High-altitude drylands face a persistent "quality-protein dilemma" in wheat production, where cold and drought jointly reduce yield and impair bread-making quality. Although Trichoderma fungi enhance plant stress resilience, their ability to concurrently improve both yield and functional grain quality under combined field stresses remains unknown. We hypothesized that seed inoculation with stress-adapted Trichoderma strains would deliver dual benefits by boosting yield and optimizing protein composition for superior dough functionality. In a two-year field trial using a randomized complete block design, fourteen Trichoderma treatments were evaluated against a non-inoculated control. Agronomic, quality, rheological, and nutritional parameters were assessed. Inoculation showed strong strain-specific effects. Elite strains, particularly T. koningii and T. harzianum, increased grain yield (up to 55% for T. koningii 1 in 2024) and harvest index. Crucially, they mitigated the quality-protein dilemma by raising protein content (e.g., T. koningii: 14.3% vs. control: 12.1%) while enhancing its functionality, resulting in stronger gluten and improved dough properties (e.g., Farinograph Quality Number up to 129.9 vs. control: 106.6). These strains also elevated grain zinc and iron concentrations and improved mineral bioavailability via favorable phytic acid-mineral ratios. Our findings demonstrate that tailored Trichoderma inoculation is a sustainable bio-strategy for dual-benefit agriculture, simultaneously enhancing yield, bread-making quality, and nutritional value of wheat under the specific marginal conditions tested here.
