TABLE 3.

The antimicrobial activity of phenolic compounds against infection process of Phytophthora sojae according their concentrations in rhizosphere soil of soybean.

Compound	Inhibition ratio (%)
	Chemotaxis	Zoospore motility	Cystospore germination	Hyphal growth
p-Hydroxybenzoic acid	0.25 ± 0.03a	13.00 ± 0.00a	2.33 ± 1.20c	−1.33 ± 2.85b
Vanillic acid	0.15 ± 0.02bc	5.00 ± 1.15b	18.00 ± 0.58b	17.67 ± 4.41a
Ferulic acid	0.11 ± 0.01c	10.00 ± 2.00a	11.33 ± 2.85b	25.00 ± 1.73a
mixture	0.18 ± 0.01b	3.67 ± 0.67b	27.00 ± 4.00a	21.33 ± 4.18a

Mixture is the complex of three phenolic acids according to their concentrations and average proportion in the rhizosphere soil of soybean. The concentration indicates that the concentrations of mixture were 1.0 time of the rhizosphere soil concentration (Mixture = vanillic acid 1.55 mg/L + ferulic acid 2.16 mg/L + p-hydroxybenzoic acid 3.29 mg/L). Different letters in the same group indicate significant differences by ANOVA test (P < 0.05). The error indicates standard error of means (n = 3).