Polyphenol oxidase (PPO) enzyme activity in tomato (Lycopersicon esculentum L.) infected by root-knot nematode, Meloidogyne incognita

An experiment was carried out for two successive years 2021 and 2022 under cage house condition in root-knot nematode infested soil (2 J2/g soil) to assess the induction of defence enzyme of polyphenol oxidase (PPO) by different fungal bio-agents against Meloidogyne incognita infecting tomato. Bio-agents viz., Trichoderma harzianum, T. viride, Purpureocillium lilacinum, Metarhizium anisopliae and Beauveria bassiana each as soil application (SA) at 5 g/kg soil and seedling treatment (ST) at 5 g/lit of water and two control treatments viz., M. incognita alone (2 J2/cc soil) and un-inoculated and untreated control was also maintained for comparison. Each treatment was replicated four times. Application of bio-agents increased the level of PPO in tomato leaf, shoot and root sample. Among all treatments application of T. harzianum were found to be the best treatment to enhance PPO activity at 15, 30 and 45 days after inoculation (DAI). However, T. harzianum not only showed the highest biochemical activity of PPO content but also showed increase in the biometric parameters like shoot length(cm), shoot weight (g), root length (cm) and root weight (g) of tomato as also reducing nematode reproduction in tomato followed by T. viride and P. lilacinum.