Effect of various potassium‐calcium ratios on cation nutrition of grape grown hydroponically

The effect of potassium (K)‐calcium (Ca) ratios on the cation nutrition of Vitis vinifera L. cv. Négrette was investigated on grafted vines grown hydroponically to gain a deeper insight into the origin of the lack of acidity of some wines. Four nutrient solutions were investigated for long duration experiments: a balanced K‐Ca nutrient solution (K=3.9 meq L^‐1 ; Ca=4.8 meq L^‐1) used as a reference, a low K (K=0.3 meq L^‐1; Ca=8.4 meq L^‐1) and a high K (K=7.1 meq L^‐1; Ca=1.6 meq L^‐1) nutrient solutions. Besides, the reference nutrient solution was enriched with Ca (K=3.9 meq L^‐1; Ca=13.8 meq L^‐1) so as to simulate the possible effects of liming. The experiments showed that, in spite of low K requirements, the high K storage capacity of cultivar Négrette might account for the low acidity of the wines. However, a strong Ca‐K antagonism was characterized: the Ca enrichment of the reference nutrient solution resulted in a 30% decrease in the K concentration of leaf blades and petioles. Liming can thus limit K uptake by the plant and contribute to increased acidity of the wines issued from cultivars grown in acid soils.     

Effect of nutrient solution salinity and ionic concentration on parsley (Petroselinum crispum Mill.) essential oil yield and content

The growth and essential oil (EO) production of parsley were evaluated in response to salinity and nutrient solution concentrations in a soilless culture. Parsley plants that were 60 days old were potted in a coconut fiber and peat moss medium and were treated with four different nutrient solutions, including T1, T2, T3 and T4. The T1 nutrient solution was the standard, the T2 and T3 solutions contained incremental macronutrient concentrations with an electrical conductivity (EC) of up to 2.2 and 3.2 dS m^?1, respectively, and the T4 solution was the same as T2 but with sodium chloride (NaCl) and an incremental macronutrient concentration with an EC of 3.2 dS m^?1. Next, these plants were grown for 90 days in a greenhouse with natural daylight in Nador, Morocco. Shoot and root growth significant decreased with increasing EC. However, the salinity that resulted from the addition of NaCl did not affect plant growth in the nutrient solutions. The optimum obtained growth and EO production were 1.2 and 2.2 dS m^?1, respectively. Consequently, the optimum EC value (based on the EO production) of parsley in the soilless culture was 1.2–2.2 dS m^?1.     

Comparison of the mineral composition of twelve standard nutrient solutions

In the past, a large number of standard nutrient solutions has been devised. To investigate if there is an essential difference between these standard solutions, the mineral composition of 12 standard nutrient solutions formulated between 1865 and 1994 are compared with each other. Half of these standard solutions contain ammonium (NH₄ ⁺) in a millimolar range. The effect of elemental speciation of the micronutrients in the 12 standard solutions on bioavailability is compared. The macronutrient composition is represented in trilinear coordinates, making a clear comparison of the proportions of both the cations and the anions possible. Also the pH and the total amount of ions present are compared.     

Effects of nitrogen form of nutrient solution on uptake and concentration macro element and morphological trait in hydroponic tulip

Effects of nutrient solution composition ratio on (Tulipa gesneriana L.) cv, ?Apricot Parrot? and ?Daytona? growth and flowering were studied hydroponics. Plants were grown with five treatments respectively: S₁(0), S₂(0.01), S₃(0.02) S₄(0.03) and S₅(0.04) meq L^.-1 ammonium or 0,0.38, 0.74, 0.11 and 0.14 ammonium (NH₄⁺)/NH₄+nitrate (NO₃)^?ratios. Flowering was accelerated by increase of ammonium level for both cultivars. Nutrition solution was not significant on the stem length of Daytona cultivar, but maximum flowering stem length occurred S₂ solution for Apricot Parrot cultivar. Increasing ammonium level, decreased potassium concentration in the aerial parts. Total nitrogen of new bulbs decreased with increasing ammonium level for both cultivars. Maximum bulblet production rate occurred in plants that were fed with S₅ solution. Maximum flower longevity was in S₂ solution for both cultivars. growth and quality of tulip were affected by ammonium level in nutrient solution, so for obtain the best flower quality must added to nutrient solution.     

