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.     

Growth and ion accumulation responses of four grass species to salinity

Ion inclusion or ion exclusion are the two main strategies developed by plants to tolerate saline environments. Shoot sodium (Na⁺), potassium (K⁺), and calcium (Ca²⁺) in four perennial grass species (tall wheatgrass, Nuttall's alkaligrass, creeping foxtail, and switchgrass) treated with nutrient solution salinity levels ranging from 2 to 32 dS m^?1 were measured. As the nutrient solution salinity was increased from 2 to 10 dS m^?1, tall wheatgrass, creeping foxtail and Nuttall's alkali grass had increased shoot Na⁺ and decreased Ca²⁺ concentration while maintaining growth suggesting that these species tolerated these changes in shoot ion concentration. In contrast, switchgrass excluded Na⁺ from the shoot and maintained K⁺ and Ca²⁺ concentrations but suffered dramatic shoot dry weight reduction. Thus, the Na⁺ exclusion mechanisms present in switchgrass were less efficient in maintaining growth under the 10 dS m^?1 nutrient solution treatment than the Na⁺ inclusion mechanisms used by the other three species.     

Nutrient dynamics of field-weathered Delmarva poultry litter: implications for land application

To develop phosphorus-based agronomic application rates of phytase-diet, bisulfate-amended Delmarva poultry litter in conservation tillage systems, nutrient release dynamics of the organic fertilizer under local weather conditions were investigated. Delmarva poultry litter was placed in polyvinyl chloride columns to a depth of 5 cm and weathered in the field for 570 days. Leachate from the columns was collected and measured for concentrations of various nutrients. Cumulative release of the nutrients as a function of weathering time was modeled, and the nutrient supply capacity was determined. Poultry litter leachate contained high contents of dissolved organic carbon (15–31,500 mg L^?1), nitrogen (N 5–7,070 mg L^?1), phosphorus (P 5–230 mg L^?1), potassium (K⁺ 2–7,140 mg L^?1), and other nutrients. Release of most nutrients occurred principally in the first 100 days, but for P and calcium (Ca²⁺), it would last for years. The release kinetics of N followed a logarithm equation, while P and K demonstrated a sigmoidal logistic pattern. The nutrient supply capacity of surface-applied Delmarva poultry litter was predicted at 10.9 kg N Mg^?1, 6.5 kg P Mg^?1, 34.7 kg K⁺ Mg^?1, 5.4 kg Ca²⁺ Mg^?1, and 14.0 kg SO ₄ ^2? Mg^?1. The results suggest that Delmarva poultry litter should be applied to conservation tillage systems at 6.6 Mg ha^?1 that would furnish 25 kg P ha^?1 and 63 kg N ha^?1 to seasonal crops. In repeated annual applications, the rate should be reduced to 5.2 Mg ha^?1, with supplemental N fertilization to meet crop N requirements.     

Heavy Metal and Nutrient Ion Accumulation by Two Black Gram Cultivars Treated with Copper and Lead

ABSTRACT

A pot experiment was conducted to examine the uptake of nutrients (K⁺ (potassium) and Ca²⁺ (calsium)) and heavy metal (Cu²⁺ (copper) and Pb²⁺ (lead)) ions by leaves, seeds, and roots of two black gram [Vigna mungo (L.) Hepper] cultivars, ‘Mash-95018’(V₁) and ‘Mash-97’(V₂) treated with copper (Cu) and lead (Pb) at 25mg L^?1 and 50mg L^?1. This study was conducted in a greenhouse in the Botanical Garden, University of Agriculture, Faisalabad, Pakistan, during the spring of 2003. Heavy-metal treatments were applied 30 d after germination, and nutrient and heavy-metal ion uptake data were collected 10 d after treatment application. Both heavy metals in both cultivars substantially reduced nutrient ion accumulation and its translocation to seeds. Leaves had proportionately more K⁺ and Ca²⁺ than that recorded for roots and seeds after heavy-metal treatments. Nevertheless, both heavy metal (Cu²⁺ and Pb²⁺) ions ware predominantly sequestered in the roots, rather than in leaves and seeds, under their respective treatments. As the external concentrations of heavy metals increased, their uptake by the respective treated plants also increased, but nutrient ion (K⁺ and Ca²⁺) uptake was gradually reduced. This result suggests a concentration-dependent phenomenon. Overall, lead (Pb²⁺) showed more toxic effects on the uptake of essential nutrients compared with Ca²⁺, while ‘Mash-97’proved more sensitive to heavy metals than ‘Mash-95018.'     

