Treatment of Potted Zebra Plant and Inch Plant with Antigibberellin Plant Growth Regulators Slows Stem Elongation in an Interior Green Wall

Authors:
Lane W. Wiens 1Department of Horticulture and Natural Resources, Kansas State University, 1712 Claflin Road, 2021 Throckmorton Plant Sciences Center, Manhattan, KS 66506-5506, USA

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Kimberly A. Williams 1Department of Horticulture and Natural Resources, Kansas State University, 1712 Claflin Road, 2021 Throckmorton Plant Sciences Center, Manhattan, KS 66506-5506, USA

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Abstract

In commercial interior green walls, plant trimming and replacement necessitated by stem elongation under low interior light levels is labor intensive and costly. Antigibberellin plant growth regulators (PGRs) may slow stem elongation and thus reduce maintenance costs in this environment. In Expt. 1, two PGRs were applied as foliar spray or drench to three spiderwort selections [two of zebra plant (Tradescantia zebrina) and one of inch plant (Tradescantia fluminensis)] immediately before installation in a green wall, each at three rates: ancymidol (ANC) foliar spray at 25, 100, and 200 mg·L−1; paclobutrazol (PBZ) foliar spray at 20, 80, and 160 mg·L−1; and PBZ drench at 1, 4, and 8 mg·L−1, along with an untreated control. In Expt. 2, 80 mg·L−1 PBZ foliar spray, 1 mg·L−1 PBZ applied via subirrigation four times, and the combination of these two treatments, was evaluated on ‘Burgundy’ zebra plant. In both experiments, plants were placed in a vertical modular tray interior green wall. Change in total stem and specific internode length were measured every 14 days after installation for 3 months to calculate growth per month. Antigibberellin application slowed internode elongation of spiderwort selections during the first month after installation. Antigibberellins were more effective in zebra plant at reducing overall stem growth rate and less so on inch plant. Across the three spiderwort selections, 25 mg·L−1 foliar spray of ANC resulted in no difference in growth rate when compared with the control, although 100 to 200 mg·L−1 foliar spray was effective. Based on the results of both experiments, moderate and high rates of PBZ, applied both as a foliar spray and drench, resulted in similar reduction in stem elongation. PBZ applied as 20 to 80 mg·L−1 foliar spray, 4 mg·L−1 drench before installation in the wall, or a combination of an 80 mg·L−1 PBZ pre-installation foliar spray and recurring 1 mg·L−1 via subirrigation (four times) were effective at growth suppression of spiderworts for at least 3 months. Even rates of PBZ of 160 mg·L−1 foliar spray or 8 mg·L−1 drench did not show phytotoxicity in treated plants and could be considered for use. We recommend a pre-installation application of 80 mg·L−1 foliar spray or 4 mg·L−1 drench for controlling stem growth across spiderwort selections. Application of antigibberellin PGRs to plants before installation in green walls slows stem growth and can contribute to reduced maintenance costs.

As more businesses recognize the many benefits of having plants in the workplace, interior green walls are becoming more common and are often used as a focal point in public spaces (McKay 2017). In most cases, professional interiorscaping firms are hired to maintain these systems. Most green walls cover a large area, making maintenance a significant expense (Fediw 2015). Plants in interior environments tend to develop unattractive growth with elongated internodes in response to low light levels, as well as low-quality light, leading to a less aesthetically pleasing plant display (Collado and Hernández 2021). To maintain green wall appearance, an interiorscaper must trim specific plants or replace them altogether. This frequent labor activity by the interiorscaping firm increases maintenance costs that must be passed on to clients.

Spiderwort (Tradescantia sp.) plants are commonly used in interior plantscaping, including zebra plant, purple heart (Tradescantia pallida ‘Purple Heart’), and oyster plant (Tradescantia spathacea) (DelPrince 2013). In commercial production, spiderwort species are grown under light conditions of 700 to 900 µmol·m−2·s−1 in hanging baskets or small pots (Griffith 1998). Spiderworts can tolerate light levels as low as 30 to 50 µmol·m−2·s−1, but more light is preferred. Plants should be maintained at a temperature between 65 and 80 °F and be allowed to dry down between watering events (DelPrince 2013; Griffith 1998). To maintain an attractive plant, vining species should be pinched regularly.

