The Role of Plant Growth Regulators in Horticulture

A special issue of Horticulturae (ISSN 2311-7524). This special issue belongs to the section "Developmental Physiology, Biochemistry, and Molecular Biology".

Deadline for manuscript submissions: 26 August 2025 | Viewed by 6209

Special Issue Editors


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Guest Editor
Department of Horticulture, Faculty of Applied Sciences, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa
Interests: stress physiology; plant growth hormones; plant growth and development

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Guest Editor
Agricultural Research Council–Vegetables, Industrial and Medicinal Plants, Private Bag X293, Pretoria 0001, South Africa
Interests: plant growth regulators; phytohormones; indigenous plant use; micropropagation; secondary metabolite production; biological activities; medicinal plants; plant tissue culture; ethnopharmacology; antimicrobial activity; ethnobotany; plant biotechnology; biostimulants; plant production
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Agricultural Research Council–Vegetables, Industrial and Medicinal Plants, Private Bag X293, Pretoria 0001, South Africa
Interests: plant growth regulators; phytohormones; plant tissue culture; plant biotechnology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The Special Issue on "The Role of Plant Growth Regulators in Horticulture" delves into the intricate mechanisms by which plant growth regulators (PGRs) control the growth, development, and physiological processes of horticultural plants. PGRs, including hormones such as auxins, gibberellins, cytokinins, abscisic acid, and ethylene, play pivotal roles in regulating various aspects of plant growth and development, ranging from seed germination to fruit ripening.

This Special Issue provides a comprehensive platform for researchers, scientists, and practitioners to explore the multifaceted functions of PGRs in horticulture and their implications for crop improvement, yield optimization, and quality enhancement. Contributions cover a wide spectrum of topics, including the following:

  1. Molecular mechanisms underlying the biosynthesis, signal transduction, and action of PGRs in horticultural plants.
  2. The regulation of plant morphogenesis, including shoot and root growth, branching, and flowering, by PGRs.
  3. Interactions between PGRs and environmental factors, such as light, temperature, and water availability, in shaping plant growth and development.
  4. The applications of PGRs in horticultural practices, including plant tissue culture, crop production, propagation, and postharvest management.
  5. The development and optimization of PGR-based strategies for crop protection, stress mitigation, and abiotic stress tolerance in horticultural plants.
  6. Novel approaches and technologies for the synthesis, formulation, and delivery of PGRs to improve their efficacy and sustainability in horticultural systems.

By elucidating the intricate roles of PGRs in horticultural plant physiology and development, this Special Issue aims to advance our understanding of fundamental plant biology principles and practical applications in horticulture. Through interdisciplinary collaboration and knowledge exchange, researchers and practitioners can harness the potential of PGRs to optimize crop performance, enhance yield and quality, and promote sustainable practices in horticultural production systems.

Dr. Mack Moyo
Prof. Dr. Stephen O. Amoo
Prof. Dr. Michael Bairu
Guest Editors

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Keywords

  • abiotic stress tolerance
  • climate change resilience
  • plant morphogenesis
  • plant growth regulators
  • plant tissue culture
  • signal transduction
  • sustainable horticulture

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Published Papers (5 papers)

