 3-week old sunflowers recorded during one day (acceleration 4300x). The movements are weaker in daylight conditions and enhanced after light turn-off. The leaves evidently move downwards at dusk and upward at dawn.

Fig.1 Changes in the intensity of circumnutations during one day. The apex outlines ellipses, lines, circles, eight-shaped tracks, or irregular zigzags. Due to the stem elongation growth (ca. 1cm/day), the series of single circumnutations forms a more or less regular spiral (Stolarz 2009).

Complex relationship between growth and circumnutations in Helianthus annuus stem. Plant Signaling & Behavior 3: 376-380

Stolarz M, Król E, Dziubińska H, Zawadzki T (2008)

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Circadian modulation of circumnutation length, period, and shape in Helianthus annuus. Journal of Plant Growth Regulation 25: 324-331

Charzewska A, Zawadzki T (2006)

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Daily and infradian rhythms of circumnutation intensity in Helianthus annuus. Physiologia Plantarum 119: 582-589 11

Buda A, Zawadzki T, Krupa M, Stolarz M, Okulski W (2003)

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