Interaction of Genotype, Environment, and Management on Organ-Specific Critical Nitrogen Dilution Curve in Wheat

Abstract

The organ-specific critical nitrogen (N c ) dilution curves are widely thought to represent a new approach for crop nitrogen (N) nutrition diagnosis, N management, and crop modeling. The N c dilution curve can be described by a power function (N c = A 1 ·W −A2 ), while parameters A 1 and A 2 control the starting point and slope. This study aimed to investigate the uncertainty and drivers of organ-specific curves under different conditions. By using hierarchical Bayesian theory, parameters A 1 and A 2 of the organ-specific N c dilution curves for wheat were derived and evaluated under 14 different genotype × environment × management (G × E × M) N fertilizer experiments. Our results show that parameters A 1 and A 2 are highly correlated. Although the variation of parameter A 1 was less than that of A 2 , the values of both parameters can change significantly in response to G × E × M. Nitrogen nutrition index (NNI) calculated using organ-specific N c is in general consistent with NNI estimated with overall shoot N c , indicating that a simple organ-specific N c dilution curve may be used for wheat N diagnosis to assist N management. However, the significant differences in organ-specific N c dilution curves across G × E × M conditions imply potential errors in N c and crop N demand estimated using a general N c dilution curve in crop models, highlighting a clear need for improvement in N c calculations in such models. Our results provide new insights into how to improve modeling of crop nitrogen–biomass relations and N management practices under G × E × M.