pH Influenced by the elemental composition of nutrient solutions

Nutrient solutions can be considered as aqueous solutions of inorganic ions. The pH of a nutrient solution is a property that is inherent to its composition. If another pH is aimed at, this can only be reached by changing the elemental composition. The pH of an aqueous solution is determined by the initial concentration of acids and bases. In the case of nutrient solutions, this is dihydrogen phosphate (H₂PO₄ ^‐), bicarbonate (HCO₃ ^‐) and/or ammonium (NH₄ ⁺). In this study, formulas are derived to calculate the pH of a nutrient solution as a function of the concentration of H₂PO₄ ^‐, NH₄ ⁺, and/or HCO₃ ^‐. The pH of a nutrient solution affects the dissociation, complexation, and precipitation reactions occurring in nutrient solutions. These chemical reactions significantly impact elemental speciation and bioavailability, and therefore, have to be taken into account in hydroponic plant nutritional research. The term “speciation”; indicates the distribution of elements among their various chemical and physical forms like: free ions, soluble complexes, chelates, ion pairs, solid and gaseous phases, and different oxidation states, all of which influences their reactivity, mobility and bioavailability. A good knowledge of the chemical reactions occurring in nutrient solutions is the first prerequisite in hydroponic plant nutritional research. The pH of a nutrient solution is determined by its initial concentration of H₂PO₄ ^‐, NH₄ ⁺, and HCO₃ ^‐.     

Elemental bioavailability in nutrient solutions in relation to precipitation reactions

In hydroponic plant nutritional research, nutrient solutions can be considered as aqueous solutions of inorganic ions. In this aqueous solution, the ions are submitted to the laws of aquatic inorganic chemistry. This means that the ions are involved in the dynamic equilibria between complexation, dissociation, and precipitation reactions. These chemical reactions seriously impact elemental speciation and bioavailability. As a result, plant roots experience a different nutritional composition. Ions withdrawn from the‐nutrient solution due to precipitation reactions, change the nutritional composition and are not available for uptake by plant roots. Like complexes, precipitates can buffer a nutrient solution, exchanging nutrients as these decrease by plant uptake. This research looks into the precipitation reactions that occur in hydroponic nutrient solutions. In the concentration range of nutrient solutions, no precipitates are formed involving potassium (K⁺), nitrate (NO₃ ^‐), ammonium (NH₄ ⁺), or sulphate (SO₄ ^2‐), while calcium (Ca²⁺) and magnesium (Mg²⁺) form mainly at a higher pH precipitates with hydrogen phosphate (HPO₄ ^2‐). Preparing nutrient solutions with tap water, calcium carbonate (CaCO₃) is likely to precipitate. A good knowledge of the chemical reactions occurring in nutrient solutions is the first prerequisite in hydroponic plant nutritional research.     

Nutrient solution concentration on pepper grown in a soilless closed system: yield,fruit quality,water and nutrient efficiency

Abstract

The aim of the experiment was to verify how the adoption of a reduced strength nutrient solution in a soilless closed system could influence the production and quality of pepper and improve the use efficiency of water and minerals. Two nutrient solutions characterized by the same ion ratio but macronutrient concentration equal to 100% or 60% were adopted. The total yield did not differ between the treatments; however the lower concentration of nutrients determined a significant reduction of incidence of unmarketable fruits (blossom-end rot) and thus a higher marketable production (+15%). Within the fruit quality characteristics the dry matter content and the titratable acidity were significantly higher adopting the full strength nutrient solution. Important differences were found when the agronomic water use efficiency was considered: the weight of marketable pepper produced per m³ of water input was about 32% higher using the reduced concentration treatment according to the lower volume of water released in the environment due to the lower renewal of recirculated nutrient solution. A similar pattern was observed for the use efficiency of the main nutrients. With reduced strength nutrient solution the amounts of nitrogen, phosphorus and potassium released per ton of marketable tomatoes were respectively 83%, 80% and 81% lower than the control. The use of a reduced strength nutrient solution in soilless closed system for pepper cultivation did not influence the total yield and improved the use efficiency of water and minerals. Moreover, the environmental impact of the system was drastically reduced.     

