Managing faba bean wilt disease through intercropping with wheat and reasonable nitrogen application: enhancing nutrient absorption and biochemical resistance in faba beans

Faba bean wilt disease is a key factor limiting its production. Intercropping of faba bean with wheat has been adopted as a prevalent strategy to mitigate this disease. Nitrogen fertilizer improves faba bean yield, yet wilt disease imposes limitations. However, faba bean-wheat intercropping is effective in controlling wilt disease. To investigate the effect of intercropping under varying nitrogen levels on the incidence of faba bean wilt disease, nutrient uptake, and biochemical resistance in faba bean. Field and pot experiments were conducted in two cropping systems: faba bean monocropping (M) and faba bean-wheat intercropping (I). At four nitrogen levels, we assessed the incidence rate of wilt disease, quantified nutrient uptake, and evaluated biochemical resistance indices of plants. The application of N decreased the incidence rate of wilt disease, with the lowest reduction observed in intercropping at the N2 level. N application at levels N1, N2, and N3 enhanced the content of N, P, K, Fe, and Mn as well as superoxide dismutase (SOD), phenylalanine ammonia lyase (PAL), and polyphenol oxidase (PPO) activities and defense gene expression in monocultured plants. Additionally, these levels increased the contents of total phenols, flavonoids, soluble sugars, and soluble proteins, and all reached their maximum in intercropping at the N2 level. The application of intercropping and N effectively controlled the occurrence of faba bean wilt disease by promoting nutrient absorption, alleviating peroxidation stress, and enhancing resistance in plants.