Activity of defensive enzymes in chilli germplasm in relation to their reaction to chilli thrips, Scirtothrips dorsalis Hood

Activity of defensive enzymes in the leaves of seven chilli germplasm collections of whicch two were resistant and five were moderately resistant to chilli thrips, Scirtothrips dorsalis Hood was studied in comparison to susceptible germplasm at Bhubaneswar, Odisha, India. The resistant chilli germplasm viz., BC-7-2-1, BC-25 and moderately resistant chilli germplam viz., BC-27-2-2, BC-21, BC-79-1, Utkal Abha and BC-406 had 5.84–8.23 μM min⁻¹ g⁻¹ peroxidase, 0.1–0.2 μM min⁻¹ g⁻¹ poly phenol oxidase and 7.39–14.16 μM min⁻¹ g⁻¹ catalase in the leaf sample respectively, as against 1.42–4.42 μM min⁻¹ g⁻¹, 0.03–0.08 μM min⁻¹ g⁻¹ and 3.18–6.36 μM min⁻¹ g⁻¹ protein in the leaves of susceptible chilli germplasm(LCA-620,BC-78-1-2 and BC-24-1) and highly susceptible check chilli germplasm (Byadagi kaddi), respectively. A significantly inverse relation existed between the activity of defensive enzymes viz., peroxidase (−0.984**), polyphenol oxidase (−0.965**), catalase (−0.965**) and the incidence of S. dorsalis. The multiple linear regression analysis revealed that all these defensive enzymes together influenced the population of S. dorsalis to an extent of 97.81 per cent.