Steviol glycosides content in cultivated Stevia rebaudiana Bertoni: A new sweet expectation from the Campania region (Italy)

Stevia rebaudiana was experimentally cultivated in the Volturno river plain (Caserta, Italy). Considering three diverse irrigation levels (T0, T50 and T100 - 0, 50 and 100% of restitution of soil water) and four harvesting times (from June to August 2015; Jn, Jl, A1 and A2), steviol glycosides (SGs) leaf production was monitored. To achieve this goal, an extraction/fractionation protocol, investigated through FT-IR (Fourier Transform-InfraRed spectroscopy) and LC-MS (Liquid Chromatography-Mass Spectrometry) techniques, was preliminarily developed.The Steviol Glycosides enriched fraction (SG-f), isolated as a white powder, consisted in seven SGs, whose identity was confirmed by tandem MS experiments. Thus, SG-f samples from plants differently irrigated, and harvested at the considered phenological stages were prepared. The application of MRM (Multiple Reaction Monitoring) analysis mode favored the relative quantitation of each SG. Data acquired highlighted that SGs were produced similarly under both irrigation and drought stress conditions, but irrigation management exerted a greater influence on dry leaf matter productivity. In fact, SG-f extraction yield (kg per ha) was 6.9-fold higher from T100 than from T0 plants. The local production of high quality Stevia plants rich in active ingredients and their purification could also encourage new scientific programs for new "km 0" sweet expectations.