Table 1. The suppression of Pythium damping-off and root rot in the cucumber by Pseudomonas protegens CHA0 and Cab57.
| Bacterial strain added* | Pythium added* | Surviving plants per flask (%)** | Shoot fresh weight per flask (g)** | Root fresh weight per flask (g)** | Colonization by P. protegens (log10 CFU/g of root) *** |
| None | – | 100 a | 0.75 a | 0.48 a | ND |
| CHA0 | – | 100 a | 0.73 a | 0.50 a | 7.43±0.22 |
| Cab57 | – | 100 a | 0.73 a | 0.48 a | 7.40±0.18 |
| None | + | 6 c | 0.18 d | 0.10 c | ND |
| CHA0 | + | 50 b | 0.35 c | 0.24 b | 8.43±0.07 |
| Cab57 | + | 73 b | 0.43 b | 0.30 b | 8.29±0.10 |
*P. protegens strains were added at 107 CFU per g of soil contained within 100-mL flasks (30 g of soil per flask), after planting three 92-h-old, sterile-grown cucumber seedlings per flask. P. ultimum was added as a millet-seed inoculum at 2.5 g/kg of soil before planting. Plants were harvested after 7 days.
**Data represent the averages of 10 replicates (flasks containing three cucumber plants) per treatment without P. ultimum and 16 replicates per treatment with P. ultimum. Means within the same column followed by different letters (a–d) are significantly different (P<0.05) according to Fisher’s protected LSD test.
***The rhizosphere-stable plasmid pME6031 containing a tetracycline-resistant determinant [49] was introduced as a selective marker into the bacterial strains to determine their root colonization capacity in soil. ND, not detected.