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Article

Effective Methods for Adventitious Root Regeneration on Weeping Fig Stems

by
Nelson Li
and
Yusen Chang
*
Department of Horticulture and Landscape Architecture, National Taiwan University, Taipei 100, Taiwan
*
Author to whom correspondence should be addressed.
Forests 2022, 13(8), 1165; https://doi.org/10.3390/f13081165
Submission received: 19 May 2022 / Revised: 19 July 2022 / Accepted: 19 July 2022 / Published: 23 July 2022
(This article belongs to the Section Urban Forestry)
Browse Figures
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Abstract

:
When transplanting mature Ficus trees, the large root balls are expensive to treat, handle, and move. This study aimed to identify the optimal wounding method and auxin treatment for regenerating adventitious roots (ARs) from weeping fig (Ficus benjamina L.) stems to uptake additional water and to compensate for fewer absorption roots in the smaller root balls at transplantation. We adopted a two-factorial experiment involving the wounding methods (three-line cut (3LC) and rectangular peel (RP)) and auxin treatments (2000 mg·L−1 Indole-3-butyric acid (IBA), 2000 mg·L−1 IBA + 2000 mg·L−1 1-naphthaleneacetic acid (NAA), and 4000 mg·L−1 IBA). The rooting rate of each treatment, the mean root number, the length of the three longest ARs, and the dry weight of ARs in each wound were evaluated. The treatment combination using 4000 mg·L−1 IBA with RP13 (rectangular peel 1/3 the perimeter of the stem) consistently exhibited the best rooting results in 2019 and 2020. It had a 100% rooting rate, a mean of 18.5 roots, a 16.8 cm root length, and a 1640 mg dry weight in the wounds. All auxin treatments demonstrated a superior rooting ability as compared to water treatments. The RP method regenerated more roots than the 3LC method. Doubling the RP length to be 2/3 of the perimeter improved the rooting ability. The locations of ARs varied under different treatment combinations, with 4000 mg·L−1 IBA on RP13 demonstrating the most diversified distribution on four edges of the wounds. Thus, it is recommended to regenerate ARs from stems of F. benjamina trees.

1. Introduction

Large mature trees often have vast canopies, and their root system can stretch from the trunk to three times the size of the canopy [1,2]. Normally, transplanted root balls retain only 5–8% of the absorption roots [3,4]. Moreover, it takes 6–49 days for the absorption roots to grow in root balls, which can be longer for mature trees [5]. The International Society of Arboriculture (ISA) and the American National Standard Institute (ANSI) suggested that transplanted root balls should be 8–12 times the size of the trunk caliper [6,7], which makes transplantation of mature trees extremely expensive and specialized equipment is necessary. Many mature trees are removed due to urban development and high transplant costs. The Ficus genus belongs to the Moraceae family and is very popular in tropical and subtropical climate zones. The canopies of these trees stretch out extensively and are characterized as having extensive spreading roots. Large mature Ficus trees usually weigh 40–80 tons, with more than 80% of the weight coming from the root balls. They make up the largest population of heritage trees in Taiwan, which are conserved by law during site development. It is a major challenge for local landscapers and arborists to transplant them.
Root pruning can promote the growth of absorption roots inside the root ball [8,9]. In Taiwan and Japan, the practice of root pruning is commonly used to densify new roots in the root ball to reduce the root ball size to 3–5 times that of the caliper [10,11,12]. However, it takes at least one growing season or six months to develop a sufficient number of roots in the root ball for transplantation. In urban areas, it is impractical to damage the pavement to perform root pruning on mature sidewalk trees and then maintain them in that position for six months before transplantation.
Air layering is used to propagate plants that do not root readily from cuttings by girdling the branches or shoots [13,14,15]. By girdling the shoots, the auxin and carbohydrates from the foliage that is translocating through the phloem are cut off and stop at the girdled line [16] and accumulate there to regenerate adventitious roots (ARs). Then, the rooted shoots can be removed with those ARs and planted as seedlings. They have a higher survival rate than cuttings because of the regenerated ARs. However, girdling the main stem kills the trees and cannot be used in transplantation.
In 2019, Li et al. [17] wounded the aerial and prop roots of heritage Indian rubber tree (Ficus elastica Roxb.) trees for AR regeneration. The heritage tree suffered from brown root rot disease, and the ground roots had to be cut off at transplant. Three different methods, i.e., cut-off (CF), girdle (GD), and rectangular peel (RP), were tested, and CF was found to be the most effective in regenerating ARs, followed by GD. The use of RP on the prop roots also regenerated ARs, although it was not as effective as CF or GD. In 2020, the growth of ARs on the prop roots enabled the heritage tree to be transplanted without ground roots and re-established in the new habitat. It would be useful if a similar practice could be applied to regenerate ARs on the stems to supplement the water uptake function of ground roots. This will allow for a smaller root ball at the transplant. However, it is unclear whether wounding the stem could regenerate ARs similarly to wounding the aerial and prop roots.
Auxin is involved in the growth and development of roots [18,19] and is central to controlling the architecture of the root system [20]. The auxin accumulation is necessary for founder cells to form rooting primordium [21,22]. However, research on the effects of auxin on the formation of ARs varies in terms of the tree species, application methods, and environmental conditions [23,24].
Although there were many studies on girdling and cutting off shoots to regenerate ARs for horticultural propagation, there is no prior research on wounding Ficus trees to stimulate the regeneration of ARs from the main stems of the mother trees. ARs that grow on the stems can be buried or wrapped with a medium, which channels them down to the ground to become supporting roots. They can be removed once the ground roots have grown out after transplantation and vigor have been established [25]. With the additional roots on the stem, the root ball size may be reduced, making the transplantation of mature Ficus trees easier and helping to conserve more mature trees by transplanting instead of removal. Furthermore, wounding stems to regenerate ARs is easier than root pruning a sidewalk tree and maintaining it for six months before transplantation in the urban area.
This study aimed to explore the most effective wounding/auxin treatment combination to regenerate ARs from the stems of the weeping fig (Ficus benjamina L.) trees.

