Water - the main component of active vegetative cages; the pas its share is necessary sometimes 90% of crude weight and more. Absolutely business in based seeds differently is: in them water can make only 15-20% of gross weight. In mature vegetative cages the water most part contains in large central vakuoli, occupying 80-90% of all volume of a cage. in turgestsentnyh cages central vakuol densely presses cytoplasm to a cellular wall, thereby promoting maintenance of the form of a cage in soft bodies of a plant, for example in leaves. The characteristic form of grassy plants depends, hence, and on hydrostatic forces. At a lack of a moisture water from vakuolej is delayed that the tourist's mountain, and then and to withering leads at first to loss. Usually plants easily recover (if zavjadanie was not too strong) as soon as they will receive again water; cages absorb water, and tourist's mountains is restored.

However, that the cage kept appropriate viability, moisture content in its protolayer should not leave for certain, rigid enough limits. Though the quantity of dropping out deposits and humidity of soil strongly fluctuate, the green plant manages to support the ovodnennost at rather constant level. it is reached thanks to reduction of losses on evaporation when waters do not suffice. Plants continuously absorb water from environment and a part of this water evaporate. transpiratsija - water evaporation by elevated bodies of a plant - is an inevitable consequence of the structure of sheet. The sheet intended for effective photosynthesis is the usually large, flat body sated with a moisture penetrated by set of a time, air courses informed with a branched out network. On the sun such body inevitably loses a lot of water. Water evaporates from a surface of damp cages mezofilla, diffundiruet on mezhkletnikam and comes to light through opened ustitsa. Closing ustits at a water lack can reduce requirement of a green plant for water, and is very strong - to a small share from the requirement peculiar to it when ustitsa are opened. however closing ustits involves also undesirable consequences: gas exchange between atmosphere and internal space of sheet that reduces efficiency of photosynthesis is broken. In this chapter we learn, how it is possible to a plant to combine necessity for savings of water with other requirements, i.e. We will discuss, as it is supported ' a water management ' plants.

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