Concentration In Nutrient Solution Research Articles

Study on the optimum nutrient solution concentration for the growth of Mint (Mentha genus)

Mint (Mentha genus) is an herbaceous herb that is fragrant useful for centuries with spices and medicinal herbs. Study on optimum nutrient solution sufficient to meet the plants’ demands regarding soilless culture of mint would be helpful for its application in plant factory, but was less reported. In the current study, 0.5 fold (×), 0.75×, 1.0× and 1.25× concentrations of Yamazaki formula nutrient solution were applied to culture the mint seedlings using river sand as the substrate. The results showed that 0.75× concentration of nutrient solution was optimum for mint seedlings across 15 to 36 days treatments, which dramatically promoted the growth rates, enhanced the content of chlorophyll, and improved yield as well as quality, followed by other desirable concentrations, ranking as 0.5×> 1.0×> 1.25× times, on growth of mint were distinct. Therefore, we concluded that the optimum concentration for mint seedling growth was 0.75× concentration, and highlighted the importance of using Yamazaki formula nutrient solution for mint seedlings growth, which potentially guides soilless cultivation of mint. Key words: Mint, Japanese raw materials, nutrition, hydroponics.

Potassium-Deficient Nutrient Solution Affects the Yield, Morphology, and Tissue Mineral Elements for Hydroponic Baby Leaf Spinach (Spinacia oleracea L.)

Nutrient supply in hydroponics can significantly influence the nutrition, taste, texture, color, and other characteristics of fruit and vegetable crops. Chronic kidney disease (CKD) is a global health problem that frequently restricts a patient’s consumption of high-potassium foods. CKD patients are advised to limit their consumption of many vegetables that are potassium (K)-rich. At the same time, reducing vegetable intake reduces the intake of healthy compounds such as vitamins, fibers and antioxidants, which are beneficial to CKD patients. In our study, we investigated the reduction of the K concentration in a hydroponic nutrient solution as a possible technique to decrease the K tissue concentration of baby leaf spinach, a dark green that is frequently recommended to be consumed in moderation for patients with CKD. A previously developed hydroponic fertilizer recipe that provides a platform to adjust individual nutrients was used to adjust K to 0, 10, 25, and 100% of the control K concentration. Tissue K levels were reduced by up to 91% with a consequent 61% reduction in dry weight and 76% reduction in fresh weight (yield) with respect to the control treatment. Overall, the results suggest that using a nutrient solution without K can significantly reduce K concentrations in baby spinach, although this will consequently reduce yields.

Organic Waste-Based Fertilizer in Hydroponics Increases Tomato Fruit Size but Reduces Fruit Quality.

In regions with intensive agricultural production, large amounts of organic waste are produced by livestock animals. Liquid digestate from manure-based biogas production could potentially serve as fertilizer if integrated with closed horticultural irrigation systems. The aim of this experiment was to investigate how fertilizer based on liquid biogas by-products of pig manure digestion can affect the growth and production of tomato plants. Integration of a nitrification bioreactor presumes a significantly lower concentration of nutrient solutions and a higher level of oxygenation than classical mineral cultivation. Therefore, additional controls were included. We compared plant growth and fruit quality traits of tomato plants grown in a hydroponic solution with organic fertilizer with two levels of mineral fertilizer. The tomatoes grown with organic waste-based liquid fertilizer showed reduced growth rates but increased mean fruit size, resulting in no significant change in total yield compared with high-mineral cultivation. The growth rate was similarly reduced in plants cultivated with low-mineral fertilizer. Plants cultivated with organic waste-based fertilizer had high Cl− concentration in xylem sap, leaves, and, ultimately, fruits. The leaves of plants cultivated with organic waste-based fertilizer contained higher concentrations of starch and soluble carbohydrate and low concentrations of phosphorous (P) and sulfur (S). The plants grown with organic waste-based or low-mineral medium showed significantly poorer fruit quality than the plants cultivated with the high-mineral solution. The low-mineral treatment increased xylem sap contribution to fruit weight because of higher root power. The organic waste-based fertilization did not change the root power but increased fruit size. In conclusion, organic waste-based cultivation is a possible solution for sustainable plant production in greenhouses. However, additional adjustment of nutrient supply is required to improve fruit quality.

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

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.

Improving Plant Health Through Nutrient Remineralization in Aquaponic Systems.

