Effects of Trichoderma asperellum Samuels, Lieckf. & Nirenberg on growth and production traits in local tomato and bean landraces.

Sustainable agronomic practices increasingly rely on the use of microbial biostimulants to enhance crop quality and resilience to environmental stresses. Among these, Trichoderma spp. Showed to improve nutrient use efficiency, stimulate plant metabolism, and enhance tolerance to abiotic stress. The present study (RUSTICO project, funded by Fondazione LGH E.T.S.) evaluated the effects of a Trichoderma asperellum strain, on plant performance, applied to the substrate at sowing in plug trays of common bean (Phaseolus vulgaris L.) and tomato (Solanum lycopersicum L.). Five landraces were selected to preserve and valorise traditional genetic resources: two bean varieties (‘Gambolò’ and ‘Vigevano’), one runner bean (‘Pietragavina’), and two tomato varieties (long-shaped fruit like ‘San Marzano’ and flattened-ribbed fruit like ‘Riccio di Parma’). Seeds were provided by the Plant Germplasm Bank of the University of Pavia. Seedlings were transplanted in open field and plant height was recorded before and after transplanting, while chlorophyll content was monitored weekly using SPAD measurements. Preliminary results indicate genotype-dependent responses to T. asperellum application, with the most pronounced effects observed during early growth stages. Treated plants exhibited higher germination in both species, regardless of variety. In tomato, treated plants showed reduced shoot height, suggesting a potential shift in carbon allocation toward root development or secondary metabolism. SPAD readings revealed variety-specific patterns: in long-shaped fruit variety, treated and control plants showed similar values overall, with higher SPAD values in treated plants toward the end of the trial; in flattened-ribbed fruit variety, treated plants exhibited slightly higher SPAD values, particularly at early stages. Similarly, bean landraces displayed genotype-dependent responses. The treatment led to increased SPAD values, particularly during the late stages of the crop cycle in Gambolò. Further analyses will investigate fruit quality traits to assess the role of this treatment in sustainable crop management and stress adaptation.