Characterization of low-N responses in maize(Zea mays L.) cultivars with contrasting nitrogen use efficiency in the North China Plain

Over-use of N fertilizer in crop production has resulted in a series of environmental problems in the North China Plain(NCP). Thus, improvement of nitrogen use efficiency(NUE) in summer maize has become an effective strategy for promoting sustainable agriculture in this region. Using twenty maize cultivars, plant dry matter production, N absorption and accumulation, yield formation, and NUE in summer maize were investigated under three N levels in two growing seasons. Based on their yield and yield components, these maize cultivars were categorized into four groups including efficient-efficient(EE) cultivars, high-nitrogen efficient(HNE) cultivars, low-nitrogen efficient(LNE) cultivars and nonefficient-nonefficient(NN) cultivars. In both two seasons, the EE cultivars improved grain yield together with increased plant biomass, and enhanced accumulative amounts as well as higher average grain yields than the other cultivar groups under deficient-N conditions. Significant correlations were observed between yield and kernel numbers(KN), dry matter(DM) amount and N accumulation at both post-silking and maturity stages. DM and N accumulation at late growth stage(i.e., from silking to maturity) contributed largely to the enhanced yield capacity and improved NUE under N-deficient conditions. Compared with the NN cultivars, the EE cultivars also showed increased N assimilation amount(NAA) and N remobilization content(NRC), and elevated N remobilization efficiency(NRE), NUE and nitrogen partial factor productivity(PFPN). Our investigation has revealed N-associated physiological processes and may provide guidance for cultivation and breeding of high yield and NUE summer maize under limited N conditions in the NCP.