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A special issue of Horticulturae (ISSN 2311-7524). This special issue belongs to the section "Vegetable Production Systems".

Deadline for manuscript submissions: closed (22 February 2022) | Viewed by 84880

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Special Issue Editors

Prof. Dr. Anastasios Siomos

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Guest Editor

Department of Horticulture, Aristotle University, 54124 Thessaloniki, Greece
Interests: vegetable crops; cultivation techniques; hydroponics; postharvest physiology; climate change

Prof. Dr. Pavlos Tsouvaltzis

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Guest Editor

Department of Horticulture, Aristotle University, 54124 Thessaloniki, Greece
Interests: plant physiology; nutritional quality; hydroponics; soilless production; postharvest biology and technology

Special Issue Information

Dear Colleagues,

Although soil is the dominant medium for growing vegetables, it is not always the ideal medium. For optimal plant growth, the root system requires an environment where the necessary nutrients, water, oxygen, appropriate temperature, and protection from pathogenic microorganisms are provided. Hydroponics was developed as a growing system that provides a better environment for the development of plant roots than in soil. In addition, it permits the production of vegetables in areas with soils that are entirely unsuitable for cultivation (deserts, coastal areas, rocky areas, etc.), ensuring faster growth and shorter harvest time, higher production per unit area, and optimal product quality, combined with efficient use of the water and nutrients. Finally, the reduced environmental impact during this production process is also noteworthy. Hydroponic cultivation has been successfully implemented in several countries in Europe and North America for more than 40 years. Today, it is the most intensive and effective system in greenhouse vegetable production, and a popular common practice (on a larger or smaller scale) in most European countries, while the most promising prospects for its expansion are exhibited in the Mediterranean, North Africa, and the Far East areas. It is estimated that it will hold a dominant position in coping with the recent environmental issues, and is expected to be embedded in the design of urban areas in the future, offering the opportunity for indoor vegetable production, taking advantage of modern high-technology accomplishments.

The proposed Special Issue on "Hydroponics in Vegetable Production" aims to present the results of recent research studies, methods, technologies, and innovative practices that are or could be applied in this field. We look forward to receiving your manuscripts and sharing the achievements at the cutting edge of vegetable production processes.

Prof. Dr. Anastasios Siomos
Prof. Dr. Pavlos Tsouvaltzis
Guest Editors

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Keywords

Systems
Equipment
Substrates
Nutrient solutions
Water
Minerals (fertilizers)
Vegetable crops

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Published Papers (13 papers)

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Research

12 pages, 2640 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Application of an Alternative Nutrient Replenishment Method to Electrical Conductivity-Based Closed-Loop Soilless Cultures of Sweet Peppers

by Tae-In Ahn and Jung-Eek Son

Horticulturae 2022, 8(4), 295; https://doi.org/10.3390/horticulturae8040295 - 30 Mar 2022

Cited by 6 | Viewed by 2317

Abstract

The nutrient replenishment method primarily impacts the nutrient variations in a closed-loop soilless culture system. However, there is still a lack of systematic approaches for the effective way of nutrient replenishment. Our previous study theoretically derived and experimentally validated an alternative nutrient replenishment method expecting synchronized total fertilizer supply to total nutrient absorption by crops and lower concentration fluctuations than conventional methods. However, no individual nutrient management has been performed. The objective of this study was to apply individual nutrient management to the alternative nutrient replenishment technique under experimental- and commercial-scale electrical conductivity (EC)-based closed-loop soilless cultures. Automated nutrient solution mixing modules and sweet peppers grown on rockwool slabs were used. Nutrient concentrations and crop productivity were compared between the closed-loop system using the alternative nutrient replenishment and the conventional open-loop systems. During early treatment, rapid decreases in K⁺ and H₂PO₄⁻ were observed in the closed-loop system. However, after the stock solution nutrient adjustment, the decreasing trend was stabilized and returned close to initial concentrations. No significant differences in sugar content, incidence of blossom-end rot, and productivity of sweet peppers were observed between the closed- and open-loop soilless cultures. We confirmed that the nutrient variation stabilizing effect of the alternative nutrient replenishment method was valid under nutrient adjustment conditions and had comparable nutrient management performance with the open-loop system. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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13 pages, 1818 KiB