Balance and concentration of nitrogen and potassium affect growth and nutrient status in soilless cultivated lisianthus

Purpose: Nitrogen (N) / potassium (K) nutrient balance has been studied for some ornamental plants, however, available information is limited. Here we investigate the optimum N and K balance and concentration for lisianthus production in soilless medium.

Materials and methods: The effect of three N / K balances: 1.43, 2.14 and 4.29, prepared by varying the concentration of N and K, were evaluated in lisianthus grown in soilless medium (volcanic rock).

Results: Plants fertigated with a N / K balance of 2.14 exhibited enhanced height and stem dry weight when compared to plants fertigated with a balance of 4.29, and a higher flower buds count and total dry weight than those fertigated with a balance of 1.43 or 4.29. Plants fertigated with a balance of 2.14 exhibited increased dry weight when N was reduced from 15 to 9?meq?L^?1 and K from 7 to 4.2?meq?L^?1, suggesting that lisianthus does not require high levels of these nutrients. Although shoot N concentration was not correlated with N concentration in the nutrient solution or balance, increasing N in the shoot was associated with higher P and Mg in the plant tissues. In general, P, Ca, and Mg in plant tissues were unaffected by the external N / K balance, however, the internal P and Mg concentrations were positively correlated with shoot dry weight. Shoot K concentration significantly increased when the N / K balance decreased, which is related to the higher concentrations of external K when the balance decreased.

Conclusions: The optimum N / K balance for lisianthus was 2.14. However, there was a concentration effect, as fertigation with solutions containing a N / K balance of 2.14 and an N and K concentration of 9 and 4.2?meq?L^?1 respectively, resulted in plants with the greatest dry weight.     

Potassium concentration effect on growth,gas exchange and mineral accumulation in potatoes

This study was conducted to evaluate the responses of potatoes to six K solution concentrations maintained with a flow‐through nutrient film system. Potato plants were grown for 42 days in sloping shallow trays containing a 1 cm layer of quartz gravel with a continuous flow of 4 ml min^‐1 of nutrient solutions having K concentrations of 0.10, 0.55, 1.59, 3.16, 6.44, 9.77 meq L^‐1. Plant leaf area, total and tuber dry weights were reduced over 25% at 0.10 meq L^‐1 of K and over 17% at 9.77 meq L^‐l of K compared to concentrations of 0.55, 1.59, 3.16 and 6.44 meq L^‐1 of K. Gas exchange measurements on leaflets in situ after 39 days of growth demonstrated no significant differences among different K treatments in CO₂ assimilation rate, stomatal conductance, intercellular CO₂ concentration, and transpiration. Further measurements made only on plants grown at 0.10, 1.59, 6.44 meq L^‐1 of K showed similar responses of CO₂ assimilation rate to different intercellular CO₂ concentrations. This suggested that the photosynthetic systems were not affected by different K nutrition. The leaves of plants accumulated about 60% less K at 0.10 meq L^‐1 of K than at higher K concentrations. However, Ca and Mg levels in the leaves were higher at 0.10 meq L^‐1 of K than at higher K concentrations. This indicates that low K nutrition not only reduced plant growth, but also affected nutrient balance between major cations.     

Response of potted anthurium (Anthurium andreanum Lind.) to the K+: Ca+2: Mg+2 balance in the nutrient solution

