| Resumen: |
The world-wide expansion of urban areas has led to an increase of municipal green waste (MGW) generation. In this study, indole-3-acetic acid (IAA), a known biostimulant, was produced using Trichoderma viride through solid-state fermentation (SSF) of MGW in a tray bioreactor. The production of IAA was optimized under SSF conditions, achieving a maximum yield of 112. 6 μg IAA g⁻ dry weight at 28 °C, 65% humidity, and 1% of L-tryptophan supplementation based on total weight. The biostimulant effectiveness was further evaluated in lettuce (Lactuca sativa L. ) germination pot tests, showing significant improvements in growth parameters, photosynthetic pigments and nutrient uptake. Fermented solids with two different IAA concentrations (112. 6 and 60. 0 μg IAA g⁻ dw) were tested on lettuce plants, resulting in higher biomass, root and shoot length, and overall vigour plant compared to a control without IAA at 7, 14, 21, 28, and 35 days after planting. Additionally, chlorophyll content, carotenoids, and the absorption of key nutrients (K⁺, Ca⁺, Mg⁺, P, S) were significantly enhanced. These findings highlight the potential of Trichoderma viride as a biostimulant producer, aligning this strategy to circular economy principles by valorising MGW into agricultural useful bioproducts, thus reducing the dependency on chemical fertilizers, while promoting sustainable agriculture. |