Abstract:Rice ammonium transporter AMT1;1 is not only an important component of soil NH+ 4-N acquisition by roots, but also involved in nitrogen transportation to shoot. In view of the current situation of environmental risks and unpromising nitrogen use efficiency caused by excessive nitrogen fertilizer input in paddy soil, it is necessary to search for the regulation strategies that can reduce nitrogen fertilizer input while maintain the current production level. In this study, a field experiment was conducted with OsAMT1;1 overexpression genetic lines by three nitrogen treatments including nitrogen deficient (LN, no nitrogen application), moderate or reduced nitrogen input (MN, N 200 kg/hm2) and nitrogen fertilizer overuse (HN, N 350 kg/hm2) to evaluate nitrogen production characteristics in the later growth period. The results showed that, compared with wild type (WT), under LN condition, OsAMT1;1 overexpression in rice plant significantly improved nitrogen nutrient statuses in plant and flag leaf, as well as enhanced biomass accumulation and yield formation. Under the MN condition, the nitrogen contents of single plant and flag leaf of OsAMT1;1 overexpression lines respectively increased by 19.84% and 24.30%, and the photosynthetic rate (Pn) and stomatal conductance (Gs) respectively increased by 40.71% and 19.39% at the grain filling stage, and the 1000-grain weight and yield respectively enhanced by 10.26% and 17.86%. At the same time, the overexpression lines recovery nitrogen use efficiency (REN) was significantly improved, physiological nitrogen use efficiency (PEN) and agronomic nitrogen use efficiency (AEN) were boosted, but not significant compared to WT. In addition, under the HN condition, the nitrogen content of OsAMT1;1 overexpressing genetic lines enhanced by 24.38%, and the plant biomass and Pn tended to be saturated at the grain filling stage, while REN was also significantly improved, PEN and AEN were significantly decreased. In conclusion, compared with nitrogen fertilizer overuse (current nitrogen input habits), OsAMT1;1 overexpression lines are more favorable to collaborate high nitrogen internal environment of the plant to achieve higher yield and to improve nitrogen use efficiency of rice in the moderate or reduced nitrogen input.