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Horticulturae
Volume 6
Issue 1
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Horticulturae, Volume 6, Issue 1 (March 2020) – 19 articles

Cover Story (view full-size image): The Brazilian Agricultural Research Corporation—Embrapa Wine and Grape, Brazil, began searching for solutions for the grape industry through the Grape Breeding Program in 1997, with studies focused on the development of hybrid seedless grapes adapted to tropical and subtropical conditions. The ‘BRS Melodia’ seedless grape was released in 2019, and it is tolerant to downy mildew, the main grape disease in subtropical humid areas, requiring fewer fungicide applications. This new seedless cultivar presents phenological and productive characteristics within the standards required by the domestic and foreign markets, and it is possible to cultivate it in an annual double cropping system under subtropical conditions. View this paper
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16 pages, 2431 KiB  
Article
Phylogenetics of Taxus Using the Internal Transcribed Spacers of Nuclear Ribosomal DNA and Plastid trnL-F Regions
by Patricia Coughlan, James C. Carolan, Ingrid L. I. Hook, Lisa Kilmartin and Trevor R. Hodkinson
Horticulturae 2020, 6(1), 19; https://doi.org/10.3390/horticulturae6010019 - 12 Mar 2020
Cited by 11 | Viewed by 5168
Abstract
Taxus is a genus of trees and shrubs with high value in horticulture and medicine as a source of the anticancer drug paclitaxel. The taxonomy of the group is complex due to the lack of diagnostic morphological characters and the high degree of [...] Read more.
Taxus is a genus of trees and shrubs with high value in horticulture and medicine as a source of the anticancer drug paclitaxel. The taxonomy of the group is complex due to the lack of diagnostic morphological characters and the high degree of similarity among species. Taxus has a wide global geographic distribution and some taxonomists recognize only a single species with geographically defined subgroups, whereas others have described several species. To address these differences in taxonomic circumscription, phylogenetic analyses were conducted on DNA sequences using Maximum Likelihood, Bayesian Inference and TCS haplotype networks on single and combined gene regions obtained for the nuclear ribosomal ITS region and the plastid trnL intron and trnL-F intergenic spacer. Evidence is presented for the sister group status of Pseudotaxus to Taxus and the inclusion of Amentotaxus, Austrotaxus, Cephalotaxus and Torreya within Taxaceae. Results are consistent with the taxonomic recognition of nine species: T. baccata, T. brevifolia, T. canadensis, T. cuspidata, T. floridana, T. fuana, T. globosa, T. sumatrana and T. wallichiana, but evidence is found for less species distinction and considerable reticulation within the T. baccata, T. canadensis and T. cuspidata group. We compare the results to known taxonomy, biogeography, present new leaf anatomical data and discuss the origins of the hybrids T. ×media and T. ×hunnewelliana. Full article
(This article belongs to the Section Genetics, Genomics, Breeding, and Biotechnology (G2B2))
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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 3671
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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9 pages, 812 KiB  
Article
Adaptability of Tree Species as Windbreaks for Urban Farms in the U.S. Intermountain West
by Sheriden M. Hansen, JayDee Gunnell, Anthony Whaley, Xin Dai, Cole Harding and Brent L. Black
Horticulturae 2020, 6(1), 17; https://doi.org/10.3390/horticulturae6010017 - 06 Mar 2020
Cited by 2 | Viewed by 2965
Abstract
Windbreaks or shelterbelts are a management tool to protect crops from damaging horizontal wind flow, and may provide a useful buffer between farmland and urbanized areas by reducing pesticide drift, dust, and noise associated with farming activities. Plant selection for windbreaks in the [...] Read more.
Windbreaks or shelterbelts are a management tool to protect crops from damaging horizontal wind flow, and may provide a useful buffer between farmland and urbanized areas by reducing pesticide drift, dust, and noise associated with farming activities. Plant selection for windbreaks in the Intermountain West can be difficult as high elevation coupled with extreme temperatures, high pH soils, and limited access to water are common. This study assessed eight tree species for suitability as a windbreak in the Intermountain West, with a particular focus on initial establishment and use at the urban–agriculture interface. Species were assessed for mortality, size, canopy density, insect and disease issues, and initial cost. Measurements of shadow characteristics were used as a novel approach to compare canopy density and porosity. Standard poplar (Populus x canadensis) and ‘Theves’ columnar poplar (Populus nigra ‘Afghanica’) were the most effective at rapid establishment, but species with more moderate growth rates, such as aspen, juniper, and hackberry, may provide lower long-term maintenance costs for the environmental conditions found in the Intermountain West. Full article
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10 pages, 556 KiB  
Article
Effect of Stand Reduction at Different Growth Stages on Yield of Paprika-Type Chile Pepper
by Israel Joukhadar and Stephanie Walker
Horticulturae 2020, 6(1), 16; https://doi.org/10.3390/horticulturae6010016 - 05 Mar 2020
Cited by 3 | Viewed by 2554
Abstract
Paprika-type chile (Capsicum annuum L.) crops are susceptible to plant population losses through pest activity, disease, and extreme weather events such as hail storms. This study was conducted to determine the influence of intensity and timing of plant population reductions on the [...] Read more.
