ETD

• abiotic stress
• biological control agents (BCAs)
• co-inoculation dynamics
• Fusarium head blight (FHB)
• spore germination

Rising global populations and crop losses caused by Fusarium head blight (FHB) highlight the need for sustainable disease-management strategies. The biocontrol fungi Trichoderma gamsii T6085 and Clonostachys rosea IK726 are effective against FHB, although partial inhibition of T. gamsii has been observed in liquid co-culture, unlike the compatibility seen in planta. To clarify how their early interactions respond to stress, this study examined germination and growth under nutrient and temperature limitation. A broad screening across carbon- and nitrogen-limited media and temperatures from 12 to 37 °C was performed using two spore densities. We then verified that the two inoculum densities produced comparable growth, confirming that they did not affect the observed patterns. Based on the screening, five representative conditions were selected for detailed flask assays. Microscopy at 6, 12, and 24 hpi was used to assess germination and developmental stages, while biomass was harvested at 24 hpi and DNA quantified by qPCR. Both fungi germinated under all stress conditions, each showing distinct temporal patterns. Co-inoculation generally indicated compatibility, with only mild, condition-dependent effects. Notably, 1/5 PDB supported balanced germination of both strains. Overall, environmental stresses modulated their interaction but did not prevent growth, supporting the feasibility of a robust dual-strain biocontrol formulation.