Journal of Tea Science Research, 2024, Vol.14, No.4, 192-201 http://hortherbpublisher.com/index.php/jtsr 195 attracting natural enemies, further supports the use of direct parasitism and predation in integrated pest management (IPM) strategies. By harnessing these mechanisms of action, beneficial microbes offer a sustainable and effective approach to managing tea pests, reducing the environmental impact of chemical pesticides, and promoting agricultural sustainability. 4 Case Studies in Tea Plantations 4.1 Successful bacterial biocontrol in tea Bacterial biocontrol agents have shown significant promise in managing tea pests and diseases. In North East India, the application of locally isolated bacteria such as Azotobacter, Azospirillum, Bacillus, and Pseudomonas has been integrated into disease management strategies. These bacteria, when used in combination with low doses of chemical fungicides and botanical extracts, have demonstrated a reduction in disease severity by up to 78.2% (Sarmah et al., 2020). Additionally, endophytic actinobacteria, particularly Streptomyces strains, have been identified for their plant growth-promoting and biocontrol traits. These strains not only enhance plant growth but also suppress major fungal pathogens (Figure 2), making them effective bioinoculants for sustainable tea cultivation (Hazarika et al., 2022). Figure 2 Evaluation of induced systemic resistance and seed germination (Adopted from Hazarika et al., 2022) Image caption: (A) Seed germination plate assay (1,2,3) Control. Non-bacterized tomato seeds, (4) KA12 bacterized seeds, (5) F. oxysporuminoculated seeds, (6) KA12 bacterized seeds, and F. oxysporuminoculated (B) Degree of disease severity in control and inoculated seeds. (C) In-planta seed germination assay. (1) Bacterized tomato seeds, (2, 3, 5, 6) non-bacterized control seeds, (4) F. oxysporum inoculated seeds, (D) growth after 14 days of germination, (1) un-inoculated control, (2) KA12 and F. oxysporum inoculated, (3) KA12 inoculated. (E) Stereomicroscopic visualization of root hairs after 14 days of seed germination (1) Un-inoculated control (2) KA12 inoculated (3) Inoculated with KA12 and F. oxysporum. Scale 100 μm (Adopted from Hazarika et al., 2022) Hazarika et al. (2022) found that the treatment of tomato seeds with Streptomyces sp. (KA12) significantly enhances seed germination and reduces disease severity caused by Fusarium oxysporum. The study demonstrated that bacterized seeds (treated with KA12) showed better germination rates compared to non-bacterized control seeds and those inoculated with F. oxysporum. In-planta assays confirmed these findings, with KA12-treated seeds exhibiting robust growth and reduced pathogen impact after 14 days. Stereomicroscopic analysis revealed that root hairs of KA12-inoculated seedlings were more developed compared to controls, indicating better root health and resilience. Overall, the application of beneficial microorganisms like Streptomyces sp. (KA12) can effectively induce systemic resistance in plants, enhancing growth and providing protection against pathogens.
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