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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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16 pages, 3977 KiB  
Article
Salinity-Induced Physiological Responses of Three Putative Salt Tolerant Citrus Rootstocks
by Lamiaa M. Mahmoud, Manjul Dutt, Christopher I. Vincent and Jude W. Grosser
Horticulturae 2020, 6(4), 90; https://doi.org/10.3390/horticulturae6040090 - 25 Nov 2020
Cited by 17 | Viewed by 4601
Abstract
Our study aimed to evaluate the physiological responses following salinity treatment of three putatively salt-tolerant Citrus rootstocks recently developed by the University of Florida’s Citrus breeding program. Four-month-old seedlings from each of the three rootstocks (HS1, HS17, and HC15) were irrigated with 0, [...] Read more.
Our study aimed to evaluate the physiological responses following salinity treatment of three putatively salt-tolerant Citrus rootstocks recently developed by the University of Florida’s Citrus breeding program. Four-month-old seedlings from each of the three rootstocks (HS1, HS17, and HC15) were irrigated with 0, 60, 80, and 100 mm NaCl solution. The seedlings were evaluated together with the salt-tolerant Cleopatra mandarin as a positive control, Volkamer lemon as a moderately salt-tolerant rootstock, and the salt-sensitive Carrizo rootstock as a negative control. Our results demonstrated that chlorophyll content, net CO2 assimilation rate (A), transpiration rate (E), and stomatal conductance (gsw) significantly decreased in response to salinity. Na+ and Cl− levels were higher in leaf tissues than in the roots. Relatively little damage to the cellular membrane was recorded in HC15 and Cleopatra rootstocks under the 100 mm NaCl treatment, along with high accumulation of total phenolic content (TPC), while HS17 had the highest proline levels. Our results indicate that HC15 and HS17 rootstocks exhibited salt tolerance capacity via different strategies under salt stress and could be suitable replacements to the commercially available, salt-tolerant Cleopatra rootstock. Full article
(This article belongs to the Special Issue Advances in Citrus Horticulture)
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19 pages, 3242 KiB  
Article
Evaluation of the Crop Water Stress Index as an Indicator for the Diagnosis of Grapevine Water Deficiency in Greenhouses
by Chen Ru, Xiaotao Hu, Wene Wang, Hui Ran, Tianyuan Song and Yinyin Guo
Horticulturae 2020, 6(4), 86; https://doi.org/10.3390/horticulturae6040086 - 20 Nov 2020
Cited by 43 | Viewed by 5049
Abstract
Precise irrigation management of grapevines in greenhouses requires a reliable method to easily quantify and monitor the grapevine water status to enable effective manipulation of the water stress of the plants. This study evaluated the applicability of crop water stress index (CWSI) based [...] Read more.
Precise irrigation management of grapevines in greenhouses requires a reliable method to easily quantify and monitor the grapevine water status to enable effective manipulation of the water stress of the plants. This study evaluated the applicability of crop water stress index (CWSI) based on the leaf temperature for diagnosing the grapevine water status. The experiment was conducted at Yuhe Farm (northwest China), with drip-irrigated grapevines under three irrigation treatments. Meteorological factors, soil moisture contents, leaf temperature, growth indicators including canopy coverage and fruit diameter, and physiological indicators including SPAD (relative chlorophyll content), stem water potential (φs), stomatal conductance (gs), and transpiration rate (E) were studied during the growing season. The results show that the relationship between the leaf-air temperature difference (Tc-Ta) and the plant water status indicators (φs, gs, E) were significant (P < 0.05), and the relationship between gs, E and Tc-Ta was the closest, with R2 values ranging from 0.530–0.604 and from 0.545–0.623, respectively. CWSI values are more easily observed on sunny days, and it was determined that 14:00 BJS is the best observation time for the CWSI value under different non-water-stressed baselines. There is a reliable linear correlation between the CWSI value and the soil moisture at 0–40 cm (P < 0.05), which could provide a reference when using the CWSI to diagnose the water status of plants. Compared with the Tc-Ta value, the CWSI could more accurately monitor the plant water status, and above the considered indictors, gs has the greatest correlation with the CWSI. Full article
(This article belongs to the Special Issue Grape Responses to Abiotic and Biotic Stresses)
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13 pages, 2447 KiB  
Article
Phylogenetic Analysis and Molecular Diversity of Capsicum Based on rDNA-ITS Region
by Kumpei Shiragaki, Shuji Yokoi and Takahiro Tezuka
Horticulturae 2020, 6(4), 87; https://doi.org/10.3390/horticulturae6040087 - 20 Nov 2020
Cited by 14 | Viewed by 5506
Abstract
The genus Capsicum is comprised of 5 domesticated and more than 30 wild species. The region of nuclear ribosomal DNA internal transcribed spacers (rDNA-ITS) has widely been used for species identification, but has rarely been used in Capsicum. In this study, the [...] Read more.
The genus Capsicum is comprised of 5 domesticated and more than 30 wild species. The region of nuclear ribosomal DNA internal transcribed spacers (rDNA-ITS) has widely been used for species identification, but has rarely been used in Capsicum. In this study, the evaluation of genetic diversity and a phylogenetic analysis were conducted using rDNA-ITS of 28 Capsicum accessions, including five domesticated and two wild species. We surveyed six conventional keys of domesticated species and another five traits in Capsicum accessions. Specific morphological characteristics were found in C. annuum, C. baccatum, and C.pubescens. Three subclones of each accession were sequenced, and rDNA-ITS polymorphisms were detected in all accessions excluding C. annuum, suggesting that incomplete concerted evolution occurred in rDNA-ITS of Capsicum. The genetic diversity was evaluated using nucleotide polymorphism and diversity. C. annuum had the lowest genetic diversity of all species in this study. The phylogenetic tree formed a species-specific clade for C. annuum, C. baccatum, and C. pubescens. The C. chinense clade existed in the C. frutescens clade, implying that it was a cultivated variant of C. frutescens. C. chacoense likely belonged to the C. baccatum complex according to its morphologic and genetic features. This study indicated that the rDNA-ITS region can be used for simple identification of domesticated Capsicum species. Full article
(This article belongs to the Section Genetics, Genomics, Breeding, and Biotechnology (G2B2))
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15 pages, 1925 KiB  
Article
Effect of High CO2 Treatment and MA Packaging on Sensory Quality and Physiological-Biochemical Characteristics of Green Asparagus (Asparagus officinalis L.) during Postharvest Storage
by Li-Xia Wang, In-Lee Choi and Ho-Min Kang
Horticulturae 2020, 6(4), 84; https://doi.org/10.3390/horticulturae6040084 - 19 Nov 2020
Cited by 9 | Viewed by 2992
Abstract
Green asparagus is vulnerable to thrips that carry microorganisms and cause deterioration in quality. The effects of 60% CO2 treatment, which is used to kill thrips, combined with perforated (P) or modified atmosphere (MA) packages during cold storage, on the sensory quality [...] Read more.
Green asparagus is vulnerable to thrips that carry microorganisms and cause deterioration in quality. The effects of 60% CO2 treatment, which is used to kill thrips, combined with perforated (P) or modified atmosphere (MA) packages during cold storage, on the sensory quality and physiological–biochemical characteristics of asparagus were investigated. MA packaging yielded an asparagus shelf-life five days longer than P packaging. The 60% CO2 treatment for 48 h at 4 °C packaged with MA film (CO2-48 h-4 °C-MA) showed a lower number of aerobic bacteria, yeast, and mold. Yellowing of asparagus was retarded, as shown by higher hue angle and chlorophyll content and lower chlorophyllase activity. Also, CO2-48 h-4 °C-MA treatment inhibited the reduction of soluble solids content in asparagus. Likewise, all high CO2 treatments showed lower electrolyte leakage (EL), with CO2-48 h-4 °C-MA demonstrating the minimum EL. The effectiveness of high CO2 on maintaining sensory qualities was observed, with a score higher than 3.0. In conclusion, CO2-48 h-4 °C-MA treatment during cold storage was effective for maintaining post-harvest sensory qualities and physiological–biological traits of asparagus, and provided strong inhibition of microflora growth during the storage period. Full article
(This article belongs to the Section Postharvest Biology, Quality, Safety, and Technology)
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19 pages, 3117 KiB  
Review
Spring Freeze Damage of Pecan Bloom: A Review
by Amandeep Kaur, Louise Ferguson, Niels Maness, Becky Carroll, William Reid and Lu Zhang
Horticulturae 2020, 6(4), 82; https://doi.org/10.3390/horticulturae6040082 - 13 Nov 2020
Cited by 6 | Viewed by 4143
Abstract
Pecan is native to the United States. The US is the world’s largest pecan producer with an average yearly production of 250 to 300 million pounds; 80 percent of the world’s supply. Georgia, New Mexico, Texas, Arizona, Oklahoma, California, Louisiana, and Florida are [...] Read more.
Pecan is native to the United States. The US is the world’s largest pecan producer with an average yearly production of 250 to 300 million pounds; 80 percent of the world’s supply. Georgia, New Mexico, Texas, Arizona, Oklahoma, California, Louisiana, and Florida are the major US pecan producing states. Pecan trees frequently suffer from spring freeze at bud break and bloom as the buds are quite sensitive to freeze damage. This leads to poor flower and nut production. This review focuses on the impact of spring freeze during bud differentiation and flower development. Spring freeze kills the primary terminal buds, the pecan tree has a second chance for growth and flowering through secondary buds. Unfortunately, secondary buds have less bloom potential than primary buds and nut yield is reduced. Spring freeze damage depends on severity of the freeze, bud growth stage, cultivar type and tree age, tree height and tree vigor. This review discusses the impact of temperature on structure and function of male and female reproductive organs. It also summarizes carbohydrate relations as another factor that may play an important role in spring growth and transition of primary and secondary buds to flowers. Full article
(This article belongs to the Section Biotic and Abiotic Stress)
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16 pages, 3510 KiB  
Article
Implementation of the Circular Economy Concept in Greenhouse Hydroponics for Ultimate Use of Water and Nutrients
by Angeliki Elvanidi, Cinthya Marilu Benitez Reascos, Elissavet Gourzoulidou, Alexander Kunze, Johannes F. J. Max and Nikolaos Katsoulas
Horticulturae 2020, 6(4), 83; https://doi.org/10.3390/horticulturae6040083 - 13 Nov 2020
Cited by 22 | Viewed by 5155
Abstract
The circular economy in agriculture aims to reduce waste while also making best use of residues by using economically viable processes and procedures to increase their value. In this study a two-level cascade cultivation system was set up under greenhouse conditions. The research [...] Read more.
The circular economy in agriculture aims to reduce waste while also making best use of residues by using economically viable processes and procedures to increase their value. In this study a two-level cascade cultivation system was set up under greenhouse conditions. The research was focused on the identification of crop species as secondary crops and the development/iterative optimization of cultivation practices. For this purpose, different crop-combinations with a primary and different secondary crops were investigated using different system-layouts. Measurements were carried out during two cultivation periods. During the 1st Period a combination of cucumber (Cucumis sativus) as primary crop, with rosemary (Rosmarinus officinalis), basil (Ocimum basilicum), and peppermint (Mentha piperita) as secondary crops, was evaluated. In the 2nd Period the drainage of tomato (Solanum lycopersicum) plants was re-used to irrigate spearmint (Mentha spicata), dill (Anethum graveolens), celery (Apium graveolens) and parsley (Petroselinum crispum) plants. In both periods, different fertigation management strategies based on the drainage solution of the primary crop were employed. The use of the cascade hydroponic system improved both crop water and nutrient use efficiency. Notably, the NO3 disposal was about 40% less as compared to a monoculture. Average fresh water consumption of secondary crop plants irrigated with diluted drainage solution was reduced by 30% in comparison to plants irrigated with fresh water. Full article
(This article belongs to the Special Issue Transformation toward Sustainability in Controlled Environment Agriculture)
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13 pages, 3291 KiB  
Article
Effects of Light-Emitting Diodes on the Accumulation of Phenolic Compounds and Glucosinolates in Brassica juncea Sprouts
by Chang Ha Park, Ye Eun Park, Hyeon Ji Yeo, Jae Kwang Kim and Sang Un Park
Horticulturae 2020, 6(4), 77; https://doi.org/10.3390/horticulturae6040077 - 09 Nov 2020
Cited by 25 | Viewed by 3919
Abstract
Recent improvements in light-emitting diode (LED) technology afford an excellent opportunity to investigate the relationship between different light sources and plant metabolites. Accordingly, the goal of the present study was to determine the effect of different LED (white, blue, and red) treatments on [...] Read more.