Antigibberellins are a class of PGRs that inhibit a plant’s synthesis of the hormone gibberellic acid (GA). A variety of commercial antigibberellin PGRs are available, but research is limited with their use across the wide range of spiderwort species and is nonexistent for their use in green walls. For potted crop production, White et al. (2005) used flurprimidol, PBZ, and uniconazole on Virginia spiderwort (Tradescantia virginiana). They demonstrated that foliar sprays of flurprimidol between 45 and 60 mg·L−1, PBZ at 120 mg·L−1, and uniconazole between 30 and 45 mg·L−1 were effective at controlling growth in this species. Latimer and Scoggins (2012) recommended daminozide foliar spray at 5000 mg·L−1, a tank mixture of daminozide and chloromequat chloride at 5000 mg·L−1, PBZ between 40 and 80 mg·L−1, uniconazole between 15 and 30 mg·L−1, and flurprimidol between 15 and 45 mg·L−1 to control growth in Virginia spiderwort. Whipker (2023) recommends 26 to 132 mg·L−1 foliar spray of ANC for zebra plant. Frank and Donnan (1975) found that 1.25 mg/ft2 ANC was effective to control growth in zebra plant.

Antigibberellin PGRs may be applied to plants before or after their installation in a living wall. Foliar spray or drench application just before shipping for installation may be made by the commercial grower, or the chemical may be applied in the irrigation solution of the living wall, as long as required reentry intervals are met.

ANC (A-Rest; SePRO Corp. Carmel, IN, USA) is a nitrogen-containing heterocycle with a pyrimidine group, and this chemical inhibits GA synthesis by blocking the conversion of ent-kaurene to ent-kaurenoic acid (Coolbaugh and Hamilton 1975). ANC is rated for use on ornamentals in greenhouses, nurseries, shade houses, and interiorscapes. The label limits the application to areas where the a.i. will not contact workers or other people by direct contact or with drift residues, and there is a 12-h reentry interval (REI). As per the current label, A-rest could be used in an interiorscape location by applying at a time when the REI would be met with no exposure to residue, such as after a facility closes.

PBZ is also a nitrogen-containing heterocycle with a triazole group that blocks GA synthesis by inhibiting the conversion of ent-kaurene to ent-kaurenoic acid (Hedden and Graebe 1985). Several formulations of this antigibberellin are available for commercial use. For example, the PBZ formulation Pac-O (OHP Inc., Bluffton, SC, USA) label does not support application to plants in an interiorscape. The label limits applications to areas where it will not contact workers or other people by direct contact or contact with drift residues, and there is a 12-h REI for this chemical. However, another PBZ formulation Bonzi (Syngenta, Basel, Switzerland) is labeled for application in interiorscapes, provided no layperson encounters the a.i. until after the REI. As per the current labels, Pac-O could be used before installing plants in a green wall, but not in the interiorscape location with the green wall; both A-Rest and Bonzi could be applied in the interiorscape.

Our objective was to determine whether the antigibberellin PGRs ANC and PBZ could be used to slow growth of spiderworts placed in a low-light interior green wall environment. Second, we wanted to optimize the post-production application method and rate of these PGRs for use in interior green walls.

Materials and methods

Two experiments were conducted with two species of spiderworts using an interior vertical modular tray living wall system (Versa Wall; GSky, Delray Beach, FL, USA) in the lobby of Throckmorton Plant Sciences Center of Kansas State University (Manhattan, KS, USA). The interior green wall was installed by Ambius (Wyomissing, PA, USA) in 2015. The green wall had 14 rows of plastic trays to hold potted plants (Versa Trays; GSky) with 36 plants per row, totaling 504 plants. Expt. 1 occurred from 22 Nov 2021 to 14 Feb 2022, and Expt. 2 occurred from 11 Apr to 4 Jul 2022.

Plant material

For Expt. 1, tip cuttings of zebra plant and inch plant were received in Manhattan, KS, USA on 12 Oct 2021 from North Carolina Farms (Indian Trails, NC, USA). ‘Burgundy’ zebra plant tip cuttings were taken on 12 Oct 2021 from a stock plant originating from Costa Farms (Miami, FL, USA). In Expt. 2, only ‘Burgundy’ zebra plant was used, and tip cuttings were taken on 28 Feb 2022. Cuttings were stuck into 4-inch terra cotta plastic pots [375 mL (Pöppelmann Plastics, Claremont, NC, USA)] and filled with peat-based soilless substrate (BX General Purpose Growing Media; Premier Horticulture Inc., Quakertown, PA, USA). Three cuttings were placed in each pot in Expt. 1, and four cuttings in Expt. 2. Cuttings were rooted and grown in a glass-glazed greenhouse (Throckmorton Plant Sciences Center) under 52% white shadecloth (PAK Unlimited Inc., Cornelia, GA, USA) for 41 d before installation in the green wall for Expt. 1 and 42 d before installation for Expt. 2. Temperature set points were 25/22 °C (day/night). Average daytime light levels for production were 161 µmol·m−2·s−1. Due to the vigorous nature of ‘Burgundy’ zebra plant, plants used in Expt. 1 were pinched to leave two to three nodes with an average height at pinch of 6 cm and height at installation of 13 cm. The other two spiderwort selections were left unpinched and had heights of 15 to 16 cm when installed in the green wall.

