为筛选紫薇（Lagerstroemia indica Linn.）氮高效基因型并明确氮效率评价的关键指标，通过盆栽氮素响应实验，对10个基因型在不同施氮水平下的生长及氮素相关指标进行了统计分析。结果显示：与未施氮处理相比，施氮处理明显促进紫薇生长，地径、株高、单株干质量均值的增幅分别为37.75%、49.53%、87.32%，但氮素生理效率均值下降了27.13%，反映高氮环境对氮素利用效率的双重影响。基因型和施氮水平对紫薇生长及氮素相关指标均具极显著影响（P<0.01），且其中8项指标存在基因型与施氮水平的互作效应，表明不同基因型氮素的响应机制存在差异。基于相关性分析和主成分分析，提取了反映生长与氮积累、氮素效率及根氮含量特征的主成分，并将10个基因型分为双高效型、高氮高效型、双低效型及低氮高效型4类，其中双高效型基因型L2（NL00325 × NL00503）和L9（NL00320 × NL00231）在2种施氮水平下均表现突出，可作为氮高效育种的优良材料。综上，本研究初步明确了适用于紫薇氮效率评价的主要指标，筛选获得优异紫薇种质。

 To screen nitrogen-efficient genotypes of Lagerstroemia indica Linn. and identify key parameters for evaluating nitrogen efficiency, statistical analyses were conducted on the growth and nitrogen related parameters of ten genotypes under different nitrogen application levels by using a pot nitrogen response experiment. The results show that compared with the no nitrogen application treatment, nitrogen application treatment obviously promotes the growth of L. indica, and the increments of averages of ground diameter, plant height, and dry mass per plant are 37.75%, 49.53%, and 87.32%, respectively, while the average of nitrogen physiological efficiency decreases by 27.13%, reflecting the dual impact of high nitrogen environment on nitrogen use efficiency. Both  genotype and nitrogen application level have extremely significant effects (P<0.01) on the growth and nitrogen related parameters of L. indica, and the interaction effects between genotype and nitrogen level are observed for eight parameters, indicating that the response mechanisms to nitrogen differ among genotypes. Based on correlation analysis and principal component analysis, principal components reflecting the characteristics of growth and nitrogen accumulation, nitrogen efficiency, and root nitrogen content are extracted. The ten genotypes are classified into four types, namely dual high-efficiency type, high-nitrogen high-efficiency type, dual low-efficiency type, and low-nitrogen high-efficiency type, among which the dual high-efficiency genotypes L2 (NL00325 × NL00503) and L9 (NL00320 × NL00231) perform. outstandingly under both nitrogen application levels, and can be used as superior materials for nitrogen-efficient breeding. In conclusion, this study preliminarily clarifies the main parameters suitable for evaluating nitrogen efficiency in L. indica, and screens out excellent germplasm of L. indica.