Effect of nitrogen application on accumulation and translocation of carbon and nitrogen compounds in two maize cultivars with different senescent appearance

Field experiments and plant analyses were carried out to investigate the effect of nitrogen (N) application on accumulation and translocation of carbon (C) and N compounds in two maize (Zea mays L.) cultivars with different senescent appearance. Two maize hybrids included "Danyu 13", an earlier senescent hybrid, and "Simi 21", a stay-green hybrid. There were four nitrogen treatments: (I) NI: 0 kg N ha(-1), (2) N2: 250 kg N ha(-1) (1/5 N as basal application and 4/5 N as top-dressing at stalk elongation stage only), (3) N3: 250 kg N ha(-1) (1/5N as basal, 2/5 N as top-dressing at stalk elongation stage and tasselling stage, respectively), (4) N4: 400 kg N ha(-1) (1/5 N as basal and 4/5 N as top-dressing at stalk elongation stage). For Simi 21, a higher percentage of sugar and starch were found in each treatment in root, stem, leaf and grain, in comparison with that for Danyu 13. The highest percentage of sugar and starch, 80% ethanol-soluble N and soluble protein N in each organ could be achieved in N3 treatment for Simi 21 and in N2 treatment for Danyu 13, respectively, which consequently benefited to translocation of C and N from vegetative parts to grain. Excessive N could not produce the highest percentage of sugar and starch, 80% ethanol-soluble N and soluble protein N, but the highest percentage of residue C and N components in each organ for both hybrids.