Evaluation of Bacillus Strains for Plant Growth Promotion and Predictability of Efficacy by In Vitro Physiological Traits

Table 5

Growth promotion effects of five Bacillus strains on wheat plants in 3^w greenhouse pot experiments, with the two strains having the highest measurements for each parameter indicated with shading.

Strain	Shoot height (cm) (% increase)^t		Shoot fresh weight (g) (% increase)					Root fresh weight (% increase)	GSF (%)^u	FIT2 (%)^v
	Trial 1	Trial 2	Trial 1	Trial 2	Trial 3	Trial 1	Trial 2	Trial 3
Bacillus megaterium R181	38a^w (15)	35 (21)	0.44a (47)	0.13 (30)	0.46 (7)	0.33a (154)	0.36a (29)	0.10a (43)	62	75
B. safensis R173	36ab (9)	31 (7)	0.42a (40)	0.11 (10)	0.54 (26)	0.29ab (123)	0.27ab (−4)	0.08ab (14)	25	38
B. simplex R180	37a (12)	33 (14)	0.31b (3)	0.13 (30)	0.59 (37)	—	—	0.07b (0)	33	33
Paenibacillus cineris R177	—	—	—	—	—	0.20bc (54)	0.24b (−14)	—	0	0
P. graminis R200	38a (15)	33 (14)	0.43a (43)	0.13 (30)	0.49 (14)	0.28ab (115)	0.18b (−36)	0.11a (57)	62	62
Control	33b	29	0.30b	0.10	0.43	0.13c	0.28ab	0.07b	NA^x	NA
ANOVA P	0.060	0.160	0.001	0.074	0.093	0.005	0.018	0.035	NA	NA

^sShoot height data for trial 3 not presented because no strains caused an increase compared to the control based on Dunnett’s test and there was no significant treatment effect in the ANOVA. ^tPercentage increase of a growth variable by bacterial treatment compared to the control. ^uGSF = growth stimulation frequency; frequency at which a strain increased growth (at 95% confidence level) in all measurements across trials. ^vFIT2 = frequency in top 2 strains category. ^wNumbers followed by the same letter in each column are not significantly different at α = 0.05 according to LSD test. ^xNA = not applicable. Significant difference between treatment and control () according to Dunnett’s test. — = no data because strain was not tested