Recent improvements in light-emitting diode (LED) technology afford an excellent opportunity to investigate the relationship between different light sources and plant metabolites. Accordingly, the goal of the present study was to determine the effect of different LED (white, blue, and red) treatments on the contents of glucosinolates (glucoiberin, gluconapin, sinigrin, gluconasturtiin, 4-methoxyglucobrassicin, 4-hydroxyglucobrassicin, glucobrassicin, and neoglucobrassicin) and phenolic compounds (4-hydroxybenzonate, catechin, chlorogenic acid, caffeate, gallate, sinapate, and quercetin) in Brassica juncea sprouts. The sprouts were grown in a growth chamber at 25 °C under irradiation with white, blue, or red LED with a flux rate of 90 μmol·m−2·s−1 and a long-day photoperiod (16 h light/8 h dark cycle). Marked differences in desulfoglucosinolate contents were observed in response to treatment with different LEDs and different treatment durations. In addition, the highest total desulfoglucosinolate content was observed in response to white LED light treatment, followed by treatment with red LED light, and then blue LED light. Among the individual desulfoglucosinolates identified in the sprouts, sinigrin exhibited the highest content, which was observed after three weeks of white LED light treatment. The highest total phenolic contents were recorded after one week of white and blue LED light treatment, whereas blue LED irradiation increased the production of most of the phenolic compounds identified, including 4-hydroxybenzonate, gallate, sinapate, caffeate, quercetin, and chlorogenic acid. The production of phenolics decreased gradually with increasing duration of LED light treatment, whereas anthocyanin accumulation showed a progressive increase during the treatment. These findings indicate that white LED light is appropriate for glucosinolate accumulation, whereas blue LED light is effective in increasing the production of phenolic compounds in B. juncea sprouts. Full article
(This article belongs to the Special Issue Urban Horticulture - New Trends and Technologies)
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15 pages, 1061 KiB  
Article
Quantitative and Qualitative Evaluation of Sorghum bicolor L. under Intercropping with Legumes and Different Weed Control Methods
by Saeid Vaezi Rad, Said Ali Reza Valadabadi, Majid Pouryousef, Saeid Saifzadeh, Hamid Reza Zakrin and Andrea Mastinu
Horticulturae 2020, 6(4), 78; https://doi.org/10.3390/horticulturae6040078 - 09 Nov 2020
Cited by 47 | Viewed by 4272
Abstract
In order to evaluate the quantity and quality of forage when intercropping forage sorghum (Sorghum bicolor L.) with lathyrus (Lathyrus sativus) and hairy vetch (Vicia villosa), and using different weed management methods such as double cropping, a factorial [...] Read more.
In order to evaluate the quantity and quality of forage when intercropping forage sorghum (Sorghum bicolor L.) with lathyrus (Lathyrus sativus) and hairy vetch (Vicia villosa), and using different weed management methods such as double cropping, a factorial experiment in a randomized complete block design with three replications was carried out at the research station of the University of Zanjan over two growing seasons (2015 and 2016). In this experiment, the intercropping of forage sorghum with lathyrus and hairy vetch at six levels with single cropping of forage sorghum, lathyrus, and hairy vetch, and three weed management strategies (no weed control, full weed control, and single weed control) was evaluated. The results showed that most forage sorghum traits were significantly (p ≤ 0.05) affected by different sowing ratios. The highest fresh forage yield of sorghum (77.9 ton/ha) and lowest (49.0 ton/ha) were obtained with sorghum + 33% hairy vetch and sorghum + 100% lathyrus, respectively. Forage qualitative traits were also affected by intercropping and weed management. The highest average acid detergent fiber (ADF), neutral detergent fiber (NDF), and total ash percentage (ASH) were obtained with 100% sorghum + 66% lathyrus and 33% hairy vetch. The results showed that sorghum intercropping with 33% lathyrus led to a significant reduction in dry matter intake and relative feed value with no weed control and single weed control. This study demonstrated that, by selecting the appropriate intercropping ratios and forage legumes, we could largely control sorghum weeds in addition to improving the quantitative and qualitative yield of sorghum forage. Full article
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16 pages, 2194 KiB  
Article
High-Tunnel Production of Strawberries Using Black and Red Plastic Mulches
by Geoffrey T. Lalk, Guihong Bi, Qianwen Zhang, Richard L. Harkess and Tongyin Li
Horticulturae 2020, 6(4), 73; https://doi.org/10.3390/horticulturae6040073 - 29 Oct 2020
Cited by 14 | Viewed by 3075
Abstract
High tunnels are economical season extension tools for strawberry (Fragaria × ananassa) growers in nonmajor strawberry producing states in the United States (US), where grower competitiveness can be increased by off-season crop production. Six June-bearing (“Camarosa”, “Camino Real”, “Chandler”, “Fronteras”, “Sensation”, [...] Read more.
High tunnels are economical season extension tools for strawberry (Fragaria × ananassa) growers in nonmajor strawberry producing states in the United States (US), where grower competitiveness can be increased by off-season crop production. Six June-bearing (“Camarosa”, “Camino Real”, “Chandler”, “Fronteras”, “Sensation”, and “Strawberry Festival”) and two day-neutral (“Albion” and “San Andreas”) strawberry cultivars were transplanted on 18 November 2017 and evaluated for their growth, yield, quality, and time of fruit harvest in a high-tunnel production system in Mississippi (US Department of Agriculture (USDA) hardiness zone 8a) during one growing season from fall 2017 to spring 2018. Effects of black and red plastic mulches were compared in producing strawberries. The high tunnel raised daily air temperatures, provided frost protection, and resulted in advanced fruit harvest by 4–6 weeks compared to local field production with the first ripe fruit produced in early March. “Camino Real”, “Chandler”, and “Strawberry Festival” produced similar highest total marketable yields of 483 g to 559 g per plant, with “Sensation” producing the lowest marketable yield of 215 g per plant. Red mulch decreased marketable yield in March but increased it in May compared with black mulch. Mulch type did not affect plant vegetative growth or strawberry fruit quality variables including berry size, soluble solid content, total phenolic content, or total anthocyanin content. Full article
(This article belongs to the Section Fruit Production Systems)
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12 pages, 12598 KiB  
Brief Report
Quantitative Trait Locus Analysis in Squash (Cucurbita moschata) Based on Simple Sequence Repeat Markers and Restriction Site-Associated DNA Sequencing Analysis
by Takuma Hashimoto, Nakao Kubo, Kanako Nishimura, Atsushi J. Nagano, Azusa Sasaki, Yasushi Nakamura and Yutaka Mimura
Horticulturae 2020, 6(4), 71; https://doi.org/10.3390/horticulturae6040071 - 22 Oct 2020
Cited by 3 | Viewed by 2814
Abstract
Squash (Cucurbita moschata) displays wide morphological and genetic variations; however, limited information is available regarding the genetic loci of squash that control its agronomic traits. To obtain basic genetic information for C. moschata, an F2 population was prepared derived [...] Read more.
Squash (Cucurbita moschata) displays wide morphological and genetic variations; however, limited information is available regarding the genetic loci of squash that control its agronomic traits. To obtain basic genetic information for C. moschata, an F2 population was prepared derived from a cross between the Vietnamese cultivar ‘Bí Hồ Lô TN 6 (TN 6)’ and the Japanese cultivar ‘Shishigatani’, and flowering and fruit traits were examined. Overall, the traits showed a continuous distribution in the F2 population, suggesting that they were quantitative traits. A linkage map was constructed based on simple sequence repeat and restriction site-associated DNA (RAD) markers to detect quantitative trait loci (QTLs). Twelve QTLs for flowering and fruit traits, as well as one phenotypic trait locus, were successfully localized on the map. The present QTLs explained the phenotypic variations at a moderate to relatively high level (16.0%–47.3%). RAD markers linked to the QTLs were converted to codominant cleaved amplified polymorphic sequence (CAPS) and derived CAPS markers for the easy detection of alleles. The information reported here provides useful information for understanding the genetics of Cucurbita and other cucurbit species, and for the selection of individuals with ideal traits during the breeding of Cucurbita vegetables. Full article
(This article belongs to the Section Genetics, Genomics, Breeding, and Biotechnology (G2B2))
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15 pages, 2087 KiB  
Article
Developing Triploid Maples
by Ryan N. Contreras and Tyler C. Hoskins
Horticulturae 2020, 6(4), 70; https://doi.org/10.3390/horticulturae6040070 - 21 Oct 2020
Cited by 3 | Viewed by 2793
Abstract
Maples are common street and shade trees throughout the temperate zone. They are widely used for their wide range of ornamental traits and adaptability, particularly to urban settings. Unfortunately, some species such as Acer tataricum ssp. ginnala (Amur maple) and A. platanoides (Norway [...] Read more.
Maples are common street and shade trees throughout the temperate zone. They are widely used for their wide range of ornamental traits and adaptability, particularly to urban settings. Unfortunately, some species such as Acer tataricum ssp. ginnala (Amur maple) and A. platanoides (Norway maple) have escaped cultivation to become pests or in some cases threaten native flora. However, these species remain economically important and are still asked for by name. To ameliorate potential future ecological damage from additional escapes, we have been breeding for sterile forms using ploidy manipulation and backcrossing to develop triploids. We began with a series of experiments to develop tetraploids of Amur, Norway, and trident (A. buergerianum) maples. Treatment of seedlings at the cotyledon or first true leaf stage was successful in inducing tetraploids of each species. Mortality, cytochimeras, and tetraploids varied among species. After identifying tetraploids, they were field planted alongside diploid cultivars and seedlings, which served as pollinizers in open-pollination. Seedlings derived from open-pollinated tetraploids were generally found to be a high percentage triploids. Thus far, no Norway or trident maple triploids have flowered but after three years we observed five, 22, and 22 Amur maple triploids flowering over three respective years with no seedlings recovered to date. Further evaluation is required but our findings are encouraging that the triploids we have developed thus far will be sterile and provide new cultivars for nursery growers and land managers. Full article
(This article belongs to the Special Issue Breeding, Genetics and Genomics of Ornamental Plants)
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11 pages, 400 KiB  
Article
Evaluation of Genotypes and Association of Traits in Watermelon Across Two Southern Texas Locations
by Edgar Correa, Subas Malla, Kevin M. Crosby and Carlos A. Avila
Horticulturae 2020, 6(4), 67; https://doi.org/10.3390/horticulturae6040067 - 15 Oct 2020
Cited by 4 | Viewed by 2309
Abstract
Watermelon is the most important horticultural crop in Texas and is grown across the state under diverse environments. Our study was conducted in the southern region of Texas to understand genotype-by-environment interactions and the contribution of yield components to yield. To accomplish this, [...] Read more.
Watermelon is the most important horticultural crop in Texas and is grown across the state under diverse environments. Our study was conducted in the southern region of Texas to understand genotype-by-environment interactions and the contribution of yield components to yield. To accomplish this, twenty genotypes were evaluated for important traits and characteristics at two locations, Uvalde and Weslaco TX, for two years, 2018 and 2019. The genotypes were evaluated for total yield, total fruit count, total soluble solids, rind thickness, fruit length, diameter and weight. Genotype-by-environment (G x E) interaction was not significant, possibly due to similarity in climatic conditions and nutrient management practices. In the grouped analysis, cultivars Crimson Diamond, Sunshade and the breeding line TAM 2 had a higher total yield. Path analysis showed a high direct effect for total fruit count and fruit diameter of 0.89 and 0.85, respectively. However, total fruit count had a high indirect effect of −0.44. Fruit weight was the only trait that showed a significant (p < 0.01) correlation towards total yield at r = 0.58. Neither of the high direct effects, total fruit count and fruit diameter, had a significant correlation. The study inferred that breeding resources could be optimized by reducing the testing location to only one representative location for measured traits in southern Texas. The indirect selection of total fruit or fruit diameter could result in better yield. The study suggested selecting for optimum total fruit and fruit diameter for higher yield. Full article
(This article belongs to the Section Fruit Production Systems)
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19 pages, 2371 KiB  
Review
Seed Geometry in the Arecaceae
by Diego Gutiérrez del Pozo, José Javier Martín-Gómez, Ángel Tocino and Emilio Cervantes
Horticulturae 2020, 6(4), 64; https://doi.org/10.3390/horticulturae6040064 - 07 Oct 2020
Cited by 10 | Viewed by 4270
Abstract
Fruit and seed shape are important characteristics in taxonomy providing information on ecological, nutritional, and developmental aspects, but their application requires quantification. We propose a method for seed shape quantification based on the comparison of the bi-dimensional images of the seeds with geometric [...] Read more.
