Resistance to bacterial wilt caused by Ralstonia solanacearum depends on the nutrient condition in soil and applied fertilizers: A meta-analysis

Soil nutrient supply and resistance to pathogen invasion are critical to crop yield during agricultural production. Crop production is often hampered by co-occurring nutrient and pathogen stresses, but the relationship between soil nutrient status and disease suppression remains unclear. Here, we conducted a meta-analysis based on 406 observations from 55 studies to decipher the relationships between soil nutrient supply and disease suppression against bacterial wilt disease caused by R. solanacearum. We found that the contents of soil organic carbon (SOC), total nitrogen (TN), available potassium (AK) and available phosphorus (AP) were significantly higher in relatively disease suppressive soils than in conducive soils. Soil AP showed a significantly negative correlation with both crop disease incidence (DI) and disease severity (DSI). SOC was significantly and negatively correlated with DI and DSI in general, but a positive correlation with DI was found when SOC content was higher than 1.3%. Then for nutrient stoichiometry in soil, we found that the ratio of carbon to nitrogen (C/N), maximum to 22, was significantly and negatively correlated to the DI, but was positively correlated to DSI when C/N was higher than about 30. And the ratio of TN to AP (TN/AP) showed significantly positive correlations with both DI and DSI in soil. Further in applied organic fertilizer, the ratio of nitrogen to phosphorus (N/P) was significantly and negatively correlated with DI when N/P was lower than about 5, but was positively correlated with DI when higher than that. Our results demonstrated that the quantity and stoichiometry of phosphorus, organic carbon and nitrogen in soil and applied fertilizer, notably the prevention of nutrient deficiency and the balance of different nutrients, play an important role in supporting soil suppressiveness to R. solanacearum wilt disease, and this implied a possible trade-off between nutrient acquisition and pathogen defense in soil ecosystems.