The exploitation of readily bioavailable fish excreta as a source of plant nutrients lies at the cornerstone of aquaponics farming. Research on nutrient cycling in aquaponic systems has devoted considerable attention to the plant uptake of dissolved nutrients in fish excreta, however, the integration of particulate-bound nutrients into downstream hydroponic farming has remained elusive. The high amount of organic carbon present in fish sludge may lead to biofouling if directly incorporated into hydroponic circulation systems, reducing the utility of incorporating fish solids on a large scale. In this study, we implemented a novel treatment system capable of reducing the carbon and nitrogen load of fish solids to produce a liquid fertilizer for a downstream hydroponics unit. Lettuce (Lactuca sativa) fertilized with exclusively a commercial nutrient solution, the biofilter effluent (coupled aquaponic system), effluent from the solids treatment system, or the latter two combined were grown in nutrient flow technique gutters downstream of a recirculating aquaculture system stocked with rainbow trout (Oncorhynchus mykiss). While crop yields were lower for the aquaponic treatments compared to lettuce grown in a commercial nutrient solution, plant sap analysis demonstrated a contrasting picture with respect to internal nutrient concentrations. Lettuce grown in the commercial hydroponic solution were deficient in several mineral nutrients (Mg, Ca, Na, and Si) nor did they have higher iron concentrations despite the significantly higher EDTA-chelated aqueous iron (460 × greater than other treatments) in the nutrient solution. Nutrient uptake in the rhizosphere was not investigated on a molecular level, although stunted rhizosphere growth in the commercial nutrient solution control suggests a weakened capacity for nutrient uptake in comparison to other treatments. Alongside the remineralization of micronutrients, the solids treatment system addressed the common issue of excess carbon leading to biofouling via a total suspended solids reduction of 87.27% ± 9.95 during the coupled aquaponics cultivation period. Ultimately, these data lead to two important conclusions. Firstly, optimizing nutrient bioavailability is not synonymous to increasing the presence of a nutrient in the water column. Secondly, estimating ideal nutrient solution concentrations involves both preventing nutrient blocking and improving bioavailability.

Pengaruh Berbagai Perlakuan Nutrisi Larutan Hidroponik Pada Pertumbuhan Tanaman Kangkung (Ipomoea aquatica)

Hydroponic cultivation systems are often applied to overcome the shortage of agricultural land in this case food crops, especially vegetables. Nutrient Film Technique (NFT) is the one of various ways to grow crops hydroponically. Hydroponic systems are carried out without the use of soil media and it can be an alternative solution for the efficient use of land. Uniformity of nutrients and nutrient solution concentration levels required to be adjusted. Nutrient solution as a water supply source and minerals. Nutrition is an important factor for the growth and quality of hydroponic plants should be appropriate in terms of the number of ion composition of nutrients. This study aimed to determined the effect of various treatments of hydroponic nutrient solution on plant growth kale. This study used a completely randomized design (CRD) with 4 treatments and 5 replications. Kale seed sowing in the growing media rockwool and nourished by nutrient A, nutrient B, combination of nutrients A and B (3: 1), or a combination of nutrients A and B (1: 3). Plant growth parameters such as plant height, number of leaves, wet weight, dry weight, and dry weight without root measured. Data were analyzed using analysis of variance ANOVA and DMRT test with α = 95%. The results showed that affect the nutrient solution hydroponic plant growth kale. Kale plants with a combination of nutrient A and nutrient B ratio of 3: 1 (treatment C) give the best response compared with other treatments.

RESPONS PERTUMBUHAN DAN HASIL TANAMAN SELEDRI (APIUM GRAVEOLENS L.) TERHADAP MEDIA TANAM DAN KONSENTRASI LARUTAN NUTRISI YANG BERBEDA PADA WICK SYSTEM

This research aims to find out 1) the interaction between the medium of planting and the concentration of nutrient solutions to the growth and yield of celery plants hydroponically. 2) types of planting media that can give different influences on the growth and yield of celery plants, and 3) concentration of nutrient solution that provides the best growth and yield of celery plants in different planting media.The research was conducted from December 2019 to February 2020 at the Integrated Laboratory of the Faculty of Agriculture of Mulawarman University, Samarinda. The research used factorial exsperiment 3×4 on Randomized Completely Block Design (RCBD), replicated three times with each treatment consisting of three plants. The first factor is the planting medium consisting of rockwool, charcoal husk, and combination of charcoal husk + tea amps. The second factor is the concentration of AB Mix nutrient solution consists of 500, 1,000, 1,500, and 2,000 ppm. The data was analyzed with test F and continued Least Significant Difference (LSD) test with a level of 5%. The results showed that there is an interaction between planting media and concentration of nutrient solution in the growth and yield of celery plants. The interaction between the combination of charcoal planting media + tea pulp and concentration of 1,500 ppm is not real with the interaction of rockwool planting media and concentration of 1,500 ppm. From various types of planting media used, charcoal husk planting media provides the best influence on the growth and yield of celery plants. Based on polynomial orthogonal test the concentration of nutrient solution with an optimum point of 1,460.84 ppm affects the growth and yield of celery plants with a maximum dry weight of 2.14 g.

