you are: Protection of plants
Structural adaptations for a survival in extreme conditions sometimes are available for plants throughout all their life, and sometimes arise only at any certain stage of development, providing with that to a plant possibility to overcome an adverse part of life cycle. appointment of the main protective adaptations consists century volume to limit water loss because its plant usually most of all does not suffice. Leaves can be covered by a thick layer voskoobraznoj kutikuly, playing a role of a water-proof barrier, and their dense opushenie and shipped ustitsa keep at a surface of sheet a layer of damp air that also reduces intensity transpiratsii (see gl. 6). At some kinds leaves very small or they absolutely are not present, i.e. At them the surface area from which there is an evaporation is limited. Often plants have juicy leaves and stalks as in them water-supplies remain. This last feature can be met not only at desert plants, but also at mnogoletnikov the Arctic and Alpine zones. it Speaks that water in soil here often happens frozen in that time when the shining sun causes intensive transpiratsiju. For vegetation of such places it is characteristic also karlikovost: plants as though nestle on the earth, weakening thereby drying up and cooling action of a wind. To inhabitants of northern areas are familiar in reference weather forecasts on ' cooling action of a wind '; promoting water evaporation, a wind the ambient temperature so the organism can suffer from a cold, even if temperature of air above the level which is for it critical cools evaporating surface therefore its temperature appears more low, than.
The Person aspires somehow to help to overcome to plants difficult time for them. For this purpose build, for example, hothouses. In them solar heat, and in the winter their closed space is caught it is possible to heat. In the summer, the truth, too a shining sun causes sometimes an overheat; therefore hothouses often paint in white colour to lower superfluous absorption of energy. coolings can be reached also, continuously passing through a hothouse a stream of air which has passed over humidifiers. (In an arid climate where evaporation occurs easily, the absorption of energy connected with transition of water from liquid in a gaseous phase, causes considerable cooling of air.) In areas with a frigid climate reliable enough protection against a cold is provided to plants with a snow cover. Bushes sensitive to a cold manage to be protected to some extent, closing them, for example, a sacking; it, of course, does not rescue from too low temperatures, but helps to save bushes from cooling action of a wind, i.e. Nevertheless represents some additional measure of protection. Orange and peach trees which badly transfer a cold, it is possible to protect from damaging action of negative temperatures with the help ' wind cars ' - the huge propellers established on towers. These propellers drive warmer air of the top layers that the temperature of leaves has not fallen below zero as a result of heat radiation to the earth. It is possible to light also in gardens small fires from the fulfilled oil or various dust; It allows to raise temperature of air on some degrees and such way to reduce heat losses by radiation, considerable enough at the clear sky. In the big scales similar procedures become, obviously, already impractical. The farmer, however, can count on more good harvest, shifting crops terms so that to occurrence of shoots last possible frosts already passed. Selectors have created much holodostojkih the grades, giving the chance to make crops in earlier terms and to prolong the vegetative period (we still will speak about these grades more low).