Phytotoxicity of essential oil from Piper nigrum L. on some selected food crops as a potential herbicide in Africa

Phytotoxicity of the essential oil (EO) of Piper nigrum L. against Solanum lycopersicum L., Zea mays L. and Vigna unguiculata L. was studied. The GC-MS analysis of the essential oil of P. nigrum shows that linalool (21.73 %) was the major component of the essential oil. The EO retarded the growth of the root and the shoot of S. lycopersicum, Z. mays and V. unguiculata. The inhibition of the root ranged from 64.8-82.8% after 120 hours with a concentration of 4 mL/L, while for the shoot, 100% inhibition was observed with 4 mL/L of the EO formulation after just 96 hours. The phytotoxic effect on the leaves was highest in V. unguiculata and least in S. lycopersicum. Phototoxicity was also observed when the EO formulations were applied to the root of the seedlings of Z. mays and V. unguiculata recorded 100% distress of the seedlings when 3 mL/L of the graded concentration was used after 24 hours. EO from P. nigrum is a potential bio-herbicide with a wide spectrum of use on plants.