During production, plants were irrigated overhead with 200 mg·L−1 nitrogen from 20N–4.3P–16.6K (Compass Minerals, Overland Park, KS, USA) when substrate surface was light in color and just as foliage was beginning to lose turgidity. Before installation, 4 g of 15N–3.9P–10K controlled-release fertilizer (OsmocotePLUS 15–9–12; Scotts MiracleGro, Marysville, OH, USA) was applied to each pot and watered in with municipal water.

Treatments

Chemicals used in Expt. 1 were ANC (A-Rest) and PBZ (Pac-O). ANC was applied as a foliar spray. PBZ was applied both as a foliar spray and as a media drench. Rates of ANC applied were 0, 25, 100, and 200 mg·L−1. PBZ foliar spray was applied at rates of 0, 20, 80, and 160 mg·L−1. PBZ media drench was applied at rates of 0, 1, 4, and 8 mg·L−1. Rates were selected based on industry PGR recommendations (Whipker 2023) and from rates used by commercial growers [Green Circle Growers (Oberlin, OH, USA), unpublished]. For foliar spray treatments, 17 mL of the treatment solution was sprayed onto each treated plant using a hand sprayer that was volume sufficient to fully cover all foliage to runoff. For media drench treatments, 60 mL of the treatment solution was applied. Distilled water was used for 0 control treatments. PGRs were applied 2 d before installation into the green wall. Plants were installed on 22 Nov 2021 and harvested on 14 Feb 2022.

In Expt. 2, only PBZ was used on ‘Burgundy’ zebra plant. The four treatments were 0 mg·L−1 control, a subirrigation application of 1 mg·L−1 PBZ applied at each irrigation event [0, 23, 51, and 78 d after installation (DAI)]; a foliar spray of 80 mg·L−1 PBZ applied before plant installation into the wall; and a combination of a 1 mg·L−1 application during subirrigation events and an 80 mg·L−1 foliar spray. To accomplish the subirrigation applications during Expt. 2 without affecting other treatments, selected plants were removed from the green wall and placed in a flat with 2000 mL of the treatment PGR solution, allowed to absorb for 1 h, and replaced in the green wall. In the foliar spray treatment, 17 mL of the treatment solution was applied to each plant 2 d before installation in the green wall.

For both experiments, plants were separated into six replications based on size and placed randomly into preselected blocks of the green wall. The blocks were established based on differences in light intensity and irrigation quantity (Fig. 1). In Expt. 1, each of six blocks had one pot of each treatment (three species × three PGR treatments × four rates) for a total of 36 plants per block and 216 experimental plants. In Expt. 2, each of six blocks had two pots of each treatment (one species × four PGR × two application methods) for a total of 16 plants per block and 96 experimental plants. Remaining slots in the green wall were populated with filler plants of the same species, or aroid species commonly used in living wall designs.

Fig. 1.
Fig. 1.

Green wall experimental design used for Expt. 1. The six blocks of treatments with the three spiderwort selections of zebra plant, ‘Burgundy’ zebra plant, and inch plant are denoted with red squares, placement of light/temperature sensors (one per block) are shown with magenta circles, sentinel pots used to determine need for irrigation are shown with blue triangles (eight dispersed throughout the green wall), and average light levels (µmol·m−2·s−1) per block are reported in white boxes. Average light levels were determined by averaging the light reading at each pot location in each block.

Citation: HortTechnology 33, 4; 10.21273/HORTTECH05178-22

Green wall light, temperature, and irrigation

Temperature and light intensity in the green wall were recorded every 15 min with an environmental monitor [HOBO Pendant MX Temperature/Light Data Logger MX2202; Onset Computer Corp., Bourne, MA, USA (light levels reported in Fig. 1)]. Temperatures in the green wall ranged from 11.7 to 22.6 °C and never had a variation of more than 2.4 °C between blocks.

To determine when to irrigate the living wall, eight sentinel plants were randomly selected across the wall and the weight of each pot was measured at container capacity; pot weights were averaged (Fig. 1). These sentinel pots were weighed each week. Once the weights reached 70% of their weight at container capacity, the green wall irrigation system was run for 1 h. The irrigation system was controlled with an irrigation controller (X-CORE; Hunter Industries, San Marcos, CA, USA). Thirty minutes after the irrigation system was finished running, the weights of the sentinel pots were again measured and averaged. The green wall irrigation system was run on 9, 28, 52, and 66 DAI in Expt. 1 and on 0, 23, 51, and 78 DAI in Expt. 2.

