Effects of calcium carbonate on the survival of Ralstonia solanacearum in soil and control of tobacco bacterial wilt

Abstract

The effects of Calcium carbonate (CaCO3) on the survival of Ralstonia solanacearum in the laboratory and on the control of bacterial wilt in the field were investigated. In the laboratory, the influences of pH and Ca2+ on bacteria were studied as well. The laboratory results showed that soils treated with CaCO3 particles (0 ~ 1 mm) significantly inhibited the survival of R. solanacearum and increased the pH by approximately 1.5 units as compared to the control. For the growth of R. solanacearum, the suitable pH range was 6.0 ~ 7.0 with pH = 6.5 being the optimal. The results of CaCl2 and NaCl showed that the growth of R. solanacearum was significantly inhibited by Ca2+ instead of Cl−. With increase of Ca2+ concentration, the pectinase activity decreased pronouncedly, while there were no obvious effects on the production of extracellular polysaccharide. The field results indicated that CaCO3 reduced disease incidence. Treatment with organic fertilizer and CaCO3 increased soil pH and lowered the R. solanacearum population nearly 100 times and increased the Ca2+ content in tobacco significantly compared to treatments without CaCO3. It is suggested that CaCO3 could serve as a potential soil amendment for the control of bacterial wilt caused by R. solanacearum.