Differences in the Accumulation and Redistribution of Dry Matter and Nmin Content in the Cultivation of two Different Maize (Zea mays L.) Cultivars for Grain
Piotr Szulc
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Department of Agronomy, Poznań University of Life Sciences,
Mazowiecka 45/46, 60-623 Poznań, Poland
Pol. J. Environ. Stud. 2012;21(4):1039–1046
A field experiment was carried out in the Department of Agronomy of Poznań University of Life Sciences on the fields of the Research and Education Unit in Swadzim in 2009-10. Two different genotypes of maize cultivated for grain that exhibited different aging rates were compared: ES Palazzo and ES Paroli “stay-green”-type cultivar. The dynamics of dry matter accumulation were assessed 10 times every 14 days. We found that together with the progress of vegetation, the “stay-green” hybrid accumulated a significantly greater amount of dry matter in comparison with the traditional cultivar. During the generative development, the differences in production of dry matter of a single plant between the examined cultivar types were even significantly greater. The absolute growth rate (AGR) of dry matter of a single plant, leaf blades, and grain was higher for the “stay-green” hybrid when compared to the other examined cultivar. In order to assess the amount of soil mineral nitrogen remaining after plant harvesting in the autumn, the Nmin method was used in the present research. The soil mineral nitrogen content (N-NH4+N-NO3) after harvesting of ES Palazzo cultivar was significantly higher in comparison with the ES Paroli “stay-green” cultivar. A higher content of both mineral nitrogen forms after plant harvesting was observed in the 0-30 cm soil layer than in the 31-60 cm soil layer, irrespective of the type of maize hybrid. The content of nitrate nitrogen N-NO3 in the total amount of Nmin in the 0-30 cm soil layer amounted to 79.6%, while at a depth of 31-60 cm it amounted to 81.2%. The examined cultivars affected the content of potassium and magnesium in soil after harvesting. However, no significant influence of maize hybrid type on the content of phosphorus and soil pH was found. A significantly lower amount of magnesium and potassium in soil after harvesting the “stay-green” cultivar when compared to the traditional cultivar proves that the main source of accumulation of these macroelements in the stage of generative growth are soil resources. This results from demand for these elements in the stage of maximum increase in biomass of generative yield. Such behavior of “stay-green”-type plants should imply a fertilization system with slow-acting fertilizers. Lack of magnesium and potassium in soil in the period of maturation of “stay-green”-type maize may be a classical example of the law of the minimum.