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Unlike in soil culture, a substrate (nutrient solution) in a hydroponics system can flow, and this can affect both nutrient uptake and plant growth. In this study, we hydroponically cultivated Swiss chard (Beta vulgaris L. ssp. cicla) under different flow rates to analyze changes in the growth, nutrient uptake, and nutrient use efficiency. When the flow rate was intensified from 2 to 4 L/min, leaf area, the fresh weight, dry weight, and root length increased. However, when the flow rate was increased from 4 to 8 L/min, values of these growth parameters decreased. The nutrient uptake had a similar trend relative to the growth parameters and nutrient use efficiency of macronutrient elements, increased as the flow rate increased. This indicates that the flow rate affects plant growth by influencing the nutrient uptake, and an increase in the flow rate can aid in improving nutrient use efficiency. In hydroponics, regulating the flow rate at a reasonable volume is recommended to increase yield by enhancing nutrient use efficiency, but too intensive a flow rate may cause excessive physical stimulation to plants and inhibit their growth. Therefore, it is important to choose an appropriate substrate flow rate for optimal hydroponics production.

Crop production under hydroponic environments has many advantages, yet the effects of solution flow rate on plant growth remain unclear. We conducted a hydroponic cultivation study using different flow rates under light-emitting diode lighting to investigate plant growth, nutrient uptake, and root morphology under different flow rates. Swiss chard plants were grown hydroponically under four nutrient solution flow rates (2 L/min, 4 L/min, 6 L/min, and 8 L/min). After 21 days, harvested plants were analyzed for root and shoot fresh weight, root and shoot dry weight, root morphology, and root cellulose and hemicellulose content. We found that suitable flow rates, acting as a eustress, gave the roots appropriate mechanical stimulation to promote root growth, absorb more nutrients, and increase overall plant growth. Conversely, excess flow rates acted as a distress that caused the roots to become compact and inhibited root surface area and root growth. Excess flow rate thereby resulted in a lower root surface area that translated to reduced nutrient ion absorption and poorer plant growth compared with plans cultured under a suitable flow rate. Our results indicate that regulating flow rate can regulate plant thigmomorphogenesis and nutrient uptake, ultimately affecting hydroponic crop quality.

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.

The amaranthaceous dwarf glasswort, Swiss chard, table beet, spinach and Mexican tea were grown in solutions containing 0, 20, 40, 80, 120, 160, 180 and 200 mol m−3 sodium chloride (NaCl). Maximum growth and increase of biomass production compared to that at 0 mol m−3 of dwarf glasswort was observed at 200 mol m−3 (245%), and Swiss chard (146%), table beet (128%) and spinach (138%) at 80 mol m−3. The growth of these species increased with increasing sodium (Na) concentration of shoot until it reached 4.18, 2.42, 1.60 and 1.58 mol kg−1, respectively. These indicate that the order of Na-loving character is dwarf glasswort >> Swiss chard > table beet = spinach. The water contents increased with increasing Na concentration until growth reached maximum in dwarf glasswort and Swiss chard. In these highly Na-loving species, Na is activity transported to shoots and utilized for producing osmotic pressure to absorb water.

Salinity is known to reduce NO 3 − uptake in many plants. Our previous study found that the increasing NaCl concentrations in media enhanced NO 3 − uptake in leaves. Here, we investigated whether nitrate ( NO 3 − ) uptake by Swiss chard (Beta vulgaris var. cicla L.) was affected more by Na+ than by K+, and elucidated which NO 3 − uptake processes were related to the application of these ions in the culture medium. Plants were grown hydroponically and subjected to 5 mM or 50 mM of either K or Na treatments for 7 days: K5 (K 5, Na 0), K50 (K 50, Na 0), Na5 (K 0, Na 5), and Na50 (K 0, Na 50). The leaf NO 3 − concentration was significantly enhanced in the Na treatments compared with the K treatments. The ratio of leaf to root NO 3 − concentrations in K5 and Na5 were 0.46 and 1.59, respectively, which indicates that NO 3 − is translocated to the leaves in the Na treatments. The NO 3 − concentration in the xylem sap, collected 6 h after the start of the treatments, was significantly higher in Na50 than in the other treatments. These are the opposite of the results for Arabidopsis, which accumulates NO 3 − in its roots to increase its salinity tolerance. Our results suggest that Na but not K enhances NO 3 − uptake and transport to the leaves in Swiss chard and that its function may relate to xylem translocation of NO 3 − .

