Application of plant growth-promoting rhizobacteria combined with compost as a management strategy against Verticillium dahliae in tomato

Figures & data

Table 1. PGPR properties of the tested rhizobacteria.

PGPR Strain	Phosphate solubilization	Potassium solubilization	Exopolysaccharides production (µg eq CR/ OD600)	Siderophores production	IAA production (µg/ml)
ER10	***	***	205.30 ± 4.83	+	282.63 ± 5.63

*: Low; **: medium; ***: High; -: absence; +: presence; IAA: Indol acetic acid; CR: Congo red

Table 2. Result of three-way ANOVA test for independent variables including compost (C), PGPR (B), Verticillium dahliae (V) treatments and their interaction.

	Tissu	B	C	V	BxC	BxV	CxV	BxCxV
Plant height		***	***	***	***	ns	*	ns
Stomatal conductance		***	***	***	***	ns	ns	ns
Photosynthetic efficiency		***	***	***	***	ns	**	***
Total fresh weight		***	***	***	***	ns	***	**
Total dry weight		***	***	***	***	ns	ns	ns
Number of leaves		***	***	***	***	ns	ns	ns
Protein	Leaf	***	***	***	***	***	***	*
	Root	***	***	***	***	ns	***	***
PPO	Leaf	**	***	***	***	***	**	ns
	Root	ns	***	***	***	***	***	***
POX	Leaf	***	***	***	***	***	***	***
	Root	ns	ns	***	***	ns	***	***
CAT	Leaf	**	***	***	***	*	***	*
	Root	***	***	**	ns	*	***	***
SOD	Leaf	ns	***	ns	*	***	**	ns
	Root	***	***	***	***	***	***	***
MDA	Leaf	**	***	***	***	***	**	**
	Root	***	***	ns	***	***	*	*
H2O2	Leaf	***	***	***	ns	***	**	***
	Root	***	***	ns	***	***	ns	**
Diameter	Fruit	*	***	***	***	***	***	***
Lycopene	Fruit	*	***	ns	**	ns	**	***
Carotenoid	Fruit	ns	***	***	ns	***	ns	ns
Water content	Fruit	***	**	**	*	***	***	***
Brix°	Fruit	***	***	***	***	***	***	***
Acidity	Fruit	***	ns	***	***	***	ns	*
Number of fruits		ns	***	***	**	ns	ns	ns
Fruit weight		***	***	***	ns	***	***	***
Maturity index	Fruit	***	***	***	**	***	***	**
Disease incidence		***	***	***	***	***	***	***
AUDPC		***	***	***	***	***	***	***
FMS		***	***	***	***	***	***	***
LAI		***	***	***	***	***	***	***
Na	Leaf	***	***	***	***	***	***	***
Ca	Leaf	ns	***	***	*	*	***	*
K	Leaf	***	***	***	***	***	***	***
Mg	Leaf	***	***	***	ns	***	***	ns
P	Leaf	ns	***	***	*	**	ns	ns

ns: not significant, *; ** and ***: significant at p ≤ 0.05; p ≤ 0.01 and p ≤ 0.001.

Fig. 1 (a) Plant height, (b) Number of leaves, (c) Total dry weight, (d) Total fresh weight of tomato plants infected by Verticillium dahliae or not in the presence of different biostimulant combination after 5 months of cultivation. Control; C: Compost; B: Plant growth-promoting Rhizobacteria; CB: Compost + Plant growth-promoting Rhizobacteria; V: V. dahliae; CV: Compost + V. dahliae; BV: Plant growth-promoting Rhizobacteria + V. dahliae; CBV: Compost + Plant Growth-promoting Rhizobacteria + V. dahliae. Data are based on five replicates; bars with different letters significantly differ according to Tukey’s HSD test at p < 0.05.

Fig. 2 (a) Photosynthetic efficiency and (b) stomatal conductance of tomato plants infected by Verticillium dahliae or not in the presence of different biostimulant combination after 5 months of cultivation. Control; C: Compost; B: Plant growth-promoting Rhizobacteria; CB: Compost + Plant growth-promoting Rhizobacteria; V: V. dahliae; CV: Compost + V. dahliae; BV: Plant growth-promoting Rhizobacteria + V. dahliae; CBV: Compost + plant growth-promoting Rhizobacteria + V. dahliae. Data are based on five replicates; bars with different letters significantly differ according to Tukey’s HSD test at p < 0.05.

