Biodynamic (BD) preparations 500 and 501 are plant strengthening agents of the biodynamic agriculture method, prepared from cow manure and powdered quartz. The resulting products are highly diluted and sprayed on soil and plants. The main purpose of these preparations is to promote the processes of energy and nutrient cycling as well as to improve plant and soil quality parameters. This study was carried out in 2013-2014, in order to evaluate the influence of biodynamic preparations 500 and 501 on the chemical composition of potato tubers: amounts of dry matter, starch and mineral elements (potassium, magnesium, phosphorus and nitrogen). The experiment included two factors: I – three coloured potato (Solanum tuberosum L) cultivars (Vitelotte, Blue Congo - purple flesh and Red Emmalie - red flesh), II – treatment with BD preparations as field sprays (four treatments: 1. Control sample (without BD preparations); 2. BD preparation 500; 3. BD preparation 501; 4. A blend of two preparations (BD preparation 500 and BD preparation 501). The research revealed that BD preparations 500 and 501 had no significant effect on the content of dry matter and mineral element in coloured potato tubers in any of the experimental variants. However, BP preparation 501, as well as a combination of both 500 and 501 BP preparations, increased the starch content in potato tubers significantly (p

21.3.2016