Optimizing phenological nitrogen status for synergistic improvement of rice grain yield and eating quality

Appropriate nitrogen (N) fertilizer practices can be used to improve rice grain quality without compromising yield formation. The aim of this study is to investigate the performance of phenological N status in predicting rice grain yield and eating scores, and provide N fertilizer management recommendations. Two indica rice cultivars were selected for 3-year field experiments with multiple N application rates. The correlation between N diagnostic indicators [nitrogen nutrition index (NNI) and integrated NNI (NNI_inte)] derived from two critical nitrogen dilution curves (CNDCs) based on shoot dry matter (DM) and leaf area index (LAI) with relative yield (RY) and relative eating score (RE) will be investigated. The optimal N fertilizer application rate obtaining high-yield and superior-quality (RY and RE ≥ 0.900) were recommended by the optimized phenological N status.

NNI and NNI_inte based on DM and LAI CNDC at each growth stage were significantly correlated with the RY and RE. The single-stage estimation performance of the NNI_inte at the tillering stage were improved. The accumulated NNI_inte (from transplanting to jointing) was better for estimating RY and RE than single-stage NNI and NNI_inte. The LAI-CNDC can comprehensively and accurately estimate RY and RE. The optimal N fertilizer application rate was recommended as 126-209 kg ha^-1, for rice to obtain high yield and good eating quality.

This finding demonstrated the potential N diagnostic tool for estimating rice yield and eating quality in precision farming system, and NNI_inte can be used to determine N requirement for rice high-yield and superior-quality. © 2025 Society of Chemical Industry.