International Journal of Tropical Agriculture and Food Systems, 4(1): 83-85, 2010
Adeniyi et al.: IJOTAFS 4(1): 2010
Fresh leaves of neem (Azadirachta indica) were collected and wash...
Adeniyi et al.: IJOTAFS 4(1): 2010

Azadirachta indica as shown in this experiment is effective in inhibiting t...
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Adeniyi et al 2010. effect of neem (azadirachta indica) leaf extracts on the rot fungus (fusarium spp) isolated from kola nuts


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Adeniyi et al 2010. effect of neem (azadirachta indica) leaf extracts on the rot fungus (fusarium spp) isolated from kola nuts

  1. 1. International Journal of Tropical Agriculture and Food Systems, 4(1): 83-85, 2010 © Tapas Institute of Scientific Research and Development, 2010 SHORT COMMUNICATION EFFECT OF NEEM (AZADIRACHTA INDICA) LEAF EXTRACTS ON THE ROT FUNGUS (FUSARIUM SPP) ISOLATED FROM KOLA NUTS D. O. Adeniyi, S. B. Orisajo and K. B. Adejobi Plant Pathology Section, Crop Protection Division, Cocoa Research Institute of Nigeria, Km 14, Ibadan-Ijebu-Ode Road, PMB. 5244, Ibadan, Nigeria Corresponding author: D. O. Adeniyi; E-mail: ABSTRACT: The storage lifespan of kola nuts is challenged by the problem of decay of nuts in storage as a result of the attack by the rot fungus (Fusarium spp). The effect of the neem leaf (Azadirachta indica) extracts on the rot fungus was investigated in order to aid extended kola nuts storage. The aqueous and ethanolic leaf extracts of neem plant in varied concentrations were used as amendments of 20 ml of potato dextrose agar (PDA) at ambient temperature. It was observed that the various concentrations (5.0, 10.0, 15.0, 20.0 and 25.0 g/cm3) of the neem leaf extracts inhibited radial growth of Fusarium spp Significantly with 20.0 and 25.0 g/cm3 having the best mean percentage inhibition of 82%. The ethanolic extracts had a higher inhibition of Fusarium spp. at lower concentrations compared to aqueous extracts but both extracts were significantly better than the control. Keywords: Kola nuts, Neem, Azadirachta indica, leaf extraction, Fusarium spp, rot fungus INTRODUCTION Cola is a tropical African genus that belongs to the family Sterculiaceae, with over a hundred species. The two most commonly used species and of greatest economic importance are the Cola acuminata and C. nitida (Lovejoy, 1980). Kola nuts are often stored immediately after harvest in baskets lined with leaves, however the high rate of transpiration forming droplets of water on their surface initiate the development of various parasitic fungi (Opeke, 2005). Cola nitida and C. acuminata were believed to be resistant and biologically robust species and have no important diseases associated with them (Russell, 1955), but reports have shown that Cola species are vulnerable to a host of fungal diseases that can attack all parts of the crop (Oludemokun, 1979). Various publications have shown that, storage of kola nuts in basket with fresh leaves at a high temperature and high humidity provokes development of various parasitic fungi, especially wet rots caused by Fusarium and Penicillium species (Oludemokun, 1979). One of the principal post harvest pathogens was found to be Fusarium sp (Gohil and Vala, 1996; Gour and Sharmaik, 1998; Pandey et al., 1992; So, 1990; Tariq and Magee, 1990). Plants have been known for their medicinal and anti-microbial properties since ancient times. Research attention has recently been focused on alternative safe and cheap methods of managing pathogenic microorganisms. Some plants extracts harbor inhibitors that alter sporulation and vegetative growth (Abdel-Raouf, 2001). Some members of the family Meliaceae are known to pathogenic properties of fungus (Ram et al., 2000). Azadirachta indica is a well-known medicinal plant. For more than 200 years, it has been used as one of the most versatile medicinal plant having a wide spectrum of biological activity. Scientists have derived some beneficial compounds from it for diseases control. Such natural plants products are biodegradable, exhibit structural diversity and rarely contain halogenated atoms (Hina, and Arshad, 2007). A large number of compounds have been isolated from various parts of neem. Those with antifungal biological activity are nimbidin, gedunin, cyclic trisulphide and cyclic tetrasulphide (Kausik et al., 2002). This study was undertaken to evaluate the antifungal potential of aqueous and ethanolic extracts of the leaves of A. indica against Fusarium spp isolated from kola nuts. 83