Open AccessEditor’s ChoiceArticle

Effect of Chitosan-Poly(Acrylic Acid) Complexes and Two Nutrient Solutions on the Growth and Yield of Two Habanero Pepper Cultivars

by Rogelio Enrique Palacios-Torres, Amadeo Santos-Chavez, Hortensia Ortega-Ortiz, Ana Rosa Ramírez-Seañez, José Antonio Yam-Tzec, Adolfo Amador-Mendoza, Antonio Juárez-Maldonado, Maribel Reyes-Osornio and Hipólito Hernández-Hernández

Horticulturae 2022, 8(3), 201; https://doi.org/10.3390/horticulturae8030201 - 24 Feb 2022

Cited by 4 | Viewed by 2473

Abstract

Chitosan (CS) is a natural polymer used in agriculture as a biostimulant that has been evaluated in different plant models. In this study, we evaluated the effect of the foliar application of chitosan–poly(acrylic acid) complexes (CS–PAA) and two nutrient solutions (A and B) on the parameters of growth and yield of two habanero pepper cultivars (Chichen Itza and Jaguar) in a greenhouse. Over the course of the experiment, eight foliar applications were carried out at 15-day intervals. Our results showed that foliar applications of CS–PAA complexes have a biostimulant effect on the habanero pepper crop by increasing the total dry biomass of the plant and the number of fruits of the two cultivars. Regarding nutrient solutions, the nutrient solution A increased the yield of the Chichen Itza cultivar; this effect was because it had a better balance of potassium and calcium compared to the nutrient solution B. These results provide advances on the use of CS–PAA complexes as a biostimulant and the management of nutrient solutions in the crop of habanero peppers. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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16 pages, 1064 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Effects of Individual and Simultaneous Selenium and Iodine Biofortification of Baby-Leaf Lettuce Plants Grown in Two Different Hydroponic Systems

by Martina Puccinelli, Fernando Malorgio, Luca Incrocci, Irene Rosellini and Beatrice Pezzarossa

Horticulturae 2021, 7(12), 590; https://doi.org/10.3390/horticulturae7120590 - 19 Dec 2021

Cited by 14 | Viewed by 3990

Abstract

The iodine (I) and selenium (Se) deficiencies affect approximately 30% and 15%, respectively, of the global population. The biofortification of vegetables is a valid way to increase the intake of iodine and selenium through the diet. This study was carried out on baby-leaf lettuce to investigate the effects on plant growth, leaf quality, and leaf I and Se accumulation of adding potassium iodide and sodium selenate, separately and simultaneously, to the nutrient solution in a floating system and aeroponics. The effect of I and Se biofortification on post-harvest quality of lettuce leaves was also evaluated. Our results evidenced that the Se and I treatments increased the content of the two microelements in lettuce leaves without any negative interactions in the plants, when applied either separately or simultaneously. Both hydroponic systems proved to be suitable for producing Se and/or I enriched lettuce. Biofortification with Se was more effective when performed in aeroponics, whereas I biofortification was more effective in the floating system. Quality of leaves during post-harvest storage was not affected by neither of the treatments. Lettuce leaves enriched with 13 µM Se and 5 µMI could be good dietary sources of Se and I without inducing toxic effects in humans. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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10 pages, 525 KiB

Open AccessArticle

Nutrient Solution Temperature Affects Growth and °Brix Parameters of Seventeen Lettuce Cultivars Grown in an NFT Hydroponic System

by Dharti Thakulla, Bruce Dunn, Bizhen Hu, Carla Goad and Niels Maness

Horticulturae 2021, 7(9), 321; https://doi.org/10.3390/horticulturae7090321 - 17 Sep 2021

Cited by 19 | Viewed by 9113

Abstract

Nutrient solution temperature in a hydroponic system affects °Brix and yield of lettuce; thus, it is important to maintain the water temperature within an appropriate range. Nutrient-film technique (NFT) trials were conducted to investigate the effects of different water temperatures (18.3 °C, 21.1 °C, and ambient) on growth and °Brix of 17 cultivars from five different types (Loose leaf, Romaine, Butterhead, Salanova, and Batavian) of lettuce. The average daily water temperature for ambient treatment was recorded to be 20 to 26.5 °C. The study was conducted in a split-plot design with three replications over time. Results indicated that water temperature affected root and shoot fresh and dry weight, plant width, and °Brix for lettuce. Lettuce grown at 21.1 °C were 15% greater for shoot fresh weight than plants grown at ambient conditions. All the growth and quality parameters of lettuce were found to be affected by cultivars, with “Coastal Star” showing the best results in both growth and °Brix parameters. All the cultivars of the Romaine type showed greater growth and °Brix, while Salanova lettuce did not perform well in all treatments compared to other lettuce types. For CO₂ assimilation, the interaction between water temperature and cultivars was significant, with “Parris Island” having the greatest rate at ambient water temperature. These results suggested that maintaining water temperature at 21.1 °C produced lettuce with greater growth and biomass but had 26% lower °Brix than lettuce grown at 18.3 °C. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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18 pages, 317 KiB

