Abstract: |
Tomato bacterial spots, caused by Xanthomonas campestris pv. vesicatoria (Xcv1) and X.
euvesicatoria (Xe2), as well as bacterial specks, caused by two strains of Pseudomonas syringae pv.
tomato (Pst1 and Pst2), represent significant threats to tomato production in the El-Sharkia governorate, often resulting in substantial yield losses. The objective of this study was to evaluate the
efficacy of various biocontrol culture filtrates, including bacteria and fungi agents, in managing the
occurrence and severity of these diseases, while also monitoring physiological changes in tomato
leaves, including antioxidant enzymes, phenolics, and pigment content. The culture filtrates from
examined Trichoderma species (T. viride, T. harzianum, and T. album), as well as the tested bacteria
(Bacillus subtilis, Pseudomonas fluorescens, and Serratia marcescens) at concentrations of 25%, 50%, and
100%, significantly inhibited the proliferation of pathogenic bacteria In vitro. For the In vivo experiments, we used specific doses of 5 mL of spore suspension per plant for the fungal bioagents at a
concentration of 2.5 × 10
7 spores/mL. The bacterial bioagents were applied as a 10 mL suspension
per plant at a concentration of 1 × 10
8 CFU/mL. Spraying the culture filtrates of the tested bioagents
two days before infection In vivo significantly reduced disease incidence and severity. Trichoderma
viride exhibited the highest efficacy among the fungal bioagents, followed by T. harzianum and T.
album. Meanwhile, the culture filtrate of B. subtilis emerged as the most potent among the bacterial
bioagents, followed by P. fluorescens. Furthermore, applying these culture filtrates resulted in elevated levels of chitinase, peroxidase, and polyphenol oxidase activity. This effect extended to increased phenol contents, as well as chlorophyll a, chlorophyll b, and carotenoids in sprayed tomato
plants compared to the control treatment. Overall, these findings underscore the potential of these
biocontrol strategies to effectively mitigate disease incidence and severity while enhancing plant
|
|
|