Abstract
Impact of growth promoting rhizobacterium Pseudomonas fluorescens 20 on the yield of spring wheat was studied in pot experiment. Plants were grown up to maturity when agrogray soil was contaminated with Ni as NiCl2·6H2O at a rate of 200 mg Ni/kg of soil against background of applying NPK fertilizers. After harvesting, content of nutrients N, P, K, Ca, Mg, Fe, Mn, Zn and Cu in grain, straw and roots was determined. N was determined by phenol technique. Resistance of plants to Ni toxicity was found under bacterial inoculation. Application of bacterium eliminated phytotoxicity of heavy metal and provided the same biomass production including grain as in control - in non-inoculated plants non-exposed Ni stress. Resistance of plants inoculated with bacterium to Ni toxicity was due to enhanced growth of root system and increase in content and accumulation of Ni in roots and, as a result this was not accompanied by increase in metal incorporation into aboveground organs. Resistance of plants inoculated with bacterium to Ni toxicity was due to enhanced growth of root system and increase in content and accumulation of Ni in roots. Application of bacterium also improved mineral nutrition of plants - increased nutrient uptake from contaminated soil. Increase in nutrient uptake by yield from contaminated soil as influenced by inoculation with bacterium was due to growth promotion and increase of plant weight in general without significant changes in content of most elements in aboveground organs and roots. Bacterium enhanced phytoextraction of heavy metal (soil cleaning) - increased Ni uptake by aboveground organs without significant changes in its content in grain and straw. Increase in Ni uptake by bacterially inoculated plants occurred without changes of soil medium reaction and was probably due to production of bacterial siderophores.
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