Response of Corn Nitrogen Remobilization and Nitrogen Use Efficiency Components to Nitrogen Availability.

Nitrogen remobilization from corn stover to grain is one of the key components of nitrogen use efficiency under N-limited conditions.  Remobilization is typically considered to increase with decreasing N availability.  To determine the nitrogen response of N remobilization and other N use efficiency components, we grew four Dekalb commercial hybrids under a range of N fertilizer rates (0, 60, 120, 180, 240 lbs N/acre).   We ran the experiment for two years,  2009 and 2010.  We characterized several nitrogen use efficiency components by the N budget method, including nitrogen remobilization, nitrogen use efficiency, post-silking N uptake, grain weight, and yield  components .  Amino acid profiles were obtained at regular intervals during the grain-filling period for ear, stalk, and leaf at 60 and 240 lbs N/acre.  Rankings among hybrids for N remobilization and post-silking N uptake were inversely related, and consistent between years and locations.  N remobilization peaked at intermediate N rates, and decreased with both high and low N availability.