Agronomic, physiological, and yield responses of Peruvian maize races under Mediterranean conditions: genotypic variation and effects of nitrogen fertilizer type

The production of maize (Zea mays L.) in southern Europe is constrained by major limitations owing to Mediterranean climate conditions, and nitrogen (N) fertilizer management has been identified as one of the major issues affecting the sustainability of maize production. A field experiment was conducted over three years in Greece to study the agronomic characteristics, physiological parameters, grain yield, and quality of two Peruvian races of maize (Piscorunto and Pagaladroga) and compare them with a commercial variety (‘Jolly’), under different N fertilizer types. The experiment was conducted in a split plot design with genotypes and N treatments (untreated (control), urea, and urea with urease and nitrification inhibitors (Urea + NI + UI)) as the main and sub-plots, respectively. The results highlighted strong genotypic effects. In particular, the commercial variety ‘Jolly’ possessed the highest values for leaf area index (LAI), soil-plant analysis development (SPAD), normalized difference vegetation index (NDVI) and grain yield across the three growing seasons. The Peruvian races gave the highest values for vigor among the growth characteristics, thousand grain weight, and grain protein content, although their overall grain yield was lower. In addition, the N fertilization significantly improved crop productivity compared with the control, with urea treated with urease and nitrification inhibitors producing the most favorable yield performance. In conclusion, the research showed that the productivity of maize in the Mediterranean climate is significantly affected by the genotype and the type of nitrogen fertilizer used, where the commercial variety of maize ‘Jolly’ showed the best yield, the Peruvian maize showed the best vigor and quality, and the urea fertilizer with nitrification and urease inhibitors was identified as the best fertilizer option to improve yield and quality productivity.