# Analysis of Floral Fragrance Components in Different Parts of _Iris typhifolia_
## 3 Results  
Figure 1 shows the radar map of the characteristic response of _Iris typhifolia_ during the bloom stage and each part of _Iris typhifolia_ in the bloom stage. The resistance ratio of the response values of the volatile substances in the bloom stage and the different parts in the bloom stage to the 10 sensors is significantly different, with the response values ranging from 0 to 3.5. The response values of the volatile substances of the flag petal to W1S (broad-methane), W1W (sulphur-organic), and W2W (sulph-chlor) sensors are higher than those of other sensors, indicating that the volatiles in this stage mainly contain short-chain alkanes, inorganic sulfide, organic sulfide, and other substances. The response values of the pendant petal substances to W1S, W1W, W2W, and W3C (aromatic) sensors are relatively high, indicating that the volatiles in this stage include methyl compounds, inorganic sulfides, organic sulfides, ammonia, and other substances. W3C shows high response values only in the volatile material samples of the vertical lobe. The response values of the volatile substances in stamens to W1S, W1W, and W2W sensors are relatively high, indicating that the volatile substances in this stage contain methyl compounds, inorganic sulfides, and organic sulfides. The response values of pistil volatile substances to W1S, W1W, and W2W sensors are relatively high, showing that the volatile substances contain methyl compounds, inorganic sulfides, and organic sulfides in this stage. In the bloom-stage Iris samples, the response values of W1S, W1W, W2S, and W2W sensors are higher than those of other sensors, which indicates that the volatile components in this stage mainly contain methane, inorganic sulfide, alcohol, and organic sulfide. The above four parts made certain contributions to these results. The principal component analysis (PCA) results of the flag petal, pendent petal, stamen, and pistil of _Iris typihifolia_ are shown in Figure 2. The contribution rate of the first principal component is 87.42% and of the second principal component is 11.80%. Together, the cumulative contribution rate of the two principal components is 99.22%. Therefore, these two principal components basically represent the main information characteristics of the sample. As can be seen from Figure 2, the stamen and pendent petal of _Iris typihifolia_ cannot be clearly distinguished by principal component analysis. That is because the floral odors of the stamen and pendent petal are close to each other. The pendant petal, pistil, and flag petal can be distinguished in this model. It turns out that the floral scents of the pendant petal, pistil, and flag petal of _Iris typihifolia_ are different. Electronic nose loading analysis is a research method for electronic nose sensors to distinguish volatile substances in samples, which mainly aims to investigate which gas substances in the sample play a major role in distinguishing and determining the contribution rate. The bloom stage of _Iris typihifolia_ and the electronic nose load analysis results of each part in the bloom stage are shown in Figure 3. Sensor W1W (sensitive to sulfides and terpenes), sensor W2W (sensitive to organic sulfides and aromatics), sensor W1S (sensitive to methane), sensor W5S (sensitive to nitrogen oxides), and sensor W2S (sensitive to alcohols and some aromatics) are far from the origin. This shows that the five sensors, W1W, W2W, W1S, W5S, and W2S, are important sensors to distinguish volatile components in different parts. It also shows that the difference in the floral components in different parts is mainly related to volatile substances such as sulfide, terpenes, organic sulfide, aromatic compounds, methane, nitrogen oxides, and alcohols [15]. Figure 1: Radar map of the characteristic response of the volatile components in _Iris typihifolia_.