Science

Permanent URI for this communityhttp://repository.kln.ac.lk/handle/123456789/1

Browse

Has files: YesSubject: search.filters.subject.essential oils

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Fungicidal and anti-aflatoxigenic effects of the essential oil of Cymbopogon citratus (DC.) Stapf. (lemongrass) against Aspergillus flavus Link. isolated from stored rice
    (The Society for Applied Microbiology, 2003) Paranagama, P.A.; Abeysekera, K.H.T.; Abeywickrama, K.P.; Nugaliyadde, L.
    Aims: To develop a natural fungicide against aflatoxigenic fungi, to protect stored rice, using the essential oil of lemongrass. Methods and Results: Aspergillus flavus Link. was isolated from stored rice and identified as an aflatoxigenic strain. Lemongrass oil was tested against A. flavus and the test oil was fungistatic and fungicidal against the test pathogen at 0Æ6 and 1Æ0 mg ml)1, respectively. Aflatoxin production was completely inhibited at 0Æ1 mg ml)1. The results obtained from the thin layer chromatographic bioassay and gas chromatography indicated citral a and b as the fungicidal constituents in lemongrass oil. During the fumigant toxicity assay of lemongrass oil, the sporulation and the mycelial growth of the test pathogen were inhibited at the concentrations of 2Æ80 and 3Æ46 mg ml)1, respectively. Conclusion: Lemongrass oil could be used to manage aflatoxin formation and fungal growth of A. flavus in stored rice. Significance and Impact of the Study: Currently, fungicides are not used to control fungal pests or mycotoxin production on stored rice. Rice treated with the essential oil of lemongrass could be used to manage fungal pests as well as the insect pests in stored rice. The essential oil is chemically safe and acceptable to consumers, as synthetic chemical fungicides can cause adverse health effects to consumers.
  • Thumbnail Image
    Item
    Efficacy of essential oils from bark and leaf of Cinnamomum zeylanicum on root knot nematode, Meloidogyne graminicola in rice seedlings and young rice plants
    (Journal of Science of the University of Kelaniya, Sri Lanka, 2011) Amarasinghe, L.D.; Wijesinghe, W.K.A.G.A.; Jayawardhane, B.K.
    The present study was conducted to evaluate the efficacy of essential oils from leaf and bark of cinnamon, Cinnamomum zeylanicum in controlling Meloidogyne graminicola and their effects on rice seedlings and young rice plants. This study was done; to determine the LC50 of essential oils of the extracts of cinnamon leaf and bark to kill 50% of second stage juveniles (J2) of Meloidogyne graminicola in rice root galls; to determine the efficacy of essential oils of cinnamon; in controlling J2 in rice seedlings and young rice plants; and on the growth of rice plants. Cinnamon bark oil sample used in the current study contained about 72% cinnamaldehyde and the leaf sample contained about 86% eugenol. LC50 for cinnamon leaf oil and cinnamon bark oil for killing 50% of juveniles of M. graminicola in rice root galls after three days of the treatment was 0.326 ppm and 0.454 ppm respectively. Number of galls in the root system of nematode infested rice seedlings was significantly reduced when they were treated with 0.9 ppm of cinnamon leaf oil and bark oil compared to untreated controls. However, the nematicidal activity between the cinnamon leaf oil and bark oil was not significantly different. The root gall index of infested young rice plants was significantly lowered when they were treated with either cinnamon leaf oil or bark oil compared to untreated controls. It was revealed that the mean plant height and the mean number of roots of essential oil treated plants were positively correlated with the number of root galls whereas, the number of dead plants and the mean percentage chlorosis were negatively correlated. Nevertheless, the mean root length did not show any significant correlation with number of root galls. This study concludes that essential oils of cinnamon leaf which contained 86% eugenol and bark which contained 72% cinnamaldehyde are similarly effective in suppression of M. graminicola in rice seedlings and young rice plants. According to the rates of application of essential oils of cinnamon leaf and bark, none of them have significant negative effect on the plant growth. Hence, they can be used as an alternative nematicide against the rice root knot nematode, M. graminicola in early stage of rice plants.