Responses to Environmental Stress in Ornamental Plants/Horticultural Plants

A special issue of Horticulturae (ISSN 2311-7524). This special issue belongs to the section "Biotic and Abiotic Stress".

Deadline for manuscript submissions: 30 April 2024 | Viewed by 16522

Special Issue Editors


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Guest Editor
Instituto Cavanilles de Biodiversidad y Biología Evolutiva. Jardí Botànic, University of Valencia, 46010 València, Spain
Interests: germination behavior; drought and salt stress; vegetation; habitat conservation

E-Mail Website
Guest Editor
Instituto Cavanilles de Biodiversidad y Biología Evolutiva. Jardí Botànic, University of Valencia, 46010 València, Spain
Interests: drought and soil stress (responses and adaptations); plant phylogeography; plant conservation

Special Issue Information

Dear Colleagues,

Minor changes in environmental factors such as increasing temperature or a low and uneven rainfall pattern represent a major impact in agrodiversity and crop productivity. In this sense, research focused on promoting climate-smart agriculture using salt and drought-tolerant seeds and plants is a good option to reduce crop risks, enhance resilience, and maintain agrodiversity. In addition, current gardening in most countries should be oriented toward the use of plants resistant to foreseeable changes in temperature and the decrease in available water, and therefore, to the use of species capable of surviving in an adverse environment using available resources. In this sense, most wild flora living in arid and semiarid conditions are of increasing interest for being used in gardening due to their ability to adapt to the environmental conditions derived from climate change.

This Special Issue on “Responses to Environmental Stress in Ornamental Plants/Horticultural Plants” covers different aspects from germination to biochemical and morphological response of ornamental and horticultural plants and related species to environmental stress. Original research providing new information on these aspects and on the use of wild resistant plants in gardening is welcomed.

Prof. Dr. Pilar Soriano
Dr. M. Isabel Martínez-Nieto
Guest Editors

Manuscript Submission Information

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Keywords

  • environmental stress
  • drought tolerance
  • salinity tolerance
  • germination response
  • halophytes
  • climate change
  • ornamental plants
  • horticultural plants
  • wild crop relatives
  • biochemical response

Published Papers (9 papers)

