Biochar suppresses Clubroot disease in Chinese cabbage by improving soil nutrient conditions and recruiting beneficial microorganisms

Clubroot, a fungal disease transmitted through soil, can significantly reduce both the productivity and quality of Chinese cabbage. Biochar is regarded as an effective soil amendment for enhancing stress resistance in plants, but there are still few studies on its use for the prevention and control of cabbage clubroot. This study involved field experiments to evaluate the effects of different biochar application rates on the soil microenvironment, cabbage quality, and clubroot incidence. Rice straw was pyrolyzed at 400 °C to produce biochar, which was then applied at rates of 0 t/hm² (CK), 24 t/hm² (BC1), 48 t/hm² (BC2), and 96 t/hm² (BC3). The results showed that biochar effectively inhibited the development of clubroot in Chinese cabbage. Moreover, when the application rate of biochar was 96 t/hm², the disease suppression rate reached 90 %. The 96 t/hm² application rate not only enhanced the health of cabbage but also significantly increased the soluble protein and vitamin C contents by 56.5 % and 337.6 %, respectively. Concurrently, the soil pH rose by 1.1 units, indicating a positive shift in soil conditions. Furthermore, biochar application led to a consequential notable increase of 97.9 %–452.0 % in soil nutrient content. In addition, qPCR and amplicon sequencing techniques revealed that biochar significantly reduced the abundance of Plasmodiophora brassicae, the causative agent of clubroot disease, while simultaneously promoting the recruitment of potentially beneficial microbes, including Sphingomonas, Gaiella, Penicillium, and Olpidium. In summary, biochar enhances the resistance of Chinese cabbage to clubroot disease by improving soil pH, nutrientavailability, and promoting beneficial microorganisms. These findings offer valuable insights into the role of biochar in enhancing agricultural productivity and sustainability.