Maize yield, rainwater and nitrogen use efficiency as affected by maize genotypes and nitrogen rates on the Loess Plateau of China

Abstract

Understanding the responses of grain yield (GY), nitrogen (N) use efficiency (NUE), rainwater use efficiency (WUE) and nitrate-N residue (NR) to different maize genotypes and the relationships of these parameters to N management is essential to determining N application rates and choose maize genotypes in rain-fed areas. A field experiment was conducted by using two maize genotypes of Zhengdan 958 (ZD958) and Wuke 2 (WK2) and three N application rates of 86, 172 and 258 kg N ha−1 with one control treatment in Yangling on the Loess Plateau of China. Grain yield, nitrate-N residue, nitrogen and rainwater use efficiency were evaluated in the 2013, 2014 and 2015 maize growing seasons. The results showed that the increasing application of N rate increased the soil NR, but no difference in soil NR was observed between the two maize genotypes at harvest. The “linear-plus-plateau” model could describe the relationship between N rates and GY, the mean values of optimal N rate and maximum GY were (149.1 vs 107.7 kg ha−1) and (7061.3 vs 6449.8 kg ha−1) in ‘ZD958’ and ‘WK2’, respectively. Nitrogen application can significantly improve WUE. Compared to ‘WK2’, ‘ZD958’ had higher WUE, with mean values of 25.5 and 23.2 kg ha-1 mm-1 in ‘ZD958’ and ‘WK2’, respectively. Nitrogen use efficiency and crop N recovery efficiency decreased sharply as the N rate increased; the mean values of NUE were 9.7 and 8.3 kg kg-1 in ‘ZD958’ and ‘WK2’, respectively. Further analysis shows that, the green leaf area index and leaf N concentration were greater in ‘ZD958’ compared with those of ‘WK2’. The findings suggest that the combination of N application rate of 149.1 kg ha−1 with the maize genotype‘ZD958’958′ would result in the maximum GY, with improve in both WUE and NUE under rain-fed conditions.