Nitrogen absorption efficiency and mechanism in Arbuscular mycorrhizal fungi - Canna indica symbiosis

Arbuscular mycorrhizal fungi (AMF) and its symbiosis with Canna indica on nitrogen (N) absorption was investigated for the remediation of contaminated soil. Canna indica plants with rhizome and leaf integrity intact were collected in spring and autumn seasons. To maintain the ideal nutrient composition, Hoagland concentrated nutrient solution was diluted with deionized water and additional nutrient solution was added periodically. Treated root samples were observed with an optical microscope and the number of hyphae and intersections as well as inoculation status were examined. High-throughput sequencing experiment was conducted to quantify AMF inoculation. Alpha diversity study was used to characterize abundance and diversity of the symbiosis. Hydroponic experiments were conducted to explore the absorption effectiveness of AMF-Canna symbiosis under different NH4+-N and NO3−-N combinations. Hyphal colonization rate was only about 5.66 ± 1.08% in seedling stage in spring, but enhanced in the adult stage in autumn (53.89 ± 1.43%). Results revealed that AMF had no significant impact on NO3−-N absorption by Canna roots, however, absorption of NH4+-N was improved by 63% under low concentration. Results revealed that when NH4+-N and NO3−-N were applied combinedly in a 1:1 ratio, their respective absorption rates were enhanced to 99.63% and 99.50%. Compared with the case of NH4+-N as N source alone, synergistic effect of NH4+-N and NO3−-N significantly changed the absorption of NH4+-N by C. indica, but its correlation with AMF inoculation was still not significant. Current findings could enhance understanding for effective N uptake and resource recovery.

Effect of nutrient solution concentration on phenology, stevioside content, total phenolic compounds and total flavonoids in leaves of Stevia rebaudiana Bertoni

Among the most interesting areas of food technology research today is the search for natural alternatives to common sweeteners. One of these is Stevia rebaudiana Bertoni, which contains antioxidants and stevioside whose concentration can be affected by factors such as plant nutrition during its production. The objective of the study was to determine the effect of mineral nutrition levels (N, P, K Ca, Mg, S, Fe, Mn, B, Zn, Cu) in Steiner nutrient solution (SNS) on phenology and to quantify chlorophyll concentration (CC), stevioside content (SC), total phenolic compounds (TPC) and total flavonoids (TF) in the leaves of Stevia rebaudiana Bertoni. Five concentrations of SNS were evaluated: 0%, 25%, 50%, 75% and 100%. The experimental design was randomized with three replications. The experimental unit consisted of six plants per treatment (6 x 3 = 18 plants). The highest plant height (18.58 cm) was obtained with the 25% and 100% SNS concentrations; while the highest fresh weight and dry weight (21.70 ± 0.70 and 4.17 ± 0.12 g/ plant) were obtained with a 50% solution. The highest CC (41.31 ± 0.93 SPAD Units) and SC (8.88 ± 0.54 mg of stevioside / g dry matter (DM) were observed with 0% SNS. The highest contents of TF (16.42 ± 1.12 µg RE / g DM) and TPC (8.57 ± 1.12 µg GAE / g DM) were obtained with a 50% SNS solution. Finally, the compounds of interest were analyzed with respect to the total biomass obtained. The 75% SNS solution resulted in the highest amount of stevioside (17.03 mg / plant) and the second highest value for TPC (27.19 µg GAE / plant) and TF (64.57 µg RE / plant) content.