Paprika-type chile (Capsicum annuum L.) crops are susceptible to plant population losses through pest activity, disease, and extreme weather events such as hail storms. This study was conducted to determine the influence of intensity and timing of plant population reductions on the final harvested yield of paprika-type chile so that informed decisions can be made regarding continuing or ending a damaged field. Two trials, one per year, were conducted in southern New Mexico. ‘LB-25’, a standard commercial cultivar, was direct seeded on 29 March 2016 and 4 April 2017. Plants were thinned at three different growth stages; early seedling, first bloom, and peak bloom. Plants were thinned to four levels at each phenological stage; 0% stand reduction (control; ~200,000 plants/ha), 60% stand reduction (~82,000 plants/ha), 70% stand reduction (~60,000 plants/ha), and 80% stand reduction (~41,000 plant/ha). In both years, the main effects of stand reduction had a significant impact on harvested yield, emphasizing the percentage of stand reduction has more of an impact on yield than timing in paprika-type red chile. Consistently, an 80% stand reduction in paprika-type chile significantly reduced fresh red chile yield by 26% to 38%. Full article
(This article belongs to the Special Issue Horticultural Crop Response to Different Environmental and Nutritional Stress)
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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 3884
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 3542
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 5917
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 3054
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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22 pages, 4357 KiB  
Article
Impact Injury at Harvest Promotes Body Rots in ‘Hass’ Avocado Fruit upon Ripening
by Melinda L. Perkins, Diane Usanase, Bo Zhang, Daryl C. Joyce and Lindy M. Coates
Horticulturae 2020, 6(1), 11; https://doi.org/10.3390/horticulturae6010011 - 05 Feb 2020
Cited by 5 | Viewed by 6036
Abstract
Global demand for avocados has risen rapidly in recent years, yet supplying fruit that consistently meets consumer expectations for quality remains a challenge in the industry. Body rots in avocado fruit are a leading cause of consumer dissatisfaction. Anecdotal evidence suggests that body [...] Read more.
Global demand for avocados has risen rapidly in recent years, yet supplying fruit that consistently meets consumer expectations for quality remains a challenge in the industry. Body rots in avocado fruit are a leading cause of consumer dissatisfaction. Anecdotal evidence suggests that body rot development may be promoted by mechanical injury at harvest and packing, despite the fruit being hard, green and mature (i.e., unripe) at these stages. Here, ‘Hass’ avocado fruit, harvested across multiple fruiting seasons from commercial orchards, were subjected to controlled impact from drop heights of 15–60 cm at the time of harvest or packing. With increasing drop height, body rot development at eating ripe stage generally occurred more frequently and produced larger lesions at the impact site and, in some experiments, elsewhere on the fruit. These findings refute a general belief that green mature avocado fruit can tolerate a degree of rough physical handling without ripe fruit quality being compromised. Ideally, best avocado harvesting and packing practice should recognize that unripe fruit must not experience drop heights of 30 cm or higher. Full article
(This article belongs to the Special Issue Postharvest Pathogens and Disease Management of Horticultural Crops)
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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 7706
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 7704
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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15 pages, 5163 KiB  
Article
Florida Citrus Nursery Trends and Strategies to Enhance Production of Field-Transplant Ready Citrus Plants
by Tripti Vashisth, Changpin Chun and Monica Ozores Hampton
Horticulturae 2020, 6(1), 8; https://doi.org/10.3390/horticulturae6010008 - 01 Feb 2020
Cited by 9 | Viewed by 3956
Abstract
The Florida citrus industry is going through major changes and considerable replanting. Many growers are planting varieties, especially rootstocks, that are potentially productive under Huanglongbing (HLB; Candidatus Liberibacter asiaticus) prevalent conditions. However, the high demand for new plant material has put tremendous pressure [...] Read more.