Fruit and seed shape are important characteristics in taxonomy providing information on ecological, nutritional, and developmental aspects, but their application requires quantification. We propose a method for seed shape quantification based on the comparison of the bi-dimensional images of the seeds with geometric figures. J index is the percent of similarity of a seed image with a figure taken as a model. Models in shape quantification include geometrical figures (circle, ellipse, oval…) and their derivatives, as well as other figures obtained as geometric representations of algebraic equations. The analysis is based on three sources: Published work, images available on the Internet, and seeds collected or stored in our collections. Some of the models here described are applied for the first time in seed morphology, like the superellipses, a group of bidimensional figures that represent well seed shape in species of the Calamoideae and Phoenix canariensis Hort. ex Chabaud. Oval models are proposed for Chamaedorea pauciflora Mart. and cardioid-based models for Trachycarpus fortunei (Hook.) H. Wendl. Diversity of seed shape in the Arecaceae makes this family a good model system to study the application of geometric models in morphology. Full article
(This article belongs to the Special Issue Feature Papers in Horticulturae)
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10 pages, 1154 KiB  
Article
Physicochemical and Bioactive Characterisation of Edible and Waste Parts of “Piel de Sapo” Melon
by Fátima Alves Miller, Joana Freitas Fundo, Ester Garcia, João Rodrigo Santos, Cristina Luisa Miranda Silva and Teresa Ribeiro Silva Brandão
Horticulturae 2020, 6(4), 60; https://doi.org/10.3390/horticulturae6040060 - 01 Oct 2020
Cited by 11 | Viewed by 3088
Abstract
Several scientific studies point fruits as rich sources of antioxidants but mainly focus on their edible part. However, fruits wastes are abundant sources of bioactive compounds and nutrients, which are considered to be health beneficial. The main purpose was to characterise juice, pulp, [...] Read more.
Several scientific studies point fruits as rich sources of antioxidants but mainly focus on their edible part. However, fruits wastes are abundant sources of bioactive compounds and nutrients, which are considered to be health beneficial. The main purpose was to characterise juice, pulp, peel and seeds of Piel de Sapo melon, in terms of several physicochemical characteristics (soluble solids content, titratable acidity, pH, potassium, colour and water activity), some bioactive compounds (total phenolics, vitamin C, chlorophylls and total carotenoids) and total antioxidant activity. Juice, pulp, peel and seeds represent 47, 19, 27 and 5% of melon total weight, respectively. Peel and seeds stood out by their higher concentration of total phenolics compounds and antioxidant activity when compared to edible parts. The highest potassium concentration was found in seeds. Chlorophylls were only detected in peel, while carotenoids were not detected in any part of the melon analysed. Juice and pulp contributed to 69% of vitamin C amount of the whole fruit. However, its concentration in peel was equivalent to the ones observed in juice and pulp. These results pointed out the importance of fruit wastes valorisation and the development of strategies for their re-utilisation. Full article
(This article belongs to the Section Plant Nutrition)
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17 pages, 2596 KiB  
Article
The Agriculture–Nutrition–Income Nexus in Tonga: Is Postharvest Loss Undermining Horticulture Market Efficiency in Tonga?
by Steven J. R. Underhill, Soane Patolo, Yuchan Zhou and Sarah Burkhart
Horticulturae 2020, 6(4), 61; https://doi.org/10.3390/horticulturae6040061 - 01 Oct 2020
Cited by 4 | Viewed by 8307
Abstract
The Kingdom of Tonga has one of the highest rates of diet-related non-communicable diseases (NCDs) in the world. Initiatives to promote pro-health dietary behaviour are possibly being compromised by poor or inconsistent consumer accessibility to affordable and safe fresh fruits and vegetables, referred [...] Read more.
The Kingdom of Tonga has one of the highest rates of diet-related non-communicable diseases (NCDs) in the world. Initiatives to promote pro-health dietary behaviour are possibly being compromised by poor or inconsistent consumer accessibility to affordable and safe fresh fruits and vegetables, referred to as the agriculture–nutrition–income nexus. While donors increasingly focus on nutrition-sensitive agriculture across the Pacific, there is little contemporary information concerning Tonga’s domestic horticultural distribution and market system, particularly in regards to food loss. This study surveyed 292 municipal and road-side vendors on Tongatapu and ‘Utu Vava’u Islands, with the aim of mapping and analyzing horticultural markets and farm supply, transport logistics, and quantifying postharvest practice and market loss. Tonga’s domestic horticultural market structure consists of a central municipal market and on Tongatapu Island, a supplementary network of urban and rural based road-side vendors. There is limited inter-island trade, with most farms located within 25 km of the central municipal market. Mean postharvest horticultural loss was very low, at 1.4% to 5.3%, with road-side vendors more vulnerable to loss. This level of loss was thought to reflect short intra-island transport distance, the type of crops being traded, and rapid market throughput, rather than a level of value chain efficiency. Vendors regulated market supply volume and price discounting and were the principal strategies to mitigate postharvest loss. While low levels of postharvest loss, short transport logistics, and fast market throughput are consistent with a relatively efficient horticulture market system, vendor practice may be impeding fresh fruit and vegetable accessibility. Full article
(This article belongs to the Section Postharvest Biology, Quality, Safety, and Technology)
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14 pages, 1680 KiB  
Article
Blue Light Does Not Affect Fruit Quality or Disease Development on Ripe Blueberry Fruit During Postharvest Cold Storage
by Yi-Wen Wang, Helaina D. Ludwig, Harald Scherm, Marc W. van Iersel and Savithri U. Nambeesan
Horticulturae 2020, 6(4), 59; https://doi.org/10.3390/horticulturae6040059 - 30 Sep 2020
Cited by 3 | Viewed by 3307
Abstract
Blueberry fruit are perishable after harvesting due to fruit softening, water loss and susceptibility to pathogens. Light, especially blue light, increases the accumulation of anthocyanins and reduces postharvest decay in some fruits, but the effect of blue light on postharvest fruit quality attributes [...] Read more.
Blueberry fruit are perishable after harvesting due to fruit softening, water loss and susceptibility to pathogens. Light, especially blue light, increases the accumulation of anthocyanins and reduces postharvest decay in some fruits, but the effect of blue light on postharvest fruit quality attributes in blueberries is unknown. In this study, we evaluated the effect of blue light on fruit quality, anthocyanin accumulation and disease development during postharvest cold storage (2 °C–4 °C) in two experiments with southern highbush blueberry ‘Star’ and rabbiteye blueberry ‘Alapaha’. Overall, diurnal blue light did not affect postharvest fruit quality attributes, such as visual defects, fruit compression, skin puncture, total soluble solid content and titratable acidity, in the two cultivars compared with their respective controls (diurnal white light or continuous darkness). Further, there was no effect of blue light on fruit color and anthocyanin accumulation. Fruit disease incidence in ‘Star’ ranged from 19.0% to 27.3% after 21 days and in ‘Alapaha’ from 44.9% to 56.2% after 24 days in postharvest storage, followed by 4 days at room temperature, but blue light had no consistent effect on postharvest disease incidence for either cultivar. Disease progression following artificial inoculations with Alternaria tenuissima and Colletotrichum acutatum in ‘Star’ was not influenced by light treatment prior to inoculation and during fruit storage. In a separate experiment, we tested the effect of blue light on color development in ‘Farthing’, a southern highbush blueberry cultivar with fruit prone to non-uniform ripening, whereby the stem-end remains green as the rest of the fruit turns blue. Although green stem-end spots turned blue over time, there was no statistically significant effect of the blue light treatment. Overall, these data indicate that blue light does not affect fruit quality attributes or disease development in ripe blueberry fruit during postharvest storage in the conditions investigated here. Full article
(This article belongs to the Section Postharvest Biology, Quality, Safety, and Technology)
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9 pages, 1537 KiB  
Article
Fertilizer Rate and Substrate Water Content Effect on Growth and Flowering of Beardtongue
by Amanda Bayer
Horticulturae 2020, 6(3), 57; https://doi.org/10.3390/horticulturae6030057 - 16 Sep 2020
Cited by 2 | Viewed by 2602
Abstract
Research has shown that reduced irrigation and fertilizer rates can still produce good plant growth when irrigation is applied efficiently to reduce leaching. The impact of reduced irrigation and fertilizer rate on flowering and plant growth would provide additional information on the potential [...] Read more.
Research has shown that reduced irrigation and fertilizer rates can still produce good plant growth when irrigation is applied efficiently to reduce leaching. The impact of reduced irrigation and fertilizer rate on flowering and plant growth would provide additional information on the potential for reduced production inputs. The objective of this research was to quantify the impact of reduced irrigation and fertilizer rate on growth and flowering of Ruby Candle beardtongue (Penstemon × ‘Ruby Candle’). A soil moisture sensor automated irrigation system was used to maintain plants at 40% volumetric water content [VWC; well-watered (WW)] or 18% VWC (reduced irrigation, RI). A controlled release fertilizer was applied at 100%, 50%, and 25% of the bag rate (12 g/plant). There was not a significant treatment effect on any flower parameter. Average plant height was greatest for plants receiving the 50% fertilizer rate (75.9 cm) and was lowest for the 100% fertilizer rate (64.5 cm). Internode length was greater for WW plants (36.9 mm) than RI plants (32.4 mm). Well-watered plants had greater fresh weight (99.1 g) than RI plants (79.2 g) and 100% fertilizer rate (97.1 g) was greater than the 25% fertilizer rate (82.7 g). Full article
(This article belongs to the Section Floriculture, Nursery and Landscape, and Turf)
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12 pages, 653 KiB  
Article
Salt Tolerance of Hydrangea Plants Varied among Species and Cultivar within a Species
by Genhua Niu, Youping Sun, Triston Hooks, James Altland, Haijie Dou and Christina Perez
Horticulturae 2020, 6(3), 54; https://doi.org/10.3390/horticulturae6030054 - 04 Sep 2020
Cited by 4 | Viewed by 3965
Abstract
A greenhouse study was conducted to assess the relative salt tolerance of 11 cultivars of hydrangea: Hydrangea macrophylla ‘Ayesha’, ‘Emotion’, ‘Mathilda Gutges’, ‘Merritt’s Supreme’ and ‘Passion’; H. paniculata ‘Interhydia’ and ‘Bulk’; H. quercifolia ‘Snowflake’; H. serrata ‘Preciosa’; and H. [...] Read more.
A greenhouse study was conducted to assess the relative salt tolerance of 11 cultivars of hydrangea: Hydrangea macrophylla ‘Ayesha’, ‘Emotion’, ‘Mathilda Gutges’, ‘Merritt’s Supreme’ and ‘Passion’; H. paniculata ‘Interhydia’ and ‘Bulk’; H. quercifolia ‘Snowflake’; H. serrata ‘Preciosa’; and H. serrata × macrophylla ‘Sabrina’ and ‘Selina’. Plants were treated with a nutrient solution at an electrical conductivity (EC) of 1.0 dS·m−1, and nutrient solution-based saline solutions at an EC of 5.0 dS·m−1 (EC 5) or 10 dS·m−1 (EC 10). The study was repeated in time (Experiments 1 and 2). In both experiments, by the fourth week after treatment, ‘Bulk’ plants in EC 10 exhibited severe salt damage with most of them dead. ‘Interhydia’ was also sensitive, showing severe salt damage in EC 10 with a high mortality rate by the end of the experiment. The leaf area and total shoot dry weight (DW) of all cultivars in EC 5 and EC 10 treatments were significantly reduced compared to the control. Leaf sodium (Na+) and chloride (Cl−) concentrations were negatively correlated with visual quality, leaf area and shoot DW. The salt-sensitive cultivars ‘Bulk’, ‘Interhydia’ and ‘Snowflake’ had inherently low leaf Na+ and Cl− concentrations in both control and salt-treated plants compared to other cultivars. Salt tolerance varied among species and cultivars within H. macrophylla. Among the 11 cultivars, H. macrophylla ‘Ayesha’ and two hybrids, ‘Sabrina’ and ‘Selina’, were relatively salt-tolerant. H. macrophylla ‘Merritt’s Supreme’ and ‘Mathilda’ were moderately tolerant. H. paniculata ‘Bulk’ was the most sensitive, followed by H. paniculata ‘Interhydia’, and then by H. serrata ‘Preciosa’ and H. macrophylla ‘Passion’, as evidenced by high mortality and severe salt damage symptoms. H. quercifolia ‘Snowflake’ and H. macrophylla ‘Emotion’ were moderately salt-sensitive. Full article
(This article belongs to the Section Floriculture, Nursery and Landscape, and Turf)
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8 pages, 3707 KiB  
Article
Mechanical Crop Load Management (CLM) Improves Fruit Quality and Reduces Fruit Drop and Alternate Bearing in European Plum (Prunus domestica L.)
by Sebastian Lammerich, Achim Kunz, Lutz Damerow and Michael Blanke
Horticulturae 2020, 6(3), 52; https://doi.org/10.3390/horticulturae6030052 - 02 Sep 2020
Cited by 11 | Viewed by 3215
Abstract
(1) Background: With ca. 10 million tons of annual production worldwide, the plum (Prunus ssp.) ranks as a major fruit crop and can suffer from small fruit size, premature fruit drop and alternate bearing, which are addressed in this paper using [...] Read more.