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Research

20 pages, 15382 KiB  
Article
Genome-Wide Identification of Cucumber Lhc Genes’ Family and Their Expression Analysis
by Yongmei Miao and Kaijing Zhang
Horticulturae 2025, 11(7), 736; https://doi.org/10.3390/horticulturae11070736 - 25 Jun 2025
Viewed by 431
Abstract
Light-harvesting chlorophyll a/b-binding (Lhc) proteins are integral membrane proteins that bind to pigment molecules, playing a critical role in photosynthetic processes, including light energy harvesting and transfer. To investigate the role of the Lhc gene family in cucumber (Cucumis sativus L), genome-wide [...] Read more.
Light-harvesting chlorophyll a/b-binding (Lhc) proteins are integral membrane proteins that bind to pigment molecules, playing a critical role in photosynthetic processes, including light energy harvesting and transfer. To investigate the role of the Lhc gene family in cucumber (Cucumis sativus L), genome-wide identification of CsLhc gene family members and analysis of their regulatory networks were carried out using bioinformation and molecular biology research methods at Anhui Science and Technology University. The results indicated that the Lhc family consisted of 21 members, being categorized into five subfamilies: Lhca, Lhcb, CP24, CP26, and CP29. The gene structure and motifs within each subfamily are generally conserved. CsLhcs are distributed on seven chromosomes, including one pair of tandem duplicates and two pairs of segmental duplicates. Six CsLhcs exhibit eight linear relationships with seven AtLhcs, and one CsLhc shows a syntenic relationship with one OsLhc. Analysis of the cis-acting elements in CsLhc promoters revealed their potential involvement in stress responses. Transcriptome data indicated that CsLhcs are minimally expressed in male flowers and roots, but highly expressed in other organs. Analysis of stress response processes revealed that all Lhc genes participate in at least one stress response. Five Lhc genes were confirmed to appear to have expression change using qPCR analysis under high temperature and salt stress. Particularly, under downy mildew, root-knot nematode stresses, and blight stress, up-regulated Lhc genes were the most abundant ones, indicating that the Lhc family acts as a significant role in the growth and development of cucumber. These results provide valuable insights for further understanding the characteristics of the CsLhc family and analyzing the function of the Lhc family in cucumber resistance to biotic/abiotic stresses and in molecular breeding. Full article
(This article belongs to the Special Issue The Role of Plant Growth Regulators in Horticulture)
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13 pages, 4060 KiB  
Article
In Vitro Cultivation of the Orchid Hybrid Rhyncattleanthe Queen Bee JLA 1 and Its Propagation Under Different Systems
by Luis Alberto Solano-Rodríguez, María Elena Galindo-Tovar, Odon Castañeda-Castro, Juan Valente Hidalgo-Contreras, Joaquín Murguía-González, Gabriela Lucero Cuatra-Xicalhua, José Guadalupe Vián-Pérez, Pablo Antonio Mendoza del Ángel and Miriam Cristina Pastelín-Solano
Horticulturae 2025, 11(7), 722; https://doi.org/10.3390/horticulturae11070722 - 21 Jun 2025
Viewed by 351
Abstract
The Orchidaceae family is of significant decorative, pharmaceutical, alimentary, and cultural importance worldwide. This family is very vulnerable due to illegal looting, habitat destruction, and climate change. The development of new hybrids helps meet the demand for specimens that possess outstanding appearance, fragrance, [...] Read more.
The Orchidaceae family is of significant decorative, pharmaceutical, alimentary, and cultural importance worldwide. This family is very vulnerable due to illegal looting, habitat destruction, and climate change. The development of new hybrids helps meet the demand for specimens that possess outstanding appearance, fragrance, and resistance characteristics and may reduce illegal looting. The objective of this research was to investigate the in vitro propagation of the hybrid Rhyncattleanthe Queen Bee JLA 1 (Rth. Queen Bee JLA 1). Shoot induction was performed with germinated seedlings that were 1 cm in length on semi-solid MS medium with different 6-Benzylaminopurine (BAP), 1-Naphthaleneacetic acid (NAA), 3-Indoleacetic acid (IAA), and 3-indolebutyric acid (IBA) concentrations. Micropropagation was conducted using a temporary immersion system (TIS), a liquid continuous immersion system (CIS), and a conventional semi-solid system (SSS). Afterwards, all regenerated seedlings underwent an acclimatization stage. The highest numbers of shoots (7.04) and leaves (14.28) were obtained with the combination of 1.5 mg L−1 BAP and 0.4 mg L−1 NAA, while the addition of 0.4 mg L−1 IBA in combination with 1.5 mg L−1 BAP enhanced the length of stems (2.12 cm) and leaves (1.88 cm). TIS produced the highest number of shoots (15.68), leaves (22.92), stem length (5.94 cm), and number of leaves (3.50) in seedlings analyzed. The combination of growth regulators BAP and NAA together with the temporary immersion system influenced both the development of the vitroplants and their vegetative development after acclimatization of the hybrid Rth. Queen Bee JLA1 orchid. Full article