Open AccessArticle

Functional, Flavor and Visual Traits of Hydroponically Produced Tomato Fruit in Relation to Substrate, Plant Training System and Harvesting Time

by Christos Mitsanis, Danai Christina Aktsoglou, Athanasios Koukounaras, Pavlos Tsouvaltzis, Theologos Koufakis, Dimitrios Gerasopoulos and Anastasios S. Siomos

Horticulturae 2021, 7(9), 311; https://doi.org/10.3390/horticulturae7090311 - 14 Sep 2021

Cited by 8 | Viewed by 3409

Abstract

Currently, a great portion of tomatoes is produced by soilless cultivation systems and the substrate selection among the various materials is one of the most important factors affecting yield and quality traits. On the other hand, grafting has been successfully used in soilless systems to ensure long-term cultivation. However, due to the high cost of grafted seedlings, plant training systems are sought. Given the fact that most literature refers to studies intended to mainly reveal production differences among treatments and the quality aspect was secondary, the present study was focused on the evaluation of tomato fruit functionality, flavor and visual traits. Tomato plants cv ‘Beef Bang F1’ were cultivated in a glasshouse hydroponic culture in four substrates: rockwool slabs, perlite in sacks, pumice in sacks and pumice in 9 L pots. The type of cultivated plants used were self-rooted or grafted onto ‘Defensor’ trained in single and double stems. Tomato fruit were harvested three times during the season (6 June, 31 July, 6 November). The fruit quality was measured based on visual (average fruit mass, and Minolta color values), flavor (dry mass, soluble solids content, titratable acidity, pH, flesh firmness) as well as functional traits (total phenolic content, ascorbic acid, lycopene, β-carotene, total carotenoid content and antioxidant capacity). Harvest time was the most important factor followed in many of these cases by the substrate (flavor and functional traits), as well as in certain cases by the plant grafting/training (flavor traits and antioxidants) or by both in some flavor traits and antioxidants. Correlation of color values with lycopene, though significant, was weak. Each individual harvest time revealed the rise in different parameters. Pumice, whether used in pot or in sack, enhanced the visual and flavor attributes the most, self-rooted plants and mid-summer harvest resulted in the highest tomato fruit quality. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

21 pages, 4066 KiB

Open AccessFeature PaperArticle

Can Biostimulants Increase Resilience of Hydroponically-Grown Tomato to Combined Water and Nutrient Stress?

by Panagiotis Kalozoumis, Christos Vourdas, Georgia Ntatsi and Dimitrios Savvas

Horticulturae 2021, 7(9), 297; https://doi.org/10.3390/horticulturae7090297 - 8 Sep 2021

Cited by 9 | Viewed by 3354

Abstract

In the current experiment, tomato (Solanum lycopersicum cv. Nostymi F1) was cultivated in an open hydroponic system under optimal or stress conditions caused by reducing the supply of nutrient solution by 35–40% and treated with biostimulants to test whether their application can increase crop resilience to combined shortage of nutrients and water. The four different biostimulant treatments were: (i) no biostimulant application, (ii) treatment with the protein-based biostimulants COUPÉ REGENERACIÓN Plus and PROCUAJE RADICULAR provided by EDYPRO, (iii) treatment with a novel biostimulant based on strigolactones, provided by STRIGOLAB and (iv) treatment with MAXICROP, a commercial product consisting of seaweed extracts. Combined stress significantly reduced NO₃⁻, P, and K in the root zone of tomato plants. However, the application of the strigolactone-based biostimulant to stressed plants maintained NO₃⁻ in the root zone to similar levels with non-stressed plants during the first and third months of cultivation. The biostimulants did not increase the vegetative plant biomass at 70 and 120 days after transplanting (DAT). The strigolactone-based biostimulant increased early leaf area development (70 DAT) and early fruit production compared to untreated plants but had no effect on total tomato yield (120 DAT). Maxicrop also increased early fruit yield, while Edypro decreased early and total yield compared to the control plants, an effect ascribed to overdosing, as the application rate was that suggested for soil-grown crops, while the plants were cultivated on an inert substrate. Strigolactone-based biostimulant and Maxicrop could be further studied by testing multiple applications during the cropping period. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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13 pages, 586 KiB