The climatic conditions of the humid tropical areas of México allow the year-round production of cut flowers and potted plants of anthurium. However, the scarce basic and applied research on tropical ornamental species limits the development of technology to increase productivity and quality. In this article, we are reporting the information as to the effect of the proportions of potassium (K⁺), calcium (Ca⁺²), magnesium (Mg⁺²) in the nutrient solution on anthurium growth using mixture analysis and response surface methodology. The sum of all the three cations was 20 meq L^?1 and each one is expressed as a fraction of this total concentration. Response surface analysis detected that spathe and leaf areas decreased in plants fed with solutions of high proportions of Mg⁺². Total shoot and root fresh weight, as well as total dry weight and root volume, also demonstrated the deleterious effects of high Mg⁺². In general, the best growth occurred in two areas of the explored space; a) an area of high Ca⁺², with optimum proportions ranging from 0.24–0.44 for K⁺, 0.54–0.68 for Ca⁺², and 0.01–0.08 for Mg⁺², and b) another area of high K⁺, on which the optimum proportions ranged 0.54–0.65 for K⁺, 0.25–0.29 for Ca⁺², and 0.10–0.21 for Mg⁺². Shoot and root K⁺, Ca⁺², and Mg⁺² concentration was significantly affected by the cation balances in the external solution, however, there was not a clear tendency as to the effect of each cation in the mixture; nonetheless, the internal K⁺: Ca⁺²: Mg⁺² balances were affected by the balances in the nutrient solution, as in the shoot they were located in a very specific area of the explored space, indicating that anthurium plants accumulated more Mg⁺² compared to what it is in the external solution, whereas Ca⁺² was lower than that of the external solution. Plants accumulated K⁺ at high rates regardless of the external balance. In conclusion, the optimum nutrient solutions for anthurium may contain very wide ratios of K⁺ as long Ca⁺² and Mg⁺² are maintained at low proportion in the nutrient solution.     

Responses of Castanopsis hystrix seedlings to macronutrient imbalances: Growth,photosynthetic pigments and foliar nutrient interactions

Imbalanced fertilization of nursery stock can lead to nutrient disorders which affect plant quality and productivity. Castanopsis hystrix Miq. is a plantation hardwood species that is being widely established in south China. Nutrient disorders are common in planting stock and difficult to manage, as the causes are unknown. Therefore, macronutrient deletion fertilizer treatments were applied to C. hystrix seedlings and foliar symptoms, growth performance, leaf area, photosynthetic pigments and foliar nutrient interactions were determined. The appearance of foliar symptoms including chlorosis, marginal scorching, necrotic spotting and leaf malformation will be useful for the initial diagnosis of fertilizer imbalances in this species in forest nurseries. Vector analysis revealed that foliar nutrient interactions tended to be enhanced under nutrient imbalance, and these findings may provide a preliminary guideline for confirming macronutrient disorders of this species in nursery production.     

Growth of a tomato crop at reduced nutrient concentrations as a strategy to limit eutrophication

In tomato (Lycopersicon esculentum L. cv Trust Fl), effects of various nutrient treatments on growth, fruit yield and quality, nutrient uptake and accumulation were studied in a hydroponic system. Reductions of macronutrient concentrations to 50% (0.5 × C) or 25% (0.25 × C) of the control (C) levels as well as cessation of replenishment of the feed solution for the last 16 days after 7 months growth at control levels, had no adverse effect on growth, fruit yield and fruit quality. However, reduction of macronutrient concentration to 10% of control (0.1 × C) reduced fruit yield by ‐30%. Steady‐state influx and net flux of NO₃ ^‐ into the roots of 4–6 week‐old seedlings had not acclimated and showed concentration dependence from 1.1 mM (0.1 × C) to 11 mM (C). Whereas, Pi and K⁺ fluxes were similar at 0.5 × C and C levels, at 0.1 × C they were significantly lower than the fluxes at higher concentrations, showing lack of acclimation at this concentration. This lack of flux acclimation may account for the adverse effects of low concentration (0.1 × C) on yield. The results have been discussed in the context of eutrophication and it is suggested that in a non‐recirculating hydroponic system, NO₃ ^‐, Pi, and K⁺ levels can be reduced to 25% of the concentrations currently being used in commercial greenhouses (C). In a recirculating system, the crop may be grown at control levels and used to deplete the feed solution for ～3 weeks prior to release of the solution to the drain.     