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Research

17 pages, 3379 KiB  
Article
Morphological, Physiological, and Molecular Stomatal Responses in Local Watermelon Landraces as Drought Tolerance Mechanisms
by Kelebogile Madumane, Lesego T. Sewelo, Metseyabeng N. Nkane, Utlwang Batlang and Goitseone Malambane
Horticulturae 2024, 10(2), 123; https://doi.org/10.3390/horticulturae10020123 - 27 Jan 2024
Viewed by 786
Abstract
Drought-tolerant plants have become a convenient model to study the mechanisms underlying drought tolerance in order to improve susceptible domesticated relatives. Various studies have shown that local landraces possess superior qualities that help them survive in harsh environmental conditions. One of the key [...] Read more.
Drought-tolerant plants have become a convenient model to study the mechanisms underlying drought tolerance in order to improve susceptible domesticated relatives. Various studies have shown that local landraces possess superior qualities that help them survive in harsh environmental conditions. One of the key mechanisms that helps with tolerance in crops is timely stomatal regulation. In this study, the physiological, morphological, and molecular stomatal responses in three drought-tolerant landraces (Clm-01–03) and hybrid (Clm-04) watermelons were evaluated under drought stress. The watermelon plants were grown under a water deficit (complete withholding of water) and non-stress conditions. The highest SPAD values were recorded for the Clm-03 and Clm-02 (50 ± 3) watermelon genotypes, and the lowest for Clm-04 (27 ± 0.37), showing this genotype’s tolerance and ability to maintain its systems during drought stress. Fluorescence parameters also gave important clues to the tolerant genotypes of Clm-02 and Clm-03 under drought stress, while the domesticated genotype showed a slow response to fluorescence parameters, which could lead to damage to the photosynthesis apparatus. During the drought period, the wild watermelon was found to have a limited stomatal opening as the drought progressed, and on day 9, it had the smallest opening of 23.1 ± 1.2 µm compared to any other genotype; most importantly, upon re-watering, it showed more rapid recovery than any other genotype. This was also expressed by mRNA quantification of stomatal aperture TFs, with an eight-fold increase in Cla004380 TFs recorded for wild watermelon. All of these mechanisms have been attributed to the tolerance mechanisms of the drought-tolerant watermelon genotype. This study provides important insight into the stomatal responses of probable tolerant watermelon accessions and suggests that improving the stomatal aperture of susceptible domesticated species would also improve their tolerance. Full article
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21 pages, 4435 KiB  
Article
Biochemical Responses to Salt Stress and Biostimulant Action in Tomato Plants Grown in Two Different Soil Types
by Javier Zuzunaga-Rosas, Dennys Silva-Valdiviezo, Roberta Calone, Ioan Lupuţ, Sara Ibáñez-Asensio, Monica Boscaiu, Héctor Moreno-Ramón and Oscar Vicente
Horticulturae 2023, 9(11), 1209; https://doi.org/10.3390/horticulturae9111209 - 07 Nov 2023
Cited by 2 | Viewed by 1565
Abstract
Soil salinity is one of the major causes of losses in agricultural production, which is accentuated by global warming. A sustainable strategy to mitigate the effects of the increasing soil salinisation is the use of biostimulants. In this study, the effect of a [...] Read more.
Soil salinity is one of the major causes of losses in agricultural production, which is accentuated by global warming. A sustainable strategy to mitigate the effects of the increasing soil salinisation is the use of biostimulants. In this study, the effect of a plant-based biostimulant was tested on tomato plants exposed to different salinity levels in loamy and sandy soils. Salinity in the soils reached a maximum value of 14.35 dS m−1. The treatments included a control (tap water) and a dose of 0.4 mL L−1 of the commercial biostimulant BALOX®, containing polyphenols and glycine betaine. After 60 days of treatment, several growth and biochemical parameters were evaluated in the plants, and different responses were found depending on the type of soil texture. Salt stress inhibited plant growth, mainly affecting the roots of plants not treated with the biostimulant, in both soil texture types. It also caused a reduction of total chlorophyll and carotenoid levels by 44% and 38%, respectively, under severe salinity conditions. High salinity induced a significant increase in ionic, osmotic and oxidative stress in