Saline soil and saline groundwater reduce agricultural productivity on drylands. We are developing a new aquaponics system to improve food productivity on such lands while effectively utilizing saline groundwater. In this study, cultivation of Swiss chard (Beta vulgaris L. spp. cicla cv. Seiyou Shirokuki) was carried out using fish wastewater with a high salt concentration (1150 mg L−1 NaCl). The levels of microelements (e.g., Fe, Mn, Zn, and Cu) in the fish wastewater were very low, so we added microelements at 100% (W100), 50% (W50), 25% (W25), and 0% (W0) of the levels in the standard hydroponics solution to the fish wastewater and investigated the effects on growth of Swiss chard. At the first harvest, yields in all wastewater treatments were as high or higher than in the control. At the second harvest, yields in W100, W50, and W25 were not significantly different from the control, while in W0 the yield was significantly lower and chlorosis was evident. At the third harvest, the yield in all wastewater treatments was less than in the control, and chlorosis symptoms were observed in W25 and W0. Since leaf Mn and Zn concentrations in W25 and W0 had decreased to below the critical values for those microelements, Mn and Zn deficiency might have contributed to the observed chlorosis and yield loss. For the cultivation of Swiss chard with fish wastewater, sufficient yield (i.e., comparable to or better than the control) without chlorosis was obtained when microelements were added at 50% of the level of the control solution. In addition, since sufficient yield was obtained even in W0 at the first harvest, it is suggested that longer-term cultivation and higher yield could be achieved by applying 50% microelements after the first harvest.

Swiss chard (Beta vulgaris var. cicla L.) is a halophilic plant, which has increased growth under moderate salinity. The stimulation of total nitrogen (N) concentration was also observed with the increase of sodium chloride (NaCl) levels in previous studies. The purpose of this study was to investigate whether the stimulation of N uptake is the result of growth stimulation or the direct effect of NaCl. We compared the effects of NaCl on nitrate (NO3–) uptake and nitrate reductase (NR) activity in halophilic Swiss chard with those in salinity-tolerant barley (Hordeum vulgare L.). Both species were grown hydroponically at NaCl concentrations ranging from 0 to 100 mmol L−1. Leaf dry weight of both species was not significantly affected by the treatments. In barley extracted leaf sap, the NO3– concentration was positively correlated with the potassium ion (K+) concentration, but negatively correlated with the sodium ion (Na+) concentration. In contrast, in Swiss chard extracted leaf sap, the Na+ and N...

A toxic protein, called bolevenine, was isolated from the toxic mushroom Boletus venenatus based on its lethal effects on mice. On SDS-PAGE, in either the presence or absence of 2-mercaptoethanol, this protein showed a single band of approximately 12 kDa. In contrast, based on gel filtration and MALDI-TOFMS, its relative molecular mass was estimated to be approximately 30 kDa and approximately 33 kDa, respectively, indicating that the protein consists of three identical subunits. This toxin exhibited its lethal activity following injection at 10mg/kg into mice. The N-terminal amino acid sequence was determined up to 18, and found to be similar to the previously reported bolesatine, a toxic compound isolated from Boletus satanas.

Ingestion of the toxic mushroom Boletus venenatus causes a severe gastrointestinal syndrome, such as nausea, repetitive vomiting, diarrhea, and stomachache. A family of isolectins (B. venenatus lectins, BVLs) was isolated as the toxic principles from the mushroom by successive 80% ammonium sulfate-precipitation, Super Q anion-exchange chromatography, and TSK-gel G3000SW gel filtration. Although BVLs showed a single band on SDS-PAGE, they were further divided into eight isolectins (BVL-1 to -8) by BioAssist Q anion-exchange chromatography. All the isolectins showed lectin activity and had very similar molecular weights as detected by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis. Among them, BVL-1 and -3 were further characterized with their complete amino acid sequences of 99 amino acids determined and found to be identical to each other. In the hemagglutination inhibition assay, both proteins failed to bind to any mono- or oligo-saccharides tested and showed the same sugar-binding specificity to glycoproteins. Among the glycoproteins examined, asialo-fetuin was the strongest inhibitor. The sugar-binding specificity of each isolectin was also analyzed by using frontal affinity chromatography and surface plasmon resonance analysis, indicating that they recognized N-linked sugar chains, especially Galbeta1-->4GlcNAcbeta1-->4Manbeta1-->4GlcNAcbeta1-->4GlcNAc (Type II) residues in N-linked sugar chains. BVLs ingestion resulted in fatal toxicity in mice upon intraperitoneal administration and caused diarrhea upon oral administration in rats.