# Plant Growth Regulators Improve the Production of Volatile Organic Compounds in Two Rose Varieties
## Results and Discussion
### Identification of VOCs Emitted from Flowers of Two Rose Varieties  
A diverse range of VOCs were produced from the flowers, as determined by principal component analysis (PCA). These are shown by the distinct clustering of rose samples according to BA treatments (Figure 5a,b) and NAA treatments (Figure 6a,b) for both rose varieties. Different VOCs were produced in response to the different BA and NAA concentrations. There was no overlap and a good separation in the VOCs was produced between the three concentrations of BA and NAA. Each PGR had different numbers of identifying compounds for the two rose varieties (Tables 1 and 2). The VOCs increased with increasing levels of BA, for instance, cis-muurola-4(14), 5-diene, which is an important compound in the perfume industry, increased from 7.61 to 33.45 in total peak area as BA levels increased from 0 to 200 mg/L in Hybrid Tea flowers (Table 2). [PERSON] et al. [34] showed that this compound was found in different tissues of _Artemisia annua_ (Sweet Annie) plants. Another aroma chemical, \(\gamma\)-cadinence, which is used for essential oils and medicinal purposes [35], increased from 0.13 to 4.14 with an increase  
Figure 4: Effects of BA and NAA application on the extraction efficacy of the total VOCs identified from flowers of two rose varieties as determined by GC-MS. Error bars are LSD at (\(p<0.05\)) (\(n=3\)). One-way ANOVA analyses were used.  
in BA from 0 to 200 mg/L in Hybrid Tea. Similarly, \(\gamma\)-muurolene increased from 9.24 to 29.91 as BA increased from 0 to 200 mg/L in Floribunda (Table 1). [PERSON] and [PERSON] [36] demonstrated that \(\gamma\)-muurolene is an important compound found in _Lippiia multiiflora_ and used in the essential oils industry. Moreover, a study on tissue cultured _Plectranthus orntus_ (Coleus) plants using BA and NAA showed that many compounds such as cis-Muurola-4(14),5-diene, \(\gamma\)-cadinene and \(\gamma\)-muurolene increased significantly and stimulated callus induction and plant growth [33]. In the current study, after NAA application at 200 mg/L, the amount of myrcene increased in Hybrid Tea. This compound is very important as an essential oil, flavor, and fragrance, as well as for health and medicinal purposes, and corresponds to the findings by [PERSON] et al. [37] from _Cannabis sativa_ plants. Prenyl acetate was produced in high quantities in Hybrid Tea after NAA application at 200 mg/L and is commonly used for many commercial and chemical purposes. In addition, PGRs have a key role in plant life cycles, as well as having an influence on all physiological processes that occur in plants. Moreover, they influence the biochemistry and metabolic processes in plants [38].  
In this study, we only selected 81 and 76 VOCs produced from BA and NAA, respectively, for further analysis. These were analyzed by MetaboAnalyst 4.0, which showed that only 20 VOCs increased significantly compared to the controls. None of the BA and NAA applications significantly decreased the concentrations of VOCs below the controls.  
Figure 5: Principal component analysis (PCA) model obtained from the classification of volatile organic compounds emitted from the flowers of Floribunda (**A**) and Hybrid Tea (**B**), based on VOCs according to BA treatments. F and H represent Floribunda and Hybrid Tea, respectively. While C (control) (red), T1 (100 mg/L) (green) and T2 (200 mg/L) (blue) represent 0, 100 and 200 mg/L BA, respectively. Three dots in each group represent \(n=3\) biological replicates.