Field experiment was carried out on the Didactic and Experimental Farm in Swadzim (52°26’ N; 16°45’ E) near Poznań, in the years 2004-2007. The three-factorial experiment was established in “split-plot” design with 4 replications. The reaction of two maize hybrid types on the application of 6 nitrogen doses and magnesium fertilization was studied. The influence of the studied factors on the content of chloroplast pigments in maize leaf blades in the phase of ear blooming (BBCH 67) was estimated. A greater content of chlorophyll a and a + b expressed in SPAD units was found in maize leaf blades of the stay-green type, as compared with leaf blades of the conventional Anjou 258 hybrid. Concentration of chlorophyll a and a + b was increasing in a linear way in the nitrogen range from 0 to 120 kg N·ha^-1, while the amount of chlorophyll expressed in SPAD units ranged from 0 to 150 kg N·ha-1. The stay-green type hybrid showed to be better nourished with nitrogen, on the basis of chlorophyll content in maize leaf blades, in the phase of ear blooming (BBCH 67), in comparison with the conventional hybrid and, at the same time, a lower nitrogen fertilization was needed. A simultaneous fertilization with magnesium increased the content of chloroplast pigments, in comparison with the application of nitrogen only. With the increase in the assimilation area of a single maize plant and of a maize stand (LAI indicator), the chlorophyll concentration in leaf blades was decreasing in a linear way.

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