Data collected

Internode length (Expt. 1) and total stem length (Expts. 1 and 2) were measured 0, 15, 29, 43, 57, and 85 DAI in Expt. 1 and 0, 14, 28, 42, 56, and 84 DAI in Expt. 2. Specific internodes and stems were selected for measurement and marked with silicone tomato grafting clips (Hydro-Gardens, Colorado Springs, CO, USA) for repeated measures. Internodes were selected from the stem of smallest length in each pot. The measured internodes were selected from the first two to four internodes at the apex of the stem (Fig. 2A). Total stem lengths were taken on the stem of medium length in each pot (Fig. 2B) from the edge of the pot to leaf tip. In Expt. 1, stem length of ‘Burgundy’ zebra plant was measured from the axial break just below the pinch.

Fig. 2.
Fig. 2.

Internode (A) and stem lengths (B) were measured on selected stems of each spiderwort selection and repeated every 2 weeks. Tomato grafting clips marked the selected tissue for repeated measurement. These images demonstrate where measurements were taken on ‘Burgundy’ zebra plant used in Expt. 1.

Citation: HortTechnology 33, 4; 10.21273/HORTTECH05178-22

In both Expts. 1 and 2, experimental design was randomized complete block, as described previously. Variance of the factorial treatment structure was analyzed with the “fit model” function of JMP Pro (version 16.0.0; SAS Institute Inc., Cary, NC, USA). All tests were conducted at the 0.05 significance level. Least square means were separated using Tukey’s mean separation procedure.

Results and discussion

Change in internode length

During the first 29 DAI in Expt. 1, internodes elongated more for zebra plant species than the other two spiderwort selections (Table 1). Plants treated with ANC foliar spray had greater internode elongation during this period than those treated with PBZ foliar spray (Table 1). The medium and high PGR concentrations resulted in less internode elongation than the control or low rates (Table 1).

Table 1.

Change in internode and stem length of zebra plant, ‘Burgundy’ zebra plant, and inch plant, and their monthly stem growth across treatments in Expt. 1. Significance levels of analysis of variance of the factorial treatment structure are shown for spiderwort selection (zebra plant, ‘Burgundy’ zebra plant, inch plant), chemical application [ancymidol (ANC) as foliar spray, paclobutrazol (PBZ) as foliar spray, or PBZ as drench], chemical concentration [control (0 mg·L−1), low (25 mg·L−1 ANC or 20 mg·L−1 PBZ), medium (100 mg·L−1 ANC or 80 mg·L−1 PBZ), high (200 mg·L−1 ANC or 160 mg·L−1 PBZ)], and their interactions.i

Table 1.

Across species and chemical application in Expt. 1, the measured internode elongated for only the first 29 d and had minimal change in length during 30 through 85 d (Fig. 3). That is, the selected internode—originally near the apex of the plant—elongated significantly only during the first month after installation in the wall. No significant change in internode elongation occurred during months 2 or 3 (Fig. 3) as the distance between the measured internode and the plant’s apex increased. Stem internodes near the base of the plant of many species, including soybean [Glycine max (Zhang et al. 2020)], sunflower [Helianthus annuus (Garrison 1973)], and bamboo [Bambusa multiplex (Wei et al. 2019)], have been shown to stop elongating after a period of time. The growth curve of an individual internode over time is sigmoidal in shape. For this reason, internode length was not an informative measure of PGR effectiveness and was only measured in Expt. 1.

Fig. 3.
Fig. 3.

Internode elongation for zebra plant and ‘Burgundy’ zebra plant averaged (A) and inch plant (B) after installation in the green wall in Expt. 1. Ancymidol foliar spray applied at 25 mg·L−1 [AL (orange)], 100 mg·L−1 [AM (light gray)], and 200 mg·L−1 [AH (yellow)]; paclobutrazol foliar spray at 20 mg·L−1 [SL (light blue)], 80 mg·L−1 [SM (green)], and 160 mg·L−1 [SH (dark blue)]; paclobutrazol media drench at 1 mg·L−1 [DL (burgundy)], 4 mg·L−1 [DM (dark gray)], and 8 mg·L−1 [DH (tan)]. Numerical SE values between treatments at each data collection date are shown; 1 mg·L−1 = 1 ppm, 1 cm = 0.3937 inch.

Citation: HortTechnology 33, 4; 10.21273/HORTTECH05178-22

The interaction between spiderwort, chemical application, and concentration in Expt. 1 was not significant (Table 1). At the onset of Expt. 1, all stem lengths were similar (data not shown). To evaluate treatment effects, the change in stem length was calculated in 1-month intervals, and the three-way interaction at no time period was significant (data not shown).

