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The essential oils extracted from Cymbopogon flexuosus, Cymbopogon winterianus, Cymbopogon martini were analyzed by trapping the volatile organic compounds using solid-phase microextraction-gas chromatography-mass spectrometry and evaluated their antifungal activity against plant fungal pathogens like Fusarium oxysporum f. sp. cepa (Hypocreales: Nectriaceae) and Sclerotium oryzae Cattan (Magnaporthales: Magnaporthaceae). The major volatile organic constituents of C. flexuosus-citral (22.94%), neral (19.88%), camphene (8.37%), cyclohexene, 1-methyl-5-(1-methylethenyl-(R) (5.75%); C. winterianus-citronellal (42.47%), D-limonene (10.86%), geraniol (9.44%), citronellol (6.25%); C. martini-geraniol (43.80%), a-ocimene (10.75%), geranyl acetate (6.35%), 2,6-octadienal, 3,7-dimethyl-(E) (5.83%), were found in concentrations higher than 5.0% (calculated as % peak area of GC-MS analysis using a nonpolar column). In addition, the antifungal tests were also demonstrated that the essential oil of C. flexuosus C. winterianus and C. martini have excellent inhibitory effect against S. oryzae and F. oxysporum. The IC50 values of essential oils from C. flexuosus, C. winterianus and C. martini against at S. oryzae and F. oxysporum were 0.42, 0.41, 1.99 and 0.73, 2.02, 2.01 μL/plate respectively. The significant aroma may be the results of combined 30 volatile organic compounds from essential oils of Cymbopogon species which could be used as safe biocontrol agents to prevent stored product commodities from fungal pathogens.

Forest fires are known to significantly alter soil nutrient availability. The study investigated the post-fire nutrient availability in the sub-tropical forest ecosystem of Koubru Hills, Manipur (North-East India). The forested ecosystem was disturbed by forest wildfire in January 2010.To study the fire effect, collection of burned and unburned soil samples from three soil depths (0-5, 5-10 and 10-15 cm) was started approximately three months after the fire event and continued at monthly intervals for a period of one year. The collected soil samples were analyzed for soil organic carbon (SOC), NH 4 +-N, Bray-extractable phosphorus, available potassium and micronutrients such as Fe, Cu, Mn and Zn. Results of the ANOVA test showed significant reduction in the SOC, NH 4 +-N and available K contents of the surface (0-5 cm) and sub-surface (5–10 and 10-15 cm) soil layers of the burned area. However, significant increases in the Bray-extractable phosphorus were observed in all the three soil depths studied. With respect to the effect of forest fire on soil micronutrient availability, results are contradictory. The available Fe depleted in all the three soil depths, whilst the available Cu declined in the 0-5 cm but increased in the 10-15 cm soil layer. The available Cu content of the 5-10 cm soil layer did not vary between the burned and unburned areas. While no significant effect of fire was observed on the available Mn contents of the 0-5 and 10-15 cm soil layers, there was a significant post-fire decrease in the Mn availability of the 5-10 cm soil layer of the burned area compared with the unburned area. Forest fire also resulted in a significant loss of the available Zn from the 0-5 and 5-10 cm soil layers of the burned area but in the 10-15 cm soil layer, no significant variation was observed between the burned and unburned areas.