Journal of Integrative Agriculture ›› 2023, Vol. 22 ›› Issue (6): 1896-1908.DOI: 10.1016/j.jia.2023.04.037

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硝铵混合供氮增强氮素吸收和同化能力是促进苗期玉米生长的驱动力

  

  • 收稿日期:2022-09-01 修回日期:2023-05-01 接受日期:2022-11-27 出版日期:2023-06-20 发布日期:2022-11-27

Increasing nitrogen absorption and assimilation ability under mixed NO3– and NH4+ supply is a driver to promote growth of maize seedlings

WANG Peng1, 2, WANG Cheng-dong1, WANG Xiao-lin1, WU Yuan-hua1, ZHANG Yan1, SUN Yan-guo1, SHI Yi1, MI Guo-hua2#   

  1. 1 Key Laboratory of Tobacco Biology and Processing, Ministry of Agriculture and Rural Affairs, Tobacco Research Institute, Chinese Academy of Agricultural Sciences, Qingdao 266101, P.R.China

    2 Department of Plant Nutrition, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193,  P.R.China

  • Received:2022-09-01 Revised:2023-05-01 Accepted:2022-11-27 Online:2023-06-20 Published:2022-11-27
  • About author:WANG Peng, Tel: +86-532-88701506, E-mail: wangpeng03@caas.cn; #Correspondence MI Guo-hua, Tel: +86-10-62734554, E-mail: miguohua@cau.edu.cn
  • Supported by:
    The study was supported by the National Basic Research Program of China (2015CB150402), the National Natural Science Foundation of China (31672221 and 31421092) and the Science Foundation for Young Scholars of Tobacco Research Institute of Chinese Academy of Agricultural Sciences (2022C03 and 20211302).

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摘要： 与单独供硝（NO3-）或者单独供铵（NH4+）相比，混合供氮能够促进苗期玉米的生长。前期研究表明，混合供氮不仅可以提高玉米的光合效率，还可以促进地上部生长素的合成来增强叶片生长，进而为碳和氮的利用构建一个较大的库。然而，该过程是否依赖于氮的吸收还尚不清楚。在此，将玉米幼苗在具有三种供氮形态（单独供硝，75/25硝铵比和单独供铵）的水培实验中进行生长。结果表明，在0-3天，混合供氮下玉米生长速率和地上部含氮量与单独供硝处理间无显著差异，在6-9天，混合供氮下玉米生长速率和地上部含氮量显著高于单独供硝处理。于此同时，虽然混合供氮条件下15NO3-与15NH4+的瞬时吸收速率较单独供硝和单独供铵相比皆有所下降，但混合供氮在6-9天具有最高的总氮吸收速率。QRT-PCR结果表明，长期混合供氮条件下根系N吸收的增加可能与长期处理下NO3-转运蛋白基因（例如ZmNRT1.1A， ZmNRT1.1B，ZmNRT1.1C， ZmNRT1.2和ZmNRT1.3）的高表达或铵转运蛋白基因（例如ZmAMT1.1A）的高表达有关，尤其是后者。此外，与单独供硝处理相比，混合供氮处理下植株地上部与根系中具有较高的谷氨酰胺合酶（GS）活性以及氨基酸含量。硝酸还原酶酶（NR）和GS酶抑制剂实验进一步证明了混合供氮情况下氮的同化能力对于玉米生长促进是至关重要的。该研究证明了混合供氮能够促进氮素吸收并进一步促进了氮的同化，而该过程可能是促进玉米上生长的主要驱动力。

Abstract:

Compared with sole nitrate (NO3–) or sole ammonium (NH4+) supply, mixed nitrogen (N) supply may promote growth of maize seedlings.  Previous study suggested that mixed N supply not only increased photosynthesis rate, but also enhanced leaf growth by increasing auxin synthesis to build a large sink for C and N utilization.  However, whether this process depends on N absorption is unknown.  Here, maize seedlings were grown hydroponically with three N forms (NO3– only, 75/25 NO3–/NH4+ and NH4+ only).  The study results suggested that maize growth rate and N content of shoots under mixed N supply was little different to that under sole NO3– supply at 0–3 d, but was higher than under sole NO3– supply at 6–9 d.  15N influx rate under mixed N supply was greater than under sole NO3– or NH4+ supply at 6–9 d, although NO3– and NH4+ influx under mixed N supply were reduced compared to sole NO3– and NH4+ supply, respectively.  qRT-PCR determination suggested that the increased N absorption under mixed N supply may be related to the higher expression of NO3– transporters in roots, such as ZmNRT1.1A, ZmNRT1.1B, ZmNRT1.1C, ZmNRT1.2 and ZmNRT1.3, or NH4+ absorption transporters, such as ZmAMT1.1A, especially the latter.  Furthermore, plants had higher nitrate reductase (NR) glutamine synthase (GS) activity and amino acid content under mixed N supply than when under sole NO3– supply.  The experiments with inhibitors of NR reductase and GS synthase further confirmed that N assimilation ability under mixed N supply was necessary to promote maize growth, especially for the reduction of NO3– by NR reductase.  This research suggested that the increased processes of NO3– and NH4+ assimilation by improving N-absorption ability of roots under mixed N supply may be the main driving force to increase maize growth.


Key words: maize ,  NO3-/NH4+ ratio ,  N absorption ,  N assimilation ,  plant growth