Assessing the Impact of a Novel Trichoderma sp. Strain STP8 on Lettuce Yield and Mineral Content

The fungal genus <i>Trichoderma</i> is highly valued in agriculture for its versatile roles, mainly as a biocontrol agent against plant pathogens. Recently, its use as a natural biofertilizer has gained attention, as <i>Trichoderma</i> spp. promotes crop growth and improves yield by enhancing the rhizosphere environment and activating plant defences. Globally, over 250 <i>Trichoderma</i>-based products dominate 60-90% of the market, but their efficacy can decline during transportation and storage. Additionally, concerns about their impact on native soil biodiversity have led to interest in using locally adapted, native strains. The novel native strain of <i>Trichoderma</i> sp. STP8 (formerly <i>T. koningiopsis</i> agg. STP8) previously showed strong antagonism against <i>Sclerotinia sclerotiorum</i> and promoted lettuce growth in greenhouse conditions. This study evaluated <i>Trichoderma</i> sp. STP8's effectiveness in field-grown lettuce, revealing yield increases of 16.6% to 30.5%. The most significant gains occurred when <i>Trichoderma</i> sp. STP8 was applied before head formation, 26 days after planting. That was in one treatment with two applications (at seedling planting and after 26 days) and another with three applications (at sowing, at seedling planting, and after 26 days). These results demonstrate <i>Trichoderma</i> sp. STP8's potential as a sustainable biocontrol and biofertilizer agent for lettuce, encouraging further research across different agricultural systems, including hydroponics and soil-less medium.