the Role of the photoperiod and temperature in growth regulation. Tsirkadnye rhythms

you are: the Role of the photoperiod and temperature in growth regulation

About any events occurring to correct periodicity in time or space, say that it svojstven a rhythm. When periodicity remains and for lack of external influences, a rhythm name endogennym. As an example can serve ' sleepy ' movements of some plants, especially from family bean (Phaseolus, Mimosa, Albizzia, Sa-manea, etc.). Leaves of these plants usually happen are located horizontally, and at night - vertically (niktinastija) in the afternoon. Such movements are easy for observing, having connected sheet a thin thread with pischikom kimografa). Records show that leaves start to reveal before the light period, and to develop - before dark. thus, movements of leaves, apparently, are made as though in a prediction of a dawn and twilight that specifies in action of any other factors besides light and darkness.

The Data about existence ' an inner clock ' has been received in experiences in which some days held sheet in the dark at constant temperature. It has appeared that thus rhythmic movements proceed with the period nearby 23 ch.

Such rhythms with the periods 20-30 ch (i.e. About one days) have received the name tsirkadnyh, from Latin words circa - nearby and dies - day. The cellular mechanism generating a rhythm, usually name internal clocks; position of sheet at any moment of a cycle shows ' tsirkadnoe time ' (time supervised internal ostsilljatorom). As movements of leaves at such plants serve as exact enough indicators tsirkadnogo to time, them sometimes name ' arrows of internal clocks '.

Tsirkadnye of fluctuation of this type meet in essence at all eukarioticheskih organisms, including microorganisms, plants and animals.

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