Configuration of greenhouse sweet basil nutritional quality in response to cultivar and growing media

Sweet basil (Ocimum basilicum L.) is one of the most common aromatic herbs cultivated all over the world. It is widely used for its aromatic and culinary purposes. Consumer demand for fresh sweet basil has been on the rise and many farmers of leafy vegetables and aromatic herbs have oriented their production schemes to include basil. The genetic material is a key preharvest factor and the major determinant of variation in yield and quality of leafy vegetables. Another important preharvest factor that may modulate yield and nutritional quality of sweet basil could be the growing medium. The aim of this research was to assess in a multi-factorial approach the effects of two sweet basil cultivars (Napoletano and Genovese) and two substrates (rockwool and an innovative inert substrate, SISAL fiber) on plant growth, marketable yield, nitrogen content and nutritional quality. The plant growth parameters, yield and especially the bioactive compounds were mostly affected by the growing media and to a lesser extent by the genetic material. When averaged over growing media, the highest leaf number was observed in 'Genovese' while an opposite trend was recorded for the leaf area. Irrespective of the sweet basil cultivar, plants grown on rockwool exhibited a higher leaf area, leaf fresh weight and dry biomass compared to those grown on SISAL fiber substrate. Contrarily to crop productivity, sweet basil grown on SISAL was characterized by high levels of lipophilic antioxidant activity, total chlorophyll and carotenoids, whereas no significant effect among treatments were recorded on total phenols. Although the yield reduction with SISAL was quite significant, the basil plants grown on this innovative substrate produced leaves with high concentrations of bioactive compounds. Additional researches should focus on elucidating the Genotype × Substrate interaction in order to select the best combinations.