3.1. Vegetative and morphological analysis
The results showed that the vegetative growth of two rose cultivars improved significantly by the use of supplemental light. Highest number of new shoots (20.52) was recorded under R90B10 treatment on ʻUtopiaʼ cultivar, while lowest numbers of new shoots was recorded for the control treatment on the ʻSamuraiʼ cultivar (4.12 number). Among supplemental light recipies, increasing the ration of B light decreased the number of new emerged shoots in both rose cultivars (Fig. 4A). Tallest shoots were observed under R90B10 on ʻUtopiaʼ cultivar, while the shortest shoots was detected in control treatment of ʻSamuraiʼ cultivar. Among supplemental light recipies, increasing the ration of B light decreased the shoot lenght in both rose cultivars (Fig. 4B). Thickest shoot diameter was observed under R90B10 treatment on ʻUtopiaʼ cultivar (6.55 mm), while, thinnest shoot diameter was detected in control treatment of ʻSamuraiʼ cultivar (4.81 mm). Among supplemental light recipies, increasing the ration of B light decreased the shoot thickness in both rose cultivars (Fig. 4C). Highest number of leaves was recorded under R90B10 treatment on ʻUtopiaʼ cultivar (572.75 number), while, lowest numbers of leaves was recorded for the control treatment on the ʻSamuraiʼ cultivar (160.75 number). Among supplemental light recipies, increasing the ration of B light decreased the number of leaves in both rose cultivars (Fig. 4D). Widest leaf area was detected under R90B10 treatment on ʻUtopiaʼ cultivar; while the lowest leaf area was observed in the control treatment of ʻSamuraiʼ cultivar. (Fig. 4E). Highest SLA was calculated for the plants under control treatment in both rose cultivars. ʻUtopiaʼ cultivar under R90B10 had the lowest SLA (Fig. 4F).
Highest root fresh weight (22.80 g) was observed under R90B10 treatment on ʻUtopiaʼ cultivar, while lowest root fresh weight was recorded for the control treatment on both rose cultivars (2.75 g). Among supplemental light recipies, increasing the ration of B light decreased root fresh weight in both rose cultivars (Fig. 5A).
Highest root dry weight was observed under R90B10 treatment on ʻUtopiaʼ cultivar, while lowest root dry weight was recorded for the control treatment in both rose cultivars. Among supplemental light recipies, increasing the ration of B light decreased root dry weight in both rose cultivars (Fig. 5B).
Highest root volume was observed under R90B10 treatment on ʻUtopiaʼ cultivar, while lowest root volume was recorded for the control treatment in both rose cultivars. Among supplemental light recipies, increasing the ration of B light decreased root volume in both rose cultivars (Fig. 5C).
3.2. Biomass analysis
The results showed that the biomass of two rose cultivars improved significantly with the use of supplemental light. Highest leaf fresh weight was achieved under R90B10 treatment on ʻUtopiaʼ cultivar, while lowest leaf fresh weight was recorded for the control treatment on the ʻSamuraiʼ cultivar (8.53 g). Among supplemental light recipies, increasing the ration of B light decreased the leaf fresh weight in both rose cultivars (Fig. 6A). Highest leaf dry weight was achieved under R90B10 treatment on ʻUtopiaʼ cultivar (29.4 g), while lowest leaf dry weight was recorded for the control treatment on the ʻSamuraiʼ cultivar (2.75 g). Among supplemental light recipies, increasing the ration of B light decreased the leaf dry weight in both rose cultivars (Fig. 6B).
The mutual effect of supplementary light treatments and two rose cultivars was not significant, but a significant effect was observed among supplementary light treatments and also between two rose cultivars.
Highest stem fresh weight was achieved under R90B10 treatment, while lowest stem fresh weight was recorded for control and R70B30 treatments (Fig. 7A). Among cultivars, ʻUtopiaʼ cultivar had more stem fresh weight than ʻSamuraiʼ (Fig. 7B).
Highest stem dry weight was calculated under R90B10 treatment, while lowest stem dry weight was recorded for the control treatment (Fig. 7C). Among cultivars, ʻUtopiaʼ cultivar had more stem dry weight than ʻSamuraiʼ (Fig. 7D).
