S06 - Session P3 - Growing sweet basil in a Floating Growing System enhances yields, reduces nitrate content, and modulates the aromatic profile

Authors: Silvana Nicola *, Patrizia Rubiolo, Barbara Sgorbini, Walter Gaino, Francesco Orsini, Giorgio Prosdocimi Gianquinto, Giuseppina Pennisi

Premium quality in culinary herbs includes high yield and year-round supply, a short supply chain for the fresh market, high safety and, ultimately, a good aroma. Floating growing systems can standardize fresh herb production, also thanks to an elevated efficiency in terms of Water and Nutrient Use. Ocimum basilicum L. 'Superbo' was grown using a Lab-Scale Pilot Plant in Floating Growing System (LSPP-FGS) from May 18 to June 6 (20 days). Four hydroponic nutrient solutions (HNS) with variable N levels and N:P:K ratios (N:P:K respectively of 6:2:6, 12:2:6, 6:4:12, 12:4:12) were used, under monitored conditions (air temperature, relative humidity, HNS pH and EC, water and HNS consumption). At harvest, biometric parameters were measured (fresh and dry weight, chlorophyll content, nitrate content) and several coefficients were calculated (dry matter - DM, water use efficiency - WUE, nitrogen use efficiency - NUE). The aromatic profile was assessed on dry material. Fertilization regimes did not affect the plant fresh biomass (3.65 kg m -2 ), DM (7.4%) and chlorophyll content (SPAD value of 27.6). While WUE was not significantly affected (48 g FW L -1 H 2 O), the NUE was higher with low N fertilization, and increased with N:P:K=6:4:12. Nitrate accumulation was higher with N:P:K=12:2:6, although still low (ca 1453 mg kg -1 FW). Twenty-three compounds were detected as typical of the aromatic profile of basil, with 7 as major components: bornyl acetate, β-farnesene, 1,8-cineole, α-bergamotene, methyl eugenol, eugenol e linalool. Eugenol was ca 32% higher in N:P:K=12:2:12 compared to other treatments, while linalool was ca 19% higher in N:P:K=6:2:6. The experiment revealed that the FGS is a suitable system for growing sweet basil, ensuring elevated productivity and high WUE in a very short growing cycle. It also confirmed that fertilization has a significant influence on the aromatic profile, namely, to increase the eugenol and the linalool contents.