Influence of nitrogen rates and Fusarium verticillioides infection on Fusarium spp. and fumonisin contamination of maize kernels

The aim of this investigation was to estimate the influence of four nitrogen (N) rates (0, 60, 120 and 180 kg ha−1) and two ear inoculation treatments (inoculated with F. verticillioides and control) of two Serbian maize hybrids NS 6030 and ZP 666 (FAO 600 maturity groups) on some productive and quality parameters. The experiments were conducted in the two growing seasons (2013–2014). Nitrogen rates demonstrated a highly significant (P ≤ 0.01) influence on the number of kernels per ear (NKE), thousand kernel weight (TKW), the incidence of Fusarium spp. (F. proliferatum, F. subglutinans, and F. verticillioides) and level of total fumonisins B1, B2, and B3 (FBs). The ear treatment showed a highly significant (P ≤ 0.01) effect on maize quality parameters (NIK, the incidence of Fusarium spp. and FBs level) and significant (P ≤ 0.05) for TKW. Among identified Fusarium spp., F. verticillioides was predominant, with the highest presence found at 120 (62.41%) and 180 kg N ha−1 (61.81%). The occurrence of F. proliferatum was not significant at 0, 60, and 120 kg N ha−1, with the highest value recorded at 120 kg N ha−1 (0.69%). The highest incidence of F. subglutinans was at 60 kg N ha−1 (4.94%). The higher presence of F. verticillioides was obtained in the inoculated (84.55%) compared to control ear treatments (36.59%), while it was vice versa for the incidence of F. proliferatum and F. subglutinans. The level of FBs was the highest at 120 kg N ha−1 (21.72 mg kg−1), especially in inoculated ear treatments (32.84 mg kg−1). A positive and significant relationship was found for NIK, with F. verticillioides and FBs level. Investigated years significantly influenced the incidence of Fusarium spp. In addition, there was a significant effect of hybrids on NIK, the incidence of Fusarium spp., and FBs levels. A higher incidence of F. proliferatum and F. verticillioides and increased FBs level were recorded in NS 6030 hybrid compare to ZP 666. The mean FBs level in all the treatments was above a maximum limit (4 mg kg−1) adopted by EU regulation for unprocessed maize. The N rates did not have a consistent effect on the incidence of Fusarium spp. and FBs level. However, a hybrid effect was more consistent on the maize quality parameters, whereby the hybrid NS 6030 was more sensitive to fungal fumonisin producers and FBs contamination than ZP 666. In addition, the effect of the years significantly influenced the incidence of Fusarium spp., but did not affect on FBs level. These