Species

A difference occurred in stem growth between the two spiderwort species used in Expt. 1, but the two selections of zebra plant behaved similarly, as ‘Burgundy’ is a variety of the zebra plant species. Inch plant had greater stem growth compared with the two selections of zebra plant over each month and the entire experiment (Table 1). Chemical PGR application more effectively reduced stem length of zebra plant than inch plant (Fig. 4C and D).

Fig. 4.
Fig. 4.

Internode and stem length growth comparisons between zebra plant and ‘Burgundy’ zebra plant averaged (A, C) and inch plant (B, D) for ancymidol (ANC) and paclobutrazol (PBZ) foliar spray and PBZ drench treatments in Expt. 1. Letters show treatment differences based on Tukey's mean separation procedure at ɑ ≤ 0.05 where treatments with the same letter are not different; 1 mg·L−1 = 1 ppm, 1 cm = 0.3937 inch.

Citation: HortTechnology 33, 4; 10.21273/HORTTECH05178-22

Chemical

PBZ was more effective than ANC at inhibiting internode expansion (Table 1); however, no difference in stem length or monthly growth rate occurred between these chemicals (Table 1). Both ANC and PBZ affect the gibberellin synthesis pathway in the same reaction step, by blocking the conversion of ent-kaurene to ent-kaurenoic acid (Coolbaugh and Hamilton 1975; Hedden and Graebe 1985). No difference in stem length occurred between a foliar spray application of PBZ and a media drench of PBZ at the rates used.

All chemical PGR applications except the lowest rate of ANC controlled stem length compared with the control throughout Expt. 1 (Table 1). The high rates of each chemical application resulted in less stem elongation than the low rate, but similar control to the medium rate, for every month except the third. This result suggests that PGR efficacy may have begun to wane 57 to 85 d (Table 1).

Rate of ANC foliar spray resulted in different internode expansion, overall change in stem length, and weekly stem growth rate over the 3-month experiment between a 100- and 200-mg·L−1 application vs. the control (Table 1). A high ANC foliar spray of 200 mg·L−1 provides the best growth regulation on both spiderwort species used (Fig. 4). For PBZ, using the chemical as a foliar spray at 20, 80, or 160 mg·L−1 or a media drench at 1, 4, or 8 mg·L−1 provides similar growth-limiting effects (Table 1, Fig. 4).

In Expt. 2, stems of ‘Burgundy’ zebra plant selected for measurement again started at similar length (Table 2). Each of the three treatments reduced stem elongation compared with the control (Table 2). This effect occurred during each of the 3 months of the experiment (Table 2) as well as overall (Fig. 5). Although the combination of 80 mg·L−1 spray and recurring 1 mg·L−1 subirrigation treatment appeared to maximize decrease in stem growth rate by month, results were not significantly different from the other PGR treatments. Therefore, the simplest chemical application strategy of PGR application as a foliar spray or drench before installation in the green wall can be recommended.

Table 2.

Stem length at day (D) zero and D84 after installation of ‘Burgundy’ zebra plant (Tradescantia zebrina) in the green wall, and change in its stem length over 3 months for each paclobutrazol treatment in Expt. 2. Mean separation values were calculated using Tukey’s mean separation procedure. Significant treatments (ɑ ≤ 0.05) have mean separation shown with letters a and b; means with the same letter are not different.

Table 2.
Fig. 5.
Fig. 5.

Treatment comparison of paclobutrazol applied as a foliar spray (80 mg·L−1), media application via subirrigation (1 mg·L−1 × 4), and a combination of a foliar spray and recurring media application (80 mg·L−1 with 1 mg·L−1 × 4) in Expt. 2 of ‘Burgundy’ zebra plant. Letters show treatment difference based on Tukey's mean separation procedure at ɑ ≤ 0.05 where treatments with the same letter are not different; 1 mg·L−1 = 1 ppm.

Citation: HortTechnology 33, 4; 10.21273/HORTTECH05178-22

Conclusion

Antigibberellin application slowed growth in internode length of spiderwort selections during the first month after installation in a green wall. Antigibberellins were more effective in zebra plant at reducing overall stem growth rate and less so on inch plant. Across varieties, 25 mg·L−1 foliar spray of ANC resulted in no difference in growth rate when compared with the control, although 100 to 200 mg·L−1 foliar spray was effective. Although ANC is an effective option at foliar spray rates >100 mg·L−1, the chemical cost is higher than the cost of PBZ applications (Table 3).

Table 3.