(This article belongs to the Special Issue The Role of Plant Growth Regulators in Horticulture)
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13 pages, 1798 KiB  
Article
Effect of Ozonated Avocado and High-Oleic Palm Oils on “Bolo Verde” Variety Squash
by Ramírez Aura, Amariles Santiago, Hurtado-Salazar Alejandro and Ceballos-Aguirre Nelson
Horticulturae 2025, 11(6), 676; https://doi.org/10.3390/horticulturae11060676 - 13 Jun 2025
Viewed by 469
Abstract
Ozonated oils have promise as biostimulants, positively affecting physiological processes that promote plant growth and biomass accumulation. However, additional research is required to clarify their mechanisms of action, optimize dosages, and define effective application strategies. This study aimed to evaluate the biostimulant effect [...] Read more.
Ozonated oils have promise as biostimulants, positively affecting physiological processes that promote plant growth and biomass accumulation. However, additional research is required to clarify their mechanisms of action, optimize dosages, and define effective application strategies. This study aimed to evaluate the biostimulant effect of three concentrations of two oils, avocado (Persea maricana Mill cv Hass) (50, 100, and 200 meqO2 kg−1) and high-oleic palm (Elaeis guineensis Jacq.) (5, 10, and 20 meqO2 kg−1), on the “Bolo Verde” squash Cucurbita moschata. The experiment followed a completely randomized design with a three-factor factorial arrangement: Factor I—type of ozonated oil; Factor II—application concentration (low, medium, and high); Factor III—application method (drench or foliar). The trial consisted of 15 experimental units, each with 32 plants, totaling 480 plants. Data were analyzed using SAS software. A one-way ANOVA was performed, and means were compared using Tukey’s test p ≤ 0.05. The drench application of high-concentration ozonated avocado oil (200 meqO2 kg−1) produced the most favorable biostimulant response, significantly increasing plant height, leaf number, root length, root volume, and total dry weight. This was followed by the drench application of low-concentration ozonated high-oleic palm oil (5 meqO2 kg−1), which yielded the highest dry matter accumulation. For the net assimilation rate (NAR) and leaf area index (LAI), the drench application of ozonated avocado oil at a high concentration resulted in 4.29 g cm−2 day−1 NAR and 7957.99 LAI, while low-concentration high-oleic palm oil recorded 4.36 g cm−2 day−1 NAR and 7208.40 LAI. Both treatments showed statistically significant differences (p < 0.05) compared to the control 2.35 g cm−2 day−1 NAR and 6780.24 LAI, indicating improved photosynthetic efficiency and leaf expansion. Similar trends were observed for crop growth rate (CGR) and relative growth rate (RGR). The drench application of high-concentration ozonated avocado oil yielded a CGR of 6.77 × 10−4 g cm−2 day−1 and RGR 0.0441953 g g−1 day−1. Low-concentration high-oleic palm oil drench application resulted in the highest CGR of 7.35 × 10−4 g cm−2 day−1 and RGR 0.0454216 g g−1 day−1. These values were significantly higher than those of the control (CGR 4.14 × 10−4 g cm−2 day−1; RGR 0.0357569 g g−1 day−1). These results suggest that the drench application of ozonated oils not only enhances photosynthesis and leaf growth but also favors the incorporation and accumulation of biomass in “Bolo Verde” squash. Full article
(This article belongs to the Special Issue The Role of Plant Growth Regulators in Horticulture)
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19 pages, 2995 KiB  
Article
Biotization with Plant Growth-Promoting Bacteria Benefits the Survival and Production of Potato (Solanum tuberosum L.) In Vitro and In Vivo
by Yulimar Castro Molina, Joyce Dória, Ana Milena Gómez Sepúlveda, Luna Queiroz Carvalho, Moacir Pasqual and Ederson da Conceição Jesus
Horticulturae 2025, 11(4), 393; https://doi.org/10.3390/horticulturae11040393 - 8 Apr 2025
Viewed by 743
Abstract
Bacterial inoculation stimulates growth and adaptation in micropropagated plants. This study evaluated the effects of biotization on in vitro seedling production and in vivo adaptation in two potato cultivars, Agatha and Duvira. Nine bacterial strains were tested for hormone production and ACC deaminase [...] Read more.
