3.4.8. Changes in IAA/ABA Ratio

According to studies, the rooting of plant cuttings has relations with not only the endogenous IAA and ABA contents but also the ratio between the two contents [25]. As shown in Figure 3H, the IAA/ABA ratio showed a trend of decreasing before increasing. In the initiation period, the control group exhibited the highest IAA/ABA ratio. Meanwhile, after callus formation, ABT-1—1000 mg·L−<sup>1</sup> presented higher IAA/ABA ratio compared with the treatment groups with 200 and 500 mg·L−1, and the control group, especially during adventitious root formation and elongation period, where the IAA/ABA ratio of ABT-1—1000 mg·L−<sup>1</sup> was 4.6 times that of the control group. This indicates that a lower IAA/ABA ratio in the early stages of cuttings is conducive to root primordia differentiation and formation, while a higher IAA/ABA value after callus formation is beneficial to root system development.

## 3.4.9. Changes in IAA/ZR Ratio

As presented in Figure 3I, the IAA/ZR values for ABT-1—1000 mg·L−<sup>1</sup> showed a trend of increasing followed by decreasing, with a slightly smaller decrease in the control group and a continuous decrease in the treatment groups with 200 and 500 mg·L−<sup>1</sup> ABT-1. In the whole rooting period, the optimal treatment 1000 mg·L−<sup>1</sup> ABT-1 had the higher

IAA/ZR values compared with other treatments and the control, indicating that a higher IAA/ZR value contributes to rooting of cuttings.
