The effect of fertilisation with different amounts of nitrogen and the application of endomycorrhizae in planting on the yield and quality of tobacco were investigated in the experimental field of the Faculty of Agriculture in Zagreb. Studies were performed in two field experiments with four treatments.

In the first experiment 20, 40 and 60 kg of calcium ammonium nitrate were used beside a non-fertilised variety. Fertilisation with phosphorus and potassium was uniform for all treatments and amounted to 60 kg P₂O₅ and 160 kg K₂O.

In the second experiment beside the same nitrogen fertilisation (0, 20, 40, 60 kg NH₄NO₃ ha^-1) tobacco seedlings were treated with special vaccine MYKOFLOR^® (mycorrhizal mycelia). Tobacco was harvested manually, topped at the beginning of flowering and harvested six times. The content of nicotine and sugar was determined in samples taken from the third harvest. The results obtained were processed by analysis of variance.

Tobacco treated with MYKOFLOR^® had significantly higher yield and better quality. In 2015, a dry year, tobacco treated with MYKOFLOR^® had stronger developed root system and a greater possibility of taking up water and dissolved macro and micro elements from the soil.

Untreated tobacco had 25-50% lower yield and lower quality of the dried leaf depending on the level of nitrogen fertilisation. In the very arid year of 2015, higher nitrogen fertilisation of tobacco without the application of mycorrhiza increased the nicotine content and reduced sugar content, which greatly affected the quality of flue-cured tobacco.