Grafting Tomato Scions on Root Knot Nematode (RKN)-Resistant Brinjal Rootstocks Complemented with Biocontrol Agents as an Integrated Nematode Management (INM) Strategy for the Development of RKN-Resistant Tomato

Root knot nematodes (RKNs; Meloidogyne spp.) are among the biotic stressors that reduce growth and yield by 25–100% in solanaceous crops like tomato. The present study screened 35 eggplant accessions against RKNs (inoculum: 1 J2/g soil). Average root galls and egg masses per root ranged from 6.66 to 196.66 and from 4.66 to 192.66, respectively. Of the 35 accessions, BR3 was identified as resistant, exhibiting low galling index (6.66 galls/root) and egg mass count (4.66 egg masses/root), along with the highest total phenolic content (1515.92 μg/g). The shaft grafting of the susceptible tomato variety Hisar Arun (scion) onto resistant eggplant accession BR3 (rootstock) achieved a 90% success rate. Three biocontrol agents, namely, Trichoderma viride, Paecilomyces lilacinus, and Pseudomonas fluorescence were applied @2 g and 4 g per kg of soil to enhance resistance against RKNs in the grafted tomato plants (Hisar Arun variety). Among these, P. lilacinus at 4 g/kg soil reduced root galls, egg masses, and final nematode population by 84.65%, 95.7%, and 82.12%, respectively, compared with positive controls. Grafted plants treated with P. lilacinus at 4 g/kg soil also exhibited superior growth parameters relative to the control plants. Hence, the Integrated Nematode Management (INM) strategy developed in the present study can be used for delivering natural resistance against root knot nematodes in tomato plants and other solanaceous crops.