Dry matter formation and nitrogen uptake in two maize cultivars differing in nitrogen use efficiency

Field experiment was conducted to investigate dry matter accumulation and N uptake under two N levels (N0 and N180) in two maize cultivars with contrasting N use efficiency. The results indicated that Xianyu 335 with high N efficiency had great tolerance to N stress. The dry matter weight and N absorption of Xianyu 335 in N0 treatment were both higher than those of Jindan 535 in N180 treatment. In maturity stage, the dry matter weight and N absorption of grain in Xianyu 335 was significant higher than Jidan 535, and those in N180 treatment was higher than N0 treatment. Moreover, the interaction between variety and N application reached extremely significant level. The dry matter weight and N absorption of grain was highest in Xianyu 335 with 180 kg/ha N application. In addition, a majority of grain carbon (85.6%-97.6%) relied on photosynthesis in the stage of grain formation, only a minority of grain carbon (2.4%-14.1%) relied on carbon translocation from vegetative organs. For Xianyu 335, nitrogen in grain mainly relied on N uptake by root at reproductive stage, which accounted for 45.4% and 59.3% of total N of grain in N0 and N180 treatment respectively; but for Jidan 535, N in grain mainly relied on N translocation from vegetative 335 the nitrogen recovery use efficiency (NRUE), nitrogen agronomic efficiency (NAE) and nitrogen partial factor productivity organs, which accounted for 65.5% and 67.9% of total N grain in N0 and N180 treatment respectively. In Xianyu (NPFP) were all higher than Jidan 535.