Use of a Portable Rapid Analysis System to Measure Nitrate Concentration of Nutrient and Soil Solution, and Plant Sap in Greenhouse Vegetable Production

A rapid analysis ion-selective electrode (ISE) system for measurement of [NO3−] in nutrient solution (NS), soil solution (SS) and petiole sap (PS) was evaluated. For each material, there were 797–2010 samples from 5 to 6 different crops, and from 2 to 4 different species. Accuracy was evaluated by linear regression (LR) with laboratory analysis (automated colorimetry, Cd reduction), and by relative error (RE), the average percentage deviation from laboratory analysis. For NS, the LR was y = 0.982x + 0.76, R² = 0.962 (n = 2010), for combined data from 5 crops (3 pepper, 2 cucumber). For SS, the LR was y = 0.975x + 1.13, R² = 0.965 (n = 797), for combined data from 5 crops (3 pepper, 2 cucumber). For undiluted PS, the LR relationship was y = 0.742x + 168.02, R² = 0.892 (n = 1425), for combined data from 6 crops (3 pepper, 2 cucumber, 1 melon). The underestimation was most pronounced at [NO3−] of >1500 mg NO3−–N L−1. For diluted petiole sap (dilution by 10 for pepper and melon, 5 for other species), the LR relationship was y = 1.010x + 99.26, R² = 0.927 (n = 1182), for combined data from 6 crops (2 pepper, 2 cucumber, 1 melon, 1 tomato). RE values for all measurements in composite datasets were 14%, 22%, 24% and 25% for NS, SS, undiluted PS and diluted PS respectively, and they were lower in concentrations most likely to be measured in practical on-farm work. The ISE system measured [NO3−] in NS, SS and diluted PS with sufficient accuracy to effectively guide on-farm decision making.

Correlations of Arsenic and Nutrient Elements in Different Tissues of Perennial Ryegrass Under Arsenic Stress

The objectives of this study were to investigate the growth and nutrient absorption in different tissues of perennial ryegrass under several levels of As stress, and to determine the relationships between absorption As and nutrient elements. As treatments at 0, 5, 10, 25, and 50 μM were applied to perennial ryegrass in hydroponic systems, and As and nutrient absorption in the mature leaves, expanded leaves, emerging leaves, and roots were determined. The effects of P, Ca, and Mg on the growth and As absorption of perennial ryegrass under As stress were also investigated. The biomass of the different tissues of perennial ryegrass decreased when the As concentration was greater than 5 μM. The As content was higher in roots relative to leaves regardless of As concentrations in nutrient solution, and leaf As content was greatest in the mature leaves and least in the emerging leaves. The As treatment reduced N, P, Ca, and Mg absorption in different tissues. A positive correlation of As content was found with the Mn content in the roots and all three kinds of leaves. The N, P, and K contents in the leaves were greatest in the emerging leaves and least in the mature leaves. The P, Ca, and Mg application decreased the As absorption of As-challenged perennial ryegrass. Our results indicated that As stress treatment reduced N, P, Ca, and Mg absorption and the As absorption was associated with leaf age and also levels of nutrients. Proper application of mineral nutrients may reduce As absorption of perennial ryegrass.

Investigation of silicon effects on some growth and biochemical parameters of Lens culinaris Medik under salt stress

Salinity is a major abiotic stress limiting plants growth and development. As silicon (Si) has been stated to alleviate salt stress in some plant species, effects of Si on Lens culinaris Medik under salinity were investigated in this study. The effects of four levels of Si in nutrient solution (0, 0.1, 0.25, and 0.5 mM) on the plant growth and physiological parameters under salinity (0, 40, and 80 mM of NaCl) were considered in a factorial experiment. Salinity decreased dry weight, stem length, leaf area, chlorophyll and anthocyanin content, potassium (K) and protein concentration, K to sodium (Na) ratio and root Si content, while increased carotenoids content. Si, especially at 0.1 mM concentration in nutrient solution, increased root and shoot length, plant dry weight and leaf area. However, higher concentrations of Si often had a negative impact on most of the characteristics. Also, some levels of Si treatment significantly increased leaf chlorophyll, carotenoids and anthocyanin, K, Si and protein content but decreased the amount of plant Na content under salinity. In overall, it seems that, the use of low levels of Si is capable to reduce harmful effects of salinity on L. culinaris and improve plant resistance to salt stress.

