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

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.