Open AccessArticle

Evaluation of Lettuce (Lactuca sativa L.) Production under Hydroponic System: Nutrient Solution Derived from Fish Waste vs. Inorganic Nutrient Solution

by Zienab F. R. Ahmed, Alghazal K. H. Alnuaimi, Amira Askri and Nikolaos Tzortzakis

Horticulturae 2021, 7(9), 292; https://doi.org/10.3390/horticulturae7090292 - 6 Sep 2021

Cited by 50 | Viewed by 29905

Abstract

Organic fresh products are appreciated and are gaining a good reputation regarding human health and environmental concerns. Despite the fact that hydroponics are commonly used in vegetable production, growers are looking for sustainable cultivation systems. Therefore, the objective of this study was to investigate the effect of using an organic-based nutrient solution (NS) derived from fish waste in a hydroponic system on the vegetative growth and production of lettuce compared to a conventional inorganic NS. Plant growth, yield, physiological and nutrient content parameters were determined. The results revealed that the overall growth and fresh biomass of the organic NS grown lettuce were relatively lower than those of the inorganic NS. Stomata density was significantly higher in inorganic grown lettuce compared to the organic one. However, the total chlorophyll, carotene, phenolic compounds, and flavonoid contents, as well as antioxidant activity were significantly higher in lettuce grown in organic NS compared to the inorganic one. Leaf nutrient content at harvest was significantly impacted by the type of used fertilizer. Based on these findings, in hydroponic system, organic liquid fertilizer derived from fish waste (as an alternative NS source) requires further improvements to achieve optimal growth and yield comparable to that of conventional inorganic NS. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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13 pages, 577 KiB

Open AccessFeature PaperArticle

Configuration by Osmotic Eustress Agents of the Morphometric Characteristics and the Polyphenolic Content of Differently Pigmented Baby Lettuce Varieties in Two Successive Harvests

by Giandomenico Corrado, Paola Vitaglione, Georgios A. Soteriou, Marios C. Kyriacou and Youssef Rouphael

Horticulturae 2021, 7(9), 264; https://doi.org/10.3390/horticulturae7090264 - 25 Aug 2021

Cited by 4 | Viewed by 1813

Abstract

Salinity eustress is one of the pre-harvest factors that can be used to improve the phytochemical profile and the quality attributes of horticultural species, and most of the studies are carried out using NaCl. In this work, we compared the effect of three mildly saline iso-osmotic nutrient solutions (NS) differing in the cation employed (either K, Na, or Ca) in baby lettuce cultivated in a floating system. Specifically, we analyzed the impact on key morphological traits and polyphenol composition in leaves in a completely randomized design experiment with the following experimental factors and levels: two differently pigmented lettuce varieties (green and full red), three NSs (20 mM KCl, 20 mM NaCl, 13.3 mM CaCl₂, each with a final ionic concentration of 40 mM), and two successive harvests. The lettuce response to mild salinity was multifaceted and with a marked role for the cultivar factor and its interactions, as also indicated by multivariate analysis. The morphological response of baby lettuce to the saline solutions was predominantly affected by the osmolarity, and ion-specific alleviating or detrimental effects were not observed. The phytochemical analysis revealed significant interactions among all tested factors, with ion-specific differences over some of the detected phenolics. This is consistent with the high sensitivity of this class of bioactive compounds to environmental factors. This work indicated that certain combinations of the experimental factors tested can be exploited to improve the biochemical profile and possibly the nutraceutical quality of baby lettuce in a floating system. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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20 pages, 3204 KiB

Open AccessArticle

Growth Characteristics, Phytochemical Contents, and Antioxidant Capacity of Trachyandra ciliata (L.f) Kunth Grown in Hydroponics under Varying Degrees of Salinity

by Sihle Ngxabi, Muhali Olaide Jimoh, Learnmore Kambizi and Charles Petrus Laubscher

Horticulturae 2021, 7(8), 244; https://doi.org/10.3390/horticulturae7080244 - 13 Aug 2021

