## 2 Result and Discussion
### Variation in Volatile Compounds from Nine Citrus Cultivars
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Compounds** & **FC \({}^{\ast}\)** & **PK \({}^{\ast}\)** & **PK \({}^{\ast}\)** & **ST** & **LBC** & **QJ** & **ERK** & **BM** & **YHY** & **ZXY** & **HY** & **Mean rank** \\ \hline Linalool & Om4 & 50.43 \({}^{\rm 1 st}\) & 17.41 \({}^{\rm 1 st}\) & 42.91 \({}^{\rm 1 st}\) & 36.11 \({}^{\rm 1 st}\) & 6.88 \({}^{\rm 1 st}\) & 7.22 \({}^{\rm 1 st}\) & 56.16 \({}^{\rm 1 st}\) & 10.10 \({}^{\rm 2 nd}\) & 30.58 \({}^{\rm 1 st}\) & 10.10 \({}^{\rm 2 nd}\) & 30.58 \({}^{\rm 1 st}\) \\ Limonene & Mh9 & 11.15 \({}^{\rm 5 th}\) & - \({}^{\ast}\) & 1.75 \({}^{\rm 1 inh}\) & 2.69 \({}^{\rm 1 st}\) & 44.95 \({}^{\rm 1 st}\) & 27.25 \({}^{\rm 1 st}\) & 2.19 \({}^{\rm 8 th}\) & 2.54 \({}^{\rm 1 st}\) & 10.09 \({}^{\rm 2 nd}\) & 10.29 \({}^{\rm 2 nd}\) \\ Indole & N2 & 3.96 \({}^{\rm 4 th}\) & 5.00 \({}^{\rm 4 th}\) & 104.14 \({}^{\rm 2 nd}\) & 6.91 \({}^{\rm 4 th}\) & 1.01 \({}^{\rm 15 th}\) & 0.16 \({}^{\rm 2 nd}\) & 5.51 \({}^{\rm 2 nd}\) & 7.18 \({}^{\rm 3 rd}\) & 4.52 \({}^{\rm 3 rd}\) & 4.96 \({}^{\rm 3 rd}\) \\ a-cital & Om23 & 0.045 \({}^{\rm 1 st}\) & - & 0.66 \({}^{\rm 1 st}\) & 11.17 \({}^{\rm 2 nd}\) & 0.911 \({}^{\rm 2 nd}\) & 24.50 \({}^{\rm 2 nd}\) & 3.07 \({}^{\rm 7 th}\) & 1.19 \({}^{\rm 1 st}\) & 1.38 \({}^{\rm 7 th}\) & 4.77 \({}^{\rm 4 th}\) \\ \(\gamma\)-terpinene & Mh12 & 1.44 \({}^{\rm 1 th}\) & 8.91 \({}^{\rm 2 nd}\) & 0.30 \({}^{\rm 2 nd}\) & 0.32 \({}^{\rm 2 nd}\) & 1.97 \({}^{\rm 1 st}\) & 3.71 \({}^{\rm 4 th}\) & 0.05 \({}^{\rm 4 nd}\) & 0.05 \({}^{\rm 2 nd}\) & 22.83 \({}^{\rm 1 st}\) & 4.40 \({}^{\rm 5 th}\) \\ \(\beta\)-pinene & Mh5 & 7.83 \({}^{\rm 2 nd}\) & 3.91 \({}^{\rm 5 th}\) & - & 7.98 \({}^{\rm 3 rd}\) & 0.81 \({}^{\rm 19 th}\) & 0.68 \({}^{\rm 18 th}\) & 1.67 \({}^{\rm 1 st}\) & - & 8.08 \({}^{\rm 4 th}\) & 3.44 \({}^{\rm 6 th}\) \\ \(\beta\)-cital & Om21 & 0.094 \({}^{\rm  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Compounds** & **FC \({}^{\text{a}}\)** & **PK \({}^{\text{b}}\)** & **ST** & **LBC** & **QJ** & **ERK** & **BM** & **YHY** & **ZXY** & **HY** & **Mean rank** \\ \hline Methyl anthranilate & N3 &  
When the profiling of flower volatiles was compared with leaf volatiles of the same citrus types from our previous studies [21], some similarities were observed. Seven volatiles, linalool, limonene, \(\beta\)-pinene, \(\gamma\)-terpinene, \(\beta\)-elemene, \(\alpha\)-cital and \(\beta\)-cital, were present as the top ten volatile in leaves and flowers at all stages, especially, linalool and limonene, in the top five in all samples analyzed (Tables 3-5) [21]. On the other hand, some striking differences were also observed between leaf and flower volatiles. For example, (\(E\))-ocimene ranked second, on average for all citrus examined, both in young and mature leaves but ranked from 4 th to 13 th in flowers; indole ranked in the top nine in all citrus except for two citrus, in flower volatiles, while it was only identified in traces from leaf of Satsuma and Hongshigan; \(\beta\)-terpinene ranked in the top six in leaves but was not detected in flowers; Methyl anthranilate was abundant in volatiles of half or fully opened flowers of Satsuma, Liubencheng, Yuhuanyou and Huyou but was not detected in leaves (Tables 3-5) [21]. Here in this study, linalool and limonene were the major flower volatiles in most cultivars, which may play important roles in attraction of pollinators and as defense compounds against herbivores and pathogens [21,42,43]. As to the occurrence of numerous volatile components belonging to different chemical classes, it has been reported that this is related to the operation of different metabolic pathways [41,44]. The increase or decrease in amount of volatiles during flower blooming stages might suggest an activation or synthesis of related terpene synthases which catalyze formation of the critical intermediate \(\alpha\)-terpinyl or pinyl cation for cyclic monoterpene and geranyl or linalyl cation for acyclic monoterenes [15].