ABSTRACT

The nematicidal effects ofdifferent biochar sources (bitter leaves, cassava peels, saw dust and poultry waste) and synthetic nematicide (Carbofuran 3G) on root-knot nematode (Meloidogyne spp.) egg hatchability, and control on mungbean (Vigna radiata (L.) Wilczek) were compared in Petri dishes, pot and field experiments (April-June 2017 and July-September 2017). The Root-knot nematode egg hatchability experiment was laid out in a Completely Randomized Design in Petri dishes placed on a laboratory bench with six treatments replicated three times including the control. Each Petri dish contained 100 eggsml'1 ofthe root-knot nematode. The treatments included: biochars of bitter leaves, cassava peels, saw dust and poultry waste and a synthetic nematicide (Carbofuran 3G). Tap water served as the control. The biochars were applied as a suspension at the rate of 0.1 g/ml while the nematicide at the rate of 0.015 g/ml. Eggs hatched were observed for 24, 48 and 72 hours. The pot experiment was arranged in a Completely Randomized Design using plastic buckets with seven treatments replicated three times including the control. Each bucket was inoculated with 2,000 nematode eggs. Similar treatments as in egg hatchability, in addition to pots with no nematode inoculation were used. The biochars were applied as powder at the rate of 20 g/pot while the nematicide at the rate of 3 g/pot. Data collected included: growth parameters (plant height and number of leaves), pod and grain yield (number of pods, weight of pods, number ofseeds per pod and weight ofseeds), shoot and root parameters (fresh and dry shoot weights, fresh root weight and number ofroot nodules), nematode galls and population (gall index, number of eggs, number ofjuveniles and reproductive factor). The field experiments (the two seasons) were conducted in a land naturally infected with root-knot nematode and were laid out in a Randomized Complete Block Design with six treatments replicated three times including the control. Similar treatments as in pot experiment excluding beds with no nematode infection were used. The biochars and the Carbofuran were applied at the same rate as in the pots. Similar data as in the pot experiment in addition to number of branches ofthe plant, initial and mid nematode populations were taken. The data collected in the three experiments were subjected to Analysis of Variance (ANOVA) and means were compared using Least Significant Difference (LSD) at 5% probability level (P<0.05) by using computer software “Genstat Discovery Edition 4”. Results obtained at the end ofthe experiments showed that bitter leaves biochar compared favourably with Carbofuran on nematode egg hatchability. Generally, the biochars compared favourably with Carbofuran on the control of root-knot nematode on mungbean but did not significantly affect yield and nodulation.