## 4 Discussion  
In this research, a non-targeted approach coupled with HS-SPME-GC-TOF-MS was applied for the identification of VOCs from the rhizomes and leaves of _K. parviflora_ plants maintained in both growth room and field conditions. The identified VOCs in the HS of the two tissues were categorized into five chemical classes. The results showed that sesquiterpenes (C\({}_{15}\)H\({}_{24}\)) were the major group in rhizomes. This result was consistent with the results of other studies on _K. parviflora_ rhizomes [15; 48; 49; 50]. In other Kaempferia species, such as _K. galanga_, phenylpropanoids constitute the largest proportion of their rhizomes [8; 91]. On the other hand, monoterpenes (C\({}_{10}\)H\({}_{16}\)) are the dominant compounds in _K. parviflora_ leaves, which is first time that this has been reported for the species. Rhizomes are grown underground and exposed to pathogenic attacks by fungi and bacteria. Sesquiterpenes are known to have antifungal and antibacterial properties [92; 11; 93]. On  
Figure 6: Boxplot diagrams for normalized peak intensities of volatile compounds identified from the rhizomes and leaves of _K. parviflora_ grown in the field, with no significant differences (\(p\)-value \(>\) 0.05) among their relative abundance. Nine VOCs with peak intensities of <100 (**a**). Two VOCs with peak intensities of >100 in both tissues (**b**). _Y_-axes are peak intensity values from GC-TOF-MS. The mean is marked with a horizontal line; the bottom and the top of the box represent the 25 th and 75 th percentiles; and the whiskers represent the minimum and maximum values. the other hand, leaves can be found above the ground, and are more exposed to insects. Monoterpenes are produced to deter insects. These two groups of VOCs exhibit a wide range of biological activities, including antioxidant, anti-inflammatory, anti-tumor, anti-malaria, and anti-neoplastic properties. They are also used for commercial purposes, such as in perfumery, aromatherapy, and food flavoring. Our findings affirm that _K. parriflora_ rhizomes and leaves are both potential sources of several active pharmacological compounds with potential commercial applications. PCA was performed to investigate the relationships between the VOCs in two tissues of _K. parriflora_ plants grown in two different environments (Figure 4). The PCA results demonstrated clear separation of the samples into four groups. The two tissues of the growth room samples were closely clustered together, indicating similar VOC profiles. This could be due to the constant light and temperature in the growth room and the plants' lower exposure to stress. On the other hand, the field samples were separated from growth room samples, possibly due to changes in the VOCs' composition and abundance. Evidence from the literature supports the finding that emissions of terpenes from plants are known to be both light- and temperature-dependent [94; 95; 96; 97]. Competitive interactions between plants, pollinator attraction, and plant defense processes stimulate terpene production [95]. These conditions were possibly more present in the uncontrolled field conditions than the growth room conditions. A significant separation of rhizome and leaf samples from the field was also observed on the PCA plot. Rhizomes are storage organs with large secretory tissues, which can explain their more diverse VOC composition and higher abundance in rhizomes than in leaves. In addition, individual samples of the two tissues showed that they were slightly scattered from each other, while those of the growth room plants were closely clustered together. This can be attributed to the different responses of the individual plants to the environment in an open field than in a controlled growth room environment. The constructed Venn diagram was used to visualize the distribution and number of identified VOCs in all samples. It was shown that there was not much difference in the identified numbers of VOCs between the two tissues in both growth conditions.