Efficacy of plant extracts to control Pyricularia grisea fungus causing rice blast in vitro

Abstract

This study was conducted to determine the resistance of Pyricularia grisea of dayflower (Commelina communis) and basil sweet (Ocimum basilicum) extracts. Antifungal activity of methanol extract from dayflower with different concentrations (0.1, 0.5, 1.0, 5.0, and 10 mg/ml) was tested on three isolates of P. grisea (isolate 1, isolate 2, and isolate 3). The antifungal activity of methanol extract from basil sweet with different concentrations (10, 20, 30, and 40 mg/ml) was tested on two isolates of P. grisea (isolate 4 and isolate 5). Results showed that both methanol extracts from dayflower and basil sweet reduced the growth of P. grisea at all tested concentrations. At the highest concentration (10 mg/ml), the leaf extract of dayflower inhibited the three strains of P. grisea (isolate 1, 2, and 3) with the zone of inhibition of 16.33; 29.67; 25.33 mm. For basil sweet at a concentration of 40 mg/ml, the extract was most resistant to P. grisea (isolate 4 and isolate 5) strains with the zone of inhibition of 65.50 and 55.00 mm, respectively. The results also indicate that the mycelial growth inhibition was high as IC50=2.35 mg/ml at isolate 2 by dayflower and IC50=19.68 mg/ml at isolate 5 by basil sweet. The extracts of dayflower and basil sweet used to inhibit the development of P. grisea in vitro initially brought positive results. Therefore, it is necessary to continue conducting experiments in vivo to gradually develop plant-based blast fungicides, contributing to minimising the harm caused by chemical fungicides.