PROTECTIVE EFFECT OF ENDOPHYTIC MICROORGANISMS ON THE GROWTH AND DEVELOPMENT OF AGRICULTURAL CROPS UNDER DROUGHT CONDITIONS

Abstract

Drought is one of the abiotic stress factors that significantly affects plant viability and productivity. Water deficiency leads to disruption of electron transport processes in mitochondria and chloroplasts, resulting in excessive generation of reactive oxygen species and the development of oxidative stress. Oxidative stress causes changes in plants at the molecular, biochemical, and physiological levels. One of the main challenges of agriculture in Kazakhstan is the shortage of water resources. A significant portion of pasture lands across the country is either unused or has undergone soil degradation, while agricultural productivity in arid regions remains low. Currently, one of the widely applied approaches to mitigate the negative impact of abiotic factors, including drought, is the method known as “priming.” This approach involves the treatment of seeds, seedlings, or young plants with biological agents that enhance their mineral nutrition and adaptive capacity. In this context, microorganisms capable of increasing drought tolerance are of particular interest for agricultural crops, as they strengthen plants’ ability to withstand stress factors and contribute to maintaining yield. The article presents data on the selection of microbial strains isolated from medicinal plants that stimulate plant growth. As a result of the screening, 67 isolates were obtained from three medicinal plants, among which three strains exhibiting the highest activity and possessing multiple valuable traits were selected. The selected endophytic microorganisms had a positive effect on plant physiological processes (morphometric parameters and photosynthesis), and also promoted a reduction in free proline content, thereby contributing to the structuring of water within cells and reducing plant turgor pressure. Keywords: abiotic stress, microorganisms, priming, agricultural crops, plant growth-promoting activity.