Evaluation of the Effect of Conventional and Stabilized Nitrogen Fertilizers on the Nutritional Status of Several Maize Cultivars (<i>Zea mays</i> L.) in Critical Growth Stages Using Plant Analysis

The study presents the results of a three year field trial aimed at assessing the nutritional status of maize in critical growth stages by means of a plant analysis in the cultivation of three maize cultivars differing in their agronomic and genetic profile. The main research problem was to demonstrate whether the availability of nitrogen from stabilized fertilizers for “stay-green” maize varieties is consistent with the dynamics of the demand for this component. This is very important from both the economic and agronomic aspect of maize cultivation. The research showed a significant response of the maize cultivars to different nitrogen fertilizer formulations, which was observed in the period from the five-leaf stage to the full flowering stage. The advantage of the fertilizer, UltraGran stabilo, over other nitrogen fertilizers in the BBCH 15 stage was demonstrated only for the cultivar, ES Metronom, which produced a greater aerial mass while maintaining the nitrogen concentration at the level of the other two maize cultivars. The nitrogen and potassium content shaped the kernel weight in the ear in the flowering stage, confirming the importance of the interaction of these two elements in forming this feature of maize as the main predictor of the grain yield. This trait (expressed by the R² coefficient) manifested each year of the study, but especially in the years with optimal weather patterns (i.e., the first year). The response of the maize cultivars to nitrogen fertilizers, especially the cultivar, ES Metronom, was manifested by an increase in the content of nutrients and chlorophyll in the ear leaf, that is considered a predictive organ for grain yield. The fertilizers, Super N-46 and UltraGran stabilo, had a positive effect on the chlorophyll content (CCI parameter) and increased its efficiency of excitation energy transfer (the F0 parameter).