(1) Background: With ca. 10 million tons of annual production worldwide, the plum (Prunus ssp.) ranks as a major fruit crop and can suffer from small fruit size, premature fruit drop and alternate bearing, which are addressed in this paper using a range of crop load management (CLM) tools. (2) Methods: Sixty 10-year-old European plum cv. “Ortenauer” trees on dwarfing St. Julien INRA GF 655/2 rootstock (slender spindle; 4.25 × 2.80 m) in a commercial orchard near Bonn (50°N), Germany, were thinned in 2 years and flower intensity assessed in the following year. Thinning was performed either mechanically (type Bonn/Baum) or chemically, with ATS (ammonium thiosulfate) or ethephon (Flordimex), or by a combination of mechanical and chemical methods, to improve fruit quality and the proportion of Class 1 fruit. Adjacent un-thinned trees served as controls. (3) Results: Natural fruit drop in June was reduced from 290 fruits per tree in the un-thinned controls to 265 fruits after ATS blossom treatment, and to 148 fruits after mechanical thinning at 380 rpm at a 5 km/h tractor speed at full bloom. The un-thinned control trees developed a large number of small, undersized fruits. The yield of Class 1 fruits increased per tree from 47% in the un-thinned controls, up to 69% after crop load management. Sugar content and fruit firmness were unaffected. (4) Conclusions: The study has shown that fruit quality (i.e., fruit size) and financial returns could be improved by either mechanical (380 rpm at 5 km/h) or chemical thinning, or a combination of both. Full article
(This article belongs to the Special Issue Feature Papers in Horticulturae)
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8 pages, 1481 KiB  
Article
Rapid In Vitro Multiplication of Non-Runnering Fragaria vesca Genotypes from Seedling Shoot Axillary Bud Explants
by Babul C. Sarker, Douglas D. Archbold, Robert L. Geneve and Sharon T. Kester
Horticulturae 2020, 6(3), 51; https://doi.org/10.3390/horticulturae6030051 - 01 Sep 2020
Cited by 2 | Viewed by 3186
Abstract
Fragaria vesca L. has become a model species for genomic studies relevant to important crop plant species in the Rosaceae family, but generating large numbers of plants from non-runner-producing genotypes is slow. To develop a protocol for the rapid generation of plants, leaf [...] Read more.
Fragaria vesca L. has become a model species for genomic studies relevant to important crop plant species in the Rosaceae family, but generating large numbers of plants from non-runner-producing genotypes is slow. To develop a protocol for the rapid generation of plants, leaf explants were compared to single axillary bud shoot explants, both from in vitro-grown Fragaria vesca seedlings, as sources of shoots for new plant production in response to benzyladenine (BA) or thidiazuron (TDZ) combined with indolebutyric acid (IBA) on Murashige and Skoog’s Basal Salt (MS) medium. BA at 2.0 and 4.0 mg L−1 and TDZ at 1.5 mg L−1 promoted the greatest number of shoots produced per shoot explant. There were no IBA effects or IBA interactions with BA or TDZ. Significant interactions between BA and IBA, but not TDZ and IBA, occurred in leaf explant callus formation and % explants with callus at 6 and 9 weeks of culture and on shoots per leaf explant at 9 weeks. TDZ treatments produced uniformly high levels of callus but low numbers of shoots. The treatment generating the most shoot production was BA at 4.0 mg L−1 plus IBA at 0.50 mg L−1. After 9 weeks of culture, leaf explants of the non-runner-producing genotype Baron Solemacher had generated 4.6 shoots per explant with the best treatment, while axillary bud explants had generated 30.8 shoots with the best treatment. Thus, in vitro culture of shoot axillary bud explants can generate high numbers of clonal shoots from a single seedling plant in vitro. Full article
(This article belongs to the Special Issue Feature Papers in Horticulturae)
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17 pages, 1302 KiB  
Article
Deficit Irrigation and Arbuscular Mycorrhiza as a Water-Saving Strategy for Eggplant Production
by M. A. Badr, W. A. El-Tohamy, S. D. Abou-Hussein and N. S. Gruda
Horticulturae 2020, 6(3), 45; https://doi.org/10.3390/horticulturae6030045 - 11 Aug 2020
Cited by 13 | Viewed by 3821
Abstract
Crop production in arid regions requires continuous irrigation to fulfill water demand throughout the growing season. Agronomic measures, such as roots-soil microorganisms, including arbuscular mycorrhizal (AM) fungi, have emerged in recent years to overcome soil constraints and improve water use efficiency (WUE). Eggplant [...] Read more.
Crop production in arid regions requires continuous irrigation to fulfill water demand throughout the growing season. Agronomic measures, such as roots-soil microorganisms, including arbuscular mycorrhizal (AM) fungi, have emerged in recent years to overcome soil constraints and improve water use efficiency (WUE). Eggplant plants were exposed to varying water stress under inoculated (AM+) and non-inoculated (AM−) to evaluate yield performance along with plant physiological status. Plants grown under full irrigation resulted in the highest fruit yield, and there were significant reductions in total yield and yield components when applying less water. The decline in fruit yield was due to the reduction in the number of fruits rather than the weight of the fruit per plant. AM+ plants showed more favorable growth conditions, which translated into better crop yield, total dry biomass, and number of fruits under all irrigation treatments. The fruit yield did not differ between full irrigation and 80% evapotranspiration (ET) restoration with AM+, but a 20% reduction in irrigation water was achieved. Water use efficiency (WUE) was negatively affected by deficit irrigation, particularly at 40% ET, when the water deficit severely depressed fruit yield. Yield response factor (Ky) showed a lower tolerance with a value higher than 1, with a persistent drop in WUE suggesting a lower tolerance to water deficits. The (Ky) factor was relatively lower with AM+ than with AM− for the total fruit yield and dry biomass (Kss), indicating that AM may enhance the drought tolerance of the crop. Plants with AM+ had a higher uptake of N and P in shoots and fruits, higher stomatal conductance (gs), and higher photosynthetic rates (Pn), regardless of drought severity. Soil with AM+ had higher extractable N, P, and organic carbon (OC), indicating an improvement of the fertility status in coping with a limited water supply. Full article
(This article belongs to the Special Issue Soil, Water and Nitrates Management in Horticultural Production)
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25 pages, 2064 KiB  
Review
The Potential of Introduction of Asian Vegetables in Europe
by Jungha Hong and Nazim S. Gruda
Horticulturae 2020, 6(3), 38; https://doi.org/10.3390/horticulturae6030038 - 03 Jul 2020
Cited by 20 | Viewed by 7319
Abstract
Increasing longevity, along with an aging population in Europe, has caused serious concerns about diet-related chronic diseases such as obesity, diabetes, cardiovascular diseases, and certain cancers. As recently noted during the coronavirus pandemic, regular exercise and a robust immune system complemented by adequate [...] Read more.
Increasing longevity, along with an aging population in Europe, has caused serious concerns about diet-related chronic diseases such as obesity, diabetes, cardiovascular diseases, and certain cancers. As recently noted during the coronavirus pandemic, regular exercise and a robust immune system complemented by adequate consumption of fruit and vegetables are recommended due to their known health benefits. Although the volume of fresh vegetable consumption in the EU is barely growing, demand for diversified, nutritious, and exotic vegetables has been increasing. Therefore, the European market for fresh Asian vegetables is expected to expand across the EU member states, and the introduction of new vegetables has enormous potential. We conducted this review to address the high number and wide range of Asian vegetable species with a commercial potential for introduction into the current European vegetable market. Many of them have not received any attention yet. Four Asian vegetables: (1) Korean ginseng sprout, (2) Korean cabbage, (3) Coastal hog fennel and (4) Japanese (Chinese or Korean) angelica tree, are further discussed. All of these vegetables possess several health benefits, are increasingly in demand, are easy to cultivate, and align with current trends of the European vegetable market, e.g., vegetables having a unique taste, higher value, are decorative and small. Introducing Asian vegetables will enhance the diversity of nutritious horticultural products in Europe, associated with all their respective consumption benefits. Future research on the Asian vegetable market within Europe is needed. In addition, experimental studies of Asian vegetables under practical conditions for their production in different European environments are required. Economic, social, and ecological aspects also ought to be considered. Full article
(This article belongs to the Special Issue Feature Papers in Horticulturae)
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13 pages, 2026 KiB  
Article
Growth and Bioactive Compounds of Salvia plebeia R. Br. Grown under Various Ratios of Red and Blue Light
by Hye Ri Lee, Hyeon Min Kim, Hyeon Woo Jeong and Seung Jae Hwang
Horticulturae 2020, 6(2), 35; https://doi.org/10.3390/horticulturae6020035 - 10 Jun 2020
Cited by 3 | Viewed by 3182
Abstract
We investigated the effects of red and blue light on the growth and content of bioactive compounds of Salvia plebeia R. Br in a closed-type plant production system (CPPS). The seedlings of Salvia plebeia R. Br. were transplanted into a deep floating technique [...] Read more.
We investigated the effects of red and blue light on the growth and content of bioactive compounds of Salvia plebeia R. Br in a closed-type plant production system (CPPS). The seedlings of Salvia plebeia R. Br. were transplanted into a deep floating technique system with nutrient recycling (pH 6.5 and electrical conductivity (EC) 1.5 dS∙m−1). The plants were cultured for a duration of 35 days at 25 ± 1 °C, with relative humidity 60 ± 5%, a 12/12 h (light/dark) photoperiod, and a light intensity of 180 µmol∙m−2∙s−1 photosynthetic flux photon density, providing standard fluorescent (FL) lighting and various light qualities of red:blue ratios (10:0, 7:3, 5:5, 3:7, and 0:10) in the CPPS. The growth characteristics of Salvia plebeia R. Br., such as leaf length, leaf area, and fresh and dry weights of shoots, were the greatest in Red only and R7B3. The leaf shape index was the highest in Blue only and specific leaf weight was lower in FL and Blue than in the other treatments. The photosynthetic rate was the highest in R7B3. The total phenolic and flavonoid concentrations per gram of fresh weight of Salvia plebeia R. Br. were higher in combined light, such as R7B3, R5B5, and B3B7, than in the monochromatic light treatments. However, the antioxidant activity per fresh weight was the highest in FL. In conclusion, the results suggest that 7:3 is the most effective red and blue light ratio for production of high quality Salvia plebeia R. Br. in a CPPS. Full article
(This article belongs to the Section Developmental Physiology, Biochemistry, and Molecular Biology)
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10 pages, 484 KiB  
Article
Premature Apple Fruit Drop: Associated Fungal Species and Attempted Management Solutions
by Khamis Youssef and Sergio Ruffo Roberto
Horticulturae 2020, 6(2), 31; https://doi.org/10.3390/horticulturae6020031 - 26 May 2020
Cited by 5 | Viewed by 3762
Abstract
The aim of this research was to determine the incidence and possible causal pathogen(s) of premature apple fruit drop (PAFD), and also to assess some fungicides for controlling the disease organisms, in order to promote a sustainable system in orchards. The prevalence and [...] Read more.
The aim of this research was to determine the incidence and possible causal pathogen(s) of premature apple fruit drop (PAFD), and also to assess some fungicides for controlling the disease organisms, in order to promote a sustainable system in orchards. The prevalence and natural incidence of apple fruit drop in cv. Anna was assessed during the 2017–2018 growing seasons in Nubaria and Cairo–Alexandria regions, Egypt. Phytopathogenic fungi were isolated from dropped fruit, and four fungicides, pyraclostrobin + boscalid, difenoconazole, carbendazim, and thiophanate methyl, were tested against the diseases in vitro and under naturally occurring infections in the field. Several phytopathogenic fungi, including Alternaria alternata, Cladosporium cladosporioides, Fusarium semitectum, and Penicillium spp., were associated with apple fruit drop. A. alternata was the most frequently isolated fungus occurring during the investigation. Pathogenicity tests confirmed that the maximum percentage of apple fruit drop was noted when petioles and fruits were inoculated with mixed fungal pathogens using branch sections with fruit. In vitro tests showed that the fungicides had a variable effect against the fungal isolates depending on the concentration used. All fungicides completely inhibited the growth of A. alternata, C. cladosporioides, and F. semitectum at 400 mg·L−1. Under naturally occurring infections, thiophanate methyl applied at fruit set had the greatest effect (81.68%) against PAFD, followed by difenoconazole (73.76%), pyraclostrobin + boscalid (70.29%), and carbendazim (66.34%). The results indicated that PAFD may in part be a result of diseases caused by certain phytopathogenic fungi, which could be controlled using a number of fungicides applied at the beginning of fruit set. Full article
(This article belongs to the Special Issue Feature Papers in Horticulturae)
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10 pages, 4102 KiB  
Communication
Fresh and Dry Weight Relations Are Predictors of Cycas micronesica Seed Age
by Thomas E. Marler and Christopher A. Shaw
Horticulturae 2020, 6(2), 29; https://doi.org/10.3390/horticulturae6020029 - 18 May 2020
Cited by 1 | Viewed by 5693
Abstract
Cycas micronesica is a foundation species in several Micronesian islands and its seeds have been a historical source of starch for the island residents. The species has become endangered by invasive specialist insect herbivores and conservationists struggle with the inability to estimate the [...] Read more.
