Increasing nitrogen absorption and assimilation ability under mixed NO_(3)^(–)and NH_(4)^(+) supply is a driver to promote growth of maize seedlings  

作　　者：WANG Peng WANG Cheng-dong WANG Xiao-lin WU Yuan-hua ZHANG Yan SUN Yan-guo SHI Yi MI Guo-hua 

机构地区：[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

出　　处：《Journal of Integrative Agriculture》2023年第6期1896-1908,共13页农业科学学报（英文版）

基　　金：supported by the National Basic Research Program of China (2015CB150402);the National Natural Science Foundation of China (31672221 and 31421092);the Science Foundation for Young Scholars of Tobacco Research Institute of Chinese Academy of Agricultural Sciences (2022C03 and 20211302)。

摘　　要：Compared with sole nitrate (NO_(3)^(-)) or sole ammonium (NH_(4)^(+)) 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 (NO_(3)^(-)only,75/25 NO_(3)^(-)/NH_(4)^(+) and NH_(4)^(+) 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 NO_(3)^(-)supply at 0–3 d,but was higher than under sole NO_(3)^(-)supply at 6–9 d.^(15)N influx rate under mixed N supply was greater than under sole NO_(3)^(-) or NH_(4)^(+) supply at 6–9 d,although NO_(3)^(-) and NH_(4)^(+) influx under mixed N supply were reduced compared to sole NO_(3)^(-) and NH_(4)^(+) supply,respectively.qRT-PCR determination suggested that the increased N absorption under mixed N supply may be related to the higher expression of NO_(3)^(-) transporters in roots,such as ZmNRT1.1A,ZmNRT1.1B,ZmNRT1.1C,ZmNRT1.2 and ZmNRT1.3,or NH_(4)^(+) absorption transporters,such as Zm AMT1.1A,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 NO_(3)^(-) 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 NO_(3)^(-) by NR reductase.This research suggested that the increased processes of NO_(3)^(-)and NH_(4)^(+) assimilation by improving N-absorption ability of roots under mixed N supply may be the main driving force to increase maize growth.

关 键 词：MAIZE NO_(3)^(-)/NH_(4)^(+)ratio N absorption N assimilation plant growth 

分 类 号：S513[农业科学—作物学]