Ancymidol (A-Rest; SePRO Corp., Carmel, IN, USA) and paclobutrazol (Pac-O; OHP Inc., Bluffton, SC, USA) costs per pot for each antigibberellin treatment applied to spiderwort selections in Expts. 1 and 2.

Table 3.

Based on the results of both experiments, moderate and high rates of PBZ, applied both as a foliar spray and drench, resulted in similar reduction in stem elongation. PBZ applied as 20 to 80 mg·L−1 foliar spray, 4 mg·L−1 drench before installation in the wall, or a combination of an 80 mg·L−1 PBZ pre-installation foliar spray and recurring 1 mg·L−1 via subirrigation (four times) were effective at growth suppression of spiderworts for at least 3 months. Even rates of PBZ of 160 mg·L−1 foliar spray or 8 mg·L−1 drench did not show phytotoxicity in treated plants and could be considered for use. We recommend a pre-installation foliar spray of 80 mg·L−1 or 4 mg·L−1 drench for controlling stem growth across spiderwort selections. Application of antigibberellin PGRs to plants before installation in green walls slows stem growth and can contribute to reduced maintenance costs.

Units

TU1

References cited

  • Collado CE, Hernández R. 2021. Effects of light intensity, spectral composition, and paclobutrazol on the morphology, physiology, and growth of petunia, geranium, pansy, and dianthus ornamental transplants. J Plant Growth Regul. 41:461478. https://doi.org/10.1007/s00344-021-10306-5.

    • Search Google Scholar
    • Export Citation
  • Coolbaugh RC, Hamilton R. 1975. Inhibition of ent-kaurene oxidation and growth by ɑ cycolopropyl-ɑ-(p-methoxyphenol)-5-pyrimidine methyl alcohol. Plant Physiol. 57:245248. https://doi.org/10.1104/pp.57.2.245.

    • Search Google Scholar
    • Export Citation
  • DelPrince JM. 2013. Interior plantscaping: Principles and practices. Delmar, Clifton Park, NY, USA.

  • Fediw K. 2015. The manual of interior plantscaping: A guide to design, installation, and maintenance. Timber Press, Inc., Portland, OR, USA.

  • Frank DF, Donnan A. 1975. Influence of A-Rest on tropical foliage plants. Proc. Florida State Hort. Soc. 88:531534.

  • Garrison R. 1973. The growth and development of internodes in Helianthus. Bot Gaz. 134:246255. https://doi.org/10.1086/336711.

  • Griffith LP. 1998. A grower’s guide: Tropical foliage plants. Ball Publishing, Batavia, IL, USA.

  • Hedden P, Graebe JE. 1985. Inhibition of gibberellin biosynthesis by paclobutrazol in cell free homogenates of Curcubita maxima endosperm and Malus pumila embryos. J Plant Growth Regul. 4:111122. https://doi.org/10.1007/BF02266949.

    • Search Google Scholar
    • Export Citation
  • Latimer JG, Scoggins H. 2012. Using plant growth regulators on containerized herbaceous perennials. Virginia Coop Ext Pub. 430-103.

  • McKay CC. 2017. Green walls: A growing trend. https://www.fmlink.com/articles/green-walls-growing-trend/. [accessed 12 Jan 2022].

  • Wei Q, Guo L, Jiao C, Fei Z, Chen M, Cao J, Ding Y, Yuan Q. 2019. Characterization of the developmental dynamics of the elongation of a bamboo internode during the fast growth stage. Tree Physiol. 39:12011214. https://doi.org/10.1093/treephys/tpz063.

    • Search Google Scholar
    • Export Citation
  • Whipker B. 2023. Plant growth regulator guide for annuals. https://www.fine- americas.com/wp-content/uploads/2023/01/PGR_GUIDE_2023-24_Annuals.pdf. [accessed 5 Mar 2023].

  • White SA, Scoggins HL, Marini RP, Latimer JG. 2005. Multivariate repeated measures analysis of plant growth regulators in Tradescantia virginiana. HortScience. 40:404408. https://doi.org/10.21273/HORTSCI.40.2.404.

    • Search Google Scholar
    • Export Citation
  • Zhang R, Shan F, Wang C, Yan C, Dong S, Xu Y, Gong Z, Ma C. 2020. Internode elongation pattern, internode diameter and hormone changes in soybean (Glycine max) under different shading conditions. Crop Pasture Sci. 71:679688. https://doi.org/10.1071/CP20071.

    • Search Google Scholar
    • Export Citation
  • Fig. 1.

