Effect of nitrogen regimes on narrowing the magnitude of maize yield penalty caused by high temperature stress in North China Plain

Further enhancement of maize (Zea mays L.) productivity will benefit from a thorough understanding of thermotolerance. The effects of nitrogen fertilization regimes (ratio of nitrogen (N) doses prior to planting: V7:V15:R3) on reducing yield penalty imposed by high temperature stress are discussed in this study. Field experiments were conducted in 2013 and 2014 using three nitrogen fertilization regimes (N1 - 120:180:0:0; N2 - 60:90:150:0; N3 - 60:90:60:90) and CK (control) treatment (1:0:0:0) to discuss the effect of nitrogen fertilization regimes on alleviating high temperature stress of spring maize. Total N rates for 2013 and 2014 were 280 and 300 kg/ha, respectively. Yield in 2013 and 2014 was averaged as 9.37 and 12.35 t/ha for N3, respectively, which was 13.47% higher than CK. During the grain-filling stage, leaf area index and the SPAD (soil plant analysis development) value in N3 were the highest, but electrical conductivity and malondialdehyde content of ear leaf in N3 were the lowest. Moreover, photosynthetic rate of ear leaf in N3 increased by 9.95% compared to CK. These results indicate that nitrogen fertilization regimes, especially with N3 treatment, can help maintain relatively higher photosynthetic supply capacity during the grain-filling stage under high temperature stress, thereby resulting in improved grain yield.