TABLE 2.

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

Concentration	Compound	Chemotaxis	Inhibition ratio (%)
			Zoospore motility	Cystospore germination	Hyphal growth
× 0.1 (0.1 times)	p-Coumaric acid	0.40 ± 0.12a	2.33 ± 1.20c	12.67 ± 0.33bc	37.33 ± 0.88a
	p-Hydroxybenzoic acid	0.53 ± 0.07a	4.67 ± 0.88b	8.33 ± 2.73c	9.00 ± 4.36b
	Vanillic acid	0.27 ± 0.07a	0.00 ± 0.00d	7.33 ± 2.73c	49.33 ± 6.36a
	Ferulic acid	0.20 ± 0.18a	0.00 ± 0.00d	7.33 ± 0.88c	37.00 ± 10.54a
	Cinnamic acid	0.13 ± 0.07a	4.00 ± 0.33bc	23.33 ± 4.05a	32.33 ± 13.20ab
	mixture	0.20 ± 0.12a	10.33 ± 0.88a	21.00 ± 4.00ab	32.33 ± 3.92ab
× 0.5 (0.5 times)	p-Coumaric acid	0.53 ± 0.07a	8.33 ± 1.76b	10.33 ± 3.18b	49.67 ± 1.45a
	p-Hydroxybenzoic acid	0.33 ± 0.07ab	8.33 ± 2.96b	10.00 ± 4.00b	23.33 ± 7.36b
	Vanillic acid	0.13 ± 0.07b	4.33 ± 1.45b	10.67 ± 2.19b	50.00 ± 3.61a
	Ferulic acid	0.47 ± 0.07a	4.67 ± 2.73b	8.67 ± 1.45b	25.33 ± 4.67b
	Cinnamic acid	0.33 ± 0.07ab	6.67 ± 2.33b	37.33 ± 7.84a	36.33 ± 9.87ab
	mixture	0.07 ± 0.07b	44.67 ± 0.88a	27.33 ± 11.67ab	43.67 ± 7.31ab
× 1 (1 times)	p-Coumaric acid	0.20 ± 0.07b	17.00 ± 4.73b	13.67 ± 2.73d	69.33 ± 15.41a
	p-Hydroxybenzoic acid	0.20 ± 0.12b	7.00 ± 2.08c	13.33 ± 2.03d	24.33 ± 8.09c
	Vanillic acid	0.07 ± 0.07b	6.67 ± 2.85c	23.67 ± 3.76c	33.67 ± 9.39bc
	Ferulic acid	0.07 ± 0.07b	6.67 ± 0.33c	27.67 ± 4.91bc	37.33 ± 4.91bc
	Cinnamic acid	0.97 ± 0.16a	15.67 ± 0.88b	37.33 ± 1.45b	25.67 ± 4.41bc
	mixture	0.90 ± 0.10a	60.00 ± 2.52a	50.00 ± 4.51a	52.67 ± 1.67ab
× 5 (5 times)	p-Coumaric acid	0.20 ± 0.07c	22.33 ± 1.76b	14.00 ± 1.53d	80.00 ± 2.52a
	p-Hydroxybenzoic acid	0.73 ± 0.24b	10.00 ± 2.31c	20.00 ± 2.89cd	29.67 ± 2.40c
	Vanillic acid	0.07 ± 0.07c	11.33 ± 1.20c	21.00 ± 3.46cd	40.33 ± 3.48c
	Ferulic acid	0.60 ± 0.07b	10.67 ± 0.88c	29.33 ± 3.28c	45.00 ± 16.52bc
	Cinnamic acid	1.27 ± 0.02a	18.67 ± 1.45b	43.67 ± 6.36b	37.00 ± 3.51c
	mixture	1.45 ± 0.02a	87.67 ± 0.67a	60.67 ± 2.40a	66.33 ± 7.88ab
× 10 (10 times)	p-Coumaric acid	0.40 ± 0.07c	29.33 ± 4.37c	57.33 ± 1.45b	90.67 ± 2.03a
	p-Hydroxybenzoic acid	0.53 ± 0.13c	21.33 ± 1.86cd	10.00 ± 1.00d	41.33 ± 7.31b
	Vanillic acid	0.13 ± 0.13c	19.67 ± 2.40d	18.67 ± 4.41c	66.00 ± 7.23a
	Ferulic acid	0.20 ± 0.13c	22.33 ± 3.18cd	56.33 ± 1.67b	31.00 ± 10.82b
	Cinnamic acid	1.30 ± 0.12b	38.00 ± 1.73b	58.00 ± 1.15b	41.00 ± 11.01b
	mixture	1.68 ± 0.13a	100.00 ± 0.00a	68.00 ± 1.73a	87.00 ± 2.52a

Mixture is consisted of five phenolic acid compounds according to their concentrations and proportion in the rhizosphere soil of maize. The concentration with (× 0.1), (× 0.5), (× 1), (× 5) and (× 10) indicate that the concentrations of mixture were 0.1, 0.5, 1.0, 5.0 and 10.0 times of the rhizosphere soil concentration (Mixture = 0.15 mg/L cinnamic acid + 26.13 mg/L p-coumaric acid + 4.93 mg/L vanillic acid + 0.50 mg/L ferulic acid + 17.11 mg/L p-hydroxybenzoic acid). Different letters in the same group indicate significant differences by ANOVA (P < 0.05). The error indicates standard error of means (n = 3).