plants, as indicated by the accumulation of toxic Na+ and Cl ions, higher proline and MDA levels, and increased antioxidant enzyme activities. However, the application of BALOX® stimulated plant growth and root system development in all experimental conditions. The areas of roots and leaves and the stem length and diameter showed higher mean values in biostimulant-treated plants on both soil types, with more pronounced differences with the controls in sandy soils. The total fresh weight showed maximum increases of 54% and 93% on loamy and sandy soils, respectively. In addition, BALOX® significantly improved the active transport of nutrients such as K+ and Ca2+, and the concentration of photosynthetic pigments by up to 64% over control values; it also allowed greater protection against salt stress as shown by a significant reduction of proline levels, by up to 36%, and MDA by 51% under strongly saline conditions. The application of BALOX® generally decreased the level of stress in the tomato plants, promoting plant growth and enhancing their biochemical responses, even on strongly salinised soils. Full article
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16 pages, 1540 KiB  
Article
Morpho-Biochemical Modification of Petunia to Saline Water and Salicylic Acid Applications
by Khalid M. Elhindi, Fahed A. Almana and Mohammed A. Al-Yafrsi
Horticulturae 2023, 9(11), 1197; https://doi.org/10.3390/horticulturae9111197 - 03 Nov 2023
Viewed by 638
Abstract
Petunia (Petunia × hybrida Hort. Vilm.-Andr.) is a well-suited plant for sustainable landscape issues in borderline areas with irrigation with saline water. Salicylic acid (SA) as a modulator performs an imperative function in modulating plant salt tolerance. However, there are a few [...] Read more.
Petunia (Petunia × hybrida Hort. Vilm.-Andr.) is a well-suited plant for sustainable landscape issues in borderline areas with irrigation with saline water. Salicylic acid (SA) as a modulator performs an imperative function in modulating plant salt tolerance. However, there are a few reports on the effect of SA on petunia plants irrigated with saline water. During the 2022/2023 season, a factorial pot experiment in a randomized complete block design was carried out in Riyadh, Saudi Arabia, to assess the effect of SA concentration (0, 500, 1000, 2000 mgL−1) on petunia plant growth, flowering, ion content, chlorophyll level, and proline concentration under irrigation with salty water (230, 1500, 3000 mgL−1). Saline water up to 3000 mgL−1 dramatically reduced plant growth, chlorophyll, ions, and flowering attributes, while the contrary was observed in proline and sodium concentrations as compared to the control treatments (irrigation with tap water). Foliar spraying with 1000 mgL−1 SA considerably boosted plant growth and flowering as well as chlorophyll, proline, and ion content compared to untreated plants under such salinity levels. Alternatively, the application of 1000 mgL−1 to normal or salinized water significantly decreased the Na content in non-treated plants under such a salinity level. Accordingly, using 1000 mgL−1 of SA under salt stress conditions could be a useful technique to lessen the mutilation induced by the use of salinized water in the era of climate change. Full article
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17 pages, 3851 KiB  
Article
Evaluation of Aging Methods on the Surface Characteristics of Hydrochar and Germination Indices for Kale Seeds
by Dengge Qin, Quan He, Seyed Mohammad Nasir Mousavi and Lord Abbey
Horticulturae 2023, 9(5), 545; https://doi.org/10.3390/horticulturae9050545 - 30 Apr 2023
Cited by 2 | Viewed by 1068
Abstract
Hydrochar derived from hydrothermal carbonization (HTC) has been recognized as a potential absorbent and horticultural substrate. However, its practical application has been limited due to its low adsorption capacity and negative effects on plant growth. To address these issues, three pre-treatment methods (water [...] Read more.
