Enhancement of vindoline and catharanthine production in Catharanthus roseus by LED light and plasma activated water

This study aimed to increase the concentrations of vindoline (VDL) and catharanthine (CAT) in Catharanthus roseus plants cultivated in an indoor farming system using artificial lighting and plasma-activated water (PAW). After a 61-days pre-treatment period under fluorescent lamps, plants were exposed to four treatments: white light (W) from the same fluorescent lamps, red light (R) from LEDs, W with PAW, and R with PAW. These combinations were evaluated at two sampling times: 45 days (T1) and 70 days (T2) after the end of pre-treatment (DAP). Results showed that R combined with PAW significantly increased VDL and CAT concentrations compared to other combinations. In particular, with PAW, R produced significantly higher VDL and CAT concentrations than W, while without PAW, VDL and CAT concentrations were comparable under W and R. Regardless of the light conditions, VDL and CAT concentrations were higher with PAW. Moreover, VDL and CAT concentrations increased from T1 to T2, reaching higher levels under R or PAW at T2. At the same sampling time, VDL and CAT levels were generally higher in plants exposed to R and in those treated with PAW. The highest VDL and CAT concentrations were observed with combined R and PAW at T2. The study concluded that: (1) VDL and CAT concentrations increase with plant age; (2) PAW enhances VDL and CAT concentrations, with its effect becoming more pronounced from T1 to T2; (3) R contributes to VDL and CAT biosynthesis, but its impact becomes significant only when combined with PAW and its effect is amplified from T1 to T2; (4) regardless of the sampling time, the treatment with R and PAW maximizes the VDL and CAT concentrations; (5) R combined with PAW at T2 is the most effective treatment; (6) if harvest timing cannot be delayed, using R and PAW offers substantial benefits.