*3.1. Morphogenesis*

It was observed that the supplementary and night-interrupting blue light increased the plant heights in this study (Figure 3A). Plants grown in LD13 + NI − 4B had the greatest height (Figure 3A), where it was 22% greater than that of plants grown in SD10. Additionally, it was observed that even plants in SD9 + 4B had a greater mean height than those in SD10.

3B).

The dry mass of plants grown under all photoperiodic treatments was greater compared to that of the plants in the SD10 control (Figure 3B). Increasing the photoperiod, as with LD13 + 4B and LD13 + NI-4B, significantly increased the dry mass of the plants in this study. The other treatments, SD9 + 4B and SD10 + NI-4B, were not as effective as the LD treatments in increasing the dry mass (Figure

Plants in SD9 + 4B had the greatest number of leaves per plant while those in SD10 had the lowest number of leaves per plant (Figure 3C). The average leaf area was the greatest for plants in LD13 + NI-4B and the smallest for plants in SD10 + NI-4B (Figure 3D). The leaf area per plant was 12% for plants in SD10 + NI-4B when compared to that for plants in SD10 (Figure 3D). Furthermore, all B light treatments except for SD10 + NI-4B increased the leaf area compared to the control (Figure 3D). The chlorophyll levels were the lowest for plants in LD13 + 4B and the highest for plants in LD13 + NI-4B (Figure 3E). Plants in LD13 + 4B had 32% lower chlorophyll contents than plants in SD10 did

**Figure 3.** The effects of the supplementary and night-interrupting B light on the plant height (**A**), dry mass (**B**), number of leaves per plant (**C**), leaf area per plant (**D**), and chlorophyll levels (**E**) in *D. grandiflorum* 'Gaya Yellow'. The control was constructed by exposing plants to a 10-h SD treatment (SD10) without any B light. Data are the mean ± S.E of the 3 biological replicates. Means accompanied by different letters significantly differ (*p* < 0.05) according to Tukey's studentized range test at a 5% significance level. **Figure 3.** The effects of the supplementary and night-interrupting B light on the plant height (**A**), dry mass (**B**), number of leaves per plant (**C**), leaf area per plant (**D**), and chlorophyll levels (**E**) in *D. grandiflorum* 'Gaya Yellow'. The control was constructed by exposing plants to a 10-h SD treatment (SD10) without any B light. Data are the mean ± S.E of the 3 biological replicates. Means accompanied by different letters significantly differ (*p* < 0.05) according to Tukey's studentized range test at a 5% significance level.

*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 The dry mass of plants grown under all photoperiodic treatments was greater compared to that of the plants in the SD10 control (Figure 3B). Increasing the photoperiod, as with LD13 + 4B and LD13 + NI − 4B, significantly increased the dry mass of the plants in this study. The other treatments, SD9 + 4B and SD10 + NI − 4B, were not as effective as the LD treatments in increasing the dry mass (Figure 3B).

(Table 2 and Figure 4). 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). The photoreceptor gene expression (*PHYA*, *PHYB*, and *CRY1*) in response to the B light was also Plants in SD9 + 4B had the greatest number of leaves per plant while those in SD10 had the lowest number of leaves per plant (Figure 3C). The average leaf area was the greatest for plants in LD13 + NI − 4B and the smallest for plants in SD10 + NI − 4B (Figure 3D). The leaf area per plant was 12% for plants in SD10 + NI − 4B when compared to that for plants in SD10 (Figure 3D). Furthermore, all B light treatments except for SD10 + NI − 4B increased the leaf area compared to the control (Figure 3D). The chlorophyll levels were the lowest for plants in LD13 + 4B and the highest for plants in LD13 + NI − 4B (Figure 3E). Plants in LD13 + 4B had 32% lower chlorophyll contents than plants in SD10 did (Figure 3E).
