Response of Zucchini to the Electrical Conductivity of the Nutrient Solution in Hydroponic Cultivation

As the demand for high-quality wild greens rises, due to their high nutritional, culinary, and medicinal properties, the potential overexploitation and excessive disruption of their natural habitats bring serious environmental problems to the foreground. However, new alternative cultivation techniques, such as hydroponic cultivation, could take advantage of rational water management, optimal fertilization management and climate adaptation, to produce high-quality wild greens, all year round. As an initial step to assess optimal hydroponic cultivation conditions for golden thistle (Scolymus hispanicus L.), in this study we evaluated the effect of N:K ratio and electrical conductivity (EC) in the supplied nutrient solution on plant growth, yield and phenology. Four nutrient solutions were applied with a low or a high N:K ratio (1.59 or 2.38 mol/mol, respectively) combined with a low or a high electrical conductivity (EC) level (2.2 and 2.8 dS m−1, respectively) in a 2 × 2 factorial experiment set as a completely randomized block design with 4 blocks and 48 plants per block. Golden thistle seedlings were planted in plastic growth-bags of hydroponic perlite substrate in an open, drip-irrigated, soilless cultivation system. The experiment commenced in December 2018, in a plastic greenhouse at the campus of the Hellenic Mediterranean University, Crete, Greece. After four months of cultivation, the post-harvest analysis showed that the high N:K ratio significantly increased the fresh weight of leaf and edible tuberous root, whereas the tested EC levels in the nutrient solution had no impact on plant fresh weight. The experimental treatments did not significantly affect leaf chlorophyll concentration (SPAD meter readings), chlorophyll fluorescence (Fv/Fm) or the number of leaves and the specific weight of the tuberous root of the plants. Our results indicate that wild golden thistle could be domesticated as an edible vegetable, and cultivated hydroponically at different seasons of the year using relatively low nutrient concentrations, thereby minimizing aquifer nitrate and phosphate pollution. A nutrient solution with a relatively high N:K ratio (here 2.38 mol/mol) is recommended for the hydroponic cultivation of golden thistle.

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Frequency of recirculation of nutrient solution in hydroponic cultivation of coriander with brackish water

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v20n5p447-454 ◽

2016 ◽

Vol 20 (5) ◽

pp. 447-454 ◽

Cited By ~ 6

Author(s):

Mairton G. da Silva ◽

Tales M. Soares ◽

Hans R. Gheyi ◽

Itamar de S. Oliveira ◽

José A. da Silva Filho ◽

...

Keyword(s):

Electrical Conductivity ◽

Experimental Design ◽

Nutrient Solution ◽

Brackish Water ◽

Block Design ◽

Hydroponic System ◽

Randomized Block Design ◽

Hydroponic Cultivation ◽

Production Losses

ABSTRACT The present study used a hydroponic system with leveled channels, in order to evaluate coriander cultivation under different intervals of nutrient solution recirculation and the use of freshwater and brackish water. The experiment was carried out in a randomized block design with five replicates, in a 2 x 4 factorial scheme, from February to March 2014. Two levels of electrical conductivity (EC) of water (0.32 and 4.91 dS m-1) and four frequencies of nutrient solution recirculation (at intervals of 0.25, 2, 4 and 8 h) were evaluated. This experimental design was adopted in the evaluations performed at 10, 15 and 25 days after transplantation (DAT). Additionally, at 21 DAT subplots were established for the evaluation of plant position (initial, intermediate and final) along the hydroponic channels. It is viable to use nutrient solution recirculation every 8 h, without production losses. The use of brackish water (EC = 4.91 dS m-1) may be an alternative for the hydroponic cultivation of coriander, despite the reduction in production, but without any damage on the visual aspect of the product. Plants grown at the initial and intermediate positions along the hydroponic channels showed higher production.

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Nutrient Use in Vertical Farming: Optimal Electrical Conductivity of Nutrient Solution for Growth of Lettuce and Basil in Hydroponic Cultivation

Horticulturae ◽

10.3390/horticulturae7090283 ◽

2021 ◽

Vol 7 (9) ◽

pp. 283

Author(s):

Hadis Hosseini ◽

Vahid Mozafari ◽

Hamid Reza Roosta ◽

Hossein Shirani ◽

Paulien C. H. van de Vlasakker ◽

...

