Effects of partial （20%） replacing NO3--N with Gly, Glu and mixed amino acids in the nutrient solution on biomass, quality and root secretion of pakchoi （Brassica chinensis L. ） were studied under the partial sterile hydroponics cultivation. Compared to the single nitrate treatment, the 20% partial replacing NO3--N with amino acids could significantly reduce biomass with decreasing of nitrate and soluble starch content in the edible part of pakchoi after 24 day＇ s treatment. The nitrate and soluble starch contents in the treatment of 20% replacing of NO3--N by Glu are lowest at 1490. 8 mg/kg and 1.77 mg/g, while the contents of soluble protein, soluble sugar, free amino acid and total N in leaves and roots are improved. The treatments of partial replacing NO3--N could change the root morphology structure and root activity, and the contents of NH4＋ -N, free amino acids, total organicC, total N and soluble protein are also significantly increased in the treatments of 20% Gly and 20% of mixed amino acid replacing NO~-N. Compared to the treatment of single nitrate, the ratios of organic nitrogen to total nitrogen in the root secretions are increased by 5.6%, 11.2% and 12. 8% in the treatments of 20% Gly, 20% Glu and 20% of mixed amino acids replacing NO3 -N, respectively. Therefore, partial replacement of NO3 by amino acids could improve the quality of pakchoi, there is a negative relationship between the biomass of pakchoiand the root secretion （0. 7 〈 r 〈0. 83 ,P 〈0. 05 ）, and the types of amino acid could significantly affect biomass, root morphology structure and the amount of root secretion.%采用局部无菌水培方法,研究了氨基酸部分替代硝态氮对小白菜产量、品质及根际分泌物的影响。结果表明,与单一硝态氮处理相比,20%氨基酸部分替代硝态氮处理小白菜产量下降,硝酸盐及可溶性淀粉含量也显著降低,其中以20%谷氨酸（Glu）处理最低,分别为1490.8 mg/kg、1.77 mg/g;提高了小白菜全氮、可溶性蛋白、可溶性糖、游离氨基酸的含量,改变其根系形态结构及根系活力;同时,20%甘氨酸（Gly）、20%混合氨基酸（AAS）处理显著提高根系分泌物中铵态氮、游离氨基酸、总有机碳及总氮、可溶性蛋白的含量,根系分泌物中有机氮占总氮的百分比在Gly、Glu、AAS处理中分别提高了5.6%、11.2%、12.8%。表明氨基酸部分替代硝态氮可改善小白菜的品质,其生物量与各根系分泌物呈明显的负相关（0.7〈r〈0.83,P〈0.05）,且氨基酸种类显著影响其生物量、根系形态以及根系分泌物各组分含量。
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