2. Materials and Methods

Two experiments were conducted in 2019 and 2020 at the nursery of Treegarden Corporation, which is in Neihu district (latitude 25° N, longitude 121° E, 16 m above sea level), a suburb of Taipei City, Taiwan, that lies within a subtropical climate zone.

2.1. 2019

The 2019 experiment used F. benjamina saplings purchased from a nursery in Changhua County (30 m above sea level) in the middle of Taiwan on 5 April 2019. The saplings were acclimated to the Treegarden nursery for three months until 8 July 2019. They were 1.8 m high with a 2 ± 0.2 cm caliper and were grown in 5-inch pots. The experiment was initiated on 9 July and lasted for 50 days. Two wounding methods were used: three-line cut (3LC) and rectangular peel (RP), as follows:
(1)
3LC: three lines were cut on the tree stem deep into the xylem at 60 cm above the ground by a sharp knife. Lines were 1 cm apart, half the length of the stem perimeter, and parallel to each other. The wound width was the thickness of the blade.
(2)
RP13: a girdle knife was used to cut a rectangular window into the xylem layer on the stem (approximately 2 × 2 cm) at 60 cm above the ground with a length of one third of the perimeter. The bark on the windows was then peeled off.
We used the 32-oz portable spray bottle to spray auxin solution thoroughly on the wounds until the liquid fully covered the wound and flowed out. There were five treatments: (a) 3LC with water (C03); (b) RP13 with water (C13); (c) RP13 with 2000 mg·L−1 in-dole-3-butyric acid (IBA)(2B13); (d) RP13 with 2000 mg·L−1 IBA + 2000 mg·L−1 1-naphthaleneacetic acid (NAA) (2NB13); and (e) RP13 with 4000 mg·L−1 IBA (4B13). Thereafter, the wounds were filled with medium (moisturized peat/coconut fiber at 1:1). We used clear plastic sheets to wrap the medium, which were tied to the stems at the top and the bottom to retain moisture. Each treatment had six replicates in a completely randomized design. Six F. benjamina saplings were left unwounded and were not sprayed to serve as the control (Table 1).
The experiment was conducted in the open air without shading. Sprinkler irrigation was installed at 2.2 m above the ground, with a frequency of 2 min every 2 h between 08:00 and 16:00. No fertilization was applied during the experimental period. Data were collected bi-weekly to observe AR regeneration through the clear plastic wrap. A mini weather station was installed to record the temperature, humidity, illuminance, and wind speed at the test site. During the experimental period, the average daily temperature ranged between 26.2 and 31.8 °C, the humidity was 74%–96%, illuminance was 88–253 wm−2, and the wind speed was 0.05–1.05 ms−1. On 28 August, the plastic wraps were opened and the wounds were washed with a spray nozzle. The number of rooted wounds for each treatment, the mean root number, and the mean length of the three longest ARs in each wound was recorded (Figure 1A–D). The number of the regenerated roots on each of the four edges of the wounds (top, bottom, left, and right) was counted and recorded. The percentage of regenerated root distribution of each edge was calculated.
ARs in each rooted wound were then excised and placed into a paper envelope for each test sample. ARs were oven-dried at 70 °C (forced convection oven, DK500; Yihder Co., Ltd., Xinbei City, Taiwan) for one week, after which the dry weights were determined and recorded.

