Fig. 3.

Combined treatment effects of two different vitamins on in vitro antibacterial activities to Ralstonia solanacearum and in planta protection against tomato bacterial wilt. (A) Relative in vitro growths of R. solanacearum during liquid cultures supplemented with combination of two different vitamins were investigated. Bacterial numbers were initially inoculated with 10⁶ cfu/ml and indirectly measured using a spectrophotometer with optical density at 600 nm. Relative bacterial growth in vitamin-treated cultures was expressed as percentage (%) compared to that in non-treated cultures. (B) Relative protection against tomato bacterial wilt by R. solanacearum (10⁶ cfu/ml) with different combinations of vitamins 3 days post-inoculation (dpi). Error bars represent the standard errors of the means of four independent experimental replications. Means followed by the same letter are not significantly different at 5% level by least significant difference test. The same letter above bars represented no significant difference between treatments. T, 2 mM thiamine; N, 2 mM niacin; P, 2 mM pyridoxine; M, 0.5 mM menadione; FW, fresh weight.