Optimization of Substrate and Nutrient Solution Strength for Lettuce and Chinese Cabbage Seedling Production in the Semi-Arid Environment of Central Myanmar

The growing population of tropical countries has led to a new awareness of the importance of vegetables as a source of essential foods and nutrients. The success of vegetable cultivation depends to a large extent on high-quality seedlings. This work aimed at evaluating the effects of different substrates and different nutrient solution concentrations on the development of lettuce and Chinese cabbage seedlings in a semi-arid tropical area. Three independent experiments were conducted at the Soil and Water Research Station at Yezin Agriculture University, Myanmar (Myanmar, 19.83° N; 96.27° E). In all experiments a randomized block design was implemented with four treatments and three repetitions. In the first experiment the adaptability of lettuce seedling to two substrates (namely a Hulls Manure mix composed by 50% of mature cattle manure and 50% of carbonized rice husk and a soil based substrate constituted by 70% local soil, 20% burned rice husk, and 10% fresh cattle manure) and two nutrient solutions with different electrical conductivities (ECs) (W0.1, stored rainwater with EC = 0.13 dS m−1 and NS1.2, nutrient solution with EC = 1.20 dS m−1) were tested. In the second and third experiments, two species (lettuce and Chinese cabbage) were assessed for their response to nutrient solution concentrations. In both crops, 4 fertigation treatments (W0.1; NS0.6; NS1.2; and NS1.8) were supplied, by modulating the concentration of a compound mineral fertilizer (15:15:15) in the following ranges: W0.1: 0 g L−1, electrical conductivity (EC) 0.13 dS m−1, NS0.6: 0.3 g L−1, EC of 0.60 dS m−1; NS1.2: 0.6 g L−1, 1.2 dS m−1 EC, and NS1.8: 0.9 g L−1, 1.8 dS m−1 EC. Adopting different substrates and applying different nutrient solutions significantly affected growth (fresh weight and leaf morphology) and some physiological parameters (stomatal conductance, leaf temperature, and leaf chlorophyll content) of lettuce and Chinese cabbage seedling. From the first experiment, the combination of the soil based substrate and NS1.2 treatments allowed us to improve the seedlings’ growth. In the second experiment, highest growth of lettuce and Chinese cabbage seedlings was associated with NS1.2 and NS1.8, respectively. The presented results allow for the optimization of both growing media and nutrient solution management when lettuce and Chinese cabbage seedling are produced in the Central Dry Zone of Myanmar.

Productive and physiological responses of jambu (Acmella oleracea) under nutrient concentrations in nutrient solution

ABSTRACT In the last years, jambu has become popular and greatly appreciated, due to its remarkable taste. Thus, hydroponically cultivated jambu is promising, since it achieves better yield and production quality. The aim of this study was to evaluate the effect of ionic concentration in nutrient solution on growth, productivity and gas exchange of jambu. The experimental design was completely randomized, with five treatments and four replicates. The treatments consisted of variations of ionic concentration using the nutrient solution proposed by Hoagland & Arnon (25, 50, 75, 100 and 125%). The length of the main stem, stem diameter, number of inflorescence, leaf area, fresh and dry biomass (shoot, root and inflorescence), photosynthesis, stomatal conductance, transpiration, internal CO2 concentration, Ci/Ca ratio and instant carboxylation efficiency were evaluated. Ionic concentrations significantly affected the studied variables, except the stem diameter, the internal CO2 concentration and the Ci/Ca ratio. The number of inflorescences and the leaf area grew linearly with maximum values (37.8 units plant-1 and 1650.8 cm2 plant-1, respectively) obtained in ionic concentration of 125%. Maximum responses were observed for shoot fresh and dry mass (63.9 and 6.9 g plant-1), root fresh and dry mass (16.7 and 2.0 g plant-1) inflorescence fresh and dry mass (11.0 and 1.8 g plant-1), respectively, at ionic concentration of 125%. Liquid photosynthesis, stomatal conductance, transpiration and instant carboxylation efficiency achieved maximum responses of 17.9 µmol CO2 m-2 s-1, 0.3 mol H2O m-2 s-1, 6.3 mmol m-2 s-1 and 0.06 with estimated concentrations of 84, 70, 80 and 83% of ionic strength, respectively. Thus, we concluded that the ionic concentration of 125% is indicated to obtain a greater biomass accumulation.

Effects of different calcium concentrations on the outdoor growth of Nostoc sphaeroids Kütz

The technology of indoor cultivation of Nostoc sphaeroids Kütz is relatively mature, but for industrial cultivation, indoor cultivation has the disadvantages of high energy consumption and high cost. In order to find the appropriate amount of calcium concentration required for outdoor cultivation, and to pave the way for mass production of Nostoc sphaeroids Kütz, in this study, the Nostoc sphaeroids Kütz wwas cultivated. The pH, chlorophyll content, polysaccharide content, protein content and phytolithoprotein content of Nostoc sphaeroids Kütz were measured in different concentrations of calcium nutrient solution. The result showed that, with the increase of calcium concentration in outdoor cultivation, the growth of Nostoc sphaeroids Kütz was firstly inhibited and then promoted.

