Effects of nitrogen management and intercropping on faba bean chocolate spot disease development

Abstract

Chocolate spot disease, incited by Botrytis fabae, is a serious faba bean disease that occurs globally. The exploration of reasonable fertilization and planting patterns will help better control this disease. Four N levels (N0: 0 kg N ha−1, N1: 45 kg N ha−1, N2: 90 kg N ha−1, and N3: 135 kg N ha−1) and two cropping patterns (faba bean monocropping, faba bean and wheat intercropping) were examined for their effects on faba bean chocolate spot disease in Kunming, Yunnan Province, China, from 2015 to 2017. Nitrogen application increased the incidence and disease index of faba bean chocolate spot disease using monocropping and intercropping. Compared with the N0 level, the N1–N3 levels increased the incidence and disease index by 5.8%–42.0% and 3.8%–46.3%, respectively. Nitrogen application also reduced the temperature and increased the relative humidity of the canopy. Compared with monocropping, intercropping created a better ecological environment within the canopy by significantly increasing the temperature and reducing the relative humidity of the canopy. The incidence and incidence index of faba bean chocolate spot disease were significantly reduced, and the disease index decreased the most using the N2 level, which showed the best disease control effect. Compared with monocropping, the faba bean yield using intercropping increased by 21.6%–46.7%, and intercropping had a high land equivalent ratio (1.28–1.42). Considering the effects of faba bean disease control and increased yield, faba bean-wheat intercropping and a nitrogen application level of 90 kg N ha−1 is a good method to control chocolate spot disease and increase the faba bean yield. This work will increase the understanding of the impact of biodiverse cultivation and fertilization on sustainable agriculture and provide information on food security.