Rice Science

Rice Science

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Appropriate Supply of Ammonia and Ammonium Nitrate Reduce Cadmium Content in Rice Seedlings by Inhibiting Cadmium Uptake and Transport

  1. State Key Laboratory for Rice Biology and Breeding, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 311401, China; State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Hunan Academy of Agricultural Sciences, Changsha 410125, China; The Key Laboratory for Quality Improvement of Agricultural Products of Zhejiang Province, College of Advanced Agricultural Sciences, Zhejiang A & F University, Hangzhou 311300, China; #These authors contributed equally to this work
  • Contact: LI Qing; QIAN Qian ; ZENG Dali
  • Supported by:

    This study was supported by the National Natural Science Foundation of China (Grant No. 31971872), the Open Research Fund of State Key Laboratory of Hybrid Rice (Grant No. 2022KF02), the National Natural Science Foundation of China (Grant Nos. 32101755, 32188102), the Zhejiang Provincial Natural Science Foundation (Grant No. LY22C130005), the Key Research and Development Program of Zhejiang Province (Grant No. 2021C02056), and the ‘Pioneer’ and ‘Leading Goose’ R&D Program of Zhejiang (Grant No. 2023C02014). We thank Prof. Zuo Renying and Dr. Lu Zhuchou, the Research Institute of Subtropical of Forestry, Chinese Academy of Forestry, for NMT technical guidance.

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Abstract:

Reasonable nitrogen (N) application is a promising strategy for reducing crop cadmium (Cd) toxicity. However, which state of N and how much N affects Cd tolerance and accumulation in rice remains unclear. This study explored the influence of different N-fertilizer forms (NH4NO3, NH4Cl, and KNO3) and dosages on Cd tolerance and absorption in Cd-stressed N-sensitive and insensitive indica accessions. The results indicated that the Cd tolerance of N-sensitive indica accessions is more robust than N-insensitive indica accessions. Furthermore, the shoot Cd contents and Cd translocation rates of both N-sensitive and insensitive indica accessions were decreased with an appropriate supply of NH4NO3 and NH4+, whereas comparable or slightly improved with increased NO3-. Unfortunately, we did not find significant and regular differences in Cd accumulation or translocation between N-sensitive and N-insensitive rice accessions. Consistent with the reduction of shoot Cd content, adding NH4NO3 and NH4+ also inhibited the instantaneous root Cd2+ uptake. The expression changes of Cd transport-related genes under different N forms and dosages suggested that the decreased shoot Cd content, caused by increased NH4NO3 and NH4+, is likely achieved by reducing the transcription of OsNRAMP1 and OsIRT1. In summary, our findings reveal that the appropriate supply of NH4NO3 and NH4+ could reduce Cd uptake and transport in rice seedlings and suggest that rational N management could reduce Cd risk in rice production.

Key words: rice, cadmium, nitrogen, nitrate, ammonium