Table 4.

Effects of plant growth-promoting rhizobacteria (PGPR) strains on severity of bacterial spot disease and plant growth.

Strainab	Disease severityc	Shoot dry weight (g)	Root dry weight (g)
Disease Control	2.11 a	2.07 bc	0.378 c
AP193	1.30 b	2.18 b	0.453 a
AP193ΔsrfAA	1.48 b	2.16 b	0.423 abc
AP193Δsfp	2.31 a	2.18 b	0.405 abc
AP193Δdif	2.06 a	2.00 c	0.389 bc
Healthy Control	0.00 c	2.38 a	0.435 ab
LSD	0.35	0.15	0.050

^aThe experimental design was a randomized complete block with 10 replications per treatment. The experiment was conducted twice. Values followed by the same letter were not significantly different (P = 0.05) according to Fischer's protected LSD.

^bOne plant was in each replication. Plants were sprayed with PGPR suspension (10⁶ CFU/ml) 1 week after transplanting, and were challenge-inoculated with pathogen solutions (10⁷ CFU/ml) 3 days after inoculating PGPR.

^cDisease severity ratings and harvest were done 14 days later. For disease severity rating, four compound leafs were selected from the bottom of each plant. The disease severity of each of the compound leaves was determined by rating the disease severity of each leaflet and calculating the average rating for the compound leaf. The leaflet was rated using a 0–4 rating scale, where 0 = healthy leaflet, 1 = < 20% necrotic area of the leaflet, 2 = 20-50% necrotic area of the leaflet, 3 = 51–80% necrotic area of the leaflet, 4 = 80–100% necrotic area of the leaflet, or fully dead leaflet.