Effect of Tamarindus indica L. Leaf Extract and Citrus sinensis L. Osbeck Peel Extract on Meloidogyne spp (Root Knot Nematodes) in Jos, Plateau State

Aim: The Aim of this study is to determine the effect of aqueous leaf extract of Tamarindus indica and peel extract Citrus sinensis on Root Knot Nematodes, in vitro.

Study Design: The experiment was carried out using a completely randomized design.

Place of Study: This study was carried out in the biology laboratory of the Department of Plant Science and Biotechnology, University of Jos, Nigeria.

Methods: Extraction of phytochemicals from Tamarindus indica leaf and Citrus sinensis peels was carried out using an aqueous solvent. Tamarindus indica leaves and Citrus sinensis peels were collected within the province of Jos, and were dried at constant room temperature to a constant weight after which pulverized, sieved and soaked in water for 24 hours. The extraction was done using the cold maceration method. Eighty (80) second-stage juveniles of Meloidogyne spp. were exposed to the extracts at different concentrations (100, 80, 60, 40, and 20mg/ml) for 6, 12, 18, 24. 30, 32 and 48 hours and, each treatment was replicated 5 times. The average number of dead nematodes per concentration were determined and recorded as mean ± SEM with statistical value at P < 0.05 considered significant.

Results: Results of phytochemical analysis showed that Alkaloids, Flavonoids, Tannins, Steroids, Phenols, and Cardioglycosides were present in T. indica leaf extracts while C. sinensis peels contains Flavonoids, Alkaloids, Saponins, Tannins, Phenols, and Resins. These phytochemicals present are suspected to be responsible for the nematicidal activities of the plants. Nematode mortality in the two treatment groups (T. indica and C. sinensis extracts) was highest at 100mg/ml concentration (48 hours of exposure); It was followed by 80mg/ml in decreasing order while the least mortality rate was recorded at 20mg/ml. Hence, as the concentration of the extracts were increased with increase in time, high nematode mortality was observed. Percentage mortality of treated nematodes was statistically significant (P < 0.05) for all concentrations of the extracts at the different time intervals when compared to the control. Statistical analysis showed that T. indica had significantly higher effect on Root-Knot nematodes mortality than C. sinensis at varying concentrations and time of exposure.

Benefits of Results: Synthetic pesticides are the principal means used to control nematodes, but the natural products may provide a safe alternative. Hence, the active compounds (phytochemicals) in T. indica L. and C. sinensis L. can be harnessed to be used as biopesticides.

Conclusion: The study suggests that extracts of T. indica and C. sinensis can be utilized in the control of root knot nematodes and may have the potential for the production of biopesticides that can be used for the control of nematodes as it displayed nematicidal activities.