Nitrogen (N) efficient cultivars can achieve relatively high grain yield under reduced N input. Normally modern stay-green maize cultivars are high-yielding and more N efficient than the old senescent cultivars. However, less is known about the genotypic difference in N use efficiency (NUE) among stay-green high-yielding cultivars. This information is crucial for further genetic improvement in NUE of the modern stay-green cultivars. In the present study, two stay-green hybrids with different NUE, Zhengdan958 (ZD958, N-efficient) and Liangyu99 (LY99, N-inefficient), were grown under 60 (LN) and 180 kg N ha⁻¹ (HN) conditions in a 4-year field experiment with split-design. The two hybrids did not differ in grain yield under HN. Under LN, grain yield and grain N content of LY99 was 23.6 % and 30.3 % lower compared to that of ZD958, respectively. LY99 had few grain number per row than ZD958. Correspondingly, floret primordia number decreased by 17.7 %, and grain abortion increased by 12.7 % in LY99 compared to ZD958. During critical period around silking, N concentration in the young ear of LY99 is lower than that in ZD958. Also, the maximum absolute ear growth rate and exponential duration of LY99 were 22.2 % and 6.0 % lower than that of ZD958 under LN, respectively. In LN conditions, the two hybrids did not differ in post-silking N accumulation. However, N remobilization from vegetative organs to grains in LY99 was 41.3 % lower than that in ZD935. In conclusion, NUE in stay-green cultivars could be improved by efficient N allocation into the young ear and vegetative-N remobilization during post-silking period under insufficient N supply.

氮素高效品种在减少氮素输入的情况下可以获得相对较高的谷物产量。通常，现代的常绿玉米品种比旧的衰老品种高产，并且氮效率更高。但是，对于保持绿色的高产栽培品种，氮利用效率（NUE）的基因型差异知之甚少。这些信息对于现代保持绿色栽培品种的NUE进一步遗传改良至关重要。在本研究中，在60（LN）和180 kg N ha ^-1下生长了两个具有不同NUE的正绿杂种，郑单958（ZD958，N效率）和Liangyu99（LY99，N低效率）。（HN）条件进行为期4年的采用分体式设计的野外试验。在HN条件下，两种杂种的籽粒产量没有差异。在LN下，LY99的籽粒产量和N含量比ZD958分别低23.6％和30.3％。LY99每行的粒数少于ZD958。相应地，与ZD958相比，LY99的小花原基数减少了17.7％，谷物流产增加了12.7％。在出丝的关键时期，LY99幼穗中的N浓度低于ZD958。此外，在LN下，LY99的最大绝对耳朵生长率和指数持续时间分别比ZD958低22.2％和6.0％。在LN条件下，两个杂种的后固氮积累没有差异。然而，LY99中从营养器官向谷物的氮转运比ZD935低41.3％。