Hydrochar derived from hydrothermal carbonization (HTC) has been recognized as a potential absorbent and horticultural substrate. However, its practical application has been limited due to its low adsorption capacity and negative effects on plant growth. To address these issues, three pre-treatment methods (water washing, microbial aging, and freezing-thawing aging) were employed to further improve the physical structure and chemical properties of hydrochar. A seed germination test with kale (Brassica oleracea var. acephala D.C) was conducted to evaluate the phytotoxicity of modified hydrochars. The results showed that microbial aging considerably enhanced the physicochemical properties of the hydrochar. Specifically, under microbial aging, the bulk density of microbial-aged hydrochar (MHC) decreased by 8.1%, the porosity increased by 24.8%, and the water-holding capacity increased by 36.54% compared to fresh hydrochar (FHC). Moreover, the surfaces of MHC and freezing-thawing aged hydrochar (FTHC) were observed with rough and cracked surfaces and macro pore structures. Fourier transform infrared (FTIR) spectroscopy revealed that the functional group’s intensities of the four hydrochar materials varied, and that MHC and FTHC had more oxygen-containing groups than the others. Additionally, the surface areas of MHC and FTHC increased by 318.64% and 238.98% compared to FHC, respectively. The seed germination test indicated the strong inhibitory effect of FHC, while MHC significantly (p < 0.05) improved the seed germination rate and root development. These findings suggest that among the different pre-treatment methods, microbial aging demonstrated the greatest potential for practical application in improving the physicochemical properties of hydrochar and promoting seed germination. This study opens up new avenues for further research on improving hydrochar and suggests that future studies should focus on optimizing the aging process. Full article
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20 pages, 5888 KiB  
Article
Understanding Particulate Matter Retention and Wash-Off during Rainfall in Relation to Leaf Traits of Urban Forest Tree Species
by Myeong Ja Kwak, Jongkyu Lee, Sanghee Park, Yea Ji Lim, Handong Kim, Su Gyeong Jeong, Joung-a Son, Sun Mi Je, Hanna Chang, Chang-Young Oh, Kyongha Kim and Su Young Woo
Horticulturae 2023, 9(2), 165; https://doi.org/10.3390/horticulturae9020165 - 27 Jan 2023
Cited by 7 | Viewed by 1458
Abstract
Dynamic particulate matter (PM) behavior on leaves depends on rainfall events, leaf structural and physical properties, and individual tree crowns in urban forests. To address this dependency, we compared the observed relationships between PM wash-off ability and leaf traits on inner and outer [...] Read more.
Dynamic particulate matter (PM) behavior on leaves depends on rainfall events, leaf structural and physical properties, and individual tree crowns in urban forests. To address this dependency, we compared the observed relationships between PM wash-off ability and leaf traits on inner and outer crown-positioned leaves during rainfall events. Data showed significant differences in the PM wash-off ability between inner and outer crown-positioned leaves relative to rainfall events due to leaf macro- and micro-structure and geometric properties among tree species. Our results showed that PM wash-off effects on leaf surfaces were negatively associated with trichome density and size of leaf micro-scale during rainfall events. Specifically, Quercus acutissima with dense trichomes and micro-level surface roughness with narrow grooves on leaf surfaces showed lower total PM wash-off in both inner (−38%) and outer (105%) crowns during rainfall. Thus, their rough leaves in the inner crown might newly capture and/or retain more PM than smooth leaves even under rainfall conditions. More importantly, Euonymus japonicus, with a thin film-like wax coverage without trichome, led to higher total PM wash-off in both inner (368%) and outer (629%) crowns during rainfall. Furthermore, we studied the changes in PM wash-off during rainfall events by comparing particle size fractions, revealing a very significant association with macro-scale, micro-scale, and geometric features. Full article
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20 pages, 3004 KiB  
Article
Relationship between Leaf Traits and PM-Capturing Capacity of Major Urban-Greening Species
by Sanghee Park, Jong Kyu Lee, Myeong Ja Kwak, Yea Ji Lim, Handong Kim, Su Gyeong Jeong, Joung-a Son, Chang-Young Oh, Sun Mi Je, Hanna Chang, Kyongha Kim and Su Young Woo
Horticulturae 2022, 8(11), 1046; https://doi.org/10.3390/horticulturae8111046 - 07 Nov 2022
Cited by 3 | Viewed by 1607
Abstract
High concentrations of airborne particulate matter (PM) in urban areas are of great concern to human health. Urban greening has been shown to be an effective and eco-friendly way to alleviate particle pollution, and attention to its role in mitigating particle pollution has [...] Read more.