Cycas micronesica is a foundation species in several Micronesian islands and its seeds have been a historical source of starch for the island residents. The species has become endangered by invasive specialist insect herbivores and conservationists struggle with the inability to estimate the age of observed seeds. To inform this agenda, we evaluated numerous Cycas micronesica seed traits to determine if any exhibited a relationship with age and a substantial change in absolute value. Of the 30 direct and derived seed traits that we evaluated, most of them were non-linear and exhibited minimal change after about 12 months in age. The only traits that emerged as unambiguous estimators of age were the quotients derived as gametophyte fresh weight/total seed fresh weight and sarcotesta dry weight/sclerotesta dry weight. These two simple metrics can be used to accurately estimate seed age for this arborescent cycad species. Full article
(This article belongs to the Section Propagation and Seeds)
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11 pages, 1444 KiB  
Article
Assessment of Two Sweet Orange Cultivars Grafted on Selected Rootstocks Grown on an Inceptisol in Puerto Rico
by Rebecca Tirado-Corbalá, Alejandro Segarra-Carmona, Manuel Matos-Rodríguez, Dania Rivera-Ocasio, Consuelo Estévez de Jensen and Jeniffer Pagán
Horticulturae 2020, 6(2), 30; https://doi.org/10.3390/horticulturae6020030 - 18 May 2020
Cited by 2 | Viewed by 3273
Abstract
Sweet oranges in Puerto Rico and other citrus-producing areas in the world have been greatly affected by the Huanglongbing disease (HLB). Historically, most of Puerto Rico’s citrus production has been located from 0–600 m above sea level, where fruit acquire a desirable color [...] Read more.
Sweet oranges in Puerto Rico and other citrus-producing areas in the world have been greatly affected by the Huanglongbing disease (HLB). Historically, most of Puerto Rico’s citrus production has been located from 0–600 m above sea level, where fruit acquire a desirable color and flavor due to climatic conditions. However, higher populations of the disease vector Diaphorina citri Kuwayama have been reported at these elevations in Puerto Rico. Although only 6.4% of the land area is located above 600 m, it is composed mainly of environmentally sensitive or non-arable land where Inceptisols are the dominant soil order. For that reason, ‘Marr’s Early’ and ‘Pera’ sweet orange (Citrus sinensis) scions grafted on ‘Carrizo’, ‘HRS 802’, and ‘HRS 812’ rootstocks were planted in Alonso clay series Inceptisol (Oxic Humudepts) at 649 m in 2010. Tree growth parameters (height, diameter, canopy volume) and yield efficiency were measured. Fruit quality was determined from juice content (%), total soluble solids [°Brix], and pH. Leaf tissue analyses showed an optimum range for Ca, Mg, Na, P, B, Cu, and Zn, an indicator of tree health. A few were high (i.e., N and P) or in excess (i.e., Fe), but no clear connection to specific scions or rootstocks could be established. Tree height, tree diameter, fruit production, and juice content were higher in both sweet oranges grafted on ‘HRS 802’ compared with those on ‘HRS 812’ and ‘Carrizo’. Therefore, ‘HRS 802’ rootstock can be recommended to local farmers growing sweet oranges in Alonso series soil. Full article
(This article belongs to the Section Fruit Production Systems)
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14 pages, 3902 KiB  
Article
Comparing Efficiencies of Two Selection Approaches for Improving Fusarium Basal Rot Resistance in Short-Day Onion after a Single Cycle of Selection
by Subhankar Mandal, Ashish Saxena, Christopher S. Cramer and Robert L. Steiner
Horticulturae 2020, 6(2), 26; https://doi.org/10.3390/horticulturae6020026 - 13 Apr 2020
Cited by 5 | Viewed by 3719
Abstract
The development of Fusarium Basal Rot (FBR)-resistant onion cultivars through field and seedling screening approaches faces tremendous challenges due to non-uniform distribution of the disease pathogen and possible multiple mechanisms of host–plant resistance. This study compared the efficiencies of these two methods for [...] Read more.
The development of Fusarium Basal Rot (FBR)-resistant onion cultivars through field and seedling screening approaches faces tremendous challenges due to non-uniform distribution of the disease pathogen and possible multiple mechanisms of host–plant resistance. This study compared the efficiencies of these two methods for increasing FBR resistance of short-day onion after a single selection cycle. Asymptomatic plants or bulbs of seven onion cultivars were selected using a seedling screen performed in a growth chamber or a field screening of mature bulbs. Original and selected populations were evaluated for their responses to FBR stress thereafter employing the same two methods used for screening. The field screening of mature bulbs was found unreliable in both selection and evaluation, likely due to a non-random distribution of the FBR pathogen and variable environmental factors present in the field. The seedling screening successfully increased FBR resistance in the selected cultivar populations revealed by a seedling evaluation. From the results, it is recommended to use a consistent method for both screening and evaluation to make the most selection progress. Full article
(This article belongs to the Section Vegetable Production Systems)
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23 pages, 1552 KiB  
Article
Alterations in the Chemical Composition of Spinach (Spinacia oleracea L.) as Provoked by Season and Moderately Limited Water Supply in Open Field Cultivation
by Christine Schlering, Jana Zinkernagel, Helmut Dietrich, Matthias Frisch and Ralf Schweiggert
Horticulturae 2020, 6(2), 25; https://doi.org/10.3390/horticulturae6020025 - 10 Apr 2020
Cited by 10 | Viewed by 5715
Abstract
The current use and distribution of agricultural water resources is highly prone to effects of global climate change due to shifting precipitation patterns. The production of vegetable crops in open field cultivation often requires demanding water applications, being impaired in regions where climate [...] Read more.
The current use and distribution of agricultural water resources is highly prone to effects of global climate change due to shifting precipitation patterns. The production of vegetable crops in open field cultivation often requires demanding water applications, being impaired in regions where climate change will increasingly evoke water scarcity. To date, increasingly occurring precipitation-free periods are already leading to moderate water deficits during plant growth, e.g., in southern Europe. Among all vegetable crops, leafy vegetables such as spinach (Spinacia oleracea L.) are particularly vulnerable to limited water supply, because leaf expansion is highly dependent on water availability. Besides biomass production, water limitation might also affect the valuable nutritional composition of the produce. Therefore, we investigated the impact of moderately reduced water supply on the chemical composition of spinach, cultivated in the open field in three consecutive years. Two different water supply treatments, full and reduced irrigation, were used in a randomized block design consisting of three sets of six plots each. In the reduced water supply treatment, the total amount of supplied water, including both irrigation and natural precipitation, amounted to 90%, 94% and 96% in 2015, 2016 and 2017, respectively, of the full, optimal water supply treatment. Spinach grown under limited water supply showed significantly higher fresh biomass-based contents of polyols (e.g., inositol, glycerol), ascorbic acid, potassium, nitrogen, phosphorous, zinc and manganese, as well as total flavonoids and carotenoids. Increased dry biomass-based levels were found for total inositol, zinc and manganese, as well as decreased levels for malic acid, fumaric acid, phosphate and chloride. Furthermore, we report a high seasonal variation of several minor phytochemicals, such as single flavonoids. Spinacetin derivatives, spinatoside-glucoside as well as a rather unusual hexuronylated methylenedioxy flavonoid showed highest amounts when grown under relatively low irradiation in autumn. Levels of patuletin derivatives tended to increase under high irradiation conditions during spring. In summary, the chemical composition of spinach was shown to be highly sensitive to moderately reduced water supply and seasonal variation, but the overall nutritional quality of fresh marketable spinach was only marginally affected when considering health-related constituents such as minerals, trace elements, flavonoids and carotenoids. Full article
(This article belongs to the Special Issue Horticultural Crop Response to Different Environmental and Nutritional Stress)
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11 pages, 511 KiB  
Article
Container Type and Substrate Affect Root Zone Temperature and Growth of ‘Green Giant’ Arborvitae
by Anthony L. Witcher, Jeremy M. Pickens and Eugene K. Blythe
Horticulturae 2020, 6(2), 22; https://doi.org/10.3390/horticulturae6020022 - 07 Apr 2020
Cited by 5 | Viewed by 3027
Abstract
Root zone temperature (RZT) in nursery containers commonly exceeds ambient temperature during the growing season, negatively impacting crop growth and quality. Black nursery containers absorb radiant heat resulting in excessive RZT, yet other types of containers and different substrates can moderate RZT. We [...] Read more.
Root zone temperature (RZT) in nursery containers commonly exceeds ambient temperature during the growing season, negatively impacting crop growth and quality. Black nursery containers absorb radiant heat resulting in excessive RZT, yet other types of containers and different substrates can moderate RZT. We conducted studies in Tennessee and Alabama to evaluate the effects of container type and substrate on RZT and growth of ‘Green Giant’ arborvitae (Thuja standishii × plicata ‘Green Giant’). Trade gallon arborvitae were transplanted into black, white, or air pruning containers filled with pine bark (PB) or 4 PB: 1 peatmoss (v:v) (PB:PM). Plants grown in PB:PM were larger and had greater shoot and root biomass than plants grown in PB, likely due to increased volumetric water content. Plant growth response to container type varied by location, but white containers with PB:PM produced larger plants and greater biomass compared with the other container types. Root zone temperature was greatest in black containers and remained above 38 °C and 46 °C for 15% and 17% longer than white and air pruning containers, respectively. Utilizing light color containers in combination with substrates containing peatmoss can reduce RZT and increase substrate moisture content thus improving crop growth and quality. Full article
(This article belongs to the Special Issue Horticultural Crop Response to Different Environmental and Nutritional Stress)
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9 pages, 271 KiB  
Article
Sulphur Dioxide Pads Can Reduce Gray Mold While Maintaining the Quality of Clamshell-Packaged ‘BRS Nubia’ Seeded Table Grapes Grown under Protected Cultivation
by Khamis Youssef, Osmar Jose Chaves Junior, Débora Thaís Mühlbeier and Sergio Ruffo Roberto
Horticulturae 2020, 6(2), 20; https://doi.org/10.3390/horticulturae6020020 - 01 Apr 2020
Cited by 16 | Viewed by 3712
Abstract
The purpose of this research is to test the efficacy of different types of SO2-generating pads on the incidence of gray mold, and on the physicochemical properties of quality of ‘BRS Nubia’ seeded table grapes grown under protected cultivation. Four types [...] Read more.
The purpose of this research is to test the efficacy of different types of SO2-generating pads on the incidence of gray mold, and on the physicochemical properties of quality of ‘BRS Nubia’ seeded table grapes grown under protected cultivation. Four types of SO2-generating pads, 5 or 8 g of sodium metabisulfite dual release pads, and 4 or 7 g of sodium metabisulfite slow release pads, were used. Grapes bunches were harvested from a vineyard covered with plastic mash and stored in a cold room at 1 ± 1 °C for 45 days followed by 6 days of shelf life at 22 ± 1 °C at a high relative humidity (>95%). The results showed that SO2-generating pads with a dual release of 5 or 8 g completely inhibited the development of gray mold at all evaluation times. Also, a high reduction of the disease incidence was achieved by using a slow release of 4 g. The study confirmed that SO2-generating pads did not alter the physicochemical properties of ‘BRS Nubia’ seeded table grapes including mass loss, berry firmness, color index, total anthocyanin concentration, total soluble solids (TSS), titratable acidity (TA), and the TSS/TA ratio. Slow release pads at 4 and 7 g reduced the percentage of shattered berries by 56 and 48% as compared to control only after 6 days of shelf life. Also, all types of SO2-generating pads reduced the stem browning score at the end of cold storage. The 5 or 8 g dual release pads and 4 g slow release pads can be considered for effective controlling of gray mold for ‘BRS Nubia’ table grapes grown under protected cultivation while maintaining grape quality. Full article
(This article belongs to the Special Issue Feature Papers in Horticulturae)
16 pages, 2656 KiB  
Article
Utilizing Pruning and Leaf Removal to Optimize Ripening of Vitis riparia-Based ‘Frontenac Gris’ and ‘Marquette’ Wine Grapes in the Northern Great Plains
by Andrew Aipperspach, James Hammond and Harlene Hatterman-Valenti
Horticulturae 2020, 6(1), 18; https://doi.org/10.3390/horticulturae6010018 - 11 Mar 2020
Cited by 10 | Viewed by 3692
Abstract
Experiments were conducted to evaluate the effects of three pruning levels (20, 30 and 40 nodes per vine) and three fruit-zone leaf removal levels (0%, 50%, and 100%) on the yield and fruit quality of Frontenac gris and Marquette wine grapes in a [...] Read more.
