analyzed (Figure 5). Plants in LD13 + 4B had the greatest expression levels of *PHYA* and *PHYB*, *3.2. Flowering and Gene Expression*

The flowering percentage of plants was 100% in all treatments (Table 2 and Figure 4). The fastest flowering induction was observed for plants in the control (SD10). It is noteworthy that plants in LD13 + 4B and LD13 + NI − 4B flowered, despite the fact that chrysanthemum is a qualitative SD plant (Table 2 and Figure 4).


**Table 2.** The effects of the supplementary and night-interrupting 10 <sup>µ</sup>mol·m−<sup>2</sup> ·s <sup>−</sup><sup>1</sup> PPFD B light on the flowering characteristics of chrysanthemum (*D. grandiflorum* 'Gaya Yellow'), after 41 days of exposure to the photoperiodic light treatments. flowering characteristics of chrysanthemum (*D. grandiflorum* 'Gaya Yellow'), after 41 days of exposure to the photoperiodic light treatments.

**Table 2.** The effects of the supplementary and night-interrupting 10 μmol·m<sup>−</sup>2·s−1 PPFD B light on the

*Plants* **2020**, *9*, x FOR PEER REVIEW 6 of 11

followed by plants in SD10 + NI-4B (Figure 5). *PHYA* had the lowest expression levels in plants in LD13 + NI-4B (Figure 5). *PHYB* was the least expressed in plants in LD13 + NI-4B (Figure 5). Plants in LD13 + NI-4B had significantly higher *CRY1* expression levels compared to plants in the other

<sup>z</sup> See Figure 2 for details on the photoperiodic treatments with B light. <sup>y</sup> Days of treatment to visible flower bud or days to visible buds. <sup>x</sup> Mean separation within columns by Duncan's multiple range test at a 5% level. \*\*\*: Significant at *p* ≤ 0.001. z See Figure 2 for details on the photoperiodic treatments with B light. y Days of treatment to visible flower bud or days to visible buds. x Mean separation within columns by Duncan's multiple range test at a 5% level. \*\*\*: Significant at *p* ≤ 0.001.

**Figure 4.** The effects of the supplementary and night-interrupting 10 μmol·m<sup>−</sup>2·s−1 PPFD B light on the flowering of chrysanthemum (*D. grandiflorum* 'Gaya Yellow'), after 41 days of exposure to the photoperiodic light treatments: side view (**A**) and top view (**B**) (see Figure 2 for details on the photoperiodic treatments with B light). **Figure 4.** The effects of the supplementary and night-interrupting 10 <sup>µ</sup>mol·m−<sup>2</sup> ·s <sup>−</sup><sup>1</sup> PPFD B light on the flowering of chrysanthemum (*D. grandiflorum* 'Gaya Yellow'), after 41 days of exposure to the photoperiodic light treatments: side view (**A**) and top view (**B**) (see Figure 2 for details on the photoperiodic treatments with B light).

Plants in SD10 had the smallest DVB whereas plants in LD13 + NI − 4B had the greatest DVB (Table 2). The DVB was observed to increase as the photoperiod increased (Table 2). The DVB of plants in LD13 + 4B was smaller than those of plants in LD13 + NI − 4B. Interestingly, plants in LD13 + 4B had 93% more flowers per plant compared to plants in the SD10 control. Plants in the SD10 control and SD9 + 4B had the lowest number of flowers (Table 2). Plants in the SD10 control had the greatest flower width (Table 2).

**Figure 5.** The effects of the supplementary and night-interrupting 10 μmol·m<sup>−</sup>2·s−1 PPFD B light on the relative gene expression levels of) *D. grandiflorum* 'Gaya Yellow' determined by real-time PCR of The photoreceptor gene expression (*PHYA*, *PHYB*, and *CRY1*) in response to the B light was also analyzed (Figure 5). Plants in LD13 + 4B had the greatest expression levels of *PHYA* and *PHYB*, followed by plants in SD10 + NI − 4B (Figure 5). *PHYA* had the lowest expression levels in plants in LD13 + NI − 4B (Figure 5). *PHYB* was the least expressed in plants in LD13 + NI − 4B (Figure 5). Plants in LD13 + NI − 4B had significantly higher *CRY1* expression levels compared to plants in the other treatments (Figure 5). *CRY1* was the least expressed in plants in LD13 + 4B (Figure 5).

*PHYA* (**A**), *PHYB* (**B**), and *CRY1* (**C**). (Details of the NI light qualities are presented in Figure 2). At each sampling date, the individual gene expression levels for the plants in the photoperiodic light treatments were divided by the mean gene expression level for plants in the SD10 control. The data

**Figure 4.** The effects of the supplementary and night-interrupting 10 μmol·m<sup>−</sup>2·s−1 PPFD B light on the flowering of chrysanthemum (*D. grandiflorum* 'Gaya Yellow'), after 41 days of exposure to the

followed by plants in SD10 + NI-4B (Figure 5). *PHYA* had the lowest expression levels in plants in LD13 + NI-4B (Figure 5). *PHYB* was the least expressed in plants in LD13 + NI-4B (Figure 5). Plants in LD13 + NI-4B had significantly higher *CRY1* expression levels compared to plants in the other

**Table 2.** The effects of the supplementary and night-interrupting 10 μmol·m<sup>−</sup>2·s−1 PPFD B light on the flowering characteristics of chrysanthemum (*D. grandiflorum* 'Gaya Yellow'), after 41 days of exposure

SD9 + 4B 100 17.7 c x 11.0 c 2.6 b LD13 + 4B 100 22.5 b 21.3 a 0.7 c LD13 + NI-4B 100 28.7 a 15.3 b 0.5 d SD10 + NI-4B 100 18.0 c 15.0 b 2.8 a SD10 100 17.5 c 11.0 c 2.9 a *F*-test \*\*\* \*\*\* \*\*\* z See Figure 2 for details on the photoperiodic treatments with B light. y Days of treatment to visible flower bud or days to visible buds. x Mean separation within columns by Duncan's multiple range

**(%) DVB y (Day) No. of Flowers/Plant Flower width (cm)** 

treatments (Figure 5). *CRY1* was the least expressed in plants in LD13 + 4B (Figure 5).

to the photoperiodic light treatments.

**Treatment z Flowering** 

test at a 5% level. \*\*\*: Significant at *p* ≤ 0.001.

**Figure 5.** The effects of the supplementary and night-interrupting 10 μmol·m<sup>−</sup>2·s−1 PPFD B light on the relative gene expression levels of) *D. grandiflorum* 'Gaya Yellow' determined by real-time PCR of *PHYA* (**A**), *PHYB* (**B**), and *CRY1* (**C**). (Details of the NI light qualities are presented in Figure 2). At each sampling date, the individual gene expression levels for the plants in the photoperiodic light treatments were divided by the mean gene expression level for plants in the SD10 control. The data **Figure 5.** The effects of the supplementary and night-interrupting 10 <sup>µ</sup>mol·m−<sup>2</sup> ·s <sup>−</sup><sup>1</sup> PPFD B light on the relative gene expression levels of) *D. grandiflorum* 'Gaya Yellow' determined by real-time PCR of *PHYA* (**A**), *PHYB* (**B**), and *CRY1* (**C**). (Details of the NI light qualities are presented in Figure 2). At each sampling date, the individual gene expression levels for the plants in the photoperiodic light treatments were divided by the mean gene expression level for plants in the SD10 control. The data are presented as the mean ± S.E of the 3 biological replicates. Means accompanied by different letters indicate significant differences (*p* < 0.05), according to Tukey's studentized range test at a 5% significance level.
