ADAPTIVE REACTIONS TO ECOLOGICAL STRESS OF PASTURE FODDER CROPS

Abstract

The adaptation of pasture forage grasses to unfavorable factors expressed in the transition of the main defense reactions to a less intensive level was studied. The regularity of the resistance variation to different plants groups across ecological-geographical origin to the main widespread stress factors was determined. Biochemical changes occur in plants due to various impacts of different extreme factors, and these changes are aimed at prolonging the effect of these factors through adaptation. In the continental climate conditions the upper layer of the soil dries up at low temperatures in winter, while in the spring and summer the soil and vegetation cover is destroyed, and the plants die thanks to dry winds and high temperatures along with a strong summer insolation. Some plant species are resistant and survive through the adaptation which allow them to avoid negative effects (resist state, ephemera, etc.), and also survive due to physiological properties that allow them to overcome the harmful effects of the environment. Annual plants concluding their ontogeny under relatively favorable conditions hibernate in the form of resistant seeds; many perennial plants - due to rhizomes. Structural adaptations to protect against stress include shallow leaf, thick pubescence and others. Many plants solve the problem of moisture deficiency by developing deep root system (Limonium, Vitex, Krascheninnikovia ceratoides, Salsola orientalis, Artemisia, and others). As a result of the research fodder plants species with a large adaptive potential to the stress, ecological and soil conditions of the semi-desert were identified. Based on phytocenotic indices and phytocoenoses productivity value it can be concluded that the vegetation cover is at the stage of ecological stress as indicated by the decrease in the share of valuable cereal forage crops in the structure of cenoses and the increase in forb abundance.