2.2. 2020

The 2020 experiment was conducted on 15 July and lasted for 50 days. The samples used in the experiment were from the same batch of F. benjamina saplings purchased in April 2019. They had been acclimated to the climate of Treegarden nursery for 15 months. The tree heights were 2 m on average. Three wounding methods and four water/auxin solutions generated 12 treatment combinations. Each treatment combination had 12 replicates. The three wounding methods were 3LC, RP13, and RP23. The 3LC and RP13 methods were performed in the same manner as those in the 2019 experiment. RP23 was similar to RP13, but the cut length was increased to two thirds of the stem perimeter (Figure 1E,F). Wounds were treated with the same water and three auxin solutions as in the 2019 experiment: water (C), 2000 mg·L−1 IBA (2B), 2000 mg·L−1 IBA + 2000 mg·L−1 NAA (2NB), and 4000 mg·L−1 IBA (4B). The same procedure as the 2019 experiment was used to wrap the wounds and irrigate the saplings for 50 days, after which the ARs were harvested. Treatment combinations are detailed in Table 1.
Analysis of variance (ANOVA) was used to identify a significant effect of treatment combinations in Costat (Version 6.400, Cohort Software, Ltd., Birmingham, UK). Least significant difference (LSD) was adopted to determine the significant difference at p < 0.05. Rooting performance was assessed using four indices: rooting rate (rooted wounds/total wounds), mean of root number, root length, and root dry weight in each wound for each treatment combination, which was similar to that of prior studies [26,27]. The SigmaPlot software (version 12.3; Systat Software, San Jose, CA, USA) was adopted to draw bar charts.

3. Results

The weather data indicated that conditions were similar in 2019 and 2020, with no significant variation (Figure 2).
The four rooting indices in both years were used to compare the AR’s regeneration ability for different treatment combinations.

3.1. 2019

The rooting rates were 100% for all auxin treatments: 4B13 (RP13 + 4B), 2B13 (RP13 + 2B), and 2NB13 (RP13 + 2NB). The water treatments of C03 (3LC + water) and C13 (RP13 + water) only exhibited 67% rooting rates (Table 2).
There were significant variations between auxin and water treatments. The mean root numbers of ARs were 24.8, 23.5, and 21 for 2B13, 2NB13, and 4B13, which were significantly higher than the one and two roots that appeared under the C01 and C13 water treatments, respectively. A significant difference in root length was also found between the auxin and water treatments. Treatments of 2B13, 2NB13, and 4B13 resulted in longer mean root lengths, i.e., 11.7, 12.9, and 13.3 cm, respectively, while C03 only exhibited root lengths of 5.2cm. The root length of C13 had 10.2 cm, which was statistically the same as 2B13, 2NB13, and 4B13. It showed that the RP13 treatments secured a longer root length than the 3LC treatment. The highest mean dry weight of 656 mg occurred with 2NB13, followed by 498 mg for the 4B13 treatment. The C13 and 2B13 treatments recorded 297 and 284 mg, which were much lower. The C03 treatment only exhibited 17 mg. 3LC wounding with water spray significantly underperformed as compared with the other treatments. The three auxin treatments exhibited better performance in rooting as compared with the water treatments. The RP13 treatments demonstrated better results than the 3LC treatments.