Bacterial inoculation stimulates growth and adaptation in micropropagated plants. This study evaluated the effects of biotization on in vitro seedling production and in vivo adaptation in two potato cultivars, Agatha and Duvira. Nine bacterial strains were tested for hormone production and ACC deaminase activity and then inoculated in vitro and re-inoculated in vivo. Growth, adaptation, and tuber production were assessed. Biotization significantly enhanced seedling growth, survival, and tuber yield. Biotized seedlings had a 1.3-fold higher survival rate than the controls. Azospirillum brasilense Ab-V5 and Rhizobium tropici CIAT 899 promoted at least one growth variable in both cultivars under in vitro and in vivo conditions. A. brasilense Ab-V5 consistently improved plant performance across production stages, with re-inoculated plants showing 1.2–1.3-fold increases in stem and root length and a 1.1-fold gain in total dry biomass. Additionally, inoculated plants produced 1.9 times more tubers than the controls. Biotization effects were strain-dependent, with A. brasilense Ab-V5 improving in vitro seedling quality and enhancing plant performance and survivability in vivo. Full article
(This article belongs to the Special Issue The Role of Plant Growth Regulators in Horticulture)
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24 pages, 14048 KiB  
Article
Polyploidization Impact on Plant Architecture of Watermelon (Citrullus lanatus)
by Eftekhar Mahmud, Hongju Zhu, Mohamed Omar Kaseb, Muhammad Zeeshan Sajjad, Nan He, Xuqiang Lu and Wenge Liu
Horticulturae 2024, 10(6), 569; https://doi.org/10.3390/horticulturae10060569 - 29 May 2024
Cited by 1 | Viewed by 2202
Abstract
Plant architecture includes traits such as plant height, stem diameter, and branching pattern, which have significant impacts on yield and fruit quality. Polyploidization can bring changes in plant architectural traits in different crops along with other agronomic and biochemical attributes; however, the specific [...] Read more.
Plant architecture includes traits such as plant height, stem diameter, and branching pattern, which have significant impacts on yield and fruit quality. Polyploidization can bring changes in plant architectural traits in different crops along with other agronomic and biochemical attributes; however, the specific physiological and biochemical mechanisms are still unclear. In this study, we utilized five watermelon lines: ‘91E7’, ‘Zhengzhou No. 3’, ‘Fanzu No. 1’, ‘Shenlong’, and ‘Houlv’, along with their corresponding autopolyploid derivatives (diploid, autotriploid, and autotetraploid) to compare plant architecture differences in different polyploidy watermelon plants. The results showed that the growth habits of diploid, triploid, and tetraploid watermelon plants were noticeably different. Triploid and tetraploid watermelon plants had greater stem diameters and larger leaf sizes. The leaf angle was also larger in polyploid watermelons than in their diploid ancestor lines. Although vine length was significantly higher in diploid watermelon, there was no significant difference in node number, indicating that the short vine length was due to the short internodal length. The major differences between diploid and polyploid watermelon plants were found in the branching pattern, as diploid watermelon lines have more branching compared to their polyploid sister lines. Furthermore, we examined the phytohormone content of diploid, triploid, and tetraploid ‘Fanzu No. 1’. The reasons for the selection of this material are its robust growth and profuse branching habit, which cause visible differences among the ploidy levels. Hormone analysis showed distinct variations in abscisic acid in the nodal and stem regions, gibberellin in the auxiliary bud regions, and brassinosteroids in the apical meristematic regions. The correlation coefficient also strongly correlated these hormones with architecture-related traits. Our findings indicated that gibberellin, ABA, and brassinosteroids might be associated with variations in plant architectural traits like branching, vine length, internodal length, stem thickness, and leaf angle among different ploidy levels of watermelon. The exogenous application of GA3 showed a positive effect on branching, whereas ABA showed a negative effect on branching. The application of brassinosteroid at the apical meristem demonstrated its effect on leaf angle, leaf size, and internodal length. The results of this study can provide a theoretical reference and valuable insights into the link between plant architecture and ploidy levels. Full article
(This article belongs to the Special Issue The Role of Plant Growth Regulators in Horticulture)
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