THE CONTROL OF BACTERIAL BLIGHT OF POMEGRANATE USING THE METHANOLIC EXTRACTS OF INDIAN BAEL AND LEUCAS ASPERA
Keywords:
Bacterial blight, Xanthomonas axonopodis (pv Punicae), Secondary metabolites, Leucas aspera, Indian bael (Aegle marmelos), Phytochemical screening, Agar disk diffusion, Zone of inhibition, Thin-layer chromatography, Fourier transform infrared spectroscopyAbstract
Objectives: Blight disease occurring due to Xanthomonas axonopodis (pv. Punicae) has been creating a problem in pomegranate cultivation whose symptoms appear on leaves as well as on fruits and stem and thereby causing a detrimental effect on yield by reducing it to nearly 70–75%. In recent years, the disease has been controlled by nanoparticles (silver and copper). We are looking forward to an organic and more economic method for the control of blight disease of pomegranate which is farmer and consumer friendly.
Methods: In the present work, the causative agent of disease was isolated from the infected pomegranate fruit which was collected from Bellary, Karnataka on nutrient agar media using streak plating method. Secondary metabolites were extracted from Leucas aspera and Indian bael using methanol as solvent from maceration and soxhlet extraction techniques for about six hours. These methods are considered as the traditional methods for extracting phenolic compounds along with the ultrasound assisted solvent extraction (UASE) method. Since UASE degrades the phenols and certain metabolites which act as nutrients we did not go for this technique. The Phytochemical screening of extracts was conducted to check the presence of secondary metabolites having antimicrobial activity. The methanolic extracts were characterised using thin layer chromatography (TLC) and Fourier transform infra-red (FTIR) spectroscopy. The antimicrobial activity for extracts of L. aspera and Indian bael were tested by agar disc diffusion method.
Results: Clear Zone of Inhibition (ZOI) were observed for methanolic extracts of L. aspera (40 mg/ml and 100mg/ml) and Indian bael (160 mg/ml) which shows that the blight disease could be controlled.
Conclusion: Indian bael methanolic extract (160 mg/ml) shows better control against growth of Xanthomonas species with higher ZOI values than L. aspera extracts (100 mg/ml and 40 mg/ml).
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