The efficacy of rice paddy herb essential oil as a herbicide and antimicrobial activity against phytopathogenic bacteria and fungi

Abstract

The essential oil (EO) derived from whole plants of the rice paddy herb collected in Thailand's central area has been studied for antimicrobial activity against phytopathogenic bacteria (Xanthomonas oryzae pv. oryzae and X. oryzae pv. oryzicola) and phytopathogenic fungi (Alternaria porri, Bipolaris oryzae, Collectotrichum gloeosporioides, Fusarium oxysporum, Phytophtophthora parasitica, and Rhizoctonia solani), and the chemical compositions. The EO contained 1-limonene (47.3%), linalool (18.5%), and (+)-trans—Mentha-2,8-diene (9.2%) as the most abundant constituents. The essential oil displayed completely antifungal activity using a percentage of mycelial growth inhibition on R. solani and B. oryzae, following potent activity on A. porri and F. oxysporum. In the case of antibacterial activity using an agar diffusion assay, the oil revealed potent activity against both bacteria tested. The 1-limonene was also evaluated against all phytopathogens, and the compound revealed better effective activity on bacteria than fungi. The results concluded that the oil could be used to develop alternative green agrochemical agents.