  2. 2. Adeniyi et al.: IJOTAFS 4(1): 2010 MATERIALS AND METHODS Fresh leaves of neem (Azadirachta indica) were collected and washed thoroughly in water. The leaves were air-dried on laboratory bench at room temperature and ground into powder using mortar and pestle. The hot water extraction of the leaves was achieved by infusing 5.0, 10.0, 15.0, 20.0 and 25.0 g of A. indica powder into 100 ml of sterile distilled water in a 250 ml conical flask in water bath at 50OC for 2 hours. This was allowed to cool and the crude extracts obtained from the infusion by filtration through sterile muslin cloth to give concentration of 5, 10, 15, 20 and 25% respectively. The ethanolic extraction of the neem leaf was prepared according to the method of (Ayoola et al., 2008). Potato dextrose agar(PDA) was prepared routinely and 10% lactic acid added to suppress bacteria growth. The Fusarium sp was isolated from the storage rot development in kolanut using the method of (Hina and Arshad, 2007), with some modifications and maintained on Agar PDA medium. The effect of neem leaf extract was tested on the mycelial growth of the isolated fungus. Five ml of each of the percent concentrations of the neem extract were mixed thoroughly with about 20 ml of PDA separately in Petri dishes and were allowed to solidify. An inoculum disc of 4 mm diameter of the pure culture of the isolate was placed on the potato dextrose extract agar in each Petri dish and replicated thrice. Five ml of sterile water in place of the extracts serve as control. The plates were incubated at ambient temperature and observations were recorded at regular interval. The toxicity of the crude and ethanolic extracts was determined against the pathogen. The percent inhibition of mycelial growth over control was calculated using the formula: Percentage of inhibition = 1 – Diameter of treated colony Diameter of control colony RESULTS AND DISCUSSION The aqueous and ethanolic extracts of the leaf of A. indica showed varying degrees of inhibition on Fusarium sp by suppressing their mycelial growth. The degree of inhibition in both methods of extraction increased with the increase in the concentration of leaf extract, but the control showed zero inhibition. The mycelial growth inhibition by the aqueous leaf extract ranged from 14 – 82% at 20 and 25% concentration, while that of the ethanolic extract was from 30 – 82% at the same extract concentrations (Table 1). Table 1: Inhibition of Aqueous and Ethanolic extracts on mycelial growth of Fusarium spp. Leaf extracts concentration Percentage Inhibition Water extracts (%) Ethanolic extracts (%) 5 14d 30d 10 25c 41c 15 32b 72b 20 82a 82a 25 82a 82a 0 (Control) 0e 0e Mean followed by the same letter in the same column are not significantly different (P=0.05) The ethanolic extract tested was shown to be more effective as it was seen to have greater percent of inhibition on the fungus compared to the aqueous extract. However, both exhibit equal inhibitions of the mycelial growth at 20 and 25% extracts concentrations. The ethanolic extracts again had higher inhibition of Fusarium spp. at lower concentrations compared to aqueous extracts. Azadirachta indica has been reported as effective against Fusarium oxysporum causing wilt disease of Solanum melogena. A. indica was effective in reducing the mycelial growth of F. oxysporum at 50% concentration of plant extracts (Siva