Cited by 11 | Viewed by 3222

Abstract

This study evaluated the effect of salinity and soilless media on the vegetative growth, phytochemicals, and antioxidant capacity of Trachyandra ciliata (wild cabbage) to develop its growth protocol and explore its potential as a natural source of secondary metabolites. Treatments consisted of different concentrations of sodium chloride (NaCl), control- 0 mM, 100 mM, 200 mM, 400 mM, while different in vitro assays were used for phytochemical and antioxidant screenings. Findings from the study showed that low salinity (100 mM) significantly increased chlorophyll content, plant height, leaf number, plant fresh weight, and production of inflorescence, particularly in Peat-Perlite-Vermiculite (PPV) medium. In contrast, the control was the most productive treatment in plant dry weight except for the inflorescence. The highest antioxidant activity was observed in 200 mM of NaCl treatment in combination with PPV medium, which also produced the highest mean values for polyphenols, while 100 mM was the best for flavonols. Therefore, T. ciliata proved to be more productive vegetatively under low salinity in combination with PPV soilless media. A combination of 200 mM + PPV treatment was also recommended for maximum production of antioxidants for T. ciliata. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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14 pages, 8822 KiB

Open AccessArticle

Effect of the Flow Rate on Plant Growth and Flow Visualization of Nutrient Solution in Hydroponics

by Bateer Baiyin, Kotaro Tagawa, Mina Yamada, Xinyan Wang, Satoshi Yamada, Sadahiro Yamamoto and Yasuomi Ibaraki

Horticulturae 2021, 7(8), 225; https://doi.org/10.3390/horticulturae7080225 - 5 Aug 2021

Cited by 18 | Viewed by 8950

Abstract

In hydroponics, the flow pattern of nutrient solution in a cultivation container affects the growth of plants. Even if the flow rate of nutrient solution is the same between containers, the flow pattern may differ based on the size and shape of the containers. Therefore, the flow pattern cannot be comprehensively described by flow rate alone. In order to identify the relationship between plant growth, root morphology, nutrient uptake, and flow pattern, a hydroponic cultivation of Swiss chard was carried out. In addition, in order to describe the flow pattern in a specific cultivation container, hydroponic flow patterns were observed via flow field visualization using particle image velocimetry. As a result, with the increase in flow rate, it was found that a specific flow rate can form an ideal flow pattern for plant growth. Under this flow pattern, nutrient absorption is promoted and roots are elongated, thereby absorbing more nutrients and further promoting plant growth. However, when the flow rate exceeds the ideal value, plant growth is hindered. In summary, identifying the ideal nutrient solution flow pattern in hydroponics can facilitate better crop production. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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11 pages, 1843 KiB

Open AccessEditor’s ChoiceArticle

Effects of Hydrogen Peroxide on Organically Fertilized Hydroponic Lettuce (Lactuca sativa L.)

by Vanessa Lau and Neil Mattson

Horticulturae 2021, 7(5), 106; https://doi.org/10.3390/horticulturae7050106 - 10 May 2021

Cited by 15 | Viewed by 6552

Abstract

Hydroponic production typically uses conventional fertilizers, but information is lacking on the use of organic hydroponic fertilizers. Development of microbial communities and biofilm that can reduce dissolved oxygen availability is a difficulty with organic hydroponics. One potential solution is the use of hydrogen peroxide (H₂O₂) which can reduce microbial populations and decompose to form oxygen. However, information is lacking on the impact of hydrogen peroxide on hydroponic crop performance. The aim of this study was to determine the effects of H₂O₂ concentrations in deep water culture hydroponics by assessing how it affects plant size and yield in lettuce (Lactuca sativa L.) “Rouxai”. In this experiment, three H₂O₂ treatments, namely the application of 0, 37.5 or 75 mg/L H₂O₂ to 4 L aerated hydroponic containers with either conventional or organic fertilizer, were compared. The containers had either fish-based organic fertilizer (4-4-1, N-P₂O₅-K₂O) or inorganic mineral based conventional nutrient solution (21-5-20, N-P₂O₅-K₂O), both applied at 150 mg/L N. Three replicates of each H₂O₂ treatment–fertilizer combination were prepared resulting in a total of eighteen mini hydroponic containers each with one head of lettuce. There were two growth cycles: fall 2018 and spring 2019. When added to conventional fertilizers, both 37.5 mg/L and 75 mg/L of H₂O₂ led to stunted growth or death of lettuce plants. However, when 37.5 mg/L of H₂O₂ was applied to organic fertilizers, the lettuce yield nearly matched that of the conventionally fertilized control, demonstrating that the application of H₂O₂ has the potential to make organic hydroponic fertilization a more viable method in the future. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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10 pages, 2188 KiB

