To decipher the biochemical bases of nitrogen (N) utilization and metabolism of silage maize in relation to growth and productivity, an untargeted metabolomic (proton NMR- and LC-QTOF-MS based) and proteomic approach was conducted on leaves of 29 hybrids cultivated in the field under optimal and reduced N fertilization. The corresponding biochemical data were analyzed either individually (PCA, ANOVA), or integrated with that of eco-physiological, developmental and yield- related traits (multi-block sparse PLS-DA). Such integrated analysis was conducted to interpret the underlying physiology concerning the plant response to a mild N deficit often occurring under agronomic conditions. The genetic diversity of the core panel of 29 European dent hybrids crossed to a flint tester was exploited to highlight common N-responsive metabolites and proteins in order to identify putative biological markers that could be used to pilot and rationalize N fertilization. The responses of metabolites, proteins, and yield-related traits to the reduced N treatment were also exploited to identify biochemical markers representative of a maize ideotype exhibiting better agronomic performances when N fertilization is limited. These markers could be used to select high- yielding commercial maize hybrids used for silage production requiring less N fertilizer inputs.
