Faba bean rust is a serious fungal disease of faba bean caused by Uromyces viciae-fabae (Pers.) J. Schröt in southwest China. The application of nitrogen fertilizer can possibly affect intercropped faba bean and wheat to control faba bean rust disease and increase the productivity of crops. To evaluate the effects of nitrogen levels and intercropping on the occurrence of faba bean rust disease and understand the mechanism involved, field trials in two planting seasons were conducted in 2016–2017 and 2017–2018. Four nitrogen levels ([N0] 0 kg ha⁻¹, [N1] 45 kg ha⁻¹, [N2] 90 kg ha⁻¹ and [N3] 135 kg ha⁻¹) and two planting patterns (faba bean monocropping and faba bean and wheat intercropping) were used. The epidemic characteristics of faba bean rust were simulated, and the canopy microclimate and nitrogen content in the plant tissues were measured. The results showed that the application of nitrogen significantly increased the maximum disease index (A) and the maximum instantaneous epidemic rate (R_max). The area under the disease progression curve (AUDPC) of monocropped and intercropped faba bean rust was the most deleterious at the N3 level. The application of nitrogen increased the nitrogen content of leaves and the relative humidity of the canopies of monocropped and intercropped faba bean during both planting seasons, while decreasing the temperature and transmittance of light. Compared with monocropping, intercropping significantly increased the yield of faba bean and reduced the AUDPC for faba bean rust disease, and the AUDPC decreased by 22.3–54.7% at the N0-N3 levels with the level of N2 serving as the most effective at reducing disease. Intercropping creates a micro-ecological environment that is not favorable for the occurrence of rust disease by significantly decreasing the relative humidity of the faba bean canopy and increasing the canopy temperature and transmittance of light. Moreover, the N content in the faba bean leaves was reduced and transferred to the pods, thus, enhancing the disease resistance of faba bean. In this study, consideration of the effects on controlling disease and the advantages of increasing yield led us to recommend the application of nitrogen at 45–90 kg ha⁻¹ as the most effective measure to control the occurrence of faba bean rust disease when faba bean and wheat were intercropped. This study provides a basis for the rational application of N fertilizer in faba bean and wheat intercropping systems, which simultaneously control crop disease and enhance crop yield.

蚕豆锈病是我国西南地区由蚕豆( Uromyces viciae-fabae (Pers.) J. Schröt)引起的蚕豆严重真菌病害。施氮肥可能影响蚕豆和小麦间作，防治蚕豆锈病，提高作物产量。为了评估氮水平和间作对蚕豆锈病发生的影响并了解相关机制，在 2016-2017 和 2017-2018 两个种植季节进行了田间试验。四种氮水平（[N0] 0 kg ha ^-1，[N1] 45 kg ha ^-1，[N2] 90 kg ha ^-1和 [N3] 135 kg ha ^-1) 和两种种植模式（蚕豆单作和蚕豆与小麦间作）。模拟蚕豆锈病的流行特征，测定冠层小气候和植物组织中的氮含量。结果表明，施氮显着提高了最大病害指数( A )和最大瞬时流行率( R _{max )。}）。单作和间作蚕豆锈病的疾病进展曲线下面积 (AUDPC) 在 N3 水平上是最有害的。施氮增加了单作和间作蚕豆在两个种植季节的叶片含氮量和冠层的相对湿度，同时降低了温度和透光率。与单作相比，间作显着提高了蚕豆的产量，降低了蚕豆锈病的AUDPC，在N0-N3水平上AUDPC降低了22.3-54.7%，其中N2水平对减少病害最有效. 间作通过显着降低蚕豆冠层的相对湿度，提高冠层温度和透光率，营造不利于锈病发生的微生态环境。此外，蚕豆叶片中的氮含量降低并转移到豆荚中，从而增强蚕豆的抗病能力。在这项研究中，考虑到控制疾病的效果和增加产量的优势，我们建议在 45-90 公斤公顷的范围内施氮^-1作为蚕豆与小麦间作时控制蚕豆锈病发生的最有效措施。本研究为蚕豆和小麦间作系统合理施用氮肥，同时防治作物病害和提高作物产量提供了依据。