[Accumulative nitrogen deficit models of wheat aboveground part based on critical nitrogen concentration].

Based on three-year field experiments, three models of critical nitrogen concentration dilution curve, nitrogen nutrition index, and accumulative nitrogen deficit were constructed for the aboveground dry matter in medium protein wheat variety Yangmai 16 and low protein wheat variety Ningmai 13, respectively. The critical nitrogen concentration dilution curve model had specific biological meaning, i. e., there existed a negative power function correlation between shoot maximum dry matter (DM) and critical nitrogen concentration (Ncnc) (Yangmai 16: Ncnc = 4.65DM(-0.4); Ningmai 13: Ncnc = 4.33DM(-0.45)), the nitrogen nutrition index model could be used for accurate diagnosis of wheat plant nitrogen status, and the accumulative nitrogen deficit model could be used for quantitative regulation of nitrogen fertilizer management. The tests of the derived equations with independent experiment data (2007-2008) showed higher accuracy and reliable prediction, suggesting that the present models could be used for the diagnosis and regulation of wheat nitrogen nutrition, providing a key technical approach to precise fertilization management in wheat production.