3.2. 2020

The experimental design included three wounding methods and four water/auxin solutions to generate 12 treatment combinations. Two-way completely randomized ANOVA was initially used to identify the significance of the effect of wounding and auxin on ARs’ rooting performance (Table 3).
There was a significant interaction between wounding and auxin factors; thus, one-way ANOVA was used for the 12 treatment combinations to evaluate their rooting performance (Table 4).
There was no significant variation in the rooting rates among different treatment combinations, although C03, C13, 2B03, and 2B23 had lower rooting rates of 83% compared with the 100% observed in the other treatment combinations. The 4B13, 2B13, and 2B23 treatments had 19, 19, and 21 roots, which were higher than the other treatment combinations. The C03, C13, and C23 water treatments had 6, 3, and 8 ARs in the wounds, much less than those observed in the auxin treatments. The 4B23, 4B13, 2B13, and 2B03 treatments had longer ARs than those observed in the other treatments. Moreover, the 4B13, 4B03, 2B23, 2B13, and 2B03 treatments possessed higher dry weights for their ARs, i.e., 1642, 1285, 1292, 1245, and 1392 mg, respectively. There was a significant improvement in root number, root length, and dry weights for auxin treatments compared to water.

3.3. AR Distribution in Wounds

In 2019, the root regeneration locations in the wounds revealed that more than 90% of ARs emerged from the upper edge of the C03 and C13 water-treated wounds (Figure 3A).
The 4B13 treatment had a more diverse distribution of AR rooting, i.e., on all four edges of the wounds, than the other treatment combinations. In 2020, all ARs were regenerated at the upper edge of the wounds for the water-treated C13 and C23 (Figure 3B). The auxin-treated wounds continued to display a more diverse distribution of rooting in the four edges of the wounds. C03 was the exception. The 4B treatments exhibited the most consistently diverse distribution of rooting locations compared to the other auxin solution treatments in 2019 and 2020.

4. Discussion

4.1. Wounding Method

Wounding is vital for regenerating ARs. Six F. benjamina saplings were not wounded nor sprayed and were used as the control. They did not develop any ARs on the stems during the experimental period. Many researchers reported that wounding enhanced AR rooting. Abdulqader et al. [28] wounded olive stem cuttings and significantly increased rooting performance compared to the unwounded stem cuttings. By incising the base of the Japanese apricot (Prunus mume) cuttings, Mayer and Pereira [29] increased the number of roots on the cuttings. Robbins et al. [30] experimented with four different wounding methods on mung bean (Vigna radiata) hypocotyls and observed more roots and more rooting locations on the cuttings with more severe cuts. Li et al. [17] reported that the severity of stress hastened the regeneration of ARs.
In our study, RP had larger wounds than 3LC, resulting in a significantly better rooting performance in 2019 and 2020. RP seemed to be a more efficient wounding method than 3LC in regenerating ARs, as evidenced by the rooting rate, number of ARs, and root length. RP23 doubled the length of RP13 wounds on the stem and developed more roots in the wounds.
The ARs are usually regenerated by stresses, including wounding (cutting, layering, and girdling), flooding, etiolation, and other culture methods [31]. Stress induces a change in stem cell specification, causing them to become root founder cells. After that, the root founder cells divide and form root primordia. Finally, the root primordia grow to become ARs. It is the de novo process to change cell specification from stem cells to create ARs, which usually requires callus formation [32]. The AR rooting rate is relatively low, and the lead time can be very long for the de novo process. Wounding the stem may not successfully regenerate ARs for all tree species.

4.2. Preformed Root Initials

Certain tree species, such as Ficus, willow (Salix), and poplar (Populous), have latent or preformed root initials on the stem, which can be developed into ARs [33,34]. They occasionally grow aerial roots when environmental stress occurs. By wounding the stem, using such methods as 3LC or RP, the preformed root initials are aroused to divide into root primordia that grow ARs. These ARs could supplement the water uptake ability of the ground roots.

