# Analysis of Floral Scent Component of Three Iris Species at Different Stages
## 3 Results
The results of the Linear Discriminant Analysis (LDA) for _Iris uniflora_, _Iris sanguinea_, and _Iris typhifolia_ are presented in Figure 4. The contribution rate of the first discriminant factor is 76.36%, and the contribution rate of the second discriminant factor is 10.28%. The cumulative contribution rate reaches 86.64%, indicating that these two discriminant factors essentially represent the main information characteristics of the samples. Figure 4 reveals that the floral fragrances of _Iris uniflora_, _Iris sanguinea_, and _Iris typhifolia_ can be significantly distinguished. Figure 2: The PCA result of the volatile components in three Iris species at different stages. Note: S1: the bud stage, S2: the bloom stage, S3: the decay stage. In comparison with Principal Component Analysis, Linear Discriminant Analysis demonstrates a more concentrated distribution, and its discrimination effect is notably higher than that of Principal Component Analysis. Figure 4: The LDA result of the volatile components in three Iris species at different stages. Note: S1: the bud stage, S2: the bloom stage, S3: the decay stage. Figure 3: The loading result of the volatile components in three Iris species at different stages. The qualitative and quantitative determination of volatile components in _Iris twilforia_ is conducted through Gas Chromatography-Mass Spectrometry (GC-MS) and spectral library retrieval. A total of 37 species are detected in the bud stage, 43 in the bloom stage, and 39 in the decay stage. The Venn diagram in Figure 5 illustrates the floral composition across different periods, with 13 identical floral components found in all three periods, 10 unique to the bud stage, 12 in bloom, and 13 in the decay stage. Quantitative determination of volatile components in _Iris uniflora_ reveals 21 species in the bud stage, 33 in the bloom stage, and 27 in the decay stage. Across the three periods, there are 11 identical floral components, 6 unique to the bud stage, 19 in bloom, and 13 in the decay stage. For _Iris sanguinea_, 23 species are detected in the bud stage, 42 in the bloom stage, and 42 in the decay stage. The three periods share 11 identical floral components, with 4 unique to the bud stage, 11 in bloom, and 21 in the decay stage. In total, 72 species are detected in _Iris twilifolia_ samples, 54 in _Iris uniflora_, and 67 in _Iris sanguinea_. The three iris species share a total of 16 identical floral components, with 21 unique to _Iris twilifolia_, 25 in _Iris uniflora_, and 17 in _Iris sanguinea_. Figures 6 and 7 respectively depict the number and relative content of floral fragrance species in three different stages of Iris. The types of compounds present at each stage include alcohols, aromatics, aldehydes, ketones, alkanes, and esters. The relative content of aldehydes in each stage is notably high, exceeding 40% and reaching an impressive 83.23% in the flower bud stage of _Iris twilifolia_. Olefin and heterocycle samples exhibit low relative contents, less than 2%. The number of ketone species remains relatively stable across all samples over time. Terpene species are generally fewer in the bud stage but exhibit a sudden increase in the decay stage and bloom stage. Although the relative content is not high, the number of terpene species reaches 11 during the decline stage of _Iris sanguinea_ and 13 during the bloom stage of _Iris twilifolia_--both having the largest number of volatile substances in each stage. However, only one species of terpene is found in _Iris uniflora_ during this time, suggesting that the aroma substances in the decay stage of _Iris uniflora_ do not rely on terpen. The number of alkane species in the flower bud stage of _Iris twilifolia_ is several times higher than that in the other two Iris types. In _Iris uniflora_, the number of aromaticity and alkane species gradually increases during the flower bud stage, full bloom stage, and decay stage. Alcohols are found abundantly only in _Iris uniflora_.