Trichoderma ghanense Promotes Plant Growth and Controls Disease Caused by Pythium arrhenomanes in Seedlings of Aerobic Rice Variety Apo

Abstract

Aerobic rice is a water-saving technology whereby improved varieties are cultivated under nonflooded conditions. However, continuous cultivation leads to proliferation of soil-borne pathogens such as Pythium spp. This study was conducted to screen for growth-promoting activity of three local isolates of Trichoderma sp. and assess the potential biocontrol activity of the best growthpromoting isolate against the virulent Pythium arrhenomanes 60 (Pa60) and P. arrhenomanes 76 (Pa76) previously isolated from diseased aerobic rice roots. Identity of Trichoderma spp. was determined through sequencing of the internal transcribed spacer (ITS) region of the rRNA gene cluster. Trichoderma isolates were screened for growth promotion of the aerobic rice variety Apo. Among the three isolates, Trichoderma ghanense CDO (TgCDO) exhibited consistent growthpromoting ability. Potential biocontrol activity of TgCDO was determined through plate assays, microscopic observations and pathogenicity tests. TgCDO exhibited antibiosis, inhibitory metabolite production and antagonistic activity against Pa60 and Pa76. TgCDO reduced the growth of Pa60 and Pa76 by 39–56% (P Key Words: aerobic rice, antibiosis, biocontrol, growth promotion, parasitism, Pythium, soil sickness, Trichoderma