Highest shoot fresh weight (22.52 g) was observed under R90B10 treatment on ʻUtopiaʼ cultivar, while lowest shoot fresh weight was recorded for the control treatment on ʻSamuraiʼ cultivar (2.75 g). Among supplemental light recipies, increasing the ration of B light decreased shoot fresh weight in both rose cultivars (Fig. 8A).
Highest shoot dry weight (9.36 g) was calculated under R90B10 treatment on ʻUtopiaʼ cultivar, while lowest shoot dry weight was recorded for the control treatment on ʻSamuraiʼ cultivar (2.6 g). Among supplemental light recipies, increasing the ration of B light decreased shoot dry weight in both rose cultivars (Fig. 8B).
The mutual effect of supplemental light treatments and two rose cultivars on flower dry and fresh weight was not significant, but a significant effect was observed among supplemental light treatments and also between two different cultivars.
Highest flower fresh weight was achieved under R90B10 treatment (15.29 g), while lowest flower fresh weight was recorded for control (7.21 g) and R70B30 (8.73 g) treatments (Fig. 9A). Among cultivars, ʻUtopiaʼ cultivar had more flower fresh weight than ʻSamuraiʼ (Fig. 9B).
Highest flower dry weight was calculated under R90B10 treatment (4.31 g), while lowest flower dry weight was recorded for the control (1.99 g) treatment (Fig. 9C). Among cultivars, ʻUtopiaʼ cultivar had more flower dry weight than ʻSamuraiʼ (Fig. 9D).
3.3. Biomass partitioning
The results showed that the biomass partitioning into the different organ of two rose cultivars was changed as the consequence of supplemental light application. Biomass partitioning of each cultivar into different parts including root, shoots, leaf, and flower was determined based on dry weight and percentage of each part in relation with the total weight of the plant. The stem and shoot are considered together as the shoot. In both cultivars, plants allocated most of their biomass into the leaf and shoot organs. ʻUtopiaʼ cultivar had lower biomass for all the plant's organs under control condition compared to the plants exposed to the supplemental light. This cultivar decreased the biomass partitioning into the root and increased biomass partitioning into the flowers. This can be an adaptive strategy to ensure the survival under limited light condition. The highest and lowest share of biomass partitioning into different organs under R90B10 treatment was calculated for shoot and flower, respectively. The highest and lowest share of biomass partitioning in control treatment was used for shoot and root, respectively. In the case of the ʻSamuraiʼ cultivar, it had lower biomass for all the plant's organs under control condition compared to the plants exposed to the supplemental light. There was almost same share of biomass into the different organs when comparision made between control and supplemental light treatments. By increasing the ratio of B light, there was a decrease in biomass allocation to the floral organs was detected (Fig. 10).
3.4. Rose flower morphology
The results showed that the rose floral morphology was improved significantly with the use of supplemental light. Tallest petal were observed under R90B10 (39.88 mm) and R70B30 (39.36 mm) treatments, while the shortest petal was detected under R80B10 (31 mm) treatment (Fig. 11A).
Thickest flower diameter was observed under R90B10 treatment on ʻUtopiaʼ cultivar (32.16 mm), while, thinnest flower diameter was detected in control treatment in both rose cultivars (Fig. 11B).
Longest receptacle was observed under R90B10 treatment on ʻSamuraiʼ cultivar. Lowest numbers of new shoots was recorded for the control treatment on ʻUtopiaʼ cultivar (Fig. 11C). Thickest receptacle was observed under R90B10 treatment on ʻUtopiaʼ cultivar (Fig. 11D).
Tallest stems were observed under R90B10 treatment on both rose cultivars, while the shortest stem was detected in control treatment on ʻSamuraiʼ cultivar (Fig. 11E).
Thickest stem diameter was observed under R90B10 treatment on both rose cultivars, while, thinnest stem diameter was detected in control treatment on ʻSamuraiʼ cultivar (Fig. 11F).
3.5. Flowering time, yield, and morphology
Flowering, yield, and morphology of the two studied rose cultivars were improved significantly by the use of supplemental light.
