Supplementary file 1_Biomass and volatile profile responses of hydroponically grown Basil (Ocimum basilicum L.) to different nutrient solution regimes.docx

High N treatment produced the highest fresh aerial weights, reaching 430 g, 408 g, and 365 g, values close to those obtained with the HNS (471 g). Intermediate N treatments showed fresh weight values of 154 g, 254 g, and 210 g, whereas low N treatments resulted in fresh aerial weights below 100 g. Aerial dry weight, leaf number, leaf area, and plant height followed the same trend.

In contrast, root parameters remained generally similar among treatments. An exploratory principal component analysis (PCA) suggested three compositional groupings: high N associated with eugenol, intermediate N with eucalyptol, and low N with linalool, with an intermediate profile for HNS. In-sample quadratic model fits yielded R² values of 0.64 for linalool, 0.82 for eugenol, and 0.73 for eucalyptol.

The model-predicted candidate combinations of N, P, and associated K were 62.2, 17.1, and 80 mg L⁻¹ for linalool; 105, 31, and 135 mg L⁻¹ for eugenol; and 58.2, 31, and 93.5 mg L⁻¹ for eucalyptol, respectively. These conditions increased the compound production indices, calculated as aerial fresh weight × relative GC peak area (%)/100, compared with the HNS reference treatment, from 8.46 to 17.43 for linalool, from 5.61 to 14.7 for eugenol, and from 1.29 to 4.10 for eucalyptol.

These findings suggest that nutrient solution formulation may influence basil biomass and the relative abundance of selected VOC constituents. The results also highlight the potential of nutrient formulation as a strategy for modulating specific VOC profiles. In addition, RSM may serve as an exploratory approach for identifying nutrient formulations associated with variations in selected VOC compounds.</p>