Evaluation of biocontrol potential of Arthrobotrys oligospora against Meloidogyne graminicola and Rhizoctonia solani in Rice (Oryza sativa L.)

Abstract

.The nematode trapping and mycoparasitic potential of Arthrobotrys oligospora was tested in vitro against Meloidogyne graminicola and Rhizoctonia solani, respectively. Five isolates of A. oligospora were isolated from different locations of India. Diversity of the trapping structures is large and highly dependent on the environmental condition and nature of the fungus. In A. oligospora, a three-dimensional adhesive net ( in response to nematode ) and hyphal coils developed around the hyphae of R. solani. In vitro trap formation and predacity were tested against second-stage juveniles of M. graminicola (J2) and the interactions between A. oligospora and R. solani were recorded. Under field conditions, we demonstrated the biocontrol potential of A. oligospora against R. solani causing sheath blight of rice (Oryza sativa) for the first time. All the isolates of A. oligospora parasitized and killed M. graminicola and R. solani. Application of A. oligospora, isolate VNS-1, in soil infested with M. graminicola and R. solani reduced the number of root knot by 57.58 – 62.02 percent, sheath blight incidence by 55.68–59.32 percent and lesion length by 54.91 – 66.66 percent under green house and miniplot (field) conditions. Applications of A. oligospora to the soil increased plant growth: shoot length by 56.4 – 68.8 percent, root length by 44.0 – 54.55 percent, fresh weight of shoot and root by 62.91 – 65.4 nd 38.9 – 44.19 percent, respectively, as compared to the plants grown in nematode infested soil.