Enhancing tomato crop protection: Utilizing microbial and botanical bioproducts to control Meloidogyne incognita population

The cultivation of tomatoes (Solanum lycopersicum L.) is seriously threatened by root-knot nematodes (Meloidogyne spp.), which can result in significant yield losses and decreased fruit quality. This study explores the efficacy of biological agents Trichoderma harzianum, Photorhabdus luminescens and Neem cake as an alternative strategy for managing M. incognita. During the study period T. harzianum caused maximum mortality 99.60 % followed by Neem cake 84.8 % and 79.2 % by P. luminescens against the infective second stage juveniles (IJ2) after 72 hr exposure period under laboratory conditions. The LC50 value and associated 95 % confidence limits were used to express the data on the in vitro nematicidal activity of biological agents. The pot experiment showed that the T. harzianum at 2 × 106 spores/10 mL suppressive effect was superior to all other treatments in terms of root gall index (RGI) (1.27), followed by Neem cake (2.07). P. luminescens at 4×104/10 mL/pot was found less effective in preventing M. incognita with the highest root gall index (RGI) (2.60). Similarly, T. harzianum had lowest number of females and egg masses (33.33, 27.00), followed by Neem cake (42.33, 48.33) and P. luminescens (58.0, 61.67). It also showed the most significant (P<0.05) decline in the nematode population (70.00) and reproduction factor (0.14) followed by Neem cake and P. luminescens in field efficacy. T. harzianum also achieved the lowest nematode egg masses and galling index. The study found that T. harzianum, Neem cake and P. luminescens treatments improved plant growth, with maximum shoot length, root length and fruit yield respectively. Nematode infection suppressed chlorophyll, carotenoid and sugar content in plants, with T. harzianum causing the most significant increase in chlorophyll and carotenoid content, followed by Neem cake and P. luminescens, with minimal increases in these parameters. These findings suggest that integrating these biological agents into nematode management strategies can offer an effective and sustainable approach for controlling root knot nematodes in tomato crop.