Knowledge of the dynamics of plant nitrogen (N) uptake at varying irrigation water levels is critical for strategizing increased N recovery efficiency (NRE), water use efficiency (WUE), and maize yield. The N dynamics were studied under various irrigation regimes to evaluate NRE, WUE, and maize yield. A pot experiment was conducted using three irrigation water regimes (50, 75, and 100% field capacity (FC)) and four N fertilizer rates (0, 1.6, 3.2, and 4.8 g pot-1) applied with two fertilizer application methods including foliar and soil applications. The highest plant growth and grain yields were achieved by application of 4.8 g N pot-1 with 100% FC. Contrarily, the maximum WUE (7.0 g L-1) was observed by the lowest irrigation water (50% FC) with the highest N fertilizer rates (4.8 g pot-1). Nitrogen concentration in the stem and grain was linearly increased by increasing N fertilizer rates with irrigation water. However, in the root, N concentration was decreased when the crop was supplied with 100% FC. In plant, maximum N uptake (6.5 mg g-1) was observed when 4.8 g N pot-1 was applied with 100% FC. Nitrogen recovery efficiency was increased by increasing N rate up to 3.2 g pot-1 with 100% FC. Therefore, for achieving maximum WUE and NRE, the highest water and N applications, respectively, are not necessary.
Keywords: Maize; Nitrogen recovery efficiency; Water use efficiency.