4.3. Auxin Solution

Auxin participates in the initial stage of AR formation. [31]. The jasmonic acid (JA) level quickly rises and peaks upon wounding. Wounding prompts the release of reactive oxygen species (ROS), polyphenols, and hydrogen sulfide, promoting adventitious rooting. Auxin builds up at the wound and increases soluble sugars for root development. [35]. A higher auxin concentration is usually preferred to promote ARs in the initial stage. Exogenous auxin helps to raise the concentration to induce AR formation [36].
Both IBA and NAA are popular exogenous auxins used for AR induction. For the quick dip or paint methods for stem cuttings, 2000 to 4000 mg·L−1 appears to be the most commonly used concentration [37]. In the 2019 and 2020 experiments, the auxin treatments exhibited much better rooting performance than water treatments. Among the three auxin solutions, the 4B treatments (IBA 4000 mg·L−1) demonstrated consistently good rooting performance. It is in line with the results of previous studies. Babaie et al. [38] propagated F. benjamina cuttings with various IBA concentrations and concluded that 4000 mg·L−1 produced the best rooting performance. Ghehsareh and Kuosh-Kuih [39], Mewar and Naithani [40], Shirzad et al. [41], and Siddiqui et al. [42] all reported 4000 mg·L−1 to be the best concentration for Ficus cuttings to root. Mansour and Khalil [43] used wounding and IBA treatments on date palm (Phoenix dactylifera) and reported that a high concentration of IBA improved the rooting performance of cuttings.

4.4. Interaction between Wounding and Auxin

When two-factorial ANOVA was adopted, a significant interaction between wounding method and auxin solution was found. This may be because jasmonic acid, ROS, auxin, cytokinin, ethylene, NO, ABA, strigolactone, and other hormones all respond to the wounding signal and have a complex involvement in the AR regeneration process [44,45]. Auxin plays a vital role in the formation of wound-initiated ARs [46,47]. However, it would not be easy to establish the exact impact of wounding and auxin on the AR regeneration process.

4.5. Rooting Locations

The upper edge developed more than 90% of ARs of the water-sprayed wounds of C03 and C13 in 2019 and 2020. It revealed that ARs were regenerated by endogenous indole-3-acetic acid (IAA) flowing down from the apical shoots via polar transport to accumulate at the upper edge of the wound [48]. The exogenous auxin sprays, including the 4B, 2NB, and 2B solutions, increased the IAA concentration on the wound’s four edges. It enabled the total IAA concentration to reach the required threshold for AR formation [36]. The diversity of rooting locations in the wound can indicate the effectiveness of the exogenous auxin spray. The 4B13 treatments in 2019 and 2020 regenerated ARs at more diverse locations on the four edges of the wounds, reflecting their special effect on AR regeneration.

4.6. Tree Age and Juvenility

Our experimental saplings were juvenile and rooted easily. The high rooting ability will provide more water uptake roots to the trees. As trees mature, their rooting ability decreases [49,50]. Mature trees, including heritage trees, require a longer lead time to regenerate ARs [51]. Hartmann et al. [52] described that the tree trunk near the tree base was chronologically the oldest but the youngest in terms of ontogenetic age. On the other hand, the branches and shoots were older in tissue maturity, although they were grown later than the trunk base. The tissue maturation is not the same for the entire plant, with meristems at the base of the tree remaining ontogenetically juvenile. Ontogenetically juvenile shoots from the base of the trunk, such as root suckers, stump sprouts, and epicormic shoots, exhibit juvenile characteristics and possess good rooting abilities. Vielba et al. [53] found that choosing those cuttings for propagating adult trees had achieved 19 to 97% rooting rates depending on the clone and rooting treatments. It justified the cone of juvenility hypothesis [54,55] that the tissues at the trunk base stay juvenile for the whole life of the tree. If we choose the wounding locations near the trunk base or root collar region of the mature trees to utilize the juvenile tissues, the finding of this research may be applied to the mature and heritage trees [56].

