Nutrient Solution In Greenhouse Research Articles

Potassium Ion‐selective Electrode with a Sensitive Ion‐to‐Electron Transducer Composed of Porous Laser‐induced Graphene and MoS2 Fabricated by One‐step Direct Laser Writing

AbstractIn this study, an ion‐selective electrode with a sensitive ion‐to‐electron transducer composed of porous laser‐induced graphene (LIG) and MoS2 (LIG‐MoS2/ISE) was fabricated to measure the potassium ion concentration in a greenhouse nutrient solution for soilless culture. Additionally, a more effective and low‐cost method was proposed for the large‐batch production and manufacture of potassium ion‐selective electrodes (K+‐ISEs) using the direct laser writing technique, which differs considerably from existing methods. Moreover, the sensing mechanism of the proposed LIG‐MoS2/ISE for potassium ion detection was investigated. The morphology and physical properties of the LIG‐MoS2/SC‐K+‐ISEs were studied by X‐ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and energy‐dispersive spectroscopy. Potentiometric measurements, chronopotentiometry, potentiometric water layer tests, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to evaluate the analytical performance of the newly developed K+‐ISEs. A Nernstian slope of 30.1 mV/decade for the activity of potassium ions in a concentration range from 10−7 to 10−2 M was determined. The EIS and chronopotentiometry results revealed that the LIG‐MoS2/SC‐K+‐ISE had a larger resistance and double‐layer capacitance than the LIG/SC‐K+‐ISE. The ion‐selective membrane (ISM) and solid‐contact layer did not have any water film between them, according to the potentiometric water layer test. The results proved that the LIG‐MoS2 nanocomposite could possibly be used as a sensitive ion‐to‐electron transducer to fabricate K+‐ISEs. The K+‐ISE fabrication method using the direct laser writing technique had a higher efficiency, enabling its broad application prospects in agriculture.

Effect of a Newly-Developed Nutrient Solution and Electrical Conductivity on Growth and Bioactive Compounds in Perilla frutescens var. crispa

We evaluated the effect of a newly-developed nutrient solution of red perilla (NSP) with various electrical conductivity (EC) levels on plant growth, mineral content, and bioactive compounds. Four-week-old seedlings were grown in greenhouse nutrient solution as control (CT) (EC 1–3 dS m−1) or NSP (EC 1–6 dS m−1). NSP 1 dS m−1 induced better growth characteristics, whereas higher EC levels inhibited plant growth. Most of the macro-elements contents significantly decreased under NSP 6 dS m−1, whereas the micro-elements contents fluctuated according to EC levels. Total phenolic concentration in NSP was lower than that in CT, and total phenolic content was highest under NSP 1 dS m−1. Total anthocyanin and antioxidant concentrations and contents increased at lower EC levels. Rosmarinic and caffeic acids concentrations increased at higher EC levels, whereas there were no significant differences in these compound contents among the EC levels. No difference in perillaldehyde concentration was observed, whereas the content was higher at lower EC levels. Overall, these results suggest that NSP 1 dS m−1 is suitable for cultivating red perilla in plant factories.

Harvesting Plants in Constructed Wetlands to Increase Biomass Production and Na+ and Cl− Removal from Recycled Greenhouse Nutrient Solution

Recycled greenhouse nutrient solution requires treatment to prevent increased concentrations of both Na+ and Cl− ions from damaging crops or impacting the environment subsequent to its discharge. Constructed wetlands (CW) planted with species capable of hyper-accumulating Na+ and Cl− may be one viable treatment option. To mitigate the unwanted ions from CW, plant material may need to be harvested and removed. Research suggests that multiple harvests throughout the growing season can maximize the CW phytoremediation potential. To determine the ideal frequency of CW plant harvesting, an 18-week, outdoor microcosm experiment was conducted in which three wetland plant species, Juncus torreyi Coville. (Torrey’s rush), Schoenoplectus tabernaemontani (C.C. Gmel.) Palla (softstem bulrush), and Typha latifolia L. (broad leaf cattail), were subjected to the following harvesting treatments: (i) one harvest, (ii) two harvests, and (iii) three harvests. The total amounts of Na+ and Cl− accumulated in the aboveground dry biomass per square meter of plant growth area were calculated. Treatments with the highest Na+ accumulation were as follows: T. latifolia with three harvests, 24.7 g m−2, T. latifolia with two harvests, 16.2 g m−2, J. torreyi with two harvests, 12.7 g m−2. Treatments with the highest Cl− accumulation were as follows: J. torreyi with two harvests, 111.3 g m−2, T. latifolia with three harvests, 94.8 g m−2, T. latifolia with two harvests, 81.4 g m−2. Harvesting, whether two or three times, increased the Na+ and Cl− accumulated by T. latifolia and J. torreyi but did not influence the Na+ and Cl− accumulation or growth of S. tabernaemontani. However, the average Na+ and Cl− removal efficiencies of the all treatments were low, between 1–5 % for Na+ and 7–15 % for Cl−, suggesting that phytodesalinization may not be the best option for Na+ and Cl− treatment.

