COMPARATIVE ANALYSIS OF ANTIOXIDANT AND FREE RADICALS SCAVENGING ACTIVITY OF LEMONGRASS OIL AND LAVENDER OIL

ABSTRACTObjective: To compare the free-radical scavenging activity of lemongrass oil and lavender oil.Methods: Lemongrass oil and lavender oil were used to assess their antioxidant effect by in vitro methods such as phytochemical tests, nitric oxideradical scavenging activity, and estimation of total phenolic content (TPC).Results: The oils were studied for different phytoconstituents and show the presence of carbohydrates, tannins, quinones, cardiac glycosides,terpenoids, phenols, and steroids in both the oils. These constituents can be used in the treatment of diarrhea, hemorrhage, cardiac failure, bacterialand fungal infections, dermatoses, burns and swollen joints, etc. The TPC of the oils were measured, and results show their use in anticancer andantioxidant effect. The nitric oxide assay of two oils shows their scavenging activity and their use in controlling blood pressure, platelet functions, etc.Conclusion: Both the oils show great antioxidant effect. They can be used as a medicinal supplement due to its natural availability and its use in cancertreatment.Keywords: Cymbopogon citratus, Lavandula angustifolia, Phytochemicals, Free radical scavengers, Antioxidants

Antagonistic potential of Trichoderma hamatum against Alternaria porri causing purple blotch disease of onion through Gas chromatography-mass spectrometry (GCMS) analysis

Alternaria porri causing purple blotch disease of onion is a destructive phytopathogen which causes severe loss in productivity. The present study aimed to unravel the antagonistic potential and efficacy of volatile organic compounds produced by various Trichoderma spp. against A. porri causing purple blotch disease of onion through Gas chromatography-mass spectrometry (GCMS) analysis. Ten isolates of Trichoderma species were isolated from the rhizospheric soil of healthy onion plants. Upon paired plate technique, the in vitro efficacy of ten Trichoderma isolates were tested against virulent isolate of Alternaria porri isolated from purple blotch disease infected onion plants. The Trichoderma isolate TIM2 showed 76.29 per cent inhibition on mycelial growth of pathogen. The effective Trichoderma isolate was identified as Trichoderma hamatum through the analysis of the rDNA of internal transcribed spacers (ITS) region and it was subjected to GC-MS analysis.  The result of GCMS analysis indicated the highest peak area and retention time with major antimicrobial bioactive compounds like Tetradecane, 2,6,10-trimethy (20.327), (1.22) and Dodecane, 2-cyclohexyl (20.079), (2.14), Heptadecane (21.222), (9.50), Octadecane (22.379), (3.58), Eicosane, 9-cyclohexyl (22.578), (1.84), 2-Propenoic acid, pentadecyl ester (23.400), (10.37), 2,6,10,14-tetramethyl (23.567), (10.37), Eicosane (27.311), (2.34), Hexadecanoic acid, methyl ester (27.918), (4.43), n-Hexadecanoic acid (29.156), (3.59) and  Tetrapentacontane, 1,54-dibromo (31.906), (3.33). These bioactive compounds identified through GCMS analysis from the crude extracts of Trichoderma hamatum exhibited a stronger antifungal activity against A. porri. Hence the application of T. hamatum for the management of purple blotch disease highly supress growth of the pathogen and reduce the disease incidence.    