4.7. Application on the Mature Heritage Trees

We cut off the aerial roots [17] and adopted the 4B13 method on the stems of F. microcarpa heritage trees in Taipei, Taiwan, to regenerate ARs in 2020 before transplant [57]. It was because F. microcarpa did not have a lot of aerial roots; hence, stem wounding for additional ARs was employed to increase the water absorption ability of this heritage tree infected with brown root rot. The heritage tree was transplanted without root ball in 2021 after cutting off all infected roots. However, the regenerated ARs could uptake enough water for transpiration to survive the tree after the transplant. Four heritage trees on the old site of Taipei City Council had to be transplanted to the other side of the construction site [58]. They were one camphor tree (Cinnamomum camphora), two Chinese banyan (F. microcarpa L.f.), and one Indian rubber heritage tree. The camphor tree had to be transplanted with a regular root ball size of eight times the caliper and transplanted with the very expensive underpinning method. The two F. microcarpa and one F. elastica heritage tree were wounded for ARs on their stems and aerial roots to regenerate ARs in 2020 and transplanted with smaller root balls of four times the caliper in 2021. The reduced root balls allowed for direct lifting without using the underpinning method and saved cost. All these trees stayed healthy and vigorous after the transplant. The regenerated ARs could sustain the transpiration requirement of the mature heritage trees with reduced root balls.

5. Conclusions

This study showed that ARs could be regenerated from the stems of weeping fig effectively by wounding like wounding the aerial roots or prop roots of F. elastica. The combination of both methods facilitated the transpiration requirement without or with reduced root balls for the transplanted mature trees.
The stem wounding methods can be applied to the other Ficus spp., such as Chinese banyan, Indian rubber, and Indian banyan trees, in addition to the weeping fig. Likely, willow and poplar with preformed root initially existing under the bark could adopt this method too. The transplant approval process for mature or heritage trees is usually lengthy. The approval lead time can be utilized to regenerate ARs before digging out the root ball for transplantation. A higher number of ARs on the aerial part may support a smaller root ball like root pruning.
The three-line cut method (3LC) can be easily practiced in the field and causes less damage to the stems and trees. It is less effective than RP but is more aesthetically pleasing.

Author Contributions

Conceptualization, N.L.; data curation, N.L.; original draft preparation, N.L.; writing—review and editing, N.L., supervision, Y.C.; validation, Y.C. All authors have read and agreed to the published version of the manuscript.

Funding

This research was financed by Treegarden Corporation as a research and development project.

Conflicts of Interest

The authors declare no conflict of interest.