Experiments were conducted to evaluate the effects of three pruning levels (20, 30 and 40 nodes per vine) and three fruit-zone leaf removal levels (0%, 50%, and 100%) on the yield and fruit quality of Frontenac gris and Marquette wine grapes in a northern production region. The study was conducted at three North Dakota vineyards located near Buffalo, Clifford, and Wahpeton, North Dakota, in 2011 and 2012. Increasing the number of buds retained increased yields and reduced pruning weights in both cultivars. Frontenac gris and Marquette yields were greatest when vines had 50% of the fruit-zone leaves removed due to heavier clusters, suggesting that the 100% fruit-zone leaf removal level was too severe. Individual berries in clusters were also heavier when vines were pruned to retain 40 buds. Frontenac gris fruit quality was similar both years and was not influenced by pruning or leaf removal levels. Marquette fruit total soluble solids content was greater in 2012 due to the warmer and longer growing season. Marquette fruit titratable acidity was lower when 100% of the fruit-zone leaves were removed. These results suggest that for the two cold-hardy hybrid wine grapes used in this study, greater bud retention levels should be investigated. Results also warrant further research into cultivar adaptiveness to northern Great Plains conditions. With further research, it is anticipated that wine grape cultivars and management practices will be identified to produce acceptable yields and fruit quality for commercial wine grape production. Full article
(This article belongs to the Special Issue Grape Responses to Abiotic and Biotic Stresses)
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20 pages, 3382 KiB  
Article
Genetic Variation in Response to N, P, or K Deprivation in Baby Leaf Lettuce
by Ivan Simko
Horticulturae 2020, 6(1), 15; https://doi.org/10.3390/horticulturae6010015 - 03 Mar 2020
Cited by 14 | Viewed by 3905
Abstract
Lettuce harvested at the baby leaf stage is a popular component of mixed salads in ready-to-use packages. Little is known, however, about response of baby leaf lettuce to nitrogen (N), phosphorus (P), and potassium (K) fertilization. Eight lettuce accessions were subjected to five [...] Read more.
Lettuce harvested at the baby leaf stage is a popular component of mixed salads in ready-to-use packages. Little is known, however, about response of baby leaf lettuce to nitrogen (N), phosphorus (P), and potassium (K) fertilization. Eight lettuce accessions were subjected to five fertilization treatments to investigate genetic differences in reaction to N, P, and K fertilization. The control treatment provided optimal levels of macronutrients for plant growth, while other treatments deprived plants of either N, P, or K. Potassium deprivation had no obvious effect on plant weight or composition, apart from substantially decreased potassium content. Nitrogen and phosphorus deprivations, however, extensively decreased fresh weight and affected plant composition. Phosphorus and nitrogen deprivation considerably increased anthocyanin content in red-colored accessions, but anthocyanin was decreased in dark green-colored accessions, indicating differences in regulation of anthocyanin biosynthesis. Correlations between fresh weight, chlorophyll, anthocyanin, nitrogen, phosphorus, and potassium content were substantially affected by selection of datasets used for analyses; some relationships were revealed when analyzed separately by individual treatments, while others were more likely to be detected when analyzed by individual accessions. Absolute (ΔABS) and relative (2ΔREL) parameters described in this study were suitable for detecting over- and underperforming accessions. The ΔABS identified the absolute Lb-fold (logarithm to the base of 2, binary logarithm) change in performance of an accession in a treatment as compared to its performance in control conditions. The 2ΔREL parameter showed relative Lb-fold change for an accession as compared to the overall mean of ΔABS values of all accessions tested in control and treatment conditions. Full article
(This article belongs to the Special Issue Fertilization Management of Horticultural Crops)
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9 pages, 806 KiB  
Brief Report
Quantitative Trait Loci (QTL) Analysis of Fruit and Agronomic Traits of Tropical Pumpkin (Cucurbita moschata) in an Organic Production System
by Angel R. Del Valle Echevarria, Alexandra Campbell, Theodore J. K. Radovich, Tia Silvasy, Sarah Moore and Michael B. Kantar
Horticulturae 2020, 6(1), 14; https://doi.org/10.3390/horticulturae6010014 - 02 Mar 2020
Cited by 6 | Viewed by 3563
Abstract
Interest in the development of organically grown vegetable crops has risen over the past decades due to consumer preferences. However, most crops that have desirable consumer traits have been bred in conventional growing conditions, and their transfer to an organic setting is challenging. [...] Read more.
Interest in the development of organically grown vegetable crops has risen over the past decades due to consumer preferences. However, most crops that have desirable consumer traits have been bred in conventional growing conditions, and their transfer to an organic setting is challenging. Here, the organically grown Hawaiian pumpkin (Cucurbita moschata) accession ‘Shima’ was crossed with the conventionally grown Puerto Rican variety ‘Taina Dorada’ to develop a backcross (BC1) population, where ‘Shima’ was the recurrent parent. A total of 202 BC1 (‘Shima’ X F1) progenies were planted in a certified organic field, and twelve traits were evaluated. We used genotype-by-sequencing (GBS) to identify the Quantitative Trait Loci (QTL) associated with insect tolerance along with commercially desirable traits. A total of 1582 single nucleotide polymorphisms (SNPs) were identified, from which 711 SNPs were used to develop a genetic map and perform QTL mapping. Reads associated with significant QTLs were aligned to the publicly available Cucurbita moschata genome and identified several markers linked to genes that have been previously reported to be associated with that trait in other crop systems, such as melon (Cucumis melo L.). This research provides a resource for marker-assisted selection (MAS) efforts in Cucurbita moschata, as well as serving as a model study to improve cultivars that are transitioning from a conventional to an organic setting. Full article
(This article belongs to the Special Issue Molecular, Genetic, and Physiological Control of Fruit and Vegetable Quality)
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13 pages, 3480 KiB  
Article
The Bacterial Soft Rot Pathogens, Pectobacterium carotovorum and P. atrosepticum, Respond to Different Classes of Virulence-Inducing Host Chemical Signals
by Paul A. Agyemang, Md Niamul Kabir, Caleb M. Kersey and C. Korsi Dumenyo
Horticulturae 2020, 6(1), 13; https://doi.org/10.3390/horticulturae6010013 - 10 Feb 2020
Cited by 12 | Viewed by 5958
Abstract
Soft rot bacteria of the Pectobacterium and Dickeya genera are Gram-negative phytopathogens that produce and secrete plant cell wall-degrading enzymes (PCWDE), the actions of which lead to rotting and decay of their hosts in the field and in storage. Host chemical signals are [...] Read more.
Soft rot bacteria of the Pectobacterium and Dickeya genera are Gram-negative phytopathogens that produce and secrete plant cell wall-degrading enzymes (PCWDE), the actions of which lead to rotting and decay of their hosts in the field and in storage. Host chemical signals are among the factors that induce the bacteria into extracellular enzyme production and virulence. A class of compounds (Class I) made up of intermediate products of cell wall (pectin) degradation induce exoenzyme synthesis through KdgR, a global negative regulator of exoenzyme production. While the KdgR− mutant of P. carotovorum is no longer inducible by Class I inducers, we demonstrated that exoenzyme production is induced in this strain in the presence of extracts from hosts including celery, potato, carrot, and tomato, suggesting that host plants contain another class of compounds (Class II inducers) different from the plant cell wall-degradative products that work through KdgR. The Class II inducers are thermostable, water-soluble, diffusible, and dialysable through 1 kDa molecular weight cut off pore size membranes, and could be a target for soft rot disease management strategies. Full article
(This article belongs to the Special Issue Postharvest Pathogens and Disease Management of Horticultural Crops)
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19 pages, 1554 KiB  
Article
Effects of Vine Water Status and Exogenous Abscisic Acid on Berry Composition of Three Red Wine Grapes Grown under Mediterranean Climate
by Massimiliano Cocco, Luca Mercenaro, Mauro Lo Cascio and Giovanni Nieddu
Horticulturae 2020, 6(1), 12; https://doi.org/10.3390/horticulturae6010012 - 07 Feb 2020
Cited by 6 | Viewed by 3071
Abstract
Beyond climatic conditions, qualitative performance is led by the intrinsic characteristics of the genotype. The aim of this study was to investigate the relationship between vine water status and exogenous abscisic acid (ABA) application on berry composition of the cultivars Cannonau, Merlot and [...] Read more.
Beyond climatic conditions, qualitative performance is led by the intrinsic characteristics of the genotype. The aim of this study was to investigate the relationship between vine water status and exogenous abscisic acid (ABA) application on berry composition of the cultivars Cannonau, Merlot and Sangiovese. The experiment, carried out in 2016 and 2017, consisted of comparing two levels of irrigation treatments, full irrigation versus a non-irrigation treatment. Within each treatment, two sub-treatments were set up: (i) 4 mL L−1 of exogenous ABA applied at veraison to clusters only and subsequently repeated after six days; (ii) a control (untreated vines). The application of different irrigation regimes confirmed that the response to water stress is highly cultivar-dependent. Berry composition was influenced differently among cultivars by water stress. In terms of metabolites, positive influences were observed with Cannonau. No significant effects were observed by spraying exogenous ABA directly on grapes. Moreover, no significant interactions were found between the application of water stress and ABA. Exogenous ABA application did not appear to be a viticultural practice capable of influencing must composition in environments characterized by severe environmental conditions such as heat and drought. Full article
(This article belongs to the Special Issue Grape Responses to Abiotic and Biotic Stresses)
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12 pages, 216 KiB  
Article
Effect of pH on Cucumber Growth and Nutrient Availability in a Decoupled Aquaponic System with Minimal Solids Removal
by Caroline Blanchard, Daniel E. Wells, Jeremy M. Pickens and David M. Blersch
Horticulturae 2020, 6(1), 10; https://doi.org/10.3390/horticulturae6010010 - 04 Feb 2020
Cited by 23 | Viewed by 7762
Abstract
Decoupled aquaponic systems are gaining popularity as a way to manage water quality in aquaponic systems to suit plant and fish growth independently. Aquaponic systems are known to be deficient in several plant-essential elements, which can be affected by solution pH to either [...] Read more.
Decoupled aquaponic systems are gaining popularity as a way to manage water quality in aquaponic systems to suit plant and fish growth independently. Aquaponic systems are known to be deficient in several plant-essential elements, which can be affected by solution pH to either increase or decrease available nutrients. To determine the effect of pH in a decoupled aquaponic system, a study was conducted using aquaculture effluent from tilapia culture tanks at four pH treatments: 5.0, 5.8, 6.5, and 7.0, used to irrigate a cucumber crop. Growth and yield parameters, nutrient content of the irrigation water, and nutrients incorporated into the plant tissue were collected over two growing seasons. pH did not have a practical effect on growth rate, internode length or yield over the two growing seasons. Availability and uptake of several nutrients were affected by pH, but there was no overarching effect that would necessitate its use in commercial systems. Nutrient concentrations in the aquaculture effluent would be considered low compared to hydroponic solutions; however, elemental analysis of leaf tissues was within the recommended ranges. Research into other nutrient sources provided by the system (i.e., solid particles carried with the irrigation water) would provide further information into the nutrient dynamics of this system. Full article
(This article belongs to the Special Issue Advances in Knowledge of Hydroponic and Aquaponic Systems II)
23 pages, 1900 KiB  
Article
Effects of Hydraulic Loading Rate on Spatial and Temporal Water Quality Characteristics and Crop Growth and Yield in Aquaponic Systems
by Teng Yang and Hye-Ji Kim
Horticulturae 2020, 6(1), 9; https://doi.org/10.3390/horticulturae6010009 - 02 Feb 2020
Cited by 27 | Viewed by 7748
Abstract
Aquaponics is a rapidly growing food-production system integrating aquaculture and hydroponic crop production through an energy-intensive water recirculation process. Crop performance and yield in aquaponics are affected by essential and toxic nutrient levels in the root zone, which can be regulated by water [...] Read more.
