Trichoderma species from rhizosphere of Oxalis corymbosa release volatile organic compounds inhibiting the seed germination and growth of Echinochloa colona

Trichoderma spp. have the potential to act as biocontrol agents for regulating plant growth. In this study, Trichoderma spp. were isolated from the rhizosphere soil of Oxalis corymbosa in sugarcane fields, and six strains were identified as T. koningiopsis, T. afroharzianum, T. atroviride, T. virens and T. asperelloides through morphology and phylogenetic analysis of ITS and tef 1 gene sequences. The activity of volatile organic compounds (VOCs) emitted by Trichoderma spp. was determined using the double-plate chamber method, revealing that five strains significantly inhibited the seed germination and growth of Echinochloa colona. Subsequently, SMPE-GC–MS and Venn analyses unveiled the presence of five common VOCs, namely phenylethyl alcohol, 2,4,6-trichloroanisole, hexadecanoic acid ethyl ester, 10(E),12(Z)-conjugated linoleic acid, and linoleic acid ethyl ester, within Trichoderma spp.. Independently, five compounds were evaluated for their inhibitory effect on the shoot growth of E. colona. Additionally, the results demonstrated that linoleic acid ethyl ester exhibited the highest inhibitory activity, while hexadecanoic acid ethyl ester was the least effective. The inhibitory effect of 2,4,6-trichloroanisole increased with concentration. Hormone analysis results indicated that VOCs influenced the concentration of abscisic acid, resulting in the maintenance of dormancy in E. colona. This study provides compelling evidence for the potential use of Trichoderma as bioherbicides.