The aim of our work was to prove that the uptake of the heavy metals – e.g. manganese – by plants can be reduced with the use of bacteria fertilisers.

The plants were grown on nutrient solution in climate chamber. The environmental circumstances were controlled. The experimental plant was maize (Zea mays L. cv. DKC5170). The composition of applied bacteria containing fertilisers were the following: (“P”): Azotobacter chrococcum and Bacillus megaterium; („B”): Azospirillum brasilense, Azotobacter vinelandii, Bacillus megaterium, Bacillus polymyxa, Pseudomonas fluorescens, Streptomyces albus; („M”): Azotobacter chroccoccum, Azospirillum ssp., Bacillus megaterium, Bacillus subtilis.

Manganese was applied in the form of Mn(NO3)2 in the following concentrations: 25 mg kg-1, 50 mg kg-1, 100 mg kg-1 and 200 mg kg-1.

According to the literature data the toxic Mn concentration for maize is 200 mg kg-1. However, we found that the 50 mg kg-1 Mn concentration was also toxic in our experiment. Positive results were gotten in many cases when 25 mg kg-1, 50 mg kg-1 and 100 mg kg-1 Mn were applied with the different bacteria fertilisers. The dry weight of shoot and root of maize increased at the 25 and 50 mg kg-1 Mn and bacteria fertiliser treatments. The dry weight of shoot increased when “P” bacteria fertiliser was applied at the 100 mg kg-1 Mn treatment. The dry weight of roots increased when “B” bacteria fertiliser was added to the 100 mg kg-1 Mn treatments. The “B” and “M” bacteria fertilisers could be compensated the negative effect of 200 mg kg-1 Mn treatment.

According to our results, the 50, 100 and 200 mg kg-1 Mn concentrations were toxic for maize. In the light of the obtained result, the bacteria fertilisers could compensate for the negative effect of Mn toxicity. This effect depends on Mn concentration – such as stress – and the applied bacteria species.

Keywords: bacteria, chlorophyll, dry weight, manganese toxicity, maize