Aquaponics is a rapidly growing food-production system integrating aquaculture and hydroponic crop production through an energy-intensive water recirculation process. Crop performance and yield in aquaponics are affected by essential and toxic nutrient levels in the root zone, which can be regulated by water flow rate. This study was conducted to examine the effects of hydraulic loading rate (HLR) on water quality and crop growth and yield in recirculating aquaponic systems set at three different loading rates: high (3.3 m3/m2/day; HFR, which is 12 times lower than recommended loading rate), medium (2.2 m3/m2/day; MFR), and low (1.1 m3/m2/day; LFR). Crop species varying in growth rate were examined for their optimal HLR: fast-growing Chinese cabbage (Brassica rapa) and lettuce (Lactuca sativa); medium-growing mustard (Brassica juncea) and chia (Salvia hispanica); and slow-growing basil (Ocimum basilicum) and Swiss chard (Beta vulgaris). Compared to LFR, HFR decreased water and leaf temperatures and total ammonium nitrogen (TAN) but increased dissolved oxygen and pH in aquaponic solution up to one and two weeks after transplant, respectively. HFR increased NO3–N concentration by 50 and 80%, respectively, compared to MFR and LFR, while reducing the exposure duration of roots to ammonia (NH3–N) and its peak concentration through rapid dissipation of the toxic compound. Lower electrical conductivity (EC) in HFR during the last two weeks of production was associated with higher plant nutrient uptake and greater biomass production. The leaf greenness, photosynthetic rate (Pn), and total plant N were significantly higher at HFR than LFR. Fish growth rate, fresh weight, and feed-conversion efficiency were also increased by HFR. The growth of fast-growing crops including total fresh weight, shoot fresh weight, leaf area, and Pn was not different between HFR and MFR, while HLR had less significant effects on the growth and performance (i.e., shoot fresh weight and whole plant photosynthesis) of slow-growing crops. In conclusion, the flow rate is an important component in aquaponic crop production as it affects spatial and temporal water characteristics and subsequently determines the growth and yield of the crops. HLR at 3.3 m3/m2/day was sufficient across the crops allowing better chemical and physical properties of the aquaponic solution for maximum yield and quality. HLR should be maintained at least at 2.2 m3/m2/day for the production of fast-growing crops but can be lowered for slow-growing crops. Full article
(This article belongs to the Special Issue Advances in Knowledge of Hydroponic and Aquaponic Systems II)
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9 pages, 975 KiB  
Article
Suitability of Hydroponically-Grown Rumex acetosa L. as Fresh-Cut Produce
by Costanza Ceccanti, Marco Landi, Luca Incrocci, Alberto Pardossi and Lucia Guidi
Horticulturae 2020, 6(1), 4; https://doi.org/10.3390/horticulturae6010004 - 09 Jan 2020
Cited by 7 | Viewed by 3453
Abstract
Sorrel (Rumex acetosa L.) is a perennial wild herb appreciated as a folk medicine and for use in folk-traditional cuisines, and its nutraceutical properties are increasingly known and studied. Nowadays, there is a lack of knowledge about the possibility of using this [...] Read more.
Sorrel (Rumex acetosa L.) is a perennial wild herb appreciated as a folk medicine and for use in folk-traditional cuisines, and its nutraceutical properties are increasingly known and studied. Nowadays, there is a lack of knowledge about the possibility of using this species as fresh-cut produce, and no reports have investigated the physiological/biochemical changes of sorrel leaves upon storage. To test the aforementioned, sorrel seedlings were cultivated in a floating system and two consecutive harvests took place: The first cut at 15 days (C1) and second cut at 30 days (C2) after sowing. Fresh-cut sorrel leaves from C1 and C2 were stored in plastic boxes at 4 °C for 15 days and chlorophylls, carotenoids, total phenols, flavonoids, ascorbic acid, and antioxidant capacity were evaluated during the storage period. During storage, sorrel leaves from the same cut did not show significant changes in total phenolic content and antioxidant capacity, which represents a positive outcome for the maintenance of the nutraceutical value of this species. For this reason, sorrel may be a very promising species as a “new” fresh-cut leafy vegetable. However, some differences were observed between the two cuts, especially in the total flavonoid and the total ascorbic acid contents. While promising, further research will be necessary to standardize the yield and the nutraceutical content of this species in different cuts, which will be necessary to introduce and promote sorrel to consumers. Full article
(This article belongs to the Special Issue Molecular, Genetic, and Physiological Control of Fruit and Vegetable Quality)
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11 pages, 1020 KiB  
Article
Phenology and Yield of the Hybrid Seedless Grape ‘BRS Melodia’ Grown in an Annual Double Cropping System in a Subtropical Area
by Renata Koyama, Wellington Fernando Silva Borges, Ronan Carlos Colombo, Ibrar Hussain, Reginaldo Teodoro de Souza and Sergio Ruffo Roberto
Horticulturae 2020, 6(1), 3; https://doi.org/10.3390/horticulturae6010003 - 06 Jan 2020
Cited by 6 | Viewed by 3735
Abstract
The development and evaluation of new cultivars of seedless grapes (Vitis spp.) with good yield and adapted to different edaphoclimatic conditions are essential to increase the competitiveness of the productive system. The present work had the objective to characterize the phenology and [...] Read more.
The development and evaluation of new cultivars of seedless grapes (Vitis spp.) with good yield and adapted to different edaphoclimatic conditions are essential to increase the competitiveness of the productive system. The present work had the objective to characterize the phenology and the yield of the new hybrid seedless grape ‘BRS Melodia’, grown in an annual double cropping system in a subtropical region. The evaluations were carried out during the 2013 summer cropping period and the 2014 off-season cropping period in a commercial area located in Marialva, PR, Brazil. The ‘BRS Melodia’ scions were grafted onto ‘IAC 766 Campinas’ rootstocks, trained in an overhead trellis system spaced at 2.5 × 2.5 m. In both seasons, the duration in days of the main phenological phases of the vines, as well as their thermal demand and their physicochemical and productive characteristics were evaluated. The ‘BRS Melodia’ seedless grapevines presented a cycle of 138 days and yield of 23.85 tons.ha−1 in the summer season, and 121 days and yield of 19.4 tons.ha−1 in the off-season crop. The soluble solids, titratable acidity, and maturation index were 15.1 °Brix, 0.5% tartaric acid and 28.5, respectively, in the summer season and 15.4 °Brix, 0.6% tartaric acid and 25.6 in the off-season crop, indicating a possibility of cultivate this new hybrid seedless grape under an annual double cropping system in subtropical conditions. Full article
(This article belongs to the Special Issue Grape Responses to Abiotic and Biotic Stresses)
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17 pages, 986 KiB  
Article
Influence of Preharvest Gibberellic Acid Treatments on Postharvest Quality of Minimally Processed Leaf Lettuce and Rocket
by Alessandro Miceli, Filippo Vetrano, Leo Sabatino, Fabio D’Anna and Alessandra Moncada
Horticulturae 2019, 5(3), 63; https://doi.org/10.3390/horticulturae5030063 - 02 Sep 2019
Cited by 25 | Viewed by 4339
Abstract
Plant growth regulators are used in high-value vegetable crops during cultivation and after harvest to increase yield, enhance crop management, and improve or retain the produce quality. The aim of this work was to evaluate the quality characteristics during cold storage of minimally [...] Read more.
Plant growth regulators are used in high-value vegetable crops during cultivation and after harvest to increase yield, enhance crop management, and improve or retain the produce quality. The aim of this work was to evaluate the quality characteristics during cold storage of minimally processed leaf lettuce and rocket, obtained from plants grown in a hydroponic floating system with mineral nutrient solutions (MNS) containing different levels of gibberellic acid (GA3). Plants were grown in greenhouse conditions on nutrient solutions containing 0, 10−8, and 10−6 M GA3. At harvest, lettuce and rocket were immediately processed as fresh-cut vegetables and stored for 21 d at 4 °C. After processing, weight loss, total soluble solids, titratable acidity, ascorbic acid and nitrate content, leaf color characteristics, and overall quality were evaluated. Adding 10−6 M GA3 to the MNS of a floating system significantly increased the yield of leaf lettuce and rocket plants and of minimally-processed leaves. In addition, preharvest GA3 treatments had positive effects on delaying senescence and enhancing shelf-life of minimally processed lettuce and rocket. The slowed senescence of GA3-treated samples maintained an overall quality over the threshold of marketability in both lettuce and rocket for up to 21 d of cold storage. Full article
(This article belongs to the Special Issue Plant Growth Regulators for Improving the Yield and Quality of Horticultural Crops)
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12 pages, 617 KiB  
Article
Does Inoculation with Arbuscular Mycorrhizal Fungi Reduce Trunk Disease in Grapevine Rootstocks?
by Taylor Holland, Patricia Bowen, Vasilis Kokkoris, Jose Ramon Urbez-Torres and Miranda Hart
Horticulturae 2019, 5(3), 61; https://doi.org/10.3390/horticulturae5030061 - 28 Aug 2019
Cited by 15 | Viewed by 4509
Abstract
Ilyonectria is a weak pathogen known for causing black foot disease in young vines, infecting roots and vascular tissues at the basal end of the rootstock and restricting the movement of water and nutrients. This negatively impacts vine establishment during transplant into the [...] Read more.
Ilyonectria is a weak pathogen known for causing black foot disease in young vines, infecting roots and vascular tissues at the basal end of the rootstock and restricting the movement of water and nutrients. This negatively impacts vine establishment during transplant into the vineyard. Arbuscular mycorrhizal (AM) fungi are symbiotic fungi that associate with most plants and have been shown to mitigate the infection and effect of pathogens. This greenhouse study was designed to determine if the mycorrhizal fungi could mitigate Ilyonectria infection and whether this was dependent on inoculation timing. ‘Riparia gloire’ grapevine rootstocks (Vitis riparia) were infected with Ilyonectria either after AM fungi, at the same time as AM fungi, or to roots that were not inoculated by AM fungi. We measured the abundance using specific markers for both the pathogen and AM fungi. Colonization by AM fungi did not suppress Ilyonectria, but instead increased the abundance of Ilyonectria. Further, mycorrhizal rootstocks did not have enhanced growth effects on physiological parameters when compared to non-mycorrhizal rootstocks. These findings stand in contrast to the general perception that AM fungi provide protection against root pathogens. Full article
(This article belongs to the Special Issue Horticultural Crop Microbiomes)
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28 pages, 1176 KiB  
Review
Recent Advances in Hormonal Regulation and Cross-Talk during Non-Climacteric Fruit Development and Ripening
by Lida Fuentes, Carlos R. Figueroa and Monika Valdenegro
Horticulturae 2019, 5(2), 45; https://doi.org/10.3390/horticulturae5020045 - 03 Jun 2019
Cited by 69 | Viewed by 11858
Abstract
Fleshy fruits are characterized by having a developmentally and genetically controlled, highly intricate ripening process, leading to dramatic modifications in fruit size, texture, color, flavor, and aroma. Climacteric fruits such as tomato, pear, banana, and melon show a ripening-associated increase in respiration and [...] Read more.
Fleshy fruits are characterized by having a developmentally and genetically controlled, highly intricate ripening process, leading to dramatic modifications in fruit size, texture, color, flavor, and aroma. Climacteric fruits such as tomato, pear, banana, and melon show a ripening-associated increase in respiration and ethylene production and these processes are well-documented. In contrast, the hormonal mechanism of fruit development and ripening in non-climacteric fruit, such as strawberry, grape, raspberry, and citrus, is not well characterized. However, recent studies have shown that non-climacteric fruit development and ripening, involves the coordinated action of different hormones, such as abscisic acid (ABA), auxin, gibberellins, ethylene, and others. In this review, we discuss and evaluate the recent research findings concerning the hormonal regulation of non-climacteric fruit development and ripening and their cross-talk by taking grape, strawberry, and raspberry as reference fruit species. Full article
(This article belongs to the Special Issue Plant Growth Regulators for Improving the Yield and Quality of Horticultural Crops)
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24 pages, 1497 KiB  
Review
Light and Microbial Lifestyle: The Impact of Light Quality on Plant–Microbe Interactions in Horticultural Production Systems—A Review
by Beatrix W. Alsanius, Maria Karlsson, Anna Karin Rosberg, Martine Dorais, Most Tahera Naznin, Sammar Khalil and Karl-Johan Bergstrand
Horticulturae 2019, 5(2), 41; https://doi.org/10.3390/horticulturae5020041 - 28 May 2019
Cited by 31 | Viewed by 7724
Abstract
Horticultural greenhouse production in circumpolar regions (>60° N latitude), but also at lower latitudes, is dependent on artificial assimilation lighting to improve plant performance and the profitability of ornamental crops, and to secure production of greenhouse vegetables and berries all year round. In [...] Read more.
