Improving grain yield and protein concentration of maize (Zea mays L.) simultaneously by appropriate hybrid selection and nitrogen management

The simultaneous improvement of grain yield and protein concentration in crop production is an important global challenge. In maize, genotype selection and nitrogen (N) management are potential methods to improve grain yield and protein concentration. A field experiment was conducted in 2015-2016 in the North China Plain to evaluate the response of grain yield and protein concentration of different modern hybrids (XY1266, ZD958 and DH618) under different N rates (0-259 kg ha(-1)). The highest grain dry matter and protein concentration were observed in DH618. The averaged maximal grain dry matter over the 2 years was 10.3 Mg ha(-1) for DH618, 6.1 % higher than for ZD958 (9.7 Mg ha(-1)) and 9.9 % higher than for XY1266 (9.4 Mg ha(-1)), and the maximal grain protein concentration in DH618 was 8.6 %, 11.1 % higher than for XY1266 (7.8 %) and 10.1 % higher than for ZD958 (7.9 %). DH618 had higher post-silking biomass accumulation, a stable high harvest index (HI), and higher post-silking N uptake as well as N harvest index (NHI) compared to the other two hybrids, meanwhile without reducing N remobilization efficiency (NRE). In DH618, high leaf N concentration after silking facilitated a higher rate of photosynthesis, further leading to greater post-silking biomass and N accumulation, and quickly remobilization of leaf N at late grain-filling stage improved the NRE and NHI. Together with choosing the right hybrid, optimisation of N management with split N application as well as appropriate N rate taking into account the residual soil mineral N could ensure both high grain dry matter and increased protein concentration in maize.