    Green wall experimental design used for Expt. 1. The six blocks of treatments with the three spiderwort selections of zebra plant, ‘Burgundy’ zebra plant, and inch plant are denoted with red squares, placement of light/temperature sensors (one per block) are shown with magenta circles, sentinel pots used to determine need for irrigation are shown with blue triangles (eight dispersed throughout the green wall), and average light levels (µmol·m−2·s−1) per block are reported in white boxes. Average light levels were determined by averaging the light reading at each pot location in each block.

  • Fig. 2.

    Internode (A) and stem lengths (B) were measured on selected stems of each spiderwort selection and repeated every 2 weeks. Tomato grafting clips marked the selected tissue for repeated measurement. These images demonstrate where measurements were taken on ‘Burgundy’ zebra plant used in Expt. 1.

  • Fig. 3.

    Internode elongation for zebra plant and ‘Burgundy’ zebra plant averaged (A) and inch plant (B) after installation in the green wall in Expt. 1. Ancymidol foliar spray applied at 25 mg·L−1 [AL (orange)], 100 mg·L−1 [AM (light gray)], and 200 mg·L−1 [AH (yellow)]; paclobutrazol foliar spray at 20 mg·L−1 [SL (light blue)], 80 mg·L−1 [SM (green)], and 160 mg·L−1 [SH (dark blue)]; paclobutrazol media drench at 1 mg·L−1 [DL (burgundy)], 4 mg·L−1 [DM (dark gray)], and 8 mg·L−1 [DH (tan)]. Numerical SE values between treatments at each data collection date are shown; 1 mg·L−1 = 1 ppm, 1 cm = 0.3937 inch.

  • Fig. 4.

    Internode and stem length growth comparisons between zebra plant and ‘Burgundy’ zebra plant averaged (A, C) and inch plant (B, D) for ancymidol (ANC) and paclobutrazol (PBZ) foliar spray and PBZ drench treatments in Expt. 1. Letters show treatment differences based on Tukey's mean separation procedure at ɑ ≤ 0.05 where treatments with the same letter are not different; 1 mg·L−1 = 1 ppm, 1 cm = 0.3937 inch.

  • Fig. 5.

    Treatment comparison of paclobutrazol applied as a foliar spray (80 mg·L−1), media application via subirrigation (1 mg·L−1 × 4), and a combination of a foliar spray and recurring media application (80 mg·L−1 with 1 mg·L−1 × 4) in Expt. 2 of ‘Burgundy’ zebra plant. Letters show treatment difference based on Tukey's mean separation procedure at ɑ ≤ 0.05 where treatments with the same letter are not different; 1 mg·L−1 = 1 ppm.

  • Collado CE, Hernández R. 2021. Effects of light intensity, spectral composition, and paclobutrazol on the morphology, physiology, and growth of petunia, geranium, pansy, and dianthus ornamental transplants. J Plant Growth Regul. 41:461478. https://doi.org/10.1007/s00344-021-10306-5.

    • Search Google Scholar
    • Export Citation
  • Coolbaugh RC, Hamilton R. 1975. Inhibition of ent-kaurene oxidation and growth by ɑ cycolopropyl-ɑ-(p-methoxyphenol)-5-pyrimidine methyl alcohol. Plant Physiol. 57:245248. https://doi.org/10.1104/pp.57.2.245.

    • Search Google Scholar
    • Export Citation
  • DelPrince JM. 2013. Interior plantscaping: Principles and practices. Delmar, Clifton Park, NY, USA.

  • Fediw K. 2015. The manual of interior plantscaping: A guide to design, installation, and maintenance. Timber Press, Inc., Portland, OR, USA.

  • Frank DF, Donnan A. 1975. Influence of A-Rest on tropical foliage plants. Proc. Florida State Hort. Soc. 88:531534.

  • Garrison R. 1973. The growth and development of internodes in Helianthus. Bot Gaz. 134:246255. https://doi.org/10.1086/336711.

  • Griffith LP. 1998. A grower’s guide: Tropical foliage plants. Ball Publishing, Batavia, IL, USA.

  • Hedden P, Graebe JE. 1985. Inhibition of gibberellin biosynthesis by paclobutrazol in cell free homogenates of Curcubita maxima endosperm and Malus pumila embryos. J Plant Growth Regul. 4:111122. https://doi.org/10.1007/BF02266949.

    • Search Google Scholar
    • Export Citation
  • Latimer JG, Scoggins H. 2012. Using plant growth regulators on containerized herbaceous perennials. Virginia Coop Ext Pub. 430-103.

  • McKay CC. 2017. Green walls: A growing trend. https://www.fmlink.com/articles/green-walls-growing-trend/. [accessed 12 Jan 2022].