Survey and surveillance on rice false smut disease severity in Tamil Nadu and the influence of wind velocity on disease progression under field conditions

The false smut disease of rice incited by Ustilaginoidea virens is a major constraint on rice production. The main aim of the present study was to ascertain the false smut disease severity in both delta and non-delta districts of Tamil Nadu through survey and surveillance and assess the correlation between the disease severity and wind velocity for the past three years, 2019, 2020 and 2021. Moreover, the present study addressed the disease distribution pattern of false smut diseases under field conditions.  The results obtained from survey results revealed that the maximum disease severity was recorded in Nagapattinam district (Nagapattinam block) with 27.45% and the minimum disease severity was recorded in the district Theni (Bodinayakanur block) with 8% in 2021. Similarly in 2019 and 2020 maximum disease severity was recorded in the following districts Thanjavur district (Orathanadu block) with 19.91% and Thanjavur district (Peravurani block) with 18.54% and the minimum disease severity was recorded in the following districts Madurai district (Madurai north block) with 4.78% and Madurai district (Usilampatti block) with 4.78% respectively. The obtained R2 values through regression analysis were 0.70, 0.79 and 0.76 in the following years, 2019, 2020 and 2021, respectively. Besides the relationship between the false smut disease development, the pattern wind direction was also assessed. By assessing the false smut disease distribution pattern under field conditions, more disease distribution was observed around the surrounding area of the paddy field as well as the diagonal path of the field which clearly revealed that wind direction influences the disease development

Antifungal activity of Trichoderma atroviride against Fusarium oxysporum.f.sp.lycopersici causing wilt disease of tomato

Fusarium oxysporum f. sp. lycopersici causing tropical wilt of tomato is a destructive phytopathogen. To study bio efficacy of fungal bio agents, fifteen isolates of Trichoderma species were isolated from rhizosphere soil of healthy tomato plants. Among the isolates, TA12 showed higher antagonistic efficacy against the pathogen. Upon analysis of the rDNA of internal transcribed spacers (ITS) and molecular data, the isolate was identified as Trichoderma atroviride. The in vitro antagonistic assessment indicated that the T. atroviride isolate caused significant inhibition of F. oxysporum f. sp. lycopersici. Trichoderma atroviride (TA12) showed antagonistic activity against F. oxysporum with mycelial inhibition of 71.25%. The culture filtrates of Trichoderma atroviride exhibited its antifungal activity against F. oxysporum with a suppression of 77.77%. Moreover, the ethyl acetate extracts of T. atroviride TA12 showed the highest antifungal potency against F. oxysporum f. sp. lycopersici. The main bioactive constituents of T. atroviride were 6-pentyl - 2H-pyran-2-one, quinoline, phenol, 2-(6-hydrazino-3-pyridazinyl) and heptadecane. In conclusion, the isolate TA12 could be exploited to develop an effective biocontrol management practice for combating Fusarium wilt disease of Fusarium oxysporum f.sp. lycopersici in tomato

Antifungal activity of Trichoderma atroviride against Fusarium oxysporum.f.sp.lycopersici causing wilt disease of tomato

Fusarium oxysporum f. sp. lycopersici causing tropical wilt of tomato is a destructive phytopathogen. To study bio efficacy of fungal bio agents, fifteen isolates of Trichoderma species were isolated from rhizosphere soil of healthy tomato plants. Among the isolates, TA12 showed higher antagonistic efficacy against the pathogen. Upon analysis of the rDNA of internal transcribed spacers (ITS) and molecular data, the isolate was identified as Trichoderma atroviride. The in vitro antagonistic assessment indicated that the T. atroviride isolate caused significant inhibition of F. oxysporum f. sp. lycopersici. Trichoderma atroviride (TA12) showed antagonistic activity against F. oxysporum with mycelial inhibition of 71.25%. The culture filtrates of Trichoderma atroviride exhibited its antifungal activity against F. oxysporum with a suppression of 77.77%. Moreover, the ethyl acetate extracts of T. atroviride TA12 showed the highest antifungal potency against F. oxysporum f. sp. lycopersici. The main bioactive constituents of T. atroviride were 6-pentyl - 2H-pyran-2-one, quinoline, phenol, 2-(6-hydrazino-3-pyridazinyl) and heptadecane. In conclusion, the isolate TA12 could be exploited to develop an effective biocontrol management practice for combating Fusarium wilt disease of Fusarium oxysporum f.sp. lycopersici in tomato