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Forests 13 01165 g001 550
Figure 1. Wounding methods to regenerate ARs on the stems of F. benjamina. (A) Three-line cut on the stem (3LC); (B) ARs on the 3LC wound; (C) rectangular peel with 1/3 of the stem perimeter (RP13); (D) ARs on the RP13 wound; (E) rectangular peel with 2/3 of the stem perimeter (RP23); and (F) ARs on the RP23 wound.
Figure 1. Wounding methods to regenerate ARs on the stems of F. benjamina. (A) Three-line cut on the stem (3LC); (B) ARs on the 3LC wound; (C) rectangular peel with 1/3 of the stem perimeter (RP13); (D) ARs on the RP13 wound; (E) rectangular peel with 2/3 of the stem perimeter (RP23); and (F) ARs on the RP23 wound.
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Forests 13 01165 g002 550
Figure 2. Comparison of the weather conditions between 2019 and 2020. (A) Temperature; (B) humidity; (C) wind speed; (D) illuminance. Lowercase letters indicate significant differences among treatments for a given trait (p < 0.05; LSD test). There were no significant changes between the 2 years. Least significant difference (LSD). p < 0.05.
Figure 2. Comparison of the weather conditions between 2019 and 2020. (A) Temperature; (B) humidity; (C) wind speed; (D) illuminance. Lowercase letters indicate significant differences among treatments for a given trait (p < 0.05; LSD test). There were no significant changes between the 2 years. Least significant difference (LSD). p < 0.05.
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Forests 13 01165 g003 550
Figure 3. Location distribution of adventitious roots’ (ARs) emergence. Most of the ARs were regenerated at the upper edge of the wounds. (A) 2019: C03 treatment had 92% of rooting wounds regenerating ARs from the upper edge, and C13 treatment had 90%. The 4B13 and 2NB13 treatments showed diverse distributions of ARs on the four edges of the wounds compared to the water treatments. (B) 2020: the three treatments in each 2B and 4B solution had more diversified distribution percentages of ARs on the four edges of the wounds. The two water treatments, C13 and C23, had all ARs concentrated at the upper edge of the wounds.
Figure 3. Location distribution of adventitious roots’ (ARs) emergence. Most of the ARs were regenerated at the upper edge of the wounds. (A) 2019: C03 treatment had 92% of rooting wounds regenerating ARs from the upper edge, and C13 treatment had 90%. The 4B13 and 2NB13 treatments showed diverse distributions of ARs on the four edges of the wounds compared to the water treatments. (B) 2020: the three treatments in each 2B and 4B solution had more diversified distribution percentages of ARs on the four edges of the wounds. The two water treatments, C13 and C23, had all ARs concentrated at the upper edge of the wounds.
Forests 13 01165 g003
Table
Table 1. Wounding/auxin treatments in 2019 and 2020. Each treatment had six replicates in 2019 and twelve replicates in 2020.
Table 1. Wounding/auxin treatments in 2019 and 2020. Each treatment had six replicates in 2019 and twelve replicates in 2020.
Treatments zWounding Methods yAuxin SolutionYear
20192020
ControlNoneWaterVV
C033LCWaterVV
C13RP13WaterVV
C23RP23Water V
2B033LC2000 mg·L−1 IBA V
2B13RP132000 mg·L−1 IBAVV
2B23RP232000 mg·L−1 IBA V
2NB033LC2000 mg·L−1 IBA + 2000 mg·L−1 NAA V
2NB13RP132000 mg·L−1 IBA + 2000 mg·L−1 NAAVV
2NB23RP232000 mg·L−1 IBA + 2000 mg·L−1 NAA V
4B033LC4000 mg·L−1 IBA V
4B13RP134000 mg·L−1 IBAVV
4B23RP234000 mg·L−1 IBA V
z C03 = (water + 3LC); C13 = (water + RP13); C23 = (water + RP23); 2B03 = (2B + 3LC); 2B13 = (2B + RP13); 2B23 = (2B + RP23); 2NB03 = (2NB + 3LC); 2NB13 = (2NB + RP13); 2NB23 = (2NB + RP23); 4B03 = (4B + 3LC); 4B13 = (4B + RP13); 4B23 = (4B + RP23). y 3LC: the three-line cut of 1/2 the stem perimeter; RP13: rectangular peeling of 1/3 of the stem perimeter; RP23: rectangular peeling of 2/3 of the stem perimeter.
Table
Table 2. Rooting performance of wounding/auxin treatments on stems of F. benjamina in 2019. Performance was evaluated using four indices: (1) rooting rate: mean of rooting percentage of rooted wounds, rooted wounds/total wounds; (2) root number: mean number of ARs in rooted wounds; (3) root length: mean of the three longest ARs in rooted wounds; and (4) root dry weight: mean dry weight in rooted wounds. Lowercase letters indicate significant differences among treatments for a given trait (p < 0.05; LSD test). ns, *, ** or ***: nonsignificant or significant at p < 0.05, 0.01, or 0.001, respectively.