Keyword(s):

Electrical Conductivity ◽

Nutrient Solution ◽

Growth Parameters ◽

Nitrogen Concentration ◽

Environmental Parameters ◽

Nutrient Loss ◽

Photon Flux ◽

Photon Flux Density ◽

Vertical Farming ◽

Hydroponic Cultivation

During the past few decades, vertical farming has attracted a lot of interest as an alternative food production method. Vertical farms use engineered growth environments and hydroponic cultivation techniques for growing plants indoors. One of the important factors in vertical farming for the cultivation of different plants is the amount of nutrients, which can be measured as electrical conductivity (EC). Studying the optimal EC is important for avoiding nutrient loss and deficiency in vertical farms. In this study, we investigated the effect of five EC levels (2, 1.2, 0.9, 0.7, and 0.5 dS m−1) of Hoagland nutrient solution on the growth and development of basil cultivar ‘Emily’ and lettuce cultivar ‘Batavia-Caipira’. During the study, the environmental parameters were kept fixed using an automatic dosing machine. The experiment was done in automatic vertical farms using the hydroponic ebb–flow cultivation technique with a temperature of 20 ± 1 °C, relative humidity of 50–60%, CO2 concentration of 450 ppm, pH = 6, the PPFD (photosynthetic photon flux density) of 215 ± 5.5 μmol m−2 s−1, and the photoperiod of 16:8 h (day/night). Each treatment was replicated four times. We studied the effects on several growth parameters (including the dry and fresh weight of leaves and roots, number of leaves, and leaf area) as well as the chlorophyll and nitrogen concentration of the leaves. According to the results, the basil and lettuce growth parameters among the five treatments have been significantly higher in the treatment with EC of 1.2 and 0.9 dS m−1. These EC values are lower than the recommended EC value given as the optimum in the previous studies. However, the concentration of chlorophyll and nitrogen show different trends and were higher in full strength of nutrient solution with EC = 2 dS m−1.

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Fuzzy Logic Controller for Automating Electrical Conductivity and pH in Hydroponic Cultivation

Applied Sciences ◽

10.3390/app12010405 ◽

2021 ◽

Vol 12 (1) ◽

pp. 405

Author(s):

Cheng-Hung Chen ◽

Shiou-Yun Jeng ◽

Cheng-Jian Lin

Keyword(s):

Electrical Conductivity ◽

Fuzzy Logic ◽

Control System ◽

Nutrient Solution ◽

Fuzzy Logic Controller ◽

Fuzzy Controller ◽

Operating Time ◽

Hydroponic System ◽

Hydroponic Cultivation ◽

Nutrient Solutions

This study proposes a fuzzy logic controller for adjusting the electrical conductivity (EC) and pH of the nutrient solution in a hydroponic system. The proposed control system detects the EC and pH of the solution through sensors and adjusts the working time of the solution pump through the fuzzy controller. Specifically, the EC and pH of the nutrient solution are maintained at specific values. A Raspberry Pi3 development board is used in the proposed control system to realize and solve the problem of adjusting the EC and pH of the solution. In the fuzzy controller, the inputs are EC and pH sensors, and the output is the operating time of the pump. Experimental results indicate that the proposed control system can effectively reduce the measurement burden and complex calculations of producers by adjusting nutrient solutions.

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Performance of Hydroponically Cultivated Geranium and Common Verbena under Salinity and High Electrical Conductivity Levels

Agronomy ◽

10.3390/agronomy11061237 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1237

Author(s):

Antonios Chrysargyris ◽

Spyridon A. Petropoulos ◽

Dejan Prvulovic ◽

Nikolaos Tzortzakis

Keyword(s):