Highest number of cut flowers was recorded under R90B10 and R80B20 treatments on ʻUtopiaʼ cultivar, while, lowest numbers of cut flower was recorded for the control and R70B30 treatments on the ʻSamuraiʼ cultivar (Fig. 12A).
Under control conditions, both cultivars spent longer time for the emergence of their first bud than the time needed for first bud emergence under supplemental light treatments. By increasing the ratio of R to B light, the time required for the appearance of the first buds decreased. The fastest first bud emergence was belonged to the ʻUtopiaʼ cultivar under R90B10, which takes in average 62.2 days for its first buds appearence (Fig. 12B).
Longest duration for flower bud coloring was detected under control treatment on ʻUtopiaʼ cultivar, while shortest time for flower bud coloring was recorded for the R90B10 treatment on the ʻSamuraiʼ cultivar (Fig. 12C). Longest duration needed to harvest the flower was recorded under control treatment on ʻUtopiaʼ cultivar, while shortest duration needed to harvest the flower was recorded for the R90B10 treatment on the ʻSamuraiʼ cultivar (Fig. 12D).
The mutual effect of supplementary light treatments and two rose cultivars on dry and fresh weight of each cut flower fresh weight than ʻSamuraiʼ (Fig. 13D). was not significant, but a significant effect was observed among supplementary light treatments and also between two different cultivars.
Highest dry weight of each cut flower was achieved under R90B10 treatment, while lowest dry weight of each cut flower was recorded for R80B20 treatment (Fig. 13A). Among cultivars, ʻSamuraiʼ cultivar had more dry weight for each cut flower than ʻUtopiaʼ (Fig. 13B).
Highest flower fresh weight of each cut flower was calculated under R90B10 treatment, while lowest flower fresh weight was recorded for the control treatment (Fig. 13C). Among cultivars, ʻUtopiaʼ cultivar had more flower.
3.6. Pigment and carbohydrate analysis
Pigment and carbohydrate of the two studied rose cultivars were significantly affected by the use of supplementary light. Highest concentration of chlorophyll a was detected under control and R70B30 treatments on ʻSamuraiʼ cultivar, while lowest chlorophyll a concentration was recorded for the R90B10 on ʻUtopiaʼ cultivar (Fig. 14A).
Highest concentration of chlorophyll b was detected under control treatment on ʻSamuraiʼ cultivar, while lowest chlorophyll b concentration was recorded for the R90B10 treatment on ʻUtopiaʼ cultivar (Fig. 14B). Lowest carotenoids was achieved in the R90B10 treatment on ʻUtopiaʼ cultivar (Fig. 14C).
Highest total chlorophyll was detected under control treatment on ʻSamuraiʼ cultivar, while lowest total chlorophyll was recorded for the R90B10 treatment on ʻUtopiaʼ cultivar (Fig. 14D).
Highest anthocyanin was detected under R90B10 treatment on ʻSamuraiʼ cultivar, while lowest anthocyanin was recorded for the control treatment on ʻUtopiaʼ cultivar (Fig. 14E).
Highest soluble carbohydrates was measured under R90B10 treatment on ʻSamuraiʼ cultivar, while lowest soluble carbohydrates was recorded for the control treatment on ʻSamuraiʼ cultivar (Fig. 14F). Highest storage carbohydrates was observed under R90B10 treatment on ʻUtopiaʼ cultivar, while lowest storage carbohydrates was recorded for the control treatment on ʻSamuraiʼ cultivar (Fig. 14G).
3.7. Chlorophyll fluorescence analysis
The results showed that chlorophyll fluorescence parameters were significantly affected by supplemental light treatments.
Flourescence emission parameters detected from the chlorophyll fluorescence analysis including: Fo, Fi, Fj, and Fm were the highest under control condition. Supplemental light applications caused a significant decrease in those parameters compared to the corresponding values in Control (Fig. 15A, B, C, E). Highest Vj was detected under Control treatment, while lowest Vj was recorded for R90B10 treatment (Fig. 15D).
Highest PIABS was recorded under R90B10 treatment, while lowest PIABS was recorded for control treatment (Fig. S1A). ABS/RC, TRo/RC, ETo/RC, and DIo/RC were the highest under control condition and supplemental light applications caused a significant decrease in those parameters compared to the control (Fig. S1B, C, D, E).