QUANTITATIVE RELATIONSHIPS BETWEEN DRY MATTER PRODUCTION AND N, P, K AND MG CONTENTS, AND PLANT NUTRITION INDICES, DEPENDING ON MAIZE HYBRIDS (ZEA MAYS L.)

The paper presents results of field experiments which purpose was to evaluate the possibility of accumulation of nitrogen, phosphorus, potassium and magnesium in the dry matter of plants throughout the growing season of two different maize varieties: SE Palazzo and ES Paroli SG. Starting from the 32nd day after the date of sowing, on ten dates, at 14-day intervals, the content of various macro-elements in the whole plant dry matter and its organs was estimated. Critical nitrogen, phosphorus, potassium and magnesium contents in the whole plant dry matter were also indicated, and the nitrogen (N-NI), phosphorus (P-NI), potassium (K-NI) and magnesium (Mg-NI) nutrition indices were calculated. It was found that as vegetation progressed, the contents of nitrogen, phosphorus, potassium and magnesium in the dry matter of the whole plant and its organs were significantly reduced. ES Paroli SG variety was characterized by a higher content of the above-mentioned components, compared to SE Palazzo. Generally, the nutrition index was more favourable (closer to 1) for the function that best approximated the actual data.