Exploration of herbicidal potential of essential oil of Pogostemon benghalensis Burmf Kuntze

Abstract

The present study investigated the chemical constituents and herbicidal activity of the essential oil extracted from the aerial parts of P. benghalensis. Azulen-2-ol,1,4 dimethyl-7-(1-methyl ethyl)- was observed to be the major component. The chemical analysis of leaf extracts revealed the presence of various phenolic compound that are known to play an important role in allelopathy. Further, the oil and leaf extract was explored for their phytotoxic potential against some weeds and crops. The study revealed that PO and extract exhibited strong phytotoxic effect on the test plants in a dose-dependent manner. In general, greater growth inhibition was observed on weeds as compared to the crops. PO caused various symptoms of visible injuries in spray-treated plants. Further, herbicidal effect of PO was studied on weeds as well as rice and wheat in field conditions. The effect of PO treatment was comparable to the effect of commercial herbicide (butachlor). Another experiement was designed to determine the possible physiological and biochemical mode of action of PO. The content of various macromolecules were significantly enhanced. However, the activity of various associated hydrolyzing enzymes were significantly decreased. It was found that Pogostemon oil exposure induced oxidative stress by disturbing the equilibrium of ROS generation and their quenching by antioxidant enzymes. In response to oil treatment, significant ultrastructural changes in the roots of A. fatua were observed using SEM and TEM. The results revealed that PO exposure caused several deformations in the test plant. newline