Electrical Conductivity ◽

Chlorophyll Fluorescence ◽

Nutrient Solution ◽

High Salinity ◽

Stomatal Resistance ◽

Water Sources ◽

Total Flavonoid ◽

Control Treatment ◽

Total Phenolic ◽

High Electrical Conductivity

Abiotic factors in nutrient solutions (NSs), such as salinity and high electrical conductivity (EC), may adversely alter plant growth and crop performance. However, there are medicinal/aromatic plants which can not only withstand these adverse conditions, but which can also increase their productivity or even enhance their quality in such conditions. As fresh water sources suitable for irrigation are becoming more and more limited, the use of low-quality water sources and hydroponic growing systems have been suggested as the main alternatives. Towards that direction, this study aims to evaluate the effect of high EC levels in NSs on geranium (Pelargonium graveolens L’Hér.) and common verbena (Verbena officinallis L.) plants cultivated in a soilless (perlite) hydroponics system. Plants were irrigated with a full nutrient solution of EC 2.1 dS m−1 and pH 5.8 until they reached a uniform size. Then, three treatments were applied, namely: (a) a control treatment with an EC of 2.1 dS m−1 in the NS, (b) a high-salinity NS created by adding 75 mM of NaCl (EC under 8.5 dS m−1) and (c) a concentrated NS with an EC of 8.5 dS m−1. In pelargonium, high salinity decreased the total phenolic and total flavonoid contents; antioxidant capacity; N, K, Mg and P content; as well as chlorophyll fluorescence, compared to the control treatment. On the other hand, increased salinity levels increased the Na and Ca content and stomatal resistance. In common verbena, salinity decreased total phenolic content and chlorophyll fluorescence but increased total flavonoid content; antioxidants; leaf K, P, Na, Cu and Zn content; and stomatal resistance, compared to the control. In both species, high EC did not affect polyphenols, flavonoids or antioxidants, whereas it increased stomatal resistance and nutrient accumulation in the leaves, and decreased chlorophyll fluorescence compared to the control treatment. Damage indices, indicated by lipid peroxidation, hydrogen peroxide production and the elevation of enzymes’ antioxidant activities, were evidenced in both saline- and high-EC-treated plants. In conclusion, despite having the same EC levels in the nutrient solution, it seems that ionic stress caused by high mineral concentrations in the nutrient solution had less severe effects on the tested plants than the relevant osmotic stress caused by high salinity due to the addition of NaCl in the nutrient solution.

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Effects of Node Position and Electric Conductivity of Nutrient Solution on Adventitious Rooting of Nasturtium (Tropaeolum majus L.) Cuttings

Agronomy ◽

10.3390/agronomy11020363 ◽

2021 ◽

Vol 11 (2) ◽

pp. 363

Author(s):

Wenshuo Xu ◽

Na Lu ◽

Masao Kikuchi ◽

Michiko Takagaki

Keyword(s):

Electric Conductivity ◽

Nutrient Solution ◽

Adventitious Rooting ◽

Cutting Propagation ◽

Apical Bud ◽

Hydroponic Cultivation ◽

Bud Position ◽

Seed Propagation ◽

Node Position

Nasturtium is a popular herbal plant, widely cultivated as culinary and medicinal plants all over the world. However, the seed propagation of nasturtium is inefficient, and in-vitro propagation is sophisticated and high-cost. In this study, the cutting propagation method was employed to produce nasturtium seedlings. We aimed to determine the optimal conditions for cutting propagation of nasturtium seedlings by investigating the effects of node position and electric conductivity (EC) of nutrient solution on the root formation of the cuttings. Cuttings from five node positions (apical bud, 2nd node, 3rd node, 4th node, and 5th node) were subjected to water and five EC (1.0, 2.0, 3.0, 4.0, and 5.0 dS m−1) treatments with a hydroponic cultivation system in a plant factory. Results showed that all cuttings rooted successfully within two weeks. The cuttings from the apical bud position rooted earliest and produced the most roots regardless of EC level. Cuttings from other node positions produced longer roots and heavier root fresh and dry weights than those from the apical bud position. The cuttings under EC of 1.0 dS m−1 had the greatest root number, the longest root length, and the heaviest root fresh and dry weights regardless of node positions. The EC of 1.0 dS m−1 is considered the best condition for nasturtium cuttings for the range of EC tested in this study, and the cuttings from all the five node positions can be used as seedling materials.