Open AccessEditor’s ChoiceArticle

A Quantitative Management of Potassium Supply for Hydroponic Production of Low-Potassium Cherry-Type Tomato Fruit for Chronic Kidney Disease Patients

by Satoru Tsukagoshi, Miho Aoki, Masahumi Johkan, Masaaki Hohjo and Toru Maruo

Horticulturae 2021, 7(4), 87; https://doi.org/10.3390/horticulturae7040087 - 19 Apr 2021

Cited by 4 | Viewed by 3425

Abstract

Chronic kidney disease (CKD) has been a global health problem in recent years. CKD patients often restrict their potassium (K) intake to avoid the high risk of hyperkalemia. In this study, quantitative K management in hydroponics was adopted to produce low K cherry-type tomato (Solanum lycopersicom L.) fruit. The total quantity of K supply per plant during the cultivation was 7.2 g (1 K), 3.6 g (1/2 K), 1.8 g (1/4 K), 0.9 g (1/8 K) and 0.6 g (1/12 K), respectively. The total fruit yield decreased to about 75% at 1/2 K and 58% at 1/12 K compared to 1 K. The fruit K content was lower in 1/4 K, 1/8 K and 1/12 K than in 1 K and 1/2 K, and the fruit from 1/8 K and 1/12 K achieved below 100 mg 100 g⁻¹ FW of K. Total soluble solid content (Brix) was 7–8% in 1 K and 1/4 K but was lower in 1/8 K and 1/12 K. Fruit acid content decreased to 87% in 1/2 K to 70% in 1/4 K and 1/8 K, and to 57% in 1/12 K of 1 K. In conclusion, quantitative K management in hydroponics is expected to produce low K tomato fruit. Fruit K content of approximately 100 mg.100 g⁻¹ FW was achieved when the quantity of K supply was 1/4 K and 1/8 K, with a relatively smaller effect on fruit yield, Brix and acid content. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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11 pages, 3011 KiB

Open AccessEditor’s ChoiceArticle

Effect of Root Restriction on the Performance of Three-Truss Cultivated Tomato in the Low-Node Pinching Order at High-Density Cultivation System

by Alex Williams Ayarna, Satoru Tsukagoshi and George Oduro Nkansah

Horticulturae 2021, 7(3), 60; https://doi.org/10.3390/horticulturae7030060 - 22 Mar 2021

Cited by 7 | Viewed by 2955

Abstract

The low-node pinching order at a high-density plant cultivation system (LN&HD) is now widely adopted for increasing tomato yield and fruit quality. The LN&HD cultivation period spans 70–120 days, employs the use of a small amount of substrate (low substrate volume), and plants are usually topped between the first and the fourth truss. Using a small amount of substrate in cultivation induces root restriction. Increasing the extent of root restriction in small pots has been adopted for increasing the fruit quality of tomato in some advanced countries. However, improving fruit quality at the expense of yield becomes a major drawback for adopting the LN&HD in Ghana. The LN&HD was introduced into Ghana mainly to increase tomato yield sustainably at a cost-effective level. This study aimed to manipulate or reduce the extent of root restriction to increase tomato yield. Information related to manipulating or reducing the extent of root restriction has not been extensively reported. Thus, an experiment was conducted (between 21 April 2019 and 11 August 2019) in the greenhouse of the University of Ghana Forest and Horticultural Research Centre, Kade-Ghana. Plants of two tomato cultivars (Jaguar and Momotaro York) were subjected to four root restriction conditions. The extent of root restriction were (1) complete root restriction in a 1.0 L volume capacity pot, (2) complete root restriction in a 1.5 L volume capacity pot, (3) partial root restriction in Rockwool-like cultivation, otherwise referred to as Cocowool, and (4) No root restriction in a trough containing 1.5 L of the substrate. The experiment was laid out in a 2 x 4 factorial in a randomized complete block. Results showed that partial root restriction in Cocowool and unrestricted roots in the trough produced the highest tomato yield and total dry matter compared to the plants that received complete root restrictions in the 1.0 and 1.5 L pots. However, the tomato’s total soluble solids increased with a complete root restriction in the 1.0 L pot. Reducing the extent of root restriction increased the yield and total dry matter of tomato. With the LN&HD, a small amount of substrate could be used (at a reduced cost) with a partial root restriction to increase the yield of tropical tomato cultivars grown in Ghana. Full article

(This article belongs to the Special Issue Hydroponics in Vegetable Production)

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