High concentrations of airborne particulate matter (PM) in urban areas are of great concern to human health. Urban greening has been shown to be an effective and eco-friendly way to alleviate particle pollution, and attention to its role in mitigating particle pollution has increased worldwide. The species-specific PM-capturing capacity of ten urban-greening species in Seoul was evaluated by leaf functional traits (average leaf area (ALA), specific leaf area (SLA), and leaf width-to-length ratio (W/L)), microstructures (roughness, stomata, and trichomes), and physicochemical traits (contact angle (θw), surface free energy (rs), the work of adhesion for water (Wa), and epicuticular wax loads (EWL)). The relationships between leaf traits and PM adsorption by leaves were revealed by Pearson’s correlations and principal component analysis (PCA). A gravimetric method was used to quantify, by particle size, the PM adsorbed on leaf surfaces or embedded in leaf epicuticular wax layers. The key factors for PM adsorption on leaf surfaces were the SLA, the mean roughness value (Ra), and stomatal size. The SLA and Ra of adaxial leaf surfaces were negatively correlated with PM accumulation on leaf surfaces, while stomatal length and width were positively correlated with surface PM load. The rs and EWL positively affected the in-wax PM load. Species-specific PM deposition was the result of complicated mechanisms of various leaf traits. Three evergreen shrub species, Buxus sinica (Rehder & E.H. Wilson) M.Cheng var. insularis (Nakai) M.Cheng, Taxus cuspidata Siebold & Zucc., and Euonymus japonicus Thunb., were efficient in capturing both surface PM and in-wax PM. The PCA revealed that the high PM accumulation efficiency of these three species might be attributable to the interaction between stomatal size and EWL. Aesculus turbinata Blume, Chionanthus retusus Lindl. & Paxton, and Rhododendron schlippenbachii Maxim. had intermediate PM adsorption ability, which might be a result of interactions among stomatal density, the Wa of adaxial surfaces, and ALA. Magnolia denudata Desr., Styphnolobium japonicum (L.) Schott, Liriodendron tulipifera L., and Ginkgo biloba L. had low PM accumulation efficiency. These four species exhibited correlations among SLA, the Ra of adaxial leaf surfaces, and W/L, which had negative effects on PM adsorption. Full article
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21 pages, 2222 KiB  
Article
Effects of NaHSO3 on Cellular Metabolic Energy, Photosynthesis and Growth of Iris pseudacorus L.
by Tian Chen, Yanyou Wu, Deke Xing and Rongrong Duan
Horticulturae 2022, 8(2), 185; https://doi.org/10.3390/horticulturae8020185 - 21 Feb 2022
Viewed by 1575
Abstract
According to the law of energy conservation, the energy consumed by plants to resist adversity is equal to the difference between photosynthetic energy and growth energy consumption and cellular metabolic energy in plants. The cellular metabolic energy is calculated based on the electrical [...] Read more.
According to the law of energy conservation, the energy consumed by plants to resist adversity is equal to the difference between photosynthetic energy and growth energy consumption and cellular metabolic energy in plants. The cellular metabolic energy is calculated based on the electrical signals in plants. This study mainly investigated the effect of NaHSO3 on the growth and energy traits of the aquatic plant Iris pseudacorus L. and explored the effect of NaHSO3 on energy consumption in the process of plant development. In this study, NaHSO3 was used for simulating sulfur pollution in water medium. During the 20-day experiment period, the response of I. pseudocorus to the polluted water sources simulated by adding different concentrations of NaHSO3 (0, 0.5, 2, 4, 10 mmol·L−1) was monitored, and the internal mechanism of the relationship between the forms of energy and the removal of sulfur pollution was analyzed. After the 20-day exposure experiment, the growth and nutrient absorption capacity were significantly inhibited, and this inhibition proved to be concentration-dependent. In addition, high concentrations (4 and 10 mmol·L−1) of NaHSO3 might affect photosynthesis by disrupting cell membrane systems as it may interfere with membrane proteins and lipids and thus alter membrane integrity. Therefore, the cellular metabolic energy was increased and the sulfur absorption by I. pseudocorus was promoted under the low concentration (0.5 mmol/L−1) compared with the control, the role of NaHSO3 in promoting the growth of I. pseudocorus is much greater than its toxic effect under low concentrations. Under the hydroponic culture which contained 0.5 mmol·L−1 of NaHSO3, I. pseudocorus grew well and absorbed more sulfur. The results can be used as a reference for the cultivation of aquatic plants dealing with sulfur pollution, and dilution strategy can be set up to treat water medium that is seriously polluted with sulfur. Full article
