Evaluation of Botanicals for the Management of Root-Knot Nematode (Meloidogyne graminicola) in Rice under Pot Conditions

Abstract

Rice (Oryza sativa L.) production is constrained by several pests and diseases, including the rice root knot nematode, Meloidogyne graminicola. This study evaluated the effectiveness of nineteen fresh green-leaf botanical amendments into soil against M. graminicola. A pot experiment was conducted in a completely randomized design with 20 treatments, comprising nineteen botanicals and an untreated inoculated control with three replications. The fresh leaves were chopped and incorporated into nematode-infested soil at 25 g/kg soil and allowed to decompose for 15 days before sowing rice seeds. Root gall number, shoot and root length, and fresh shoot and root weight were recorded at 25 and 50 days after sowing (DAS). At 50 DAS, all botanical treatments reduced gall formation compared with the untreated control, which recorded 24.00 galls/plant. The lowest gall numbers were recorded with Cannabis sativa (1.56 galls/plant) and Jatropha curcas (1.78 galls/plant). Several botanicals also significantly improved plant growth. Aegle marmelos produced the longest shoot length (49.89 cm), Chenopodium album the longest root length (15.78 cm), Datura alba the highest shoot fresh weight (3.01 g), and Azadirachta indica the highest root fresh weight (3.88 g). Considering both nematode suppression and plant growth, C. album, D. alba, A. indica, and A. marmelos showed promising overall performance. These botanicals, therefore, warrant further evaluation under field conditions.