and also viscosity of cytoplasm. At drought-resistant plants these indicators will be higher. In selection work use such indicator as the content of statolitny starch in a chekhlik. Genetically caused sign of a of plants is ability of their vegetative bodies (especially leaves to accumulate proline during a drought. Thus concentration of proline increases by 10 — 100 times. In proline a significant amount of nitrogen which for the subsequent metabolic reactions on a drought stocks up.
Gemikserofita, or polukserofita — it plants which are incapable to transfer dehydration and an overheat. Viscosity and an of a protoplast at them insignificant, differs in a high transpiration, deep root system which can subsoil water that provides uninterrupted supply
Plants of droughty areas are called as kserofita (from the Greek xeros — dry). They are capable to adapt in the course of development to an atmospheric and soil drought. Characteristic signs of kserofit — the insignificant sizes of their evaporating surface, and also the small sizes of elevated part in comparison with underground. Kserofita — it usually herbs or undersized bushes. They are divided into some types. We give classification of kserofit by P. A. Genkel.
The is influenced by fertilizers: the potash and phosphoric it, nitric, especially in high doses — reduce. The of a number of crops is raised by (zinc, copper, etc.). Resistance to a drought in field conditions is promoted by cultivation agricultural with observance of zone technologies of their cultivation.
Spraying of plants in a drought auxin, tsitoki-niny or gibberelliny strengthens negative effect of water deficiency on a plant. Processing tsitokininy in reparations after a drought restores functions of plants.
At ABK drought development, activating proline synthesis, to storage of hydrate water in a cage, slows down synthesis of RNA and proteins, collecting in roots, synthesis detains tsitokini-on, promotes transfer of a metabolism of cages to the rest mode. In the conditions of water deficiency are noted increase
Drought resistance is defined by ability of a vegetable organism as little as possible to change processes of an exchange of in the conditions of insufficient water supply. At more plants at the accruing dehydration synthetic processes remain more long, are not damaged or membrane systems of cages, their normal homeostasis are less damaged, normal fiyoziko-chemical properties of protoplasm (viscosity, elasticity, permeability) remain; the kseromorfizm is more expressed.
I. V. Michurin, trying to receive drought-resistant grades, grew up plants in the conditions of an insufficient. The plants which transferred a small drought repeatedly maintain it with smaller losses, become more to dehydration.
Drought-resistant types and plant varieties are capable without to lose harm part of the water and even during the periods of the greatest dryness not to close the ustyitsa and to continue photosynthesis. Therefore at a number of cultures, including at wheat, one of important signs of drought resistance is the daily course of ustyichny movements. N. A. Maximov noted that steady wheat in the conditions of droughty climate of the Rostov holds the ustiyets opened throughout the day whereas less steady Canadian wheat closes them early in the morning, and therefore early stops photosynthesis and yields a harvest. Distinctions in drought resistance between separate grades and cultures are defined also by development of root system, existence of water-supplies in stalks or roots, and character of a sheet surface, etc.
Stipakserofshpa — it is a feather grass, a tyrs and other narrow-leaved steppe cereals. They are steady against an overheat, well use a of an intermittent rain. Maintain only short-term shortage of water in the soil.
Succulents — very resistant to an overheat and steady against an, during a drought they do not lack for water because contain a large number it and slowly spend. The root system at them is branched out extensively in the top layers of earth thanks to what during the rainy periods of a plant quickly water. These are cactuses, an aloe, a sedum, threshed.