Poinsettia growth,tissue nutrient concentration,and nutrient uptake as influenced by nitrogen form and stage of growth

Growth, development, and uptake of essential nutrients as influenced by nitrogen (N) form and growth stage was evaluated for ‘Freedom’ poinsettias (Euphorbia pulcherrima Willd. Ex Klotz.). Treatments consisted of five nitrate (NH₄ ⁺):ammonium (NO₃ ^‐) ratios (% NH₄ ⁺:% NO₃ ^‐) of 100:0, 75:25, 50:50, 25:75, and 0:100 with a total N concentration of 150 mg L^‐1. Plants were grown in solution culture for ten weeks under greenhouse conditions. Nutrient uptake data was combined into three physiological growth stages. Growth stage I (GSI) included early vegetative growth (long days). Growth stage II (GSII) began at floral induction and leaf and bract expansion (short days). Growth stage III (GSIII) was from visible bud through anthesis and harvest. Dry weights for all plant parts and height increased as the ratio of NO₃ ^‐ increased. Leaf area and bract area were maximized with 25:75 and 50:50 N treatments, respectively. Nitrogen treatments significantly affected foliar nutrient concentrations with calcium (Ca⁺⁺) and magnesium (Mg⁺⁺) being highest when NO₃ ^‐ was the predominant N form. Uptake of each macronutrient was averaged across all treatments and divided into physiological growth stages (GS) to identify peak demand periods during the growth cycle. The greatest uptake of NH₄ ⁺ and NO₃ ^‐ was from the early vegetative stage to floral induction (GSI). Phosphorus (P), potassium (K⁺), and Mg⁺⁺ uptake were greatest from floral induction to visible bud (GSII) and Ca⁺⁺ uptake remained relatively unchanged through GSI and GSII. Uptake was lowest for all nutrients from visible bud to anthesis (GSIII). Results from this study clearly indicate that peak demand periods for macronutrient uptake existed during the growth cycle of poinsettia.     

Nitrate/ammonium ratio effects on nutrient solution pH,dry matter yield,and nitrogen uptake of sorghum 1

Abstract

Sorghum [Sorghum bicolor (L.) Moench] seedlings were grown in nutrient solutions in a growth chamber to investigate the effects of different ratios of NO₃ ^– and NH₄ ⁺ on nutrient solution pH, dry matter yield, and N uptake. Nutrient solutions and plant tissues were assayed throughout the time plants grew in the nutrient solutions.

Nutrient solution pH depended on source of N. The pH rose to near 8 with NO₃ ^– as the sole source of N and decreased to near or below 4 with NH₄ ⁺ added to the solutions. Upon depletion of NH₄ ⁺ from solution, pH values rose abruptly to near 8 and remained near this value throughout the duration of the experiments. Dry matter yield was generally higher for plants grown with some NH₄ ⁺ compared to plants grown with NO₃ ^– alone. Nitrogen uptake was generally higher in plants grown with the higher proportions of NH₄ ⁺. Nitrogen concentrations remained unchanged with plant age as NO₃ ^–/ NH₄ ⁺ ratio varied. For solutions low in NH₄ ⁺, N concentrations in roots increased with plant age. Severe Fe deficiency appeared in plants when solution pH reached and remained above 7.     

Soil tillage effects on monovalent cations (Na+ and K+) in vertisols soil solution

Potassium is an essential macronutrient for plants; it is characterized by increased photosynthetic activity by ensuring a better utilization of light energy, also acts as a regulator of cell osmotic pressure, decreasing transpiration and helping to maintain cell turgidity. However, the sodium is not an essential element for plants, although it is beneficial to certain crops, in some instances can replace the potassium and osmotic regulation making and turgidity of the cells, this effect is greatest when the supply of potassium is deficient (Wild, 1992). Both elements, in periods of aridity, delayed the wilting of plants to maintain cellular osmotic potential and in cold periods, they lower the freezing point of sap (Navarro and Navarro, 2000).This is an experiment to study the influence of soil management techniques on the monovalent cations in soil solutions at different depths. The cropping systems studied are conventional tillage, minimum tillage and direct drilling.Conventional tillage releases more Na⁺ and K⁺ to the soil solution than the conservative techniques. In the case of Na⁺, the conventional tillage soil solution has an average concentration of 0.563 meq/L compared to 0.303 meq/L of minimum tillage and 0.340 meq/L of direct drilling. As for the K⁺, the soil solution concentration of conventional tillage is 0.097 meq/L, compared to 0.079 meq/L of the solution of minimum tillage and 0.056 meq/L of direct drilling.The behavior for the two cations studied is distinct at different depths. The Na⁺ is more abundant in water samples of soil taken in depth. Therefore, the salinization risk may take place in the subsoil, especially in conventional tillage where the Bw₁ horizon values are three times higher than in the Ap horizon, while the K⁺ is more abundant in the surface horizon. Conventional tillage and minimum tillage techniques, in the Ap horizon have a similar pattern with a K⁺ concentration average of 0.15 meq/L and 0.14 meq/L, respectively, resulting in lower values for direct drilling.Studies on clay soils have not been performed previously because of the difficulty presented by these soils when soil solution extracted for analysis. We analyzed the monovalent cations (sodium and potassium) from soil solution; because the soil solution is the immediate source of sodium and potassium for plants.     

