*2.2. Photoperiodic Light Treatments*

Plants were grown with light at an intensity of 180 µmol m−<sup>2</sup> s <sup>−</sup><sup>1</sup> PPFD provided by white MEF50120 LEDs (More Electronics Co. Ltd., Changwon, Korea) (Figure 1A). The different photoperiods used in this experiment, as well as the lighted period during the NI (referred to as 'photoperiod' hereafter) were as follows: B light with a wavelength of 450 nm was used for 4 h to either (1) extend

the photoperiod at the end of a 9-h SD as the sole light source (SD9 + 4B), (2) provide NI following the 13-h LD (LD13 + NI − 4B), (3) provide NI after the 10-h SD (SD10 + NI − 4B), or (4) supplement W LEDs at the end of a 13-h LD (LD13 + 4B) (Figures 1B and 2). The control was constructed by exposing the plants to a 10-h short-day treatment (SD10) without B light. B light at an intensity of <sup>10</sup> <sup>±</sup> <sup>3</sup> <sup>µ</sup>mol· <sup>m</sup>−<sup>2</sup> ·s <sup>−</sup><sup>1</sup> PPFD was provided by LEDs for the photoperiodic light treatments. A HD2102.1 digital photometer (Delta OHM, Padova, Italy) measured the average PPFD 20 cm above the bench top, for each light treatment. The lighting was adjusted such that the same PPFD levels were provided to the plants regardless of the light treatment. A USB 2000 Fiber Optic Spectrometer (Ocean Optics Inc., Dunedin, FL, USA; detects wavelengths between 200 to 1000 nm) scanned the spectral distribution in 1-nm wavelength intervals 25 cm above the bench top. NI following the 13-h LD (LD13 + NI-4B), (3) provide NI after the 10-h SD (SD10 + NI-4B), or (4) supplement W LEDs at the end of a 13-h LD (LD13 + 4B) (Figures 1B and 2). The control was constructed by exposing the plants to a 10-h short-day treatment (SD10) without B light. B light at an intensity of 10 ± 3 μmol·m−2·s−1 PPFD was provided by LEDs for the photoperiodic light treatments. A HD2102.1 digital photometer (Delta OHM, Padova, Italy) measured the average PPFD 20 cm above the bench top, for each light treatment. The lighting was adjusted such that the same PPFD levels were provided to the plants regardless of the light treatment. A USB 2000 Fiber Optic Spectrometer (Ocean Optics Inc., Dunedin, FL, USA; detects wavelengths between 200 to 1000 nm) scanned the spectral distribution in 1-nm wavelength intervals 25 cm above the bench top. NI following the 13-h LD (LD13 + NI-4B), (3) provide NI after the 10-h SD (SD10 + NI-4B), or (4) supplement W LEDs at the end of a 13-h LD (LD13 + 4B) (Figures 1B and 2). The control was constructed by exposing the plants to a 10-h short-day treatment (SD10) without B light. B light at an intensity of 10 ± 3 μmol·m−2·s−1 PPFD was provided by LEDs for the photoperiodic light treatments. A HD2102.1 digital photometer (Delta OHM, Padova, Italy) measured the average PPFD 20 cm above the bench top, for each light treatment. The lighting was adjusted such that the same PPFD levels were provided to the plants regardless of the light treatment. A USB 2000 Fiber Optic Spectrometer (Ocean Optics Inc., Dunedin, FL, USA; detects wavelengths between 200 to 1000 nm) scanned the spectral distribution in 1-nm wavelength intervals 25 cm above the bench top.

*Plants* **2020**, *9*, x FOR PEER REVIEW 3 of 11

**Figure 1.** The spectral distribution of lights used in this experiment: daily W light provided by white LEDs (**A**) and B light from blue LEDs used as the supplementary and night-interrupting light (**B**). **Figure 1.** The spectral distribution of lights used in this experiment: daily W light provided by white LEDs (**A**) and B light from blue LEDs used as the supplementary and night-interrupting light (**B**). LEDs (**A**) and B light from blue LEDs used as the supplementary and night-interrupting light (**B**).

**Figure 2.** Supplementary and night-interrupting blue (B) light schemes employed in this study. B light was used for 4 h to either (1) extend the photoperiod at the end of a 9-h SD as the sole light source (SD9 + 4B), (2) provide NI following a 13-h LD (LD13 + NI-4B), (3) provide NI after a 10-h SD (SD10 + **Figure 2.** Supplementary and night-interrupting blue (B) light schemes employed in this study. B light was used for 4 h to either (1) extend the photoperiod at the end of a 9-h SD as the sole light source (SD9 + 4B), (2) provide NI following a 13-h LD (LD13 + NI-4B), (3) provide NI after a 10-h SD (SD10 + NI-4B), or (4) supplement the W light at the end of a 13-h LD (LD13 + 4B). Plants in the control were **Figure 2.** Supplementary and night-interrupting blue (B) light schemes employed in this study. B light was used for 4 h to either (1) extend the photoperiod at the end of a 9-h SD as the sole light source (SD9 + 4B), (2) provide NI following a 13-h LD (LD13 + NI − 4B), (3) provide NI after a 10-h SD (SD10 + NI − 4B), or (4) supplement the W light at the end of a 13-h LD (LD13 + 4B). Plants in the control were grown with a 10- hour SD treatment (SD10) without any B light.

NI-4B), or (4) supplement the W light at the end of a 13-h LD (LD13 + 4B). Plants in the control were

grown with a 10- hour SD treatment (SD10) without any B light.

grown with a 10- hour SD treatment (SD10) without any B light.
