Genotypic differences in nitrogen uptake and utilization of sweet maize

Twenty-two varieties of sweet maize (Zea mays L. saccharata Sturt) released recently in China were used in this study to evaluate their genotypic differences in nitrogen (N) uptake and N utilization efficiency (NUE) under the same N fertilization condition. The results indicated that fresh ear and kernel yield, N uptake, and NUE were significantly different among varieties. The range for N uptake was 126.6#8722;243.8 kg/ha, and the range of NUE for fresh ear and kernel was 43.5#8722;62.0 kg/kg and 28.4#8722;46.0 kg/kg, respectively. The results of cluster analysis indicated that three varieties (JF5, SM9701 and JSW) had high yield, N uptake and NUE for both fresh ear and fresh kernel. Average N uptake was 214.4 kg/ha, and average NUE for fresh ear and kernel was 50.8 kg/kg and 38.2 kg/kg, respectively. By path analysis, it was found that the effect of total N uptake on yield was far greater than the effect of NUE on yield. So the improvement of total N uptake was crucial for improving fresh ear and kernel yield of sweet maize, which was the basis to increase NUE.