Table 2. Rooting performance of wounding/auxin treatments on stems of F. benjamina in 2019. Performance was evaluated using four indices: (1) rooting rate: mean of rooting percentage of rooted wounds, rooted wounds/total wounds; (2) root number: mean number of ARs in rooted wounds; (3) root length: mean of the three longest ARs in rooted wounds; and (4) root dry weight: mean dry weight in rooted wounds. Lowercase letters indicate significant differences among treatments for a given trait (p < 0.05; LSD test). ns, *, ** or ***: nonsignificant or significant at p < 0.05, 0.01, or 0.001, respectively.
LSD TestTreatment zRooting %Root NumberRoot LengthDry Weight
in cmin mg
Significance p = 0.03 *p = 0.000 *p = 0.008 **p = 0.001 **
Control0000
C0360 b1 b5.2 b17 c
C1367 ab2 b10.2 ab297 bc
2B13100 a24.8 a11.7 a284 bc
2NB13100 a23.5 a12.9 a656 a
4B13100 a21 a13.3a498 ab
Wounding methods p = 0.06 nsp = 0.005 ***p = 0.000 ***p = 0.0027 **
RP1393 a30 a12.4 a457 a
3LC67 a6 b5.2 b17 b
Auxin effect p = 0.02 **p = 0.000 ***p = 0.02 **p = 0.0036 **
Control67 b12 b7.7 b157 b
Auxin100 a24 a12.8 a484 a
z Treatment description listed in Table 1.
Table
Table 3. Rooting performance of wounding/auxin treatments on stems of F. benjamina in 2020 using two-way completely randomized ANOVA. Performance was evaluated using four indices: (1) rooting rate; (2) root number; (3) root length; and (4) root dry weight. Lowercase letters indicate significant differences among treatments for a given trait (p < 0.05; LSD test). ns or ***: nonsignificant or significant at p < 0.001, respectively. There was significant interaction between wounding methods and auxin solution factors.
Table 3. Rooting performance of wounding/auxin treatments on stems of F. benjamina in 2020 using two-way completely randomized ANOVA. Performance was evaluated using four indices: (1) rooting rate; (2) root number; (3) root length; and (4) root dry weight. Lowercase letters indicate significant differences among treatments for a given trait (p < 0.05; LSD test). ns or ***: nonsignificant or significant at p < 0.001, respectively. There was significant interaction between wounding methods and auxin solution factors.
LSD TestTreatment zRooting %Root NumberRoot LengthDry Weight
Significance
Wounding methodp = 0.58 nsp = 0.024 *p = 0.604 nsp = 0.000 ***
Auxin solutionp = 0.04 *p = 0.000 ***p = 0.000 ***p = 0.86 ns
Interactionp = 0.27 nsp = 0.022 *p = 0.008 **p = 0.006 **
z Two-factorial analysis: 3 wounding methods (3LC, RP13, and RP23) × 4 auxin solutions (water, 2B, 2NB, and 4B) = 12 treatment combinations. Treatment description listed in Table 1.
Table
Table 4. Rooting performance of wounding/auxin treatments on stems of F. benjamina in 2020 using one-way completely randomized ANOVA. Performance was evaluated using four indices: (1) rooting rate; (2) root number; (3) root length; and (4) root dry weight. Lowercase letters indicate significant differences among treatments for a given trait (p < 0.05; LSD test). ns, *, **, or ***: nonsignificant or significant at p < 0.05, 0.01, or 0.001, respectively.
Table 4. Rooting performance of wounding/auxin treatments on stems of F. benjamina in 2020 using one-way completely randomized ANOVA. Performance was evaluated using four indices: (1) rooting rate; (2) root number; (3) root length; and (4) root dry weight. Lowercase letters indicate significant differences among treatments for a given trait (p < 0.05; LSD test). ns, *, **, or ***: nonsignificant or significant at p < 0.05, 0.01, or 0.001, respectively.
LSD TestTreatment zRooting %Root NumberRoot Lengthin cmDry Weightin mg
Significance p = 0.11 nsp = 0.000 ***p = 0.000 ***p = 0.001 ***
C0383 a6 gh15 bcde1209 bcd
C1383 a3 h10 g761 ef
C23100 a8 fg13 defg813 def
2B0383 a12 def17 ab1392 ab
2B13100 a19 ab17 abc1245 abc
2B2383 a21 a16 abcd1292 ab
2NB03100 a12 def11 fg846 cdef
2NB13100 a11 ef14 cdef655 f
2NB23100 a16 abcd12 efg1210 bcd
4B03100 a16 bcd15 bcde1285 ab
4B13100 a19 abc17 abc1642 a
4B23100 a15 cde19 a1085 bcde
z Treatment description in Table 1.
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Li, N.; Chang, Y. Effective Methods for Adventitious Root Regeneration on Weeping Fig Stems. Forests 2022, 13, 1165. https://doi.org/10.3390/f13081165

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Li N, Chang Y. Effective Methods for Adventitious Root Regeneration on Weeping Fig Stems. Forests. 2022; 13(8):1165. https://doi.org/10.3390/f13081165

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Li, Nelson, and Yusen Chang. 2022. "Effective Methods for Adventitious Root Regeneration on Weeping Fig Stems" Forests 13, no. 8: 1165. https://doi.org/10.3390/f13081165

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