Evaluation of diverse okra germplasm for identification of source of resistance to root-knot nematode, Meloidogyne incognita

Aim: The present study was carried out to identify the okra germplasm resistant to root-knot nematode for cost effective and environment friendly management of root-knot-nematode, Meloidogyne incognita. Methodology: A total of 239 diverse accessions (acc.) of okra were evaluated under net house conditions. Experiments were conducted in 10 cm diameter pots filled with 500 g soil with challenge inoculation of 1000 second stage juveniles of root-knot nematodes. Resistance assessment was done after 42 days of inoculation based on the number of root galls developed. The resistant accessions were identified and re-evaluated under controlled conditions to validate the resistance. Results: Based on root galling index, host response of 239 accessions (acc.) was observed as Immune (0 acc.), resistant (8 acc.), moderately resistant (19 acc.), moderately susceptible (28 acc.), susceptible (145 acc.) and highly susceptible (46 acc.). Repeated evaluation of 8 resistant accessions of okra (EC306737, EC305619, EC360672, EC360927, IC022232, IC117074, IC255758 and IC39140) showed consistent root-knot nematode resistance by these accessions. Final population and reproduction factor of root-knot nematode were found significantly low in identified resistant accessions. Interpretation: These eight identified accessions are novel for root-knot nematode resistance and therefore, important for future use in crop breeding programmes for root-knot nematode resistance in okra. Key words: Abelmoschus esculentus, Host plant resistance, Root-knot nematode