# Plant Growth Regulators Improve the Production of Volatile Organic Compounds in Two Rose Varieties
## Results and Discussion
### Analysis of VOCs after BA and NAA Application  
A total of 81 components were identified from both rose varieties after the application of BA. Eight VOCs produced by Hybrid Tea flowers were significantly (\(p<0.05\)) different from the controls (double distilled water) as determined by one-way ANOVA and post-hoc tests (Figure 2a). In contrast, the Floribunda flowers produced five VOCs that were significantly (\(p<0.05\)) different from the controls (Figure 3a). The accurate collection of VOCs is very important for the analysis of flower volatiles. Various methods have been used to analyze volatile compounds, including HS-SPME [28]. Unfortunately, the VOCs obtained from extracted oils rarely provide the natural aroma of flowers because of thermal artifacts produced during the steam distillation process that typically occur at 60-70 \({}^{\circ}\)C [29]. The HS-SPME fiber method is favorable for the analysis of volatiles emitted from flowers because high-temperature artefacts are minimized during the process [30]. Overall, the different rose varieties showed differences in the quantity and quality of the volatile compounds produced (Tables 1 and 2). A total of 76 compounds were identified from the two rose varieties after NAA application. Five compounds showed significant (\(p<0.05\)) differences for Hybrid Tea (Figure 2b), while two compounds were significant (\(p<0.05\)) for Floribunda (Figure 3b), compared to the control. The two PGRs induced different types, amounts, and quantities of VOCs emitted from the flowers. The HS-SPME technique was used to analyze the emission of volatile organic compounds from fresh  
Figure 1: Comparison of the main peak areas at different sampling times for the analysis of volatile compounds collected from flowers of two rose varieties. Bars represent least significant differences (LSD) of the means at (\(p<0.05\)) (\(n=3\)). Figure 2: Volatile organic compounds collected from Hybrid Tea flowers after application of benzyladenine BA (**A**) and naphthalene acetic acid NAA (**B**), the red dots represent the volatile compounds which are significantly (\(p<0.05\)) different to the total collected volatile compounds. Principal component analysis PCA analyses were used with one-way ANOVA. flowers of two rose varieties [24] and chrysanthemum [31]. The results correspond to a recent study by [PERSON] et al. [25], which showed that as the concentration of BA applied to Hybrid Tea and Floribunda increased from 0 to 200 mg/L, the number of metabolites produced increased significantly. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**RT.**} & \multirow{2}{*}{**Compounds**} & \multirow{2}{*}{**RI**} & \multicolumn{3}{c}{**Mean of Peaks at BA (mg/L)**} & \multicolumn{3}{c}{**Mean of Peaks at NAA (mg/L)**} \\ \cline{5-9}  & & & **0** & **100** & **200** & **0** & **100** & **200** \\ \hline
8.82 & Propyl glycolate & 928 & 1.33 & 1.23 & 2.64 * & 0.32 & 0.30 & 0.58 \\
10.55 & \(\alpha\)-Pinene & 939 & 3.56 & 4.02 & 6.40 * & 4.61 & 5.60 & 5.43 \\
13.52 & D-Limonene & 1018 & 0.11 & 0.84 & 1.09 * & 2.52 & 2.03 & 2.38 \\
25.24 & Caryophyllene & 1396 & 21.56 & 27.90 & 24.88 & 25.38 & 31.83 & 51.21 * \\
25.42 & Isocaryophyllene & 1424 & 27.46 & 28.72 & 22.86 & 17.03 & 34.62 & 37.11 * \\
26.59 & \(\gamma\)-Muurolene * & 1494 & 9.24 & 12.06 & 29.91 * & 26.66 & 23.97 & 27.09 \\ \hline \hline \end{tabular}  
* (*) represents significant differences between different concentrations of BA and NAA (0 (control), 100 and 200 mg/L); RT—retention time; RI—retention index based on alkane series; ND—not detected; \({}^{\dagger}\)—compounds that increased significantly with LSD \(p\leq 0.05\) in Floribunda rose with increasing concentrations of BA and NAA compared to the control.  
\end{table} 
Table 1: Identification of VOCs that differed significantly (\(p\leq 0.05\)) between flowers of Floribunda rose after being treated with different concentrations of BA and NAA.