旨在探明水稻在膜下滴灌下根系形态、构型、氮利用效率变化及其与分形维数的关系。于2021—2022年，以氮高效品种(T-43)和氮低效品种(垦-26)为材料，设置滴灌(drip irrigation, DI)、淹灌(flooding irrigation, FI)2种方式与4种施氮水平(0、150、300和450 kg hm^-2)的盆栽试验。基于盒维数法结合根系图像分形分析程序计算根系形态的分形维数和分形丰度，研究滴灌及施氮对水稻产量、氮素利用效率、根系形态、构型、分形维数、分形丰度的影响。结果表明，(1) 在相同施氮水平下，与淹灌相比，滴灌处理下T-43和垦-26细根百分比、根长密度(root length density, RLD) β值、氮肥农学利用效率(nitrogen agronomic efficiency, NAE)显著提高(分别为6.8%~14.5%和9.9%~17.2%、0.65%~5.45%和0.32%~3.43%、12.1%~22.4%和12.2%~20.5%)；>0.5 mm RLD、0~40 cm土层表面积密度(surface area density, SAD)和根体积密度(RLD)、分形维数(fractal dimension, FD)、分形丰度(fractal abundance, FA)显著降低，造成产量降低(3.8%~37.4%和7.6%~48.3%)。(2) 滴灌模式下，施氮显著提高了水稻根系FD和FA，T-43在施氮量为300 kg hm^-2时，FD和FA最高(分别为1.55和14.07)；垦-26在施氮量为450 kg hm^-2时最高(分别为1.62和14.78)。(3) 相关分析表明，FD、FA与直径0.1~0.3 mm RLD、0~10 cm土层根长和根质量密度、产量、氮素稻谷生产效率呈显著正相关，与30~40 cm土层表面积密度呈显著负相关。因此，在滴灌条件下，氮高效品种“T-43”配施300 kg hm^-2氮肥，能够增加细根根长密度比例，优化表层根系形态分布，提高根系分形维数和丰度，进而实现滴灌水稻产量和氮肥利用效率协同提高。

The aim of this study was to explore the changes of root morphology, configuration, and nitrogen use efficiency of rice under mulched drip irrigation and their relationship with fractal dimension. From 2021 to 2022, a pot experiment was conducted with two irrigation methods of drip irrigation (DI) and flooding irrigation (FI) and four nitrogen (N) application levels (0, 150, 300 and 450 kg hm^-2) using high nitrogen efficient (high-NUE) cultivar (T-43) and low-NUE cultivar (Ken-26) as the experimental materials. Based on the box-counting method combined with the root image fractal analysis program, the fractal dimension and fractal abundance of root morphology were calculated, and the effects of drip irrigation and nitrogen application on rice yield, nitrogen use efficiency, root morphology, configuration, fractal dimension, and fractal abundance were studied. The results showed that: (1) under the same N application level, compared with FI, the fine root percentage, root length density (RLD) β value, and N agronomic efficiency (NAE) of the two varieties under DI were significantly increased (6.8%–14.5% and 9.9%–17.2%, 0.65%–5.45% and 0.32%–3.43%, 12.1%–22.4% and 12.2%–20.5%); >0.5 mm RLD, surface area density (SAD) and root bulk density (RLD), fractal dimension (FD), fractal abundance (FA) were significantly lower in the 0-40 cm soil layer, resulting in lower yields (3.8%–37.4% and 7.6%–48.3%). (2) Under DI, nitrogen application significantly increased FD and FA of rice roots. T-43 had the highest FD and FA when the nitrogen application rate was 300 kg hm^-2 (1.55 and 14.07), and Ken-26 had the highest FD and FA when the nitrogen application rate was 450 kg hm^-2 (1.62 and 14.78). (3) Correlation analysis showed that FD and FA were significantly or extremely significantly positively correlated with RLD of 0.1–0.3 mm in diameter, root length, and root mass density, yield and N grain production efficiency in 0–10 cm soil layer, and significantly negatively correlated with the surface area density in 30–40 cm soil layer. Therefore, under drip irrigation, the high-NUE cultivar "T-43" with 300 kg hm^-2 N fertilizer can increase the proportion of fine root length density, optimize the distribution of surface root morphology, and increase the fractal dimension and abundance of the root system, thus achieving a synergistic increase in the yield of drip-irrigated rice and the efficiency of nitrogen fertilizer utilization.