Context

Yield components play a decisive role in regulating the potential crop grain yields, and their formation is greatly influenced by in-season nitrogen (N) management, as N is essential of optimizing crop growth.

Objectives

To test the applicability of critical N dilution curve based instantaneous N nutrition index (NNI) and integrated NNI (NNI_inte) in-season prediction of grain yield and its components in wheat.

Methods

This study evaluated the applicability of the critical N dilution curve for predicting grain yield and yield components in wheat by establishing the relationships of NNI and NNI_inte with relative grain yield (RY), dry matter (RDM), number of spikes (RPN), number of grains per spike (RGN), and grain weight at different growth stages of wheat. Data were acquired from six multi-N rates field experiments conducted in eastern and central China.

Results

The RY, RPN, and RDM were estimated by NNI and accumulated NNI_inte during different growth stages of wheat. The higher R² values of relationships observed during the middle to later growth stages compared with early growth stages indicated that the early growth stages might not be suitable for estimating wheat grain yield and yield components. The NNI_inte specifically during booting to anthesis stage showed improved accuracy estimating the number of grains per spike compared to other stages.

Conclusions

Overall, the estimation performance based on accumulated NNI_inte was superior compared to NNI or NNI_inte during the single growth stage of wheat. The above models provided comprehensive and accurate estimates dry matter at maturity, grain yield and yield components as early as the anthesis stage.

Implications

The findings provided valuable insights for predicting grain yield and yield components in intensive wheat cropping systems, and also offer practical guidance for precisely scheduling N management.