Effects of nutrient solution concentration on plant growth and phytochemical accumulation in substrate-grown spinach

Effects of nutrient solution concentration on plant growth and phytochemical accumulation in substrate-grown spinach

Effects of silica nanoparticles and calcium chelate on the morphological, physiological and biochemical characteristics of gerbera (Gerbera jamesonii L.) under hydroponic condition

A factorial experiment, in the form of completely randomized design with two factors, was conducted in four replicates to investigate the effects of silica nanoparticles (nanoparticle-SiO2) and calcium chelate (Ca-chelate) on gerbera (Gerbera jamesonii L.). The first factor was nanoparticle-SiO2 concentration in nutrient solution (at four levels of 0, 20, 40 and 80 mg L−1) and the second factor was Ca-chelate concentration in nutrient solution (at four levels of 0, 60, 120 and 240 mg L−1). Number of leaves, number of flowers, number of flower buds and aborted flower buds, time of flowering, flower vase life, flower color, percentages of ash and lignin in stem, petal protein, as well as the amounts of silica and calcium in stem, leaf and root were measured. Compared to control, the treatment of 80 mg L−1 of nanoparticle-SiO2 with 60 mg L−1 of Ca-chelate increased the number of flowers by 182%. Moreover, applying 60 mg L−1 of Ca-chelate and 20 mg L−1 of nanoparticle-SiO2 led to flowers with 1.5 times higher longevity and 27% increase in flowering rate. The highest flower bud numbers and the lowest bud abortion were obtained in the treatment with 80 mg L−1 of nanoparticle-SiO2 and 60 mg L−1 of Ca-chelate. The highest concentration of calcium in stem, leaf and root as well as the highest amount of protein, pigment intensity and degree of transparency were observed in the treatment with 240 mg L−1 of Ca-chelate and 80 mg L−1 of nanoparticle-SiO2.

Inexpensive ion-selective electrodes for the simultaneous monitoring of potassium and nitrate concentrations in nutrient solutions.

A fast, simple and inexpensive potentiometric method has been developed for the determination of the major ions potassium and nitrate in nutrient solutions, by means of ion-selective electrodes (ISEs) based on plasticized polyvinyl membranes containing an ion-exchanger. Tridodecylmethylammonium chloride (TDMACl) and potassium tetrakis(4-chlorophenyl)borate (KTClPB) were used as ion-exchangers for the nitrate and potassium electrodes, respectively. Electrode membranes built with different plasticizers, bis-[2-ethylhexyl]-sebacate (DOS), tricresyl phosphate (TCP) and 2-nitrophenyloctyl ether (NPOE), were tested, and NPOE was selected. The electrodes were calibrated over both wide and narrow concentration ranges and residual analysis was made. Based on the results of these calibrations, the method of standard addition was developed and found to be suitable for the simultaneous determination of potassium and nitrate in nutrient solutions. A large group of samples taken from different stages of hydroponic crops was analysed. Several approaches recommended for statistical comparisons of the results obtained by potentiometric and by reference methods were tested, obtaining satisfactory results. The potentiometric methodology developed is promising for monitoring the concentration of these essential nutrients in nutrient solutions.

Commercial substrates and nutrient concentrations in the production of arugula microgreens

The objective of this study was to evaluate the effects of different substrates and concentrations of nutrient solutions in the production of arugula (Eruca sativa Miller) microgreens grown in a protected environment at the campus of the Faculty of Agronomy of the Federal University of Rio Grande do Sul (UFRGS), in Porto Alegre, Brazil. The treatments consisted of the combination of five commercial substrates, CSC® vermiculite (S1), Green-Up phenolic foam (S2), S10 Beifiur® organic (S3), Carolina Soil® seedlings (S4), and Carolina Soil® organic (S5) and three concentrations of nutrients in the nutrient solution (0, 50, and 100%). A 5x3 factorial arrangement was used, in a completely randomized experimental design with three replicates. The addition of nutrients in the irrigation solution favored substrates S1, S4, and S5. Substrate S2 showed better performance with the addition of 50% of the total concentration of nutrients. Substrate S3 without the addition of the nutrient solution showed average values very close to the use of the nutrient solution, which can be considered in the evaluation of production costs of microgreens, generating savings to producers.

Effects of Nutrient Solution Concentration, Cultivars, and Culture Methods on Leaf Resistance of Tomato Plant

Effects of Nutrient Solution Concentration, Cultivars, and Culture Methods on Leaf Resistance of Tomato Plant