In vitro and in planta nematicidal activity of black pepper (Piper nigrum L.) leaf extracts

In this study, biological control of root-knot nematode (Meloidogyne incognita) by aqueous leaf extracts of black pepper was investigated. Results revealed that the leaf extracts inhibited nematode survival and other life parameters in a dose-dependent manner. Black pepper leaf extract was able to penetrate the nematode egg mass matrix and significantly reduce the percentage of egg hatching along with fatal effects on J(2)s and simultaneous enhancement of tomato plant growth. Egg viability after treatment was found to be less sensitive to the aqueous extracts than J(2)s, based on LC50 values. Complete mortality of J(2)s was recorded for 40, 60, and 80% dilutions of extracts, while 100% egg inhibition was only observed with the undiluted standard extracts (SE). The leaf extracts significantly inhibited, egg production and egg hatching after treatment. Specific activities of the resistance-related enzymes; peroxidase (PDX), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) increased significantly as a result of treatment with leaf extracts. Maximum activities of PDX, PPO and PAL were observed at the fifth day after treatment. Results suggested that aqueous leaf extracts of black pepper show significant, sustainable and eco-friendly nemato-toxic effects through inactivation of growth and eradication of M. incognita. This study provides information for use of black pepper leaf extracts for control of M. incognita and could be a possible replacement for synthetic nematicides with fewer side effects in the soil and on crops. (C) 2017 Elsevier Ltd. All rights reserved.