Testing Rhizobia for Natural and Anthropogenic Saline Soils and Subsoils

Abstract

The area of naturally saline lands in Russia is approximately 30 million hectares. Currently, the growth of anthropogenic saline areas is associated with the extraction of minerals (agricultural ore) and the formation of drilling pits when drilling wells for the exploration and extraction of hydrocarbons. The number of drilling pits with high salt content in the Khanty-Mansi Autonomous Okrug is about 3 thousand. About the same number of them is found in the Yamalo-Nenets Autonomous Okrug. In the south of the Tyumen region, their number is increasing in the Uvat district. Reclamation of these areas includes the technical and biological phases of reclamation. The biological stage involves the use of phytomeliorant crops. Inclusion of the legume component in phytomeliorants implies its joint use with a preparation of active strain of nodule bacteria. The aim of the research was to identify the most salt-tolerant strain of lupine nodule bacteria under different chemistry and degree of salinity of the environment. In order to test lupine rhizobia for salt tolerance and salinity chemistry, laboratory experiments were set up in petri dishes. Lupine rhizobia strains 363a, 367a, and 375a were taken directly from the rhizotorphin preparations, and the degree of dilution was brought to a certain titer corresponding to about 80 colonies per Petri dish. The presented results of the experiments showed that the colonies of lupine rhizobia react extremely negatively to the concentration of salts in the nutrient medium of 0.3% or higher. This is true for both neutral and sodium salinity. Out of the three strains of rhizobia studied, sample 367a was the most salt tolerant. Strains 363a and 375a were less resistant to salinization. For the first time, strains of lupine rhizobia were tested for salt tolerance in relation to different chemistry and degree of salinity identical to anthropogenic soils and saline soils.