Abstract Book V-NanoDay

The utilisation of beneficial microorganisms with nanocarriers, like biochar, presents an innovative solution for enhancing agricultural productivity whilst concomitantly reducing reliance on chemical inputs. The present study evaluated the effectiveness of Streptomyces ambofaeciens S9, isolated from Helianthus annuus L. seeds, in promoting the growth of the latter in a variety of substrates. The selected strain was characterised for indole-3-acetic acid (IAA) production, phosphorus solubilization, and ACC- deaminase activity, mechanisms that render it suitable for agricultural use. The experiments were conducted under greenhouse using a randomized block design and Rhizoboxs. Effectiveness of biochar (Natural Biochar, Silpa Srl) as amender and nanocarrier was tested using peat and peat: biochar mixtures (10:90% w/w), in the presence and absence of bacterial inoculation. Plant growth parameters were evaluated 40 days after sowing. Respect to biochar treatment, inoculation with S9 increased root length by 30%, fresh biomass by 50%, and dry biomass by 35%. Furthermore, a 25% increase in chlorophyll a and a 30% increase in chlorophyll b were observed, indicating enhanced photosynthetic efficiency. Biochar improved substrate properties, while its combination with S9 resulted in more pronounced synergistic effects, evidenced by increased soil microbiological activity and proline levels (1.13 nmol/mg FW), indicative of greater tolerance to abiotic stress. Overall, the integrated use of S9 and biochar at 5-10% w/w represents an effective strategy for increasing crop resilience and the sustainability of production systems. The activities were carried out as part of the project “Bio.SOUTH – Combined fertilization wgith BIOchar to sustain mOUnTain production of Heliantus annus.