*3.3. Correlation Analysis of Architectural Traits in EN2019 and EN2020*

Table 2 shows the Pearson correlations between the nine phenotypic traits in EN2019 and EN2020. In total, there were 72 pairs of architecture correlations in EN2019 and EN2020. Among all the architectural traits, the positive correlation between the number of leaf nodes and total number of lateral buds was the strongest, whose correlation coefficients in EN2019 and EN2020 were 0.913 and 0.986, respectively, followed by the positive correlation between primary branch length and primary branch diameter, whose correlation coefficients were 0.639 and 0.661, respectively. Similarly, the negative correlation between primary branch length and number of upper primary branches in EN2019 was the strongest, with a correlation coefficient of −0.317; in EN2020, the negative correlation between primary branch diameter and number of upper primary branches was the strongest, with a correlation coefficient of −0.466.

#### *3.4. Cluster Analysis of the Architectural Traits of 195 Spray Cut Chrysanthemum Species*

Cluster analysis was performed using both the K-means clustering algorithm and the Pedigree clustering algorithm based on the nine architectural traits during the twoyear period (Figure 2). The best preset number of K calculated by K-means in EN2019 and EN2020 was 5 (Figure 2a,b), which was verified by pedigree clustering (Figure 2c,d). However, in EN2019, the 195 spray cut chrysanthemum varieties were divided into six categories according to the pedigree clustering diagram, which was inconsistent with the results of the K-means clustering; in EN2020, the distribution of varieties in the pedigree clustering diagram was nearly the same as that in the K-means clustering diagram.


**EN2019**

Number of lateral flower buds

Stem diameter Primary branch diameter

Primary branch angle

Primary branch length

−0.232 \*\*

 0.322 \*\*

 0.096

 0.063

 0.113 Note: \*\* and \* indicate significant differences at the 0.01 and 0.05 probability levels, respectively.

 0.063

 0.057

 0.351 \*\*

 0.250 \*\*

 0.028 −0.215 \*\*

 0.341 \*\*

 0.257 \*\*

 0.026 −0.242 \*\*

 0.240 \*\*

−0.019 −0.466 \*\*

−0.253 \*\*

−0.402 \*\*

 0.513 \*\*

 0.368 \*\*

−0.108

 1 −0.191 \*\*

 0.109

 1

 0.147 \*

−0.031

−0.279 \*\*

 0.579 \*\*

 0.394 \*\*

 1

 0.264 \*\*

 0.661 \*\*

 0.147 \*

 1

 0.160 \*

−0.074

−0.041

 0.534 \*\*

 0.044

 0.639 \*\*

 0.148 \*

 1

*Horticulturae* **2022**

 **Branch Length** , *8*, 458

 0.142 \*

−0.059

−0.138

−0.317 \*\*

**Figure 2.** Cluster analysis map of 195 spray cut chrysanthemum varieties in EN2019 and EN2020. (**a**) K-means cluster of 195 spray cut chrysanthemum varieties in EN2019; (**b**) K-means cluster of 195 spray cut chrysanthemum varieties in EN2020; (**c**) Pedigree cluster of 195 spray cut chrysanthemum varieties in EN2019; (**d**) Pedigree cluster of 195 spray cut chrysanthemum varieties in EN2020. Different colors in every figure refer to different clusters.

Therefore, the categories in EN2020 were more suitable for summarizing the 195 spray cut chrysanthemum varieties. As shown in Figure 3, the 195 were divided into five categories, accounting for 3.08%, 12.31%, 29.74%, 13.85% and 41.45% of all the varieties, of which the typical architecture types were summarized. In the first category, there were only six varieties, represented by Nannong Taoliu (Figure 3a), which had a low startingbranch height, long primary branches, a semispreading plant growth habit and a large number of secondary branches. There were tertiary branches on the plants only in the first category. The second category, represented by Nannong Meifengche (Figure 3b), included 24 varieties, which had loosely distributed branches and longer primary branches. There were fewer leaf nodes and secondary branches on the plants in the second category. The third category, represented by Nannong Cuilongzhao (Figure 3c), included 58 varieties whose starting-branch height was lower than 1/3 of the total plant height. The plants in this category had a relatively large distribution of flowering branches and secondary branches. The fourth category, represented by Nannong Songmang (Figure 3d), included 27 varieties, which had a higher starting-branch height and shorter flowering branches. These compact flowering branches displayed a nearly spherical appearance. The fifth category, represented by Nannong Bingqing (Figure 3e), included 80 varieties, the plants of

which had a relatively large amount of leaf nodes. The flowering branches of the plants in this category displayed a tower-like shape.

**Figure 3.** Five representative varieties with different architectural traits among 195 spray cut chrysanthemum. (**a**) Nannong Taoliu; (**b**) Nannong Meifengche; (**c**) Nannong Cuilongzhua; (**d**) Nannong Songmang; (**e**) Nannong Bingqing. Bars = 10 cm. In each sub figure, the left one refers to an intact plant, middle one refers to an intact plant without leaves and the right one refers to an intact plant without leaves and flowers.
