Transpiratsija. The external factors regulating movements ustits

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When the plant lacks the waters closing cages ustits become languid and ustichnye cracks are closed that prevents the further loss of water. Until recently in it saw the main mechanism allowing a plant to avoid excessively strong zavjadanija. It was found out, however, that plants have other, faster and more effective way to suppress transpiratsiju. At early stages of water deficiency at many plants the maintenance of one of hormones, namely abstsizovoj acids (ABK) sharply raises (see gl. 10). Any way it leads to outflow To + from closing cages and as consequence to loss of water and closing ustits. The graceful experiences showing this effect, have been spent with so-called zavjadajushchim (willty) mutaltom a tomato, received casually in experiments with a x-ray irradiation of seeds of one of usual grades. This mutant differs that it quickly zavjadaet even at the smallest lack of water because ustitsa at it are always open. It was found out that at this mutant maintenance ABK, it in 10 times more low, than at a parental grade is sharply lowered. When mutant plants have processed ABK, them ustitsa began to be closed and tourist's mountains was restored faster. Obviously, at this grade of a tomato closing ustits is regulated or most abstsizovoj by acid, or any product of its metabolic transformations. It was found out later that processing by small doses ABK can cause closing ustits and in other plants. It was revealed also that at a water lack the maintenance endogennoj ABK after what ustitsa are closed raises. Thus, one of the important physiological functions of hormone ABK is, apparently protection of plants from issushenija. About other reguljatornyh functions of this hormone it is told in gl. 10.

Considering value of opening and closing ustits in a plant life, it is not necessary to be surprised to that movements ustits are regulated not only water supply of plants, but also and some other factors of an environment. At many plants, for example, opening ustits depends first of all on maintenance СО2 in air filling podustichnuju an air cavity. If concentration СО2 falls there below 0,03%, i.e. Below level, normal for atmospheric air tourist's mountains of closing cages increases and ustitsa open. Usually in such result results the illumination of closing cages stimulating in them photosynthetic activity owing to which maintenance СО2 in the adjacent cavities filled with air decreases. Opening ustits can be caused also it is artificial, deleting СО2 from air, and closing - increase of concentration СО2 in air. This regulation ustichnyh movements СО2 allows to understand, why ustitsa are usually opened in the afternoon and closed at night.

ustits under the influence of light it is possible to explain Opening partially to that owing to photosynthesis concentration СО2 in sheet decreases. However light renders also other, more direct action. Protolayers of closing cages of onions which do not contain hloroplastov, at illumination by dark blue light bulk up, but this effect is shown only in the event that at the environment there are salts kalija. A pigment absorbing dark blue light which stimulates inflow of ions To + and increase tourist's-mountain, - it, apparently, flavoproteid, described in gl. 11.

Usually intensity transpiratsii definitely changes throughout day. At first at a dawn it sharply enough increases and, continuing to increase, reaches a maximum by noon. After that, if the temperature is too high, there comes some recession which the small lifting corresponding to decrease of temperature follows. Intensity fluctuations transpiratsii reflect changes in a condition ustichnyh cracks. Closing ustits during midday time partially speaks, high concentration СО2 in sheet that is characteristic for this time of days. Level СО2 in sheet depends on a parity okorostej breath and photosynthesis, and. Speed of breath with rise in temperature grows quickly enough while photosynthesis process is less sensitive to temperature. In addition to it, to closing ustits at midday o'clock promotes, possibly, and that at this time in connection with a lack of water of sheet concentration abstsizovoj acids increases.

So, we were convinced that ustichnye movements are regulated by environment major factors: light, in temperature, moisture content in soil, humidity of air and concentration СО2 in air; all these variables influence such internal factors, as the maintenance of water and concentration abstsizovoj acids in sheet. Besides, rhythmic fluctuations otverstosti ustits, made even for lack of external influences take place also. These rhythmic fluctuations are regulated internal ostsilljatorom - plant internal clocks about which we will speak in gl. 12. The Fig. 6.15 illustrates a daily course ustichnyh the movements, regulated by internal rhythms and external factors together.