Mineral nutrition of plants in applying growth-promoting rhizospherebacteriain copper-contaminated soil

Impact of growth-promoting rhizobacteria of genus Pseudomonas application on mineral nutrition of spring wheat in growing on artificially Cu-contaminated in elevated concentration agrogray soil were studied in pot experiment. Plants were grown up to shooting stage with copper nitrate contamination at a rate of 300 mg Cu/kg of soil against background of PK fertilization. Content of Cu and other elements in shoots and roots after combustion in mixture of HNO₃: HClO₄ (2:1) was determined by inductively coupled plasma emission-optical spectrometry, potassium by flame photometry. N content was determined by indophenol technique after combustion of plant material in dilute sulfuric acid with catalyst. Bacteria application increased plant resistance to elevated copper concentration and increased plant weight, thereby reducing phytotoxicity of heavy metal. Positive effect of bacteria was due to improvement in mineral nutrition of plants – increase in uptake of biophilic elements N, P, K, Ca, Mg, Fe, Mn and Zn from contaminated soil. At the same time, bacteria as a whole did not affect content of almost all elements in plant shoots and increased uptake of elements by plants due to the promotion of their growth, probably as a result of production of physiologically active compounds by bacteria. Growth promotion of heavy metal-contaminated plants and elevated it uptake by plants in application of bacteria occurred without changes in soil medium reaction. Improving mineral nutrition of plants, along with increasing barrier ability of root system to increase of heavy metal uptake by roots in application of all bacteria, are main mechanisms for growth promoting contaminated plants.