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SEMI-HYDROPONIC CULTIVATION AS A SELECTION TOOL FOR ALUMINUM TOLERANCE IN FORAGE GRASSES

Revista Engenharia na Agricultura - REVENG ◽

10.13083/reveng.v24i4.654 ◽

2016 ◽

Vol 24 (4) ◽

pp. 350-356

Author(s):

Gustavo André Colombo ◽

Aurélio Vaz-de-Melo ◽

Gilberto Coutinho Machado Filho ◽

André Silva de Sousa

Keyword(s):

Nutrient Solution ◽

Aluminum Toxicity ◽

Aluminum Tolerance ◽

Dry Weight ◽

Panicum Maximum ◽

Forage Grasses ◽

Breeding Programs ◽

Brachiaria Humidicola ◽

Hydroponic Cultivation ◽

Constant Improvement

The constant improvement of selection methods is necessary in order to optimize efficiency of breeding programs for aluminum tolerance. Thus, the aim of this study was to establish a vase volume to the ideal semi-hydroponic cultivation of forage grasses subjected to stress by aluminum in nutrient solution. The experimental design completely randomized, with four replicates, each replicate consisting of one plant per vase. The treatments were arranged in a factorial design 4x5, being the first factor consists of four genotypes of forage grasses Brachiaria Humidicola; Brachiaria brizantha cv. Piatã; Panicum maximum cv. Massai and Panicum maximum cv. Mombaça) and the second consisting of five separate volumes plastics vases where seedlings were grown (0.2; 0.25; 0.3; 0.35 and 0.4 dm³). The grasses grown in a semi-hydroponics system irrigated with nutrient solution rich in aluminum (3 mg L-1). Was measured plant height, dry weight of aereal part and root length. The semi-hydroponic cultivation in aluminum increased nutrient solution is effective in differentiation of forage grasses genotypes in relation to aluminum tolerance. Pots volumes near 0.3 dm3 promote greater development for root and aerial part attributes in forage grasses grown in nutrient solution with aluminum toxicity.

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Nutrient and inorganic solute (Na+ and Cl-) content in green onion plants under hydroponic cultivation using brackish water

Ciência e Agrotecnologia ◽

10.1590/1413-7054202044013320 ◽

2020 ◽

Vol 44 ◽

Author(s):

Carlos Donato da Silva Souza ◽

Geronimo Ferreira da Silva ◽

Sirleide Maria de Menezes ◽

José Edson Florentino de Morais ◽

José Amilton Santos Júnior ◽

...

Keyword(s):

Nutrient Solution ◽

Brackish Water ◽

Hydroponic System ◽

Brackish Waters ◽

Randomized Design ◽

Hydroponic Cultivation ◽

Salinity Levels ◽

Completely Randomized Design ◽

Harmful Effects ◽

Different Levels

ABSTRACT Cultivation using brackish waters can result in nutritional and metabolic imbalances in several plant species, consequently reducing the production of dry matter (DM) and accumulation of toxic ions (Na+ and/or Cl-) in plants. We evaluated the DM production, and nutrient and inorganic solute (Na+ and Cl-) content in green onion plants (cv. Todo Ano Evergreen - Nebuka) under different levels of nutrient solution salinity in combination with circulation frequencies of this solution. Two experiments were conducted in a hydroponic system, using a completely randomized design, in a 6 × 2 factorial scheme, with five replicates: six levels of nutrient solution salinity (1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 dS m-1) and two solution circulation frequencies (twice and thrice a day). In Experiment I, the evapotranspired depth was replaced using brackish water that was used to prepare each of the salinity levels (used exclusively), whereas in Experiment II, brackish water was used only to prepare each of the salinity levels and public water was used (electrical conductivity [ECw] = 0.12 dS m-1) for replacement in all treatments. The increase in the nutrient solution salinity reduced the production of DM and accumulation of nutrients; the reductions were more pronounced when brackish waters were used exclusively (Experiment I). However, the circulation of solutions thrice a day resulted in the harmful effects of the salinity effect. Replacing the evapotranspirated blade with water supply (Experiment II) mitigated the deleterious effects of salinity. Moreover, three circulations of the nutrient solution daily resulted in lower accumulation of inorganic Na+ and Cl- solutes and increased accumulation of nutrients N, P, K+, Ca2+, Mg2+, and S in the culture.

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