RESPONSE OF POTATO TO SOIL CONTAMINATION WITH MERCURY NEUTRALISED WITH SOIL IMPROVING SUBSTANCES

Holding in mind the negative effect of mercury on environment, an experiment has been conducted in order to determine the influence of this metal on yield and chemical composition of potato grown on soil treated with various neutralizing substances. The study consisted of a pot experiment, carried out in Kick-Brauckmann pots filled with 9 kg soil each. The soil material was subjected to simulated contamination with mercury sulphate added in the following doses: 0, 50, 100 and 150 mg Hg kg(-1). Another experimental factor comprised application of several inactivating substances, such as zeolite, lime and bentonite. Zeolite and bentonite were added in the amounts equal 3 % of the whole soil mass in a pot whereas the dose of lime corresponded to 1 Hh of soil. All the pots received identical NPK fertilization. Edible potato of a moderately early, 'Zebra' cultivar, was the test plant. Increasing soil contamination with mercury depressed the yield of tubers and mass of potato herbage. The largest yield decline was observed in the trials subjected to the most severe mercury contamination. As for potato tubers, a decline in their yield reached 63 % in the series with lime down to 31 % in the series with zeolite. The maximum potato herbage loss under the effect of mercury pollution was 48 % in the series with zeolite down to 23 % in the series with lime. Moreover presence of mercury in soil also affected the chemical composition of potato. Increasing rates of mercury in soil caused a rather regular depression in the content of potassium in potato tubers and herbage.