The effect of soil salinization on the composition and abundance of microbial communities in the rhizosphere soil of cotton

Аннотация

This paper presents the results of a comparative analysis of the microbial communities of the rhizosphere soil of cotton grown on saline (Kashkadarya region) and non-saline (Tashkent region) soils. It was found that salinization significantly reduces the species diversity of microorganisms, especially among bacteria and micromycetes. Microorganisms resistant to salt stress, in particular representatives of the genus Bacillus, dominated on saline soil, while beneficial and metabolically active genera such as Pseudomonas, Trichoderma and Azotobacter prevailed on non-saline soil. Differences in the number of ammonifiers, phosphorus-mobilizing bacteria, actinomycetes and other physiological groups of microorganisms were revealed. The data obtained The American Journal of Agriculture and Biomedical 22 https://www.theamericanjournals.com/index.php/tajabe Engineering The American Journal of Agriculture and Biomedical Engineering emphasize the significant impact of salinization on the microbiomes in different environmental and soil structure of microbial communities, which is important conditions, plants are able to form the so-called “core” for the development of adaptive microbial microbiome, consisting of symbiotic microorganisms technologies aimed at restoring soil fertility and that are adapted to rhizosphere conditions and have increasing the sustainability of agroecosystems under specific trophic preferences [13]. Moreover, it is saline conditions. suggested that these key taxa undergo a process of co- adaptation with host plants, ensuring efficient colonization of the rhizosphere by certain plant species Keywords: Rhizosphere, cotton, microbial or genotypes [14]. communities, microbiome, soil salinization, In this regard, the aim of the study was to identify the biodiversity, phosphorus-mobilizing bacteria, quantitative and qualitative characteristics of the actinomycetes, fungi, sustainability of microbial communities of the rhizosphere soil of cotton agroecosystems. grown on saline and non-saline soils, as well as to assess the effect of salinity on the composition, number and Introduction: Soil microbial communities play a key diversity of physiological and taxonomic groups of role in the formation and functioning of the microorganisms. rhizosphere zone. The rhizosphere is a narrow zone of METHODS soil adjacent to the root system of plants, which Soil samples were collected in the flowering and fruiting contains many microorganisms that actively interact phases of cotton in triplicate from two regions of with both the plant and the environment. This area is Uzbekistan (Kashkadarya and Tashkent regions). Soil considered one of the most dynamic and complex was collected from the rhizosphere of cotton by interfaces in terrestrial ecosystems [1, 2]. Systematic carefully removing plants and extracting the soil study of these communities is a promising approach to attached to the roots. Agrochemical parameters of the ensuring the sustainability and biological well-being of soil: Kashkadarya region (saline soil): pH 7.95; nitrogen - soil ecosystems [3, 4]. At the same time, the number 0.043%; phosphorus - 0.16%; potassium - 0.55%; and structure of microbiota are influenced by many organic matter - 0.22%; total salts - 1.72%; electrical factors, among which an important place is occupied conductivity - 3.79 EC/m; Tashkent region (non-saline by both biotic and abiotic components of the soil): pH 7.69; nitrogen - 0.039%; phosphorus - 0.14%; environment [2, 5]. These factors have a high degree potassium - 0.89%; organic matter - 0.35%; total salts – of variability and often have a combined, interrelated 0.08%; electrical conductivity – 0.18 EU/m. effect on the microbial population of the soil [6]. The physiological groups of microorganisms were Soil salinization is one of the most significant abiotic seeded using the deep method from various dilutions of stress factors that has a negative impact on the the soil suspension on the following nutrient media: stability of agricultural production. It leads to changes meat-peptone agar (MPA) for ammonifying bacteria, in the physicochemical characteristics of the soil Czapek medium for growing micromycetes, Pikovskaya environment, contributes to a decrease in microbial medium for phosphorus-mobilizing microorganisms, diversity and generally worsens the condition of the Eshby medium for oligonitrophilic microorganisms, soil, limiting its biological productivity [7, 8]. It is known starch-ammonia agar (SAA) for actinomycetes, that bacteria living in the rhizosphere, a narrow zone Getchenson medium for cellulose-decomposing of soil adjacent to plant roots, play an important role microorganisms, and soil agar medium for humus- in stimulating plant growth and increasing their decomposing microorganisms. The crops were placed in resistance to stress conditions [9]. Plant-associated a thermostat at a temperature of 28 °C. Micromycetes microbiomes are increasingly recognized as cr