Use of phosphorus-sorbing materials to remove phosphate from greenhouse wastewater

High phosphate content in wastewater is currently a major issue faced by the North American greenhouse industry. Phosphate-sorbing material filters could provide a means of removing phosphate from wastewater prior to discharge to the environment, but the characterization of economically viable materials and specific recommendations for greenhouse wastewater are not available. Batch and column experiments were used to examine the capacity of two calcium-based waste materials, basic oxygen furnace slag and a concrete waste material, to remove phosphate from greenhouse nutrient solution at varied operating conditions. Material columns operating at a hydraulic retention time (HRT) of 3 h consistently removed >99% of influent phosphate at a concentration of 60 mg/L over repeated applications and demonstrated high phosphate retention capacity (PRC) of 8.8 and 5.1 g P/kg for slag and concrete waste, respectively. Both materials also provided some removal of the micronutrients Fe, Mn and Zn. Increasing HRT to 24 h increased P retention capacity of slag to >10.5 g P/kg but did not improve retention by concrete waste. Decreasing influent phosphate concentration to 20 mg/L decreased PRC to 1.64 g P/kg in concrete waste columns, suggesting fluctuations in greenhouse wastewater composition will affect filter performance. The pH of filter effluent was closely correlated to final P concentration and can likely be used to monitor treatment effectiveness. This study demonstrated that calcium-based materials are promising for the removal of phosphate from greenhouse wastewater, and worthy of further research on scaling up the application to a full-sized system.

Plant Species for the Removal of Na+ and Cl– from Greenhouse Nutrient Solution

Certain ions such as Na+ and Cl– can accumulate in recirculating greenhouse nutrient solutions and can reach levels that are damaging to crops. An option for the treatment of this problem is phytodesalinization with Na+ and Cl– hyperaccumulating plants that could be added to existing water treatment technologies such as constructed wetlands (CWs). Two microcosm experiments were conducted to evaluate eight plant species including Atriplex prostrata L. (triangle orache), Distichlis spicata (L.) Greene (salt grass), Juncus torreyi Coville. (Torrey’s rush), Phragmites australis (Cav.) Trin. ex Steud. (common reed), Spartina alterniflora Loisel. (smooth cordgrass), Schoenoplectus tabernaemontani (C.C. Gmel.) Palla (softstem bulrush), Typha angustifolia L. (narrow leaf cattail), and Typha latifolia L. (broad leaf cattail) for their Na+ and Cl– accumulation potential. An initial (indoor) experiment determined that J. torreyi, S. tabernaemontani, T. angustifolia, and T. latifolia were the best candidates for phytodesalinization because they had the highest Na+ and Cl– tissue contents after exposure to Na+ and Cl–-rich nutrient solutions. A second (outdoor) experiment quantified the Na+ and Cl– ion uptake (grams of each ion accumulated per m2 of microcosm). J. torreyi, S. tabernaemontani, T. angustifolia, and T. latifolia accumulated 5.8, 3.9, 8.3, and 9.2 g·m−2 of Na+ and 25.7, 18.2, 31.6, and 27.2 g·m−2 of Cl–, respectively. Of the eight species, T. latifolia and S. tabernaemontani showed the greatest potential to accumulate Na+ and Cl– in a CW environment, whereas S. alterniflora, D. spicata, and P. australis showed the least potential.

