Effect of Split Basal Fertilisation and Top-Dressing on Relative Chlorophyll Content and Yield of Maize Hybrids

The aim of this study was to determine the nitrogen requirement of maize, the optimal timing and amount of nutrient application, based on long time series data. An additional objective was to examine the response of the relative chlorophyll content of maize to nitrogen fertilisation. The examinations were carried out in a long-term field experiment at the University of Debrecen between 2016 and 2022, using two maize hybrids with different genotypes. Spatial and temporal changes in the N status of maize leaves were monitored using the Soil and Plant Analysis Development (SPAD) instrument. In addition to the non-fertilised (A(0)) treatment, six fertiliser treatments were applied (spring basal fertilisation: 60 and 120 kg N ha(-1), A(60); A(120)). Basal fertilisation was followed by two occasions of top-dressing at phenological stages V6 and V12, at rates of +30-30 kg N ha(-1) (V6(90) and V6(150), and V12(120) and V12(180)). The CMR (Chlorophyll Meter Reading), averaged over the examined years, genotypes and fertiliser treatments, were lowest in the V6 phenological phase (40.23 +/- 5.57, p < 0.05) and highest in R1 (49.91 +/- 8.41, p < 0.05). A(120) fertiliser treatment increased the relative chlorophyll content by 5.11 compared to the non-fertilised treatment, 1.67 more than A60 treatment. The basal fertilisation treatment substantially increased the yield (A(60): +30.75%; A(120): +66.68%) compared to the A(0) treatment averaged over years and genotypes. Based on the obtained research results, a basal treatment of 120 kg N ha(-1) is recommended and it can be concluded that, under appropriate water supply conditions (rainfall, irrigation), nitrogen top-dressing applied in V6 phenophase results in a significant yield increase compared to basal fertilisation.