  • Wei Q, Guo L, Jiao C, Fei Z, Chen M, Cao J, Ding Y, Yuan Q. 2019. Characterization of the developmental dynamics of the elongation of a bamboo internode during the fast growth stage. Tree Physiol. 39:12011214. https://doi.org/10.1093/treephys/tpz063.

    • Search Google Scholar
    • Export Citation
  • Whipker B. 2023. Plant growth regulator guide for annuals. https://www.fine- americas.com/wp-content/uploads/2023/01/PGR_GUIDE_2023-24_Annuals.pdf. [accessed 5 Mar 2023].

  • White SA, Scoggins HL, Marini RP, Latimer JG. 2005. Multivariate repeated measures analysis of plant growth regulators in Tradescantia virginiana. HortScience. 40:404408. https://doi.org/10.21273/HORTSCI.40.2.404.

    • Search Google Scholar
    • Export Citation
  • Zhang R, Shan F, Wang C, Yan C, Dong S, Xu Y, Gong Z, Ma C. 2020. Internode elongation pattern, internode diameter and hormone changes in soybean (Glycine max) under different shading conditions. Crop Pasture Sci. 71:679688. https://doi.org/10.1071/CP20071.

    • Search Google Scholar
    • Export Citation
Lane W. Wiens 1Department of Horticulture and Natural Resources, Kansas State University, 1712 Claflin Road, 2021 Throckmorton Plant Sciences Center, Manhattan, KS 66506-5506, USA

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Kimberly A. Williams 1Department of Horticulture and Natural Resources, Kansas State University, 1712 Claflin Road, 2021 Throckmorton Plant Sciences Center, Manhattan, KS 66506-5506, USA

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Contributor Notes

We thank Jacob Hueste and Megan Nelson for assisting with greenhouse space preparations and pest management. This manuscript has been assigned Contribution no. 23-040-J from the Kansas Agricultural Experiment Station (KAES). This project was supported by KAES. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the KAES. From a graduate research project by L.W.W.

K.A.W. is the corresponding author. E-mail: kwilliam@ksu.edu.

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  • Fig. 1.

    Green wall experimental design used for Expt. 1. The six blocks of treatments with the three spiderwort selections of zebra plant, ‘Burgundy’ zebra plant, and inch plant are denoted with red squares, placement of light/temperature sensors (one per block) are shown with magenta circles, sentinel pots used to determine need for irrigation are shown with blue triangles (eight dispersed throughout the green wall), and average light levels (µmol·m−2·s−1) per block are reported in white boxes. Average light levels were determined by averaging the light reading at each pot location in each block.

  • Fig. 2.

    Internode (A) and stem lengths (B) were measured on selected stems of each spiderwort selection and repeated every 2 weeks. Tomato grafting clips marked the selected tissue for repeated measurement. These images demonstrate where measurements were taken on ‘Burgundy’ zebra plant used in Expt. 1.

  • Fig. 3.

    Internode elongation for zebra plant and ‘Burgundy’ zebra plant averaged (A) and inch plant (B) after installation in the green wall in Expt. 1. Ancymidol foliar spray applied at 25 mg·L−1 [AL (orange)], 100 mg·L−1 [AM (light gray)], and 200 mg·L−1 [AH (yellow)]; paclobutrazol foliar spray at 20 mg·L−1 [SL (light blue)], 80 mg·L−1 [SM (green)], and 160 mg·L−1 [SH (dark blue)]; paclobutrazol media drench at 1 mg·L−1 [DL (burgundy)], 4 mg·L−1 [DM (dark gray)], and 8 mg·L−1 [DH (tan)]. Numerical SE values between treatments at each data collection date are shown; 1 mg·L−1 = 1 ppm, 1 cm = 0.3937 inch.

  • Fig. 4.

    Internode and stem length growth comparisons between zebra plant and ‘Burgundy’ zebra plant averaged (A, C) and inch plant (B, D) for ancymidol (ANC) and paclobutrazol (PBZ) foliar spray and PBZ drench treatments in Expt. 1. Letters show treatment differences based on Tukey's mean separation procedure at ɑ ≤ 0.05 where treatments with the same letter are not different; 1 mg·L−1 = 1 ppm, 1 cm = 0.3937 inch.

  • Fig. 5.

    Treatment comparison of paclobutrazol applied as a foliar spray (80 mg·L−1), media application via subirrigation (1 mg·L−1 × 4), and a combination of a foliar spray and recurring media application (80 mg·L−1 with 1 mg·L−1 × 4) in Expt. 2 of ‘Burgundy’ zebra plant. Letters show treatment difference based on Tukey's mean separation procedure at ɑ ≤ 0.05 where treatments with the same letter are not different; 1 mg·L−1 = 1 ppm.

 

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