Continuous Lighting Promotes Plant Growth, Light Conversion Efficiency, and Nutritional Quality of Eruca vesicaria (L.) Cav. in Controlled Environment With Minor Effects Due to Light Quality

Abstract

Light-emitting diode lamps can allow for the optimization of lighting conditions in artificial growing environments, with respect to light quality, quantity, and photoperiod extension, to precisely manage resources and crop performance. Eruca vesicaria (L.) Cav. was hydroponically cultured under three light treatments to investigate the effect on yield and nutritional properties of rocket plants. A treatment of (W-12h) having a12/12 h light/dark at 600 μmol m^-2 s^-1 provided by LEDs W:FR:R:B = 12:2:71:15 was compared with two treatments of continuous lighting (CL), 24 h light at 300 μmol m^-2 s^-1 provided by cool white LEDs (W-CL), and by LED R:B = 73:27 (RB-CL). CL enhanced the growth of the rocket plants: total fresh biomass, leaf fresh weight, and shoot/root ratio increased in W-CL, and leaf dry weight, leaf dry matter %, root fresh and dry weight, and specific leaf dry weight (SLDW) increased in RB-CL. Total carbon content was higher in RB-CL, whereas total nitrogen and proteins content increased in W-12h. Both W-CL and RB-CL increased carbohydrate content in the rocket leaves, while W-CL alone increased the sugar content in the roots. Fibers, pigments, antioxidant compounds, and malic acid were increased by CL regardless of the light spectrum applied. Nitrate was significantly reduced in the rocket leaves grown both in W-CL and RB-CL. Thus, the application of CL with low light intensity can increase the yield and quality value of rocket, highlighting that careful scheduling of light spectrum, intensity, and photoperiod can improve the performance of the crop.

Keywords: carbohydrate; controlled environment agriculture (CEA); fibers; nitrate; rocket.

Figure 1

Morphological differences in Eruca vesicaria (L.) Cav. grown under three different light-emitting diode (LED) treatment conditions. Treatment 1—(W-12h): photoperiod of 12-h light/12-h dark; photosynthetic photon flux density (PPFD) was 600 μmol m⁻² s⁻¹, LEDs W:FR:R:B = 12:2:71:15. Treatment 2—(W-CL): photoperiod of 24 h continuous light (CL); PPFD was 300 μmol m⁻² s⁻¹, cool white LEDs. Treatment 3—(RB-CL): photoperiod of 24-h continuous light; PPFD was 300 μmol m⁻² s⁻¹, LEDs R:B = 73:27. All the light treatments received the same daylight integral (DLI) (25.92 mol quanta m⁻² day⁻¹).