Compost Teas and Reused Nutrient Solution Suppress Plant Pathogens In Vitro

In vitro testing was conducted to evaluate the inhibition potential of three compost teas (pine bark, manure, and vermicasting), Root Rescue Landscape Powder® (a mix of mycorrhizae and other beneficial microbes), waste diatomaceous earth (DE; from beer brewing), and a greenhouse nutrient solution, which had been reused for 20 years on six plant pathogens: Fusarium foetens, Rhizoctonia solani, Sclerotinia sclerotiorum, Phytophthora cryptogea, Pythium intermedium, and P. ultimum. The test materials showed in vitro inhibition on most of the test pathogens. Pine bark tea suppressed growth of all six pathogens, and inhibition exceeded 50% after 10 days of coincubation. Vermicasting tea showed over 40% inhibition against S. sclerotiorum and F. foetens; manure tea showed 42% inhibition against F. foetens; DE showed 40% inhibition against F. foetens, S. sclerotiorum, and R. solani; whereas reused greenhouse nutrient solution showed 56.7% inhibition against R. solani and 43.4% inhibition against F. foetens; Root Rescue showed 66% inhibition against P. intermedium. The results suggest that the six test materials have potential in the control of these soil- and water-borne pathogens in plant production system.

Absorção de chumbo e potencial de fitorremediação de Canavalia ensiformes L.

A fitoextração é uma importante técnica usada para descontaminar áreas poluidas por metais pesados. Conseqüentemente, o entendimento das respostas fisiológicas de espécies tropicais com relação à tolerância aos níveis crescentes de contaminantes é fundamental considerando seu possível uso para fitoextração de metais pesados de áreas contaminadas. O objetivo deste estudo foi conhecer o potencial fitoextrator de Canavalia ensiformes L. para o chumbo (Pb). As plantas foram cultivadas em solução nutritiva em casa de vegetação sobre condições parcialmente controladas. O Pb foi testado nas concentrações de 100, 200 e 400 mmol.L-1. O experimento foi montado em blocos ao acaso, usando um esquema fatorial 4 x 1, com três repetições. Foram realizadas análises fisiológicas com o acompanhamento de sintomas, das massas frescas e secas tanto da parte aérea como das raízes, da área foliar, das alturas das plantas e do conteúdo de Pb na solução nutritiva, nas raízes e na parte aérea das plantas. As amostras das plantas (parte aérea e raiz) e da solução nutritiva foram submetidas às análises químicas para determinação de Pb usando a digestão via seca. As plantas de Canavalia ensiformes foram boas acumuladoras e tolerantes ao Pb, demonstrando seu potencial como fitoextratoras para esse metal.

SELECTION OF WATER SPINACH-GENOTYPES (IPOMOEA AQUATICA FORSSK.) FOR CULTIVATION IN GREENHOUSES

ISHS VII International Symposium on Protected Cultivation in Mild Winter Climates: Production, Pest Management and Global Competition SELECTION OF WATER SPINACH-GENOTYPES (IPOMOEA AQUATICA FORSSK.) FOR CULTIVATION IN GREENHOUSES

Detection of Xanthomonas campestris pv. pelargonii in geranium and greenhouse nutrient solution by serological and PCR techniques

Specificity of a new monoclonal antibody, 2H5, to Xanthomonas campestris pv. pelargonii, causal agent of geranium bacterial blight, was determined by enzyme-linked immunosorbent assay (ELISA) and immunofluorescence tests on 14 strains of X. c. pelargonii, 12 strains of other X. campestris pathovars, 3 strains of other Xanthomonas spp., 3 strains of other plant pathogens, and 43 saprophytic bacteria isolated from geranium. X. c. pelargonii was detected in tissue from symptomatic and asymptomatic geraniums sampled from commercial growers, and artificially inoculated plants, by monoclonal antibody-based tests. The intensity of response in ELISA was only moderately correlated (r = 0.56) with symptom severity, while symptom severity was not correlated (r = 0.16) with the number of fluorescing cells in immunofluorescence. The bimodal frequency distribution of ELISA and immunofluorescence results served to validate arbitrarily chosen positive/negative threshold values. Most positive ELISA and immunofluorescence test results were confirmed by the polymerase chain reaction (PCR) using published primers (Manulis et al., 1994. Appl. Environ. Microbiol 60, 4094-4099). In contrast to plant tissue, the bacterium was detected in greenhouse nutrient solution with greater sensitivity by immunofluorescence and PCR than by ELISA. Sensitivity of detection was enhanced 100-fold by concentration of the bacteria by centrifugation.