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15 pages, 949 KiB  
Article
Changes in Morpho-Anatomical and Eco-Physiological Responses of Viburnum tinus L. var lucidum as Modulated by Sodium Chloride and Calcium Chloride Salinization
by Veronica De Micco, Carmen Arena, Chiara Amitrano, Youssef Rouphael, Stefania De Pascale and Chiara Cirillo
Horticulturae 2022, 8(2), 119; https://doi.org/10.3390/horticulturae8020119 - 28 Jan 2022
Cited by 3 | Viewed by 2483
Abstract
Salinity in water and soil is among the major constraints to the cultivation of ornamental crops since it can affect their growth and aesthetic value. A greenhouse experiment was carried out to assess whether the application of two different salts (80 mM NaCl [...] Read more.
Salinity in water and soil is among the major constraints to the cultivation of ornamental crops since it can affect their growth and aesthetic value. A greenhouse experiment was carried out to assess whether the application of two different salts (80 mM NaCl or 53.3 mM CaCl2, with a final ionic concentration of 160 mM) could differently modulate the anatomical and physiological acclimation of an important ornamental species such as Viburnum tinus L. var. lucidum. Eco-physiological analyses (e.g., leaf gas exchange and chlorophyll a fluorescence emission) were performed and leaves were subjected to light microscopy analysis to quantify functional anatomical traits through digital image analysis. Results showed that the two iso-osmotic solutions induced different structure-mediated physiological alterations in V. tinus plants. Photosynthesis was lowered by CaCl2 treatments (−58%) more than by NaCl (−37%), also due to the occurrence of photodamage apart from stomatal limitations. Neither Na+ nor Cl exhibited toxic effects in leaf lamina structure which was reflected in the limited reduction in dry matter accumulation. Overall data were interpreted focusing on the coordination among leaf structural and functional traits suggesting that the fine control of functional anatomical traits contributes to physiological acclimation to both stressful conditions. Full article
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16 pages, 3800 KiB  
Article
Particulate Matter (PM) Adsorption and Leaf Characteristics of Ornamental Sweet Potato (Ipomoea batatas L.) Cultivars and Two Common Indoor Plants (Hedera helix L. and Epipremnum aureum Lindl. & Andre)
by Jong Kyu Lee, Do Yeon Kim, Sang Hee Park, Su Young Woo, Hualin Nie and Sun Hyung Kim
Horticulturae 2022, 8(1), 26; https://doi.org/10.3390/horticulturae8010026 - 27 Dec 2021
Cited by 10 | Viewed by 4141
Abstract
Particulate matter (PM) is a serious threat to human health, climate, and ecosystems. Furthermore, owing to the combined influence of indoor and outdoor particles, indoor PM can pose a greater threat than urban PM. Plants can help to reduce PM pollution by acting [...] Read more.
Particulate matter (PM) is a serious threat to human health, climate, and ecosystems. Furthermore, owing to the combined influence of indoor and outdoor particles, indoor PM can pose a greater threat than urban PM. Plants can help to reduce PM pollution by acting as biofilters. Plants with different leaf characteristics have varying capacities to capture PM. However, the PM mitigation effects of plants and their primary factors are unclear. In this study, we investigated the PM adsorption and leaf characteristics of five ornamental sweet potato (Ipomea batatas L.) cultivars and two common indoor plants (Hedera helix L. and Epipremnum aureum Lindl. & Andre) exposed to approximately 300 μg m−3 of fly ash particles to assess the factors influencing PM adsorption on leaves and to understand the effects of PM pollution on the leaf characteristics of plants. We analyzed the correlation between PM adsorption and photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), leaf area (LA), leaf width/length ratio (W/L), stomatal density (SD), and stomatal pore size (SP). A Pearson’s correlation analysis and a principal component analysis (PCA) were used to evaluate the effects of different leaf characteristics on PM adsorption. The analysis indicated that leaf gas exchange factors, such as Pn and Tr, and morphological factors, such as W/L and LA, were the primary parameters influencing PM adsorption in all cultivars and species tested. Pn, Tr, and W/L showed a positive correlation with PM accumulation, whereas LA was negatively correlated. Full article
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