Studies on Biology, Molecular Characterization and Eco-friendly Management of Root Knot Nematode (Meloidogyne Graminicola) of Basmati Rice

Abstract

Root knot nematode (Meloidogyne graminicola) has been reported a serious pest of paddy, especially in light textured soil and irrigated upland condition. It causes damage to nurseries and main field. The main characteristic symptoms produced by M. graminicola are terminal hook shaped or spiral galls on the roots and other symptoms of damage include patches of stunted and yellowish plants in field. Fifty three promising rice varieties were screened against rice root knot nematode out of which 33 were basmati and 20 were non-basmati under pot condition to know the response of the varieties against root knot nematode. Out of 53 varieties in which 18 variety showed moderately susceptible reaction viz., Unnat Pusa Basmati, CSR 30, Malviya Basmati, Kasturi Basmati, Silky, PR-13, Tilak Chandan, Satthi, Ganga Kaveri 7029, Sarju 52, Ganga Masuri, Dhan Rekha, BRRI 26, PR-21, HRK-47, PR-14, Benam Badsha & B-40 and rest 35 variety were shown susceptible reaction against rice root-knot nematode. No any variety was shown resistant and highly susceptible reaction against root knot nematode. Pathogenicity tests confirmed the nematode impact on basmati rice crop causing galls formation on roots in relation to inoculum levels. The life cycle of rice root knot nematode was completed in 25-31 days after inoculation in which, duration of second, third, fourth, adult and eggs stages lasted for 3-7, 8-12, 13-16, 25-28 and 30-31 days respectively. Molecular characterization of the nematode, using ITS, D2-D3 28s rRNA, cox II-16S rRNA and Mg-F3/Mg-R2 primers, identified the presence of M. graminicola in rice fields with high nucleotide homology. For management of rice root knot nematode, use of chemicals is becoming more expensive and undesirable due to environmental hazards. Use of bio control agents coupled with organic amendments is an eco-friendly, sustainable and economically feasible method for nematode management. In-vitro study of culture filtrate of selected bio-agents was tested on larval mortality and egg hatching of M. graminicola. Among all the bio-agents Trichoderma spp. isolate S13 was found more effective with 71.65% larval mortality and 45% egg hatching at 10 % concentration at 72 hours after inoculation. Whereas in control larval mortality 3.30% and egg hatching 83.30% was recorded at 72 hours. Pot experiment was conducted to study the efficacy of selected bio-agents on management of root knot nematode and plant growth parameter of rice plant. On the basis of two years observations, minimum 8.67, 7.66 galls/plant and maximum 30.56, 49.11 cm shoot length in Trichoderma isolates S13 @ 5g/kg of soil perform better results as compared to other bio-agents at 60 DAS. Field experiment was conducted to see the efficacy of selected bio-agents in the management of root knot nematode. Minimum (10.66, 10.44) galls /plants, maximum shoot length (81.06 & 104.67 cm) and maximum yield (13.66 and 12.96 q/ha) were recorded in soil application of Trichoderma isolates S13 @ 20 g/m2 in years 2022 and 2023 respectively at 60 days after transplanting. On the basis of present study it has been observed that Trichoderma isolate S13 is performing well in the management of rice root knot nematode. It may be a better component of integrated management program for rice root knot nematode.