*3.1. Observation of Rooting Progress of Vegetable Mulberry and Fruit Mulberry*

As revealed by observation, for the treatment groups of both vegetable mulberry (Figure 1) and fruit mulberry (Figure 2), the incision at the base began to swell and crack to produce callus tissue at 18 days after the cuttings, and adventitious roots started to form and emerge from the bark between 18–28 days after the cuttings. From 28 to 48 days after the cuttings, numerous adventitious roots were generated and continued to elongate. Compared with the treatment group, the control group of vegetable mulberry and fruit mulberry cuttings exhibited later rooting progress. The rooting process of vegetable mulberry and fruit mulberry cuttings could be divided into three stages, namely the initiation stage (1–18 days), the callus tissue generation stage (18–28 days), and the adventitious root generation and elongation stage (28–48 days).

**Figure 1.** Rooting process of vegetable mulberry cuttings. (**A**): 1-day morphology of vegetable mulberry cuttings; (**B**): 18-day morphology of vegetable mulberry cuttings; (**C**): 18–28-day morphology of vegetable mulberry cuttings; (**D**): 28–48-day morphology of vegetable mulberry cuttings.

**Figure 2.** Rooting process of fruit mulberry. (**a**): 1-day morphology of fruit mulberry cuttings; (**b**): 18-day morphology of fruit mulberry cuttings; (**c**): 18–28-day morphology of fruit mulberry cuttings; (**d**): 28–48-day morphology of fruit mulberry cutting.

#### *3.2. Effects of Different Treatments on Rooting of Vegetable Mulberry Hardwood Cuttings*

The effects of different treatments on the rooting of vegetable mulberry hardwood cuttings are exhibited in Table 4. After treatment with plant growth hormones, the rooting rate, average number of roots, average root length, average longest root length, and root system index of vegetable mulberry were all promoted to varying degrees, increasing before decreasing with the increase in concentration of plant growth hormones. Regarding the rooting rate, the highest rooting rate was observed in ABT-1—1000 mg·L−1, and the average rooting rate was 63.3%, 4.1 times higher than that of the control group (15.3%), and notably higher than that of other treatments (*p* < 0.01). For average number of roots, the average highest number of roots was noticed in ABT-1—1000 mg·L−1, with 8.89 roots per cutting, followed by ABT-1—500 mg·L−<sup>1</sup> and IBA—1000 mg·L−<sup>1</sup> (with no remarkable difference between the two). For average root length, the optimal treatment was exhibited in IBA—1000 mg·L<sup>−</sup>1, with an average root length of 4.8 cm, 3.8 cm longer than that of the control group. For average longest root length, IBA—1000 mg·L−<sup>1</sup> had the highest value, with an average longest root length of 8.4 cm, 82.9% greater than that of the control group. There was no notable difference between ABT-1—1000 mg·L−<sup>1</sup> and IBA—1000 mg·L−1. Additionally, considering effectiveness evaluation of cuttings, the root system index is also a key indicator. ABT-1—1000 mg·L−<sup>1</sup> had the greatest root system index, which was 25.3, 120.5 times greater than that of the control group, and remarkably higher than that of other treatment groups and the control group. To sum up, the best results were achieved by applying 1000 mg/L−<sup>1</sup> ABT-1 in treating vegetable mulberry hardwood cuttings, thereby promoting the generation of numerous strong roots for vegetable mulberry.

**Table 4.** Effects of different treatments on rooting indices of vegetable mulberry hardwood cuttings.


Note: Values in the table are expressed as mean ± standard error. Different letters within the same column indicate notable differences, while same letters suggest no notable differences. In addition, capital letters denote remarkable differences between treatments at *p* < 0.01 level, while lowercase letters signify obvious differences at *p* < 0.05 level. The same applies to the following tables.

As indicated by the results of the analysis of variance for the five rooting indices (Table 5), both the type and quality concentration of plant growth hormones had extremely obvious effects on all rooting indices (*p* < 0.01), and there was a notable interaction between the type and quality concentration of plant growth hormones. Regarding the magnitude of the F value, the type of plant growth hormones had the greatest effect on vegetable mulberry hardwood cuttings, followed by the quality concentration.


**Table 5.** Analysis of variance for the results of vegetable mulberry cuttings.

Note: \*\* indicates notable difference at the 0.01 level of mean difference. The same applies to the following tables.

#### *3.3. Effects of Different Treatments on Rooting of Fruit Mulberry Hardwood Cuttings*

The effects of different treatments on the rooting of fruit mulberry hardwood cuttings are exhibited in Table 6. The results indicated great differences in rooting among different treatments. The highest rooting rate was observed in ABT-1—500 mg·L<sup>−</sup>1, reaching 68.7% that was 5.2 times higher than the control group, and obviously different from other treatments (*<sup>p</sup>* < 0.05). Except for IBA—1500 mg·L−1, all treatments had higher values for average number of roots, average root length, and average longest root length compared with the control group. Among them, ABT-1—500 mg·L−<sup>1</sup> had the average highest number of roots and average longest root length, namely 10.1 and 9.3 cm, respectively; ABT-1— 200 mg·L−<sup>1</sup> had the average longest root length, namely 5.2 cm. According to multiple comparisons, there was a notable difference in average number of roots between ABT-1— 200 mg·L−<sup>1</sup> and ABT-1—500 mg·L−1, but no obvious difference in average root length and average longest root length between ABT-1—200 mg·L−<sup>1</sup> and ABT-1—500 mg·L−1. Regarding the root system effect index, ABT-1—500 mg·L−<sup>1</sup> had the highest value of

34.3, remarkably higher than other treatment groups. Nevertheless, the rooting rates of 200 mg·L−<sup>1</sup> IAA (9.3%) and 1500 mg·L−<sup>1</sup> IBA (0) treatment groups were lower than that of the control group (13.3%) suggesting that high concentration of plant growth hormones does not play a role in promoting the growth of fruit mulberry even while inhibiting its growth. As illustrated by data analysis, the optimal concentration of ABT-1 for fruit mulberry cuttings was 500 mg·L<sup>−</sup>1.


**Table 6.** Effects of different treatments on rooting index of fruit mulberry hardwood cuttings.

Note: Values in the table are expressed as mean ± standard error. Different letters within the same column indicate notable differences, while same letters suggest no notable differences. In addition, capital letters denote remarkable differences between treatments at *p* < 0.01 level, while lowercase letters signify obvious differences at *p* < 0.05 level.

The variance analysis of the two-factor completely randomized block design model was conducted for the observation results of fruit mulberry, with the results presented in Table 7. According to the results, the types and quality concentrations of growth hormones had notable effects on all rooting indices (*p* < 0.01), and there was an obvious interaction between growth hormone types and quality concentrations. Based on the F values, it can be inferred that the quality concentrations have the greatest effect on fruit mulberry hardwood cuttings, followed by the types of growth hormones.

**Table 7.** Analysis of variance for the results of fruit mulberry cuttings.



**Table 7.** *Cont.*

Note: \*\* indicates notable difference at the 0.01 level of mean difference. The same applies to the following tables.
