Response of nitrogen nutritional indices of maize leaves to different mineral-organic fertilization


Maize crop growth rate during the course of vegetation is strongly dependent on nitrogen supply. The most critical stages of maize response to this nutrient are exhibited both in very early growth stages, as related to the stage from five (six) to eight leaves, and in the period from tasselling to the blister stage. Among many indicators of plant nitrogen nutritional status, the most promising include nitrate reductase and acid invertase activity, since the enzymes significantly affect the growth of new tissues. Two series of field experiments were conducted in 2009 and 2010 to evaluate the effect of six fertilization treatments, differing in the prevailing source of nitrogen (from pure mineral to classical organic), on nitrate concentration, nitrate reductase and acid invertase activity and finally on the assimilation area of a single maize plant or the ear leaf. A significant effect of each fertilization treatment on all the examined maize plant characteristics was observed, but it was mostly seasonally variable. Nitrate reductase was linearly affected by the nitrate concentration in maize leaves. Both evaluated indices of acid invertase showed a curvilinear effect on the maize plant morphological characteristics. Therefore it can be concluded that excessive acid invertase activity may inhibit the growth rate of the maize assimilation area in the flowering stage.


assimilation area; maize; nitrogen; organic fertilizers

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