Turnip growth,leaf yield,and leaf nutrient composition responses to nitrogen forms

’Shogoin’ turnip plants (Brassica rapa L.) were grown in sand culture under five nitrate:ammonium (NO₃:NH₄) ratios (N:N of 1:0, 3:1, 1:1, 1:3, 0:1). The leaves expressed symptoms of NH₄ toxicity (reduced growth and curly leaves with dark‐green areas surrounding yellow spots) when NH₄ was the dominant nitrogen (N) form. Increasing NO₃ in the nutrient solution significantly (p<0.01) increased leaf and root fresh weight and dry weight. Leaf nutrient concentration and composition of all elements analyzed, except N and calcium (Ca), responded quadratically (p<0.01) to NO₃:NH₄ ratios, and the highest values were observed with the 1:0 [for molybdenum (Mo)], 3:1 ([or magnesium (Mg)], 1:1 [for boron (B), coper (Cu), iron (Fe), manganese (Mn ), and zinc (Zn)] or 1:3 [for phosphorus (P) and potassium (K)] treatments. Nitrogen and Ca leaf concentration responses were linear and highest at 0:1 and at 1:0, respectively. Cultural practices and fertilizer applications should maintain NO₃ as the dominant N form in the root zone, and the continuous use of NH₄‐ based or NH4‐releasing fertilizers is not recommended for the production of high yields of turnip greens.     

Growth,Nitrate Accumulation,and Macronutrient Concentration of Pakchoi as Affected By External Nitrate-N: Amino Acid-N Ratio

ABSTRACT

A study was carried out to determine the influence of nitrogen (N) sources on the growth, nitrate (NO₃ ^?) accumulation, and macronutrient concentrations of pakchoi (Brassica chinensis L.) in hydroponics. Plants were supplied with NO₃ ^? and two amino acids (AA), glutamic acid (Glu), and glutamine (Gln), at six NO₃ ^?-N/AA-N molar ratios: (1) 100:0, (2) 80:20, (3) 60:40, (4) 40:60, (5) 20:80, (6) 0:100. The total N concentration was 12.5 mmol/L for all treatments in nutrient solutions. Both AAs reduced plant growth with decreasing NO₃ ^?-N/AA-N ratios, but the reduction was for Gln than for Glu. At 80:20 NO₃ ^?-N: Gln-N ratio, the Gln had no significant effect on pakchoi fresh weights. Decreasing NO₃ ^?-N/AA-N ratios reduced NO₃ ^? concentrations in the plant, regardless of AA sources. Adding an appropriate portion of AA-N to nutrient solutions for hydroponic culture increased concentrations of N, phosphorus (P), and potassium (K) in pakchoi shoots. Substituting 20% or less of NO₃ ^?-N with Gln-N in hydroponic culture will increase the pakchoi quality by reducing NO₃ ^? concentration and increasing mineral nutrient concentrations in shoots without significant reduction of crop yields.     

Impact of organic and inorganic fertilizers on yield,taste, and nutritional quality of tomatoes