Chloride and Sulfate Salinity Effects on Selenium Accumulation by Tall Fescue

The discovery of high levels of Se in soil and water samples from the San Joaquin Valley, California, and of its responsibility for deformity and death of wildlife at Kesterson National Wildlife Refuge have renewed interest in the bioaccumulation of this element. Greenhouse nutrient solution culture and field experiments were conducted to examine the effects of Cl and SO4 salt on growth and Se accumulation in tall fescue (Festuca arundinacea Schreb.) cultivars Alta, Falcon, and Olympic. Sulfate salt substantially reduced growth inhibition and Se accumulation. Tall fescue from the field irrigated with water low in salinity had higher tissue Se concentration than plants from the field irrigated with water high in salinity. No difference in tissue Se concentration was found among the three tall fescue cultivars; however, forage‐type Alta produced the most shoot biomass and accumulated the most total Se. The soil irrigated with water high in salinity had 10 times higher Se concentration thansoil irrigated with water low in salinity. The highest soil Se concentration was found in the top 15 cm of soil. Growing fescue for one year reduced soil Se by 50%. Selenium concentrations below 15‐cm depth were lower and similar between the bare soil and the soil under tall fescue. Both the high and low salinity water irrigations did not cause high levels of Se accumulation by the tall fescue cultivars unless there was continual addition of Se into the system. This study generated important information for Se bioaccumulation management in soils with elevated salinity and Se levels.

Diniconazole's effect on peanut (Arachis hypogaea L.) growth and development

Greenhouse nutrient solution studies demonstrated that diniconazole will decrease peanut (Arachis hypogaea L.) shoot growth when either root or shoot applied. Root growth and development were decreased by root and, to a lesser extent, by shoot uptake of diniconazole. Diniconazole is apparently xylem translocated, but not phloem translocated. Concentrations of 200 ppb ES isomer of diniconazole in nutrient solution (root uptake) increased specific leaf weight and starch deposits in the leaf. Field applications of 193 g ES isomer ha−1 of diniconazole reduced main stem height by 33%, leaf area index by 16%, and total vegetative dry weight by 19%, but had no effect on average leaf size. Decreased germination of seeds from plants treated with 1435 g ha−1 diaminozide was associated with increased seed dormancy. Seed dormancy was counteracted by either ethylene gas or storage for 150 days after harvest. Soil applications of diniconazole were more effective than foliar appliations in reducing vine growth. Diniconazole's ER isomer is a broad spectrum fungicide that reduced damage (when compared to the control) bySclerotium rolfsii andRhizoctonia solani. The reduced damage by these diseases was thought to be the primary reason for the significant pod yield increase (when compared to the control) observed with the diniconazole treatments. In drought-stressed plots, populations of the two-spotted spider mite (Tetranychus urticae) were increased by diniconazole.

Soil-bound 3,4-dichloroaniline: source of contamination in rice grain.

Halogenated anilines (3,4-dichloroaniline or 3-chloroaniline) have been detected in all tested market rice samples (STILL and MANSAGER 1969). The parent compounds of these residues were assumed to be the herbicides employed on the respective fields. The herbicide propanil (3,4-dichloropropionanilide) is a selective herbicide for weed control in rice fields (SMITH 1961). In soil and plants, especially rice plants, propanil is rapidly hydrolyzed to propionic acid and 3,4-dichloroanillne (DCA) (BARTHA and PRAMER 1970, STILL and KUEIRIAN 1967). The former is completely degraded while most of the DCA persists in form of soilbound residues (BARTHA 1971, HSU and BART}IA 1974a). The pesticide is usually applied to rice fields when plants are very young; therefore, the aniline appearing in rice grains must have originated from soil and/or plant storage sites. We thought it important to determine the source of this contaminant of market rice and wish to report here the results of some studies on the mobility of persistent anilines using radiolabeled DCA applied to soil and to leaves of developing rice plants. EXPERIMENTAL Soil. The soil employed in these experiments was obtained through the courtesy of R. J. Smith, U.S.D.A., and originated from a rice field in Arkansas. To improve its texture, the soll was mixed with sand at a soil/sand ratio of 1:3 and filled to 2.5 cm from the top of nine 23 cm x 23 cm porcelain pots (side draining). The pots were watered and additional soil added So that all nine pots contained the same volume. Rice Plants. All plants were maintained in the greenhouse for a 28-week period (December 16 to July 9). Untreated rice seed (Oryza sativa var. Starbonnet) was obtained from the Jacob Hartz Seed Co., Stutgart, Arkansas, and was germinated in vermiculite. Watered with a routine greenhouse nutrient solution, seedlings were allowed to develop to the 3-4 leaf stage. Plants at the 4-1ear stage were then selected and transplanted to the soil/