Effect of Soil Amendments on the Growth Parameters of Okra Infested with Root-Knot Nematode (Meloidogyne incognita)

Aims: To evaluate the efficacy of Trichoderma harzianum, Neem cake, and poultry manure on the growth performance of okra infected with Meloidogyne incognita.

Study Design: The experiment was laid out in a completely randomized design.

Place and Duration of Study: Department of Botany, University of Calabar, between April 2022 and August, 2022.

Methodology: Soil samples were collected at the depth of 0-15cm using auger, heat sterilized and spread out in a shade for 7days to cool before use for planting okra seed. Galled roots of okra plants were blended and emptied into 1000ml beaker. This was the inoculum used for plant inoculation. Pure culture of T. harzianum inoculated into a steril petri dishes and allowed to sporulate. Neem cake and poultry manure were applied at the rate of 10g and 20g per planting pot. Holes were excavated around the base of the okra plant and 1g of T. harzianum spores was used for inoculation. Data were collected on plant height, number of leaves, petiole length, and percentage leaf abscission.

Results: Number of leaves on pot treated with M. incognita, T. harzianum and 20 g of neem cake was significantly (p≤ 0.05) different from all other pots. Data obtained indicates that after 3 weeks of planting all the treatment combinations had significant (p≤0.05) impact on the crops grown in pots treated with 10 g of neem cake which was not significantly (p>0.05) different. Data obtained on plant height in pots with the treatment combinations (M1T1N0, M1T0N1, M1T0N2, M0T0N2, M0T0N0, M0T0P1 and M0T0P0) were significantly (p≤ 0.05) different. Results on petiole length grown in pots with treatment combinations (M1T1N2, M0T1N1 and M0T0P1) were not significantly (p> 0.05) different from the control.

Results shows that the highest percentage of abscised leaves was observed on plant treated with T. harzianum and Neem cake with 66.4%. Results from other treatments were as follows, M0T0N1 (62.3%), M1T1N0 (58.6%), M0T0N2 (56.3%), M1T0N1 (52.9%) and M1T1N2 (51.2%). Result obtained on soil amendment with poultry manure revealed that pots treated with 20t/ha of poultry manure had impact on plant height which was significant (p≤ 0.05).

Conclusion: Based on the data obtained on the growth parameters, it can be concluded that T. harzianum and neem cake significantly increased the growth of okra infested with M. incognita and the impact was significantly shown on the plant height and petiole length. Number of leaves were significantly different at 3 and 5 weeks after planting. T. harzianum has be proven to be of economic value in agriculture both as biocontrol agent and soil nutrient booster.