In a greenhouse experiment, tomato plants were grown in sand culture to test whether different fertilization regimes (mineral or organic fertilizers) at low (500 mg N plant^–1 week^–1) and high (750 mg N plant^–1 week^–1) nitrogen levels affected yield, nutritional quality, and taste of the fruits. In the mineral‐fertilizer treatments, nitrate‐ or ammonium‐dominated nutrient solutions were used. Organic fertilizer was supplied as fresh cut grass‐clover mulch (a total of 2.4 kg and 3.6 kg were given per plant at low and high N level, respectively) without (orgN) and with additional sulfur fertilization (orgN+S). Yields of red tomatoes from the organically fertilized plants were significantly lower (1.3–1.8 kg plant^–1) than yields from plants that received mineral fertilizer (2.2–2.8 kg plant^–1). At the final harvest, yields of green tomatoes in the organic treatment with extra sulfur were similar (1.1–1.2 kg plant^–1) to the NO ‐dominated treatments at both nutrient levels and the NH ‐dominated treatment at high nutrient level. Organic fertilizers released nutrients more slowly than mineral fertilizers, resulting in decreased S and P concentrations in the leaves, which limited growth and yield in the orgN treatments. Analysis of tomato fruits and plants as well as taste‐test results gave no conclusive answer on the relationship between sugar or acid contents in the fruits, macronutrient content of plant leaves and fruits, and perceived taste. Sugar contents were higher in the fruits given mineral fertilizer, whereas acid contents were higher in the fruits given organic fertilizer. Preference in taste was given to the tomatoes from plants fertilized with the nitrate‐dominated nutrient solution and to those given organic fertilizer with extra sulfur. Thus, a reduction in growth, which was expected to lead to a higher concentration of compounds like sugars and acids, did not result in better taste. Overall, it can be concluded that an appropriate nutrient supply is crucial to reach high yields and good taste.     

Effect of Barium on Growth and Macronutrient Nutrition in Tanzania Guineagrass Grown in Nutrient Solution

Barium has been identified as a toxic element to most plants, although for grasses the toxicity has not been determined. A greenhouse experiment was performed to evaluate the effect of barium on growth parameters, barium accumulation, and macronutrient concentration in Tanzania guineagrass (Panicum maximum Jacq.), cultivated in nutrient solution. Five barium rates and a control were set in a complete randomized block design, with four replications. Forage yield, leaf area, barium, and macronutrient concentrations and accumulation were measured. Leaf area and yield sharply decreased with increase of barium concentration in the nutrient solution. The greatest barium concentration and accumulation were found in culms and sheaths. Toxic barium concentrations were estimated to be 1.24 mmol L^?1 (170 mg L^?1) in nutrient solution and 225 mg kg^?1 in the diagnostic leaf, and the main symptoms of toxicity were interveinal chlorosis followed by necrotic spots in the leaf laminae of the grass.     

Magnesium-fortified phosphate fertilizers improve nutrient uptake and plant growth without reducing phosphorus availability

Magnesium (Mg) deficiency can significantly limit crop yield and quality. Separate application of straight Mg fertilizer is unattractive because of additional labor costs. Meanwhile, bulk blending Mg with other macronutrient fertilizers is also a suboptimal solution because bulk blended fertilizers often yield poor nutrient distributions. One rapid and economical alternative to alleviating Mg deficiency is to co-granulate macronutrient fertilizers with Mg. However, few commercial products have implemented this approach. One of the barriers hindering the production of Mg-fortified phosphorus (P) fertilizers is the assumption that precipitation of P with Mg will reduce P solubility. In this study, four Mg compounds, anhydrous magnesium sulfate (MgSO₄), magnesium oxide (MgO), anhydrous magnesium chloride (MgCl₂), and dolomite (CaMg(CO₃)₂), were co-granulated with mono-ammonium phosphate (MAP), and their granule strength, Mg and P availabilities, and agronomic effectiveness were evaluated. Results showed that there were no significant differences in P solubility between Mg-fortified MAP and MAP treatments. X-ray diffraction (XRD) indicated that the Mg species after co-granulation were boussingaultite (Mg(NH₄)₂(SO₄)₂·6H₂O), schertelite (Mg(NH₄)₂H₂(PO₄)₂·4H₂O), magnesium hydrogen phosphate (Mg(H₂PO₄)₂), and dolomite (CaMg(CO₃)₂). A pot experiment using an acidic soil demonstrated an average 9.6-fold increase in shoot Mg uptake, 3.0-fold increase in shoot P uptake, and 3.2-fold increase in soybean shoot dry matter in Mg-fortified MAP treatments, compared to those in MAP treatment. The current study provides a simple, effective, and low-cost approach for the addition of Mg to macronutrient fertilizers, to minimize Mg deficiency.