Fig. 3 (a) phosphorous, (b) potassium, (c) magnesium, (d) calcium, (e) sodium in the leaves of tomato plants infected by Verticillium dahliae or not in the presence of different biostimulants combination after 5 months of cultivation. Control; C: Compost; B: Plant growth-promoting Rhizobacteria; CB: Compost + Plant growth-promoting Rhizobacteria; V: V. dahliae; CV: Compost + V. dahliae; BV: Plant growth-promoting Rhizobacteria + V. dahliae; CBV: Compost + plant growth-promoting Rhizobacteria + V. dahliae. Data are based on five replicates; bars with different letters significantly differ according to Tukey’s HSD test at p < 0.05.

Fig. 4 Severity of the disease caused by Verticillium dahliae on tomato plants infected by V. dahliae in the presence of different biostimulant combination after 5 months of cultivation. V: V. dahliae; CV: Compost + V. dahliae; BV: Plant growth-promoting Rhizobacteria + V. dahliae; CBV: Compost + Plant growth-promoting Rhizobacteria + V. dahliae. Data are based on five replicates.

Fig. 5 (a) Disease incidence, (b) Leaf alteration index, (c) AUDPC, (d) FMS caused by Verticillium dahliae on tomato plants infected by V. dahliae in the presence of different biostimulant combination after 5 months of cultivation. V: V. dahliae; CV: Compost + V. dahliae; BV: Plant Growth-Promoting Rhizobacteria + V. dahliae; CBV: Compost + Plant Growth-Promoting Rhizobacteria + V. dahliae. Data are based on five replicates; bars with different letters significantly differ according to Tukey’s HSD test at p < 0.05.

Fig. 6 (a) (H₂O₂) in the leaves, (b) in the root; Malondialdehyde MDA (c) in the leaves and (d) in the root of tomato plants infected by Verticillium dahliae or not in the presence of different biostimulant combination after 5 months of cultivation. Control; C: Compost; B: Plant Growth-Promoting Rhizobacteria; CB: Compost + Plant Growth-Promoting Rhizobacteria; V: V. dahliae; CV: Compost + V. dahliae; BV: Plant Growth-Promoting Rhizobacteria + V. dahliae; CBV: Compost + Plant Growth-Promoting Rhizobacteria + V. dahliae. Data are based on five replicates; bars with different letters significantly differ according to Tukey’s HSD test at p < 0.05.

Fig. 7 (a) Peroxidase (POX), (b) Polyphenoloxidase (PPO), (c) Superoxide dismutase (SOD), (d) Catalase (CAT) in the leaves and roots of tomato plants infected or not by the pathogen Verticillium dahliae after 5 months. Data are based on five replicates; bars with different (n = 5) letters significantly differ according to Tukey’s HSD test at p < 0.05.

Fig. 8 (a) Total weight of tomato fruits; (b) Fruit number; (c): Fruit diameter of tomato plants infected by Verticillium dahliae or not in the presence of different biostimulant combination after 5 months of cultivation. Control; C: Compost; B: Plant Growth-Promoting Rhizobacteria; CB: Compost+ Plant Growth-Promoting Rhizobacteria; V: V. dahliae; CV: Compost + V. dahliae; BV: Plant Growth-Promoting Rhizobacteria + V. dahliae; CBV: Compost + Plant Growth-Promoting Rhizobacteria + V. dahliae. Data are based on five replicates; bars with different letters significantly differ according to Tukey’s HSD test at p < 0.05.

Fig. 9 (a) Total fruit weight, (b) Fruit number, (c) Fruit diameter, (d) Maturity index of tomato plants infected by Verticillium dahliae or not in the presence of different biostimulant combination after 5 months of cultivation. Control; C: Compost; B: Plant Growth-Promoting Rhizobacteria; CB: Compost+ Plant Growth-Promoting Rhizobacteria; V: V. dahliae; CV: Compost + V. dahliae; BV: Plant Growth-Promoting Rhizobacteria + V. dahliae; CBV: Compost + Plant Growth-Promoting Rhizobacteria + V. dahliae. Data are based on five replicates; bars with different letters significantly differ according to Tukey’s HSD test at p < 0.05.