Fig. 2.

Disease suppression by vitamin treatments against bacterial wilt of detached tomato leaves. (A) Different concentrations of four vitamins (thiamine, niacin, pyridoxine, and menadione) were evaluated for disease development of the tomato bacterial wilt at 3 days post-inoculation (dpi). Relative fresh weight (FW) of the detached tomato leaves by petiole-dipping inoculation with R. solanacearum (10⁶ cfu/ml) was shown. Protection by vitamin treatment against tomato bacterial wilt was presented as relative FW (%) of the vitamin-treated leaves compared with that of the inoculated leaves without any vitamin. Arrows indicate the minimum visible phytotoxic doses of each vitamin to the detached tomato leaves. (B) Relative reduced wilting symptom against tomato bacterial wilt by R. solanacearum (10⁷ cfu/ml) with different doses of thiamine treatment at 3 and 5 dpi. Error bars represent the standard errors of the means of the 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.