Horticultural greenhouse production in circumpolar regions (>60° N latitude), but also at lower latitudes, is dependent on artificial assimilation lighting to improve plant performance and the profitability of ornamental crops, and to secure production of greenhouse vegetables and berries all year round. In order to reduce energy consumption and energy costs, alternative technologies for lighting have been introduced, including light-emitting diodes (LED). This technology is also well-established within urban farming, especially plant factories. Different light technologies influence biotic and abiotic conditions in the plant environment. This review focuses on the impact of light quality on plant–microbe interactions, especially non-phototrophic organisms. Bacterial and fungal pathogens, biocontrol agents, and the phyllobiome are considered. Relevant molecular mechanisms regulating light-quality-related processes in bacteria are described and knowledge gaps are discussed with reference to ecological theories. Full article
(This article belongs to the Special Issue Advanced Greenhouse Horticulture: New Technologies and Cultivation Practices)
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16 pages, 1628 KiB  
Article
A Comparison of Plant Growth Rates between an NFT Hydroponic System and an NFT Aquaponic System
by Wilson Lennard and James Ward
Horticulturae 2019, 5(2), 27; https://doi.org/10.3390/horticulturae5020027 - 09 Apr 2019
Cited by 19 | Viewed by 11870
Abstract
A comparison of leafy green plant species’ (lettuce (Lactuca sativa L.), dill (Anethum graveolens L.), rocket (Eruca sativa), coriander (Coriandrum sativum L.), and parsley (Petroselinum crispum)) growth rates was performed between an Nutrient Film Technique (NFT)hydroponic [...] Read more.
A comparison of leafy green plant species’ (lettuce (Lactuca sativa L.), dill (Anethum graveolens L.), rocket (Eruca sativa), coriander (Coriandrum sativum L.), and parsley (Petroselinum crispum)) growth rates was performed between an Nutrient Film Technique (NFT)hydroponic system, using standard commercial nutrient solution, and an NFT aquaponic system, using fish waste from Grass Carp, (Ctenopharyngodon idella) which provided the majority of the nutrients required by the plants. The results demonstrated that the aquaponic method performed well, and, in many cases, the growth rates produced were similar to those of the hydroponic method. Lettuce growth was compared across three seasons (summer, winter, and spring), and, in all cases, the aquaponically-grown lettuce equalled, or bettered, the hydroponic equivalent. Herb growth was compared over a five-month period (February to June—summer/autumn), and in 17 out of 23 comparisons, the aquaponic method produced results similar to those of the hydroponic method. Thus, while the NFT method may not be the most appropriate technical approach for aquaponic integration, the results suggest that the overall aquaponic method has the potential to produce plant growth rates at least equal to those of standard hydroponics. Full article
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22 pages, 583 KiB  
Review
Risk of Human Pathogen Internalization in Leafy Vegetables During Lab-Scale Hydroponic Cultivation
by Gina M. Riggio, Sarah L. Jones and Kristen E. Gibson
Horticulturae 2019, 5(1), 25; https://doi.org/10.3390/horticulturae5010025 - 15 Mar 2019
Cited by 49 | Viewed by 11041
Abstract
Controlled environment agriculture (CEA) is a growing industry for the production of leafy vegetables and fresh produce in general. Moreover, CEA is a potentially desirable alternative production system, as well as a risk management solution for the food safety challenges within the fresh [...] Read more.
Controlled environment agriculture (CEA) is a growing industry for the production of leafy vegetables and fresh produce in general. Moreover, CEA is a potentially desirable alternative production system, as well as a risk management solution for the food safety challenges within the fresh produce industry. Here, we will focus on hydroponic leafy vegetable production (including lettuce, spinach, microgreens, and herbs), which can be categorized into six types: (1) nutrient film technique (NFT), (2) deep water raft culture (DWC), (3) flood and drain, (4) continuous drip systems, (5) the wick method, and (6) aeroponics. The first five are the most commonly used in the production of leafy vegetables. Each of these systems may confer different risks and advantages in the production of leafy vegetables. This review aims to (i) address the differences in current hydroponic system designs with respect to human pathogen internalization risk, and (ii) identify the preventive control points for reducing risks related to pathogen contamination in leafy greens and related fresh produce products. Full article
(This article belongs to the Special Issue Food Safety Pertinent to Fresh Produce)
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11 pages, 241 KiB  
Article
Citrulline and Arginine Content of Taxa of Cucurbitaceae
by Jordan L. Hartman, Todd C. Wehner, Guoying Ma and Penelope Perkins-Veazie
Horticulturae 2019, 5(1), 22; https://doi.org/10.3390/horticulturae5010022 - 04 Mar 2019
Cited by 23 | Viewed by 14636
Abstract
Watermelon is the most significant, natural plant source of L-citrulline, a non-proteinaceous amino acid that benefits cardiovascular health and increases vasodilation in many tissues of the body. Watermelon is a member of the Cucurbitaceae, which includes squash, melon, pumpkin, and cucumber. It is [...] Read more.
Watermelon is the most significant, natural plant source of L-citrulline, a non-proteinaceous amino acid that benefits cardiovascular health and increases vasodilation in many tissues of the body. Watermelon is a member of the Cucurbitaceae, which includes squash, melon, pumpkin, and cucumber. It is possible that other cucurbits could be good sources of citrulline or of arginine, its direct precursor. Twenty-one cultigens were evaluated in triplicate at two locations in North Carolina to estimate citrulline and arginine amounts and variation due to cultigen, replication, and environment. Cultigens containing the highest amount of citrulline (based on LS means) in g/kg fresh weight were ’Crimson Sweet’ watermelon (2.85), ’Dixielee’ watermelon (2.43), casaba-type melon (0.86), mouse melon (0.64), and horned melon rind (0.45). Additionally, mouse melon, horned melon, and bitter gourd (arils) may be interesting sources of arginine-family amino acids, perhaps because of their large seed and aril content relative to mesocarp. Full article
10 pages, 836 KiB  
Article
Assessing Quantitative Criteria for Characterization of Quality Categories for Grafted Watermelon Seedlings
by Filippos Bantis, Athanasios Koukounaras, Anastasios Siomos, Georgios Menexes, Christodoulos Dangitsis and Damianos Kintzonidis
Horticulturae 2019, 5(1), 16; https://doi.org/10.3390/horticulturae5010016 - 02 Feb 2019
Cited by 27 | Viewed by 3848
Abstract
Vegetable grafting is a practice employed worldwide since it helps prevent biotic and abiotic disorders, and watermelon is one of the most important species grafted. The objective of this study was to set critical limits for the characterization of quality categories for grafted [...] Read more.
Vegetable grafting is a practice employed worldwide since it helps prevent biotic and abiotic disorders, and watermelon is one of the most important species grafted. The objective of this study was to set critical limits for the characterization of quality categories for grafted watermelon seedlings. Specifically, watermelon (scion) seedlings were grafted onto squash (rootstock) seedlings, moved into a healing chamber for 7 days, and then transferred into a greenhouse for seven more days. At 7 and 14 days after grafting, experienced personnel assessed grafted seedling quality by categorizing them. The categories derived were Optimum and Acceptable for both time intervals, plus Not acceptable at 14 days after grafting. Optimum seedlings showed greater leaf area, and shoot and root fresh and dry weights at both time intervals. Moreover, they had greater stem diameter, root-to-shoot ratio, shoot dry weight-to-length ratio and Dickson’s quality index compared to the other category at 14 days after grafting. Therefore, Optimum seedlings would likely develop into marketable plants of high quality, with better establishment in the field. Not acceptable seedlings showed considerably inferior development, while Acceptable seedlings were between the other categories, but were still marketable. Full article
(This article belongs to the Special Issue Advanced Greenhouse Horticulture: New Technologies and Cultivation Practices)
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10 pages, 1039 KiB  
Article
Evaluation of Two Wild Populations of Hedge Mustard (Sisymbrium officinale (L.) Scop.) as a Potential Leafy Vegetable
by Marta Guarise, Gigliola Borgonovo, Angela Bassoli and Antonio Ferrante
Horticulturae 2019, 5(1), 13; https://doi.org/10.3390/horticulturae5010013 - 01 Feb 2019
Cited by 17 | Viewed by 5373
Abstract
The minimally processed industry is always looking for produce innovation that can satisfy consumer needs. Wild leafy vegetables can be a good source of bioactive compounds and can be attractive for the consumer in term of visual appearance and taste. In this work, [...] Read more.
The minimally processed industry is always looking for produce innovation that can satisfy consumer needs. Wild leafy vegetables can be a good source of bioactive compounds and can be attractive for the consumer in term of visual appearance and taste. In this work, Sisymbrium officinale (L.) Scop., commonly called hedge mustard, was grown in a greenhouse and evaluated as a potential leafy vegetable. Two wild populations, Milano (MI) and Bergamo (BG), were grown in peat substrate and harvested at the commercial stage for the minimally processing industry. Leaf pigments such as chlorophyll and carotenoids were determined as well as chlorophyll a fluorescence parameters. Total sugars, antioxidant compounds such as ascorbic acid, phenolic index, total phenols, anthocyanins, and nitrate were determined at harvest. Significant differences between wild populations were found in April with higher nitrate content in BG, 2865 mg/kg FW than in MI, 1770 mg/kg FW. The nitrate levels of S. officinale measured in the present study are significantly lower than the maximum NO₃ level allowed in other fresh leafy vegetables. Ascorbic acid measured in November was higher in MI compared BG with values of 54.4 versus 34.6 mg/100 g FW, respectively. The chlorophyll a fluorescence data showed that BG reached optimal leaf functionality faster than MI. Overall results indicated that Sisymbrium officinale (L.) Scop. can be suggested as a potential leafy vegetable for the minimally processed industry. Full article
(This article belongs to the Special Issue Advanced Greenhouse Horticulture: New Technologies and Cultivation Practices)
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20 pages, 1641 KiB  
Review
Irrigation of Greenhouse Crops
by Georgios Nikolaou, Damianos Neocleous, Nikolaos Katsoulas and Constantinos Kittas
Horticulturae 2019, 5(1), 7; https://doi.org/10.3390/horticulturae5010007 - 15 Jan 2019
Cited by 64 | Viewed by 10977
Abstract
Precision agricultural greenhouse systems indicate considerable scope for improvement of irrigation management practices, since growers typically irrigate crops based on their personal experience. Soil-based greenhouse crop irrigation management requires estimation on a daily basis, whereas soilless systems must be estimated on an hourly [...] Read more.
Precision agricultural greenhouse systems indicate considerable scope for improvement of irrigation management practices, since growers typically irrigate crops based on their personal experience. Soil-based greenhouse crop irrigation management requires estimation on a daily basis, whereas soilless systems must be estimated on an hourly or even shorter interval schedule. Historically, irrigation scheduling methods have been based on soil or substrate monitoring, dependent on climate or time with each having both strengths and weaknesses. Recently, plant-based monitoring or plant reflectance-derived indices have been developed, yet their potential is limited for estimating the irrigation rate in order to apply proper irrigation scheduling. Optimization of irrigation practices imposes different irrigation approaches, based on prevailing greenhouse environments, considering plant-water-soil relationships. This article presents a comprehensive review of the literature, which deals with irrigation scheduling approaches applied for soil and soilless greenhouse production systems. Irrigation decisions are categorized according to whether or not an automatic irrigation control has the ability to support a feedback irrigation decision system. The need for further development of neural networks systems is required. Full article
(This article belongs to the Special Issue Advanced Greenhouse Horticulture: New Technologies and Cultivation Practices)
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20 pages, 2274 KiB  
Review
Response of Mediterranean Ornamental Plants to Drought Stress
by Stefania Toscano, Antonio Ferrante and Daniela Romano
Horticulturae 2019, 5(1), 6; https://doi.org/10.3390/horticulturae5010006 - 14 Jan 2019
Cited by 98 | Viewed by 9045
Abstract
Ornamental plants use unique adaptive mechanisms to overcome the negative effects of drought stress. A large number of species grown in the Mediterranean area offer the opportunity to select some for ornamental purposes with the ability to adapt to drought conditions. The plants [...] Read more.
Ornamental plants use unique adaptive mechanisms to overcome the negative effects of drought stress. A large number of species grown in the Mediterranean area offer the opportunity to select some for ornamental purposes with the ability to adapt to drought conditions. The plants tolerant to drought stress show different adaptation mechanisms to overcome drought stress, including morphological, physiological, and biochemical modifications. These responses include increasing root/shoot ratio, growth reduction, leaf anatomy change, and reduction of leaf size and total leaf area to limit water loss and guarantee photosynthesis. In this review, the effect of drought stress on photosynthesis and chlorophyll a fluorescence is discussed. Recent information on the mechanisms of signal transduction and the development of drought tolerance in ornamental plants is provided. Finally, drought-induced oxidative stress is analyzed and discussed. The purpose of this review is to deepen our knowledge of how drought may modify the morphological and physiological characteristics of plants and reduce their aesthetic value—that is, the key parameter of assessment of ornamental plants. Full article
(This article belongs to the Special Issue Abiotic Stress Effects on Performance of Horticultural Crops)
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