et al., 2008). The present results are also in agreement with the earlier report by Govindachariu et al. (1999) that A. indica showed high antifungal activity against spore germination of F. oxysporum and Colletotrichum lindemuthianum. Extracts of Tridax procumbens and Capparis deciduas were also reported to totally inhibit spore germination of F. oxysporum (Bindu and Padma, 2009). The aqueous extracts of A. inidica significantly suppressed the biomass of Macrophomina phaseolina. There was a gradual decrease in fungal biomass with the increase in extract concentration (Hina and Arshad, 2007). 84
  3. 3. Adeniyi et al.: IJOTAFS 4(1): 2010 CONCLUSION Azadirachta indica as shown in this experiment is effective in inhibiting the mycelial growth of Fusarium spp in-vitro. Azadirachta indica could thus serve as inhibitor of Fusarium spp. associated with kola nuts as observed in this experiment. REFERENCE Abdel-Raouf, M. K. (2001). Phytofungitoxic properties in the aqueous extracts of some plants. Pakistan Journal of Biological Sciences, 4(4): 392 – 394. Ayoola, G. A., Coker, H. A. B., Adesegun, S. A., Adepoju-Bello, A. A., Obaweya, K., Ezennia, E. C. and Atangbayila, T. O. (2008). Phytochemical screening and Antioxidant Activities of some selected medicinal plants used for Malaria Therapy in Southwestern Nigeria. Tropical Journal of Pharmaceutical Research. 7(3): 1019 – 1024. Bindu, S. and Padma, K. (2009). In vitro antifungal potency of some plant extracts against Fusarium oxysporum. International Journal of Green Pharmacy, Pp: 63 – 64. Gohil, V. P. and Vala, G. D. (1996). Effect of extracts of some medicinal plants on the growth of Fusarium moniliforme. J. Mycol. Pl. Pathol., 26(1): 110 – 111. Gour, H. N. and Sharmaik, C. (1998). Inhibitions of growth, sporulation and phytotoxicity of Fusarium oxysporum fungal species cumini, a wilt pathogen of cumin by plant extracts. J. Mycol. Pl. Pathol., 2: 76 – 77. Govindachariu, T. R., Suresh, G. and Masilamani, S. (1999). Antifungal activity of Azadirachta indica leaf hevane extract. Fitoterapia, 70: 417 – 420. Hina, A. and Arshad, J. (2007). Evaluation of antifungal activity of Meliaceae family against Macrophomina phaseolina. Mycopath., 5(2): 81 – 84. Kausik, B., Ishita, C., Ranajit K. B. and Uday, B. (2002). A review. biological activities and medicinal properties of neem (Azadirachta indica). Current Science, 82(11): Lovejoy, P. E. (1980). Kola in the history of West Africa. Cashier d’Etudes Africaines, 77 – 78: 97 – 134. Oludemokun, A. A. (1979). A review of Cola diseases. Pans, 25: 265 – 269. Opeke, L. K. (2005). Tropical commodity tree crops. Spectrum Books Limited, Ibadan, Nigeria. Pandey, J. C., Kumar, R. and Gupta, R. C. (1992). Possibility of biological control of rhizome rot of ginger by different antagonists. Progressive Horticulture, 24(3-4): 227 – 232. Ram, M. S., Ilavazhagan, G., Sharma, S. K., Dhanraj, S. A., Suresh, B., Parida, M. M., Jana, A. M., Devendra, K. and Selvamurthy, W. (2000). Antimicrobial activity of a new vaginal contraceptive NIM-76 from neem oil (Azadirachta indica). J. Ethnopharmacol., 71: 377–382. Russell, T. A. (1955). The kola of Nigeria and Cameroon. Trop. Agric., 32: 210 – 240. Siva, N., Gamesan, S., Banumathy, N. and Muthuchelian, V. (2008). Antifungal effect of leaf extract of some Medicinal plants against Fusarium oxysporum causing wilt disease of Solanum melogena L. Ethanobotanical Leaflets, 12: 156 –163. So, M. L. (1990). Antifungal activities of mangrove plants. Proceeding of the 3rd International Conference on Plant Protection in the tropics, Malaysia Plant Protection Society Malaysia , 2: 95 – 98. Suleiman, M. N., Emua, S. A. and Taiga, A. (2008). Effect of aqueous leaf extracts on a spot fungus (Fusarium Sp) isolated from cowpea. American-Eurasian J. Sust. Agri., 2(3): 261 – 263. Tariq, V. N. and Magee, A. C. (1990). Effect of volatile from garlic bulb extract on Fusarium oxysporum sp. Lycopersici. Mycol. Res., 94(5): 617 – 620. 85