The Florida citrus industry is going through major changes and considerable replanting. Many growers are planting varieties, especially rootstocks, that are potentially productive under Huanglongbing (HLB; Candidatus Liberibacter asiaticus) prevalent conditions. However, the high demand for new plant material has put tremendous pressure on citrus nurseries and has created a bottleneck in production. Often it can take more than one year to produce field-transplant ready plants in nurseries; therefore, there is a critical need to accelerate plant production. This three-part study was conducted with the following objectives: (1) determine citrus nursery trends; (2) evaluate use of compost for rootstock germination; and, (3) evaluate use of compost for rootstock seedling growth. According to the nursery survey, rootstock seed germination and seedling growth were the most time-consuming, taking 6–8 months. Moreover, it was apparent from the survey results that 44% of the citrus nurseries were experimenting with potting mixes to achieve adequate plant growth and quality. Our greenhouse study demonstrated successful use of yard waste compost in place of peat moss in a potting mix. With use of 37% to 50% of compost in the potting mix, the overall germination rate and mean emergence time were improved to 70% in less than four weeks for US-897 rootstock as compared to no compost in the potting mix. In addition, 37% to 50% compost resulted in higher biomass accumulation in seedlings. When seedlings of rootstocks C-32 and Flying Dragon were grown with 37% to 50% compost, the growth rate and, therefore, percentage of successful budding were significantly increased as compared to no compost. In addition, substrate analysis indicated that a high compost potting media was rich in mineral nutrients, hence the use of fertilizer in nurseries could be minimized. Altogether, use of compost in place of peat moss seems promising and could accelerate germination and growth of rootstocks, reducing the production time as well as cost. Full article
(This article belongs to the Section Fruit Production Systems)
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12 pages, 600 KiB  
Article
Quality, Yield, and Biomass Efficacy of Several Hydroponic Lettuce (Lactuca sativa L.) Cultivars in Response to High Pressure Sodium Lights or Light Emitting Diodes for Greenhouse Supplemental Lighting
by Erica Hernandez, Michael B. Timmons and Neil S. Mattson
Horticulturae 2020, 6(1), 7; https://doi.org/10.3390/horticulturae6010007 - 27 Jan 2020
Cited by 19 | Viewed by 6031
Abstract
Lettuce is an economically important crop that can be grown either in the field or greenhouse. Different challenges are present in either environment; therefore, cultivar selection is important. For hydroponic greenhouse lettuce there is relatively little published information on cultivar selection under different [...] Read more.
Lettuce is an economically important crop that can be grown either in the field or greenhouse. Different challenges are present in either environment; therefore, cultivar selection is important. For hydroponic greenhouse lettuce there is relatively little published information on cultivar selection under different lighting sources. The objective of phase 1 was to determine the influence of lighting using high pressure sodium (HPS) or light emitting diodes (LED) on plant fresh weight, height, tip burn index, bolting, and Brix. Phase 2 was similar to phase 1 but with fewer cultivars (1) to allow for greater number of replicates per treatment per crop cycle. Each experiment consisted of three crop cycles over time per phase. Light sources were controlled using an algorithm, Light and Shade System Implementation (LASSI), to achieve a constant average daily light integral under each treatment and crop cycle. Electrical consumption and efficacy (fresh weight per kWh) from each treatment was estimated using data collected on power consumption from representative lamps multiplied by the number of fixtures and the hours fixtures were on per crop cycle. In phase 1, the fresh weight of 2 to 3 cultivars was greater under HPS and 1 to 2 cultivars under LED, depending on production cycle. The HPS-grown lettuce tended to have more tip burn and bolting in crop cycles 1 and 2, with cycle 3 showing similar tip burn incidence. Bolting was only consistently observed in one cultivar, ‘Teodore’. The LED array used less than half as much electricity as the HPS array, while producing relatively similar size lettuce, therefore, leading to electrical efficacies two- to three-times higher in LED than in HPS treatments. In phase 2, significant differences in height were found in ‘Greenstar’ and ‘Xandra’, with HPS producing larger plants than LED. Significant differences were also found in diameter in ‘Greenstar’, ‘Xandra’, ‘Locarno’, and ‘Crunchita’, with HPS again being larger than LED. Full article
(This article belongs to the Special Issue Advances in Knowledge of Hydroponic and Aquaponic Systems)
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4 pages, 157 KiB  
Editorial
Acknowledgement to Reviewers of Horticulturae in 2019
by Horticulturae Editorial Office
Horticulturae 2020, 6(1), 6; https://doi.org/10.3390/horticulturae6010006 - 23 Jan 2020
Viewed by 1690
Abstract
Rigorous peer-review is the corner-stone of high-quality academic publishing. The editorial team greatly appreciates the reviewers who contributed their knowledge and expertise to the journal’s editorial process over the past 12 months [...] Full article
8 pages, 1921 KiB  
Article
Effect of Partial Excision of Early Taproots on Growth and Components of Hydroponic Carrots
by Masaru Sakamoto, Masanori Wada and Takahiro Suzuki
Horticulturae 2020, 6(1), 5; https://doi.org/10.3390/horticulturae6010005 - 13 Jan 2020
Cited by 4 | Viewed by 4050
Abstract
Hydroponics provides a stable root environment that can be easily controlled. In this paper, we investigated the effect of partial excision of early taproots of hydroponic carrots on their growth and components. Carrot taproots were excised after 30 days from sowing at 5 [...] Read more.
