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  1. EFFICIENCY OF SOME LOCAL PLANTS ESSENTIAL OIL AGAINST SEED-BORNE AND SEED TRANSMITED FUNGI OF RICEKABORE K.B1. ; KOÏTA E1. ; OUEDRAOGO I1.et NEBIE R2.(1) Institut de l’Environnement et de Recherches Agricoles (INERA)(2) Institut de Recherche en Sciences Appliquées et Technologies ; Département Substances Naturelles (IRSAT)Burkina Faso

  2. HEADLINES • Introduction • Objectives • Materials and Methods • Results • Discussion • Conclusions and Perspectives • Aknowledgement

  3. INTRODUCTION • Importance of rice as food crop • Biotic Constraints to production • Seed-borne fungi as major mean of rice diseases transmission and dissemination. • Increasing dependance of rice roduction upon the use of conventionnal pesticides. • Negative impact on Environment and health • Need in research of alternate biopesticides • Research Hypotheses : Some traditionnal local plant species used as medical substances could have fungicide properties (Kaboré et al.,2002)

  4. OBJECTIVES • OVERALL OBJECTIVE • Identify local plant species with bio pesticides properties that can be used in agriculture. • SPECIFIC OBJECTIVES • Identify local plant species with essential oil presenting fongicide properties; • Determine efficient level of application of essential oil for rice seed treatment against fungal mycoflor.

  5. MATERIAL AND METHODS (contd) • local plants species used for study: • Cymbopogon citratus (D.C.) Stapf. Common french name : citronnelle (Poaceae ); • Cymbopogon giganteus Chiov ( Poaceae ); • Lippia multiflora Moldenke, (Verbenaceae) Common french name : thé de Gambie ; • Ocimum basilicum L, (Lamiaceae).

  6. MATERIAL AND METHODES • Rice variety used : IR6623275-5-12 • Seed-borne fungi and their contamination level (%) : • Bipolarisoryzae = 28,5 • Curvulariaoryzae = 11,5 • Curvularialunata = 13,5 • Fusariummoniliforme = 48,5 • Phomasorghina = 19,5

  7. Cymbopogoncitratus

  8. MATERIAL AND METHODS (contd) • Essential oil was extracted by hydrodistillation with a Clevenger apparatus from fresh leaves collected from the different species during rainy season 2004. • Essential oil of Ocimum basilicum L., Cymbopogon citratus (DC) Stapf, Cymbopogon giganteus Chiov.et Lippia multiflora Moldenkewas used at the concentration of 1% ; 1,5% et 2% corresponding respectively to 10 ml, 15 ml et 20 ml per litre of media ( PDA)

  9. MATERIAL AND METHODS(contd) • The conventionnal control for cereal seed treatment fungicide was Calthio DS( 20 % of Lindane and 25 % of Thiram. This product was incorporated into the media (2,5 g per litre of PDA media) • Seed treatment • Seed health testing by the blotter method • Four replicates of 50 seed (25 seeds per Petri dish) were soaked for 20 to 24 hours in essential oil emulsion (1%, 1,5% and 2%) ; • Incubation à 22°C

  10. MATERIAL AND METHODS (contd) • Radial growth measurement of the fungi • Essential oils were incorporated into the PDA media at the concentration of 1%, 1,5% and 2%. • Petri disheswere incubated at 28°C under alternate cycles of 12h of NUV light and 12h of darkness. • Measurement of radial growth (cm) after 3, 5 , 7 and 10 days of incubation (perpendicular diametre Method). • Experimental design : Split plot with oils as main factor and concentrations as secondary factor.

  11. MATERIAL AND METHODS (contd) • Efficiency of extracts (Greche et Hajjaji, 2000) : E(%) = 100[DMT-DMH]/ DMT where DMT represents the mean diametre of the control (non treated) and DMH the mean diametre of the treatment with essential oil. • Data were analysed for ANOVA with STATVIEW/SAS software and the means were separated by the Student- Newman- Keuls test

  12. RESULTS

  13. ANOVA • ANOVA indicated significant différencies between the traetments for the test of radial growth of the fungi as well as the test of seed germination ; • No significant difference was observed between the tested concentrations

  14. Efficiency of essential oils • All the four tested essential oils inhibited the radial growth of the fungi : Bipolaris oryzae, Curvularia lunata Fusarium moniliforme and Phoma sorghina. • When considering the different concentrations, these oils reduced significantly the incidence of the four seed-borne fungal species as compared to the controls.

  15. a b c d e Pétri dishes presenting efficiency of C. Citratus essential oil againstCurvularia lunata (a=concentration 1%, b=concentration 1,5 %, c=concentration 2 %, d=non treated control , e= control calthio).

  16. Global seed contamination following treatment with essential oil

  17. Incidence of Seed –borne fungi after seed treatment with essential oil (B. oryzae, C. lunata, F. moniliforme et P. sorghina

  18. DISCUSSION • Essential oil of C. citratus, C. giganteus, L. multiflora and O. basilicum reduced significantly the incidence of seed contamination by the fungi and inhibited the radial growth of fungal colonies as compared to the different controls. • The presence of citral in the essential oil of C. citratus(Djibo., 2000), and also the presence of oxygenous components like linalol and eugénol in essential oil of O. basilicum(Nébié et al., 2002) could explain antifungic properties of these two plant species.

  19. DISCUSSION (Contd) • These results are comparable to those of Dongma (2002) who evaluated in vito the antifungic activity of essential oil of Citrus limon and Citrus latifolia against the inciting fungus of citrus phaeoramulariosis  (Phaeoramularia angolensis). • Concerning the seed germination test by the blotter method, essential oils of C. citratus and C. giganteus were highly efficient against the fungi but were slightly phytotoxic. Dabiret (2004) came to the same conclusion that essential of the genus Cymbopogon has a negative effect on seed germination.

  20. CONCLUSIONS • Essential oils ofC. citratus, C. giganteus, L. multiflora and O. basilicumhave antifongic properties. • For the firts time, efficency of L. multiflora oil in improving the germination capacity of rice seed under laboratory conditions was demonstrated. • Essential oil of Lippia did not exhibited any phytotoxic effect at the testedconcentrations as compared to oils of Cymbopogon, and Ocimum; moreover; it reduced by up to 28,81 % the incidence of seed-borne and seed-transmitted fungi.

  21. PERSPECTIVES • The tested concentrations of some essential oils used in this study should be lowered because of the observed phytotoxicity they produced on the seed germination tested by the blotter method..

  22. AKNOWLEDGEMENTWe like to thank Adama OUATTARA and Raphaël SANOU for their technical contribution to the realization of the present work .

  23. Thank you for your attention ASANTE SANA

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