Greenhouse evaluation of putative bacterial isolates
As shown in Table 1, both KA19 and SE were effective
(P 0.05) in reducing black rot lesions compared to the
untreated control in two independent trials involving either
a foliar spray or the combined seed soak and soil drench.
The combined (KA19 ? SE) treatment was comparatively
more effective than the single strains in the respective
application methods. The combined seed and soil application method was more effective than foliar spray in reducing the lesions when using either single or combined
strains. In the foliar spray application method, there was no
significant difference between KA19 and SE, when applied
alone. In summary, the combined strains (KA19 ? SE)
were significantly more effective (P 0.05) in controlling
black rot lesions when the mode of application was combined seed and soil drench.
As shown in Table 2, in plant growth promotion analysis, it was observed that the dry matter content of the mature
B. campestris seeds did not change by the application of
both strains (either alone or combined) in comparison to
untreated plants. However, the expression analysis of dry
matter of 100 seeds showed a significant increase (particularly in seed treatment followed by soil drench; P 0.05)
in dry matter in comparison with untreated plants. The
content of lipids in the seeds increased significantly (mg/
100 seeds; P 0.05) with the application of strains as
combined seed treatment and soil drench as well as foliar
spray in comparison to untreated plants. Interestingly, the
Bacillus SE isolate was more effective in plant growth
promotion than Pseudomonas KA19.
As shown in Fig. 1, the population density of Xccrif?
declined in all treatments including the control, from 0 to
3 weeks post-application of antagonists in soil. Six weeks
after soil treatment, the population of Xcc was reduced in
the KA19 and SE single strain- and combined strain
(KA19 ? SE)-treated samples. However, 9 weeks after soil
treatment, the Xcc population was significantly lower in soil
treated with the combined strains (KA19 ? SE; P 0.05).