Hydroponics provides a stable root environment that can be easily controlled. In this paper, we investigated the effect of partial excision of early taproots of hydroponic carrots on their growth and components. Carrot taproots were excised after 30 days from sowing at 5 cm, 10 cm, and 15 cm from the stem base (C5, C10, and C15) and compared with nonexcised control plants. Time-course measurements revealed the taproot lengths of C10 and C15 plants gradually decreased. After 28 days of treatment, C5 taproot tips showed the most rounded shape among root-excised plants. Control plants possessed long taproots that were not enlarged at the site more than 15 cm from the stem base. Taproot fresh weight was lower in C5 plants and higher in C15 plants compared with controls. Although taproot sugar concentrations did not differ between treatments, total phenol concentration was higher in C5 taproots. These data suggest that partial removal of early taproots can regulate the shape and ingredients of hydroponic carrots. Full article
(This article belongs to the Special Issue Advances in Knowledge of Hydroponic and Aquaponic Systems)
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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 3444
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 3712
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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12 pages, 4031 KiB  
Article
Quantifying Tree Hydration Using Electromagnetic Sensors
by Lance V. Stott, Brent Black and Bruce Bugbee
Horticulturae 2020, 6(1), 2; https://doi.org/10.3390/horticulturae6010002 - 03 Jan 2020
Cited by 6 | Viewed by 3303
Abstract
An automated method of determining tree water status would enable tree fruit growers, foresters and arborists to reduce water consumption, reduce orchard maintenance costs and improve fruit quality. Automated measurements could also be used to irrigate based on need rather than on fixed [...] Read more.
An automated method of determining tree water status would enable tree fruit growers, foresters and arborists to reduce water consumption, reduce orchard maintenance costs and improve fruit quality. Automated measurements could also be used to irrigate based on need rather than on fixed schedules. Numerous automated approaches have been studied; all are difficult to implement. Electromagnetic sensors that measure volumetric water content can be inserted in tree trunks to determine relative changes in tree water status. We performed automated measurements of dielectric permittivity using four commercially available electromagnetic sensors in fruit tree trunks over the 2016 growing season. These sensors accurately measure the ratio of air and water in soils, but tree trunks have minimal air-filled porosity. The sensors do respond, however, to bound and unbound water and the relative change in the output of the sensors thus provides an indication of this ratio. Sapwood is the hydro-dynamically responsive component of trunk anatomy and is nearest the bark. Sensor response improved when the waveguides were exposed to a greater percentage of sapwood. Irrigation-induced increases of approximately 0.5 MPa in stem water potential were associated with 0.5 unit increases in dielectric permittivity. Electromagnetic sensors respond to bound water in trees and thus have the potential to indicate tree water status, especially when the sensor rods are in contact with sapwood. Sensor modifications and/or innovative installation techniques could enable automated measurements of tree water status that could be used to precision irrigate trees. Full article
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13 pages, 482 KiB  
Article
The Occurrence of Shiga Toxin-Producing E. coli in Aquaponic and Hydroponic Systems
by Yi-Ju Wang, Amanda J. Deering and Hye-Ji Kim
Horticulturae 2020, 6(1), 1; https://doi.org/10.3390/horticulturae6010001 - 02 Jan 2020
Cited by 26 | Viewed by 10686
Abstract
Food safety concerns have been raised over vegetables and herbs grown in aquaponics and hydroponics due to the reuse of wastewater and spent nutrient solutions. This study was conducted to determine the occurrence of foodborne pathogens in greenhouse-based aquaponic and hydroponic systems. Fish [...] Read more.
Food safety concerns have been raised over vegetables and herbs grown in aquaponics and hydroponics due to the reuse of wastewater and spent nutrient solutions. This study was conducted to determine the occurrence of foodborne pathogens in greenhouse-based aquaponic and hydroponic systems. Fish feces, recirculating water, roots, and the edible portions of lettuce, basil, and tomato were collected at harvest, and microbiological analyses were conducted for the bacterial pathogens Shiga toxin-producing Escherichia coli (STEC), Listeria monocytogenes, and Salmonella spp. Enrichments and selective media were used for the isolation, and presumptive positive colonies were confirmed by PCR. STEC was found in fish feces, in the water of both systems, and on the surface of the roots of lettuce, basil, and tomato regardless of the system. However, contaminated water did not lead to the internalization of STEC into the roots, leaves, and/or fruit of the plants. Meanwhile, L. monocytogenes and Salmonella spp. were not present in any samples examined. Our results demonstrated that there are potential food safety hazards for fresh produce grown in aquaponic and hydroponic production systems. Full article
(This article belongs to the Special Issue Advances in Knowledge of Hydroponic and Aquaponic Systems)
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