RESPONSE OF LISIANTHUS TO IRRIGATION WITH SALINE WATER: ION RELATIONS

Eustoma grandiflorum (Raf.) Shinn. (lisianthus) is a moderately salt tolerant species that can be produced commercially under irrigation with saline wastewaters prevalent in two salt-affected areas of California. The objective of the present studies was to determine the effect of irrigation with saline waters of two different compositions on the ion accumulation and ion relations of lisianthus ‘Pure White’ and ‘Echo Blue’. The ionic composition of irrigation waters simulated the compositions typical of i) seawater dilutions (SWD) and ii) concentrations of Colorado River water (CCRW). Electrical conductivities (EC) of SWD and CCRW were between 2 and 12 dS · m^?1. Plants irrigated with CCRW were higher in Ca²⁺ compared to plants irrigated with SWD water. Calcium was also higher in ‘Pure White’ than in ‘Echo Blue’. Increasing EC of irrigation water caused a significant decrease in shoot and leaf Ca²⁺ concentration in ‘Echo Blue’, but had no effect on Ca²⁺ content of ‘Pure White’ shoots and leaves. Magnesium concentration in ‘Echo Blue’ was higher than in ‘Pure White’. Electrical conductivity did not significantly affect Mg²⁺ concentration of either cultivar, despite the increasingly higher external concentration. Potassium concentration of young and mature leaves of ‘Echo Blue’ increased as EC increased from 2 to 8 dS · m^?1, then decreased significantly once EC exceeded 8 dS · m^?1. Potassium concentration of ‘Pure White’ leaves decreased over the range of salinity treatments tested, suggesting that the reduced potassium ion (K⁺) activity at EC levels of 8 dS · m^?1, or less, that resulted in lower leaf?K⁺ in ‘Pure White’ did not cause a decrease in K⁺ uptake in ‘Echo Blue’. Increases in external Na⁺ caused a significant increase in Na⁺ in ‘Pure White’ leaves and these plants exhibited the best growth even when levels of Na⁺ were high enough to be considered detrimental for growth.     

Influence of the Modification of Nutritional Parameters in Aglaonema commutatum: K+, Ca2+, Mg2+ and Na+

Abstract

This trial was carried out to establish an appropriate nutrient solution for Aglaonema commutatum and to investigate the nutritional effects generated by modifications in the solution. Six treatments were tested: control (T₀; pH 6.5, E.C. 1.5 dS m^?1, 6 mmol L^?1 NO₃ ^?‐N, and 6 mmol L^?1 K⁺); high nitrogen (N) level (T₁; 9 mmol L^?1 6:3 NO₃ ^?–NH₄ ⁺); N form (T₂; 6 mmol L^?1 N‐NH₄ ⁺); high K⁺ level (T₃; 12 mmol L^?1 K⁺); high electrical conductivity (T₄; E.C. 4 dS m^?1, 25 mmol L^?1 NaCl), and basic pH (T₅; pH 8). At the end of the cultivation, leaf, shoot, and root dry weights and elemental concentrations were determined. Nutrient contents and total plant uptake were calculated from the dry weights and nutrient concentrations. Plant K⁺ uptake increased with application of K⁺ or basic nutrient solution. The uptake and transport of calcium (Ca) were enhanced by the use of NO₃ ^?‐N and inhibited by the presence of other cations in the medium (NH₄ ⁺, K⁺, Na⁺) and by basic pH. Magnesium (Mg) uptake increased with NO₃ ^?‐N application and with pH. Sodium (Na) uptake was the highest in the saline treatment (T₄), followed by the basic pH treatment. Sodium accumulation was detected in the roots (natrophobic plant), where the plant generated a physiological barrier to avoid damage. Dry weight did not differ significantly (p<0.05) among treatments except in the NaCl treatment. These results may help in the formulation of nutrient solutions that take into account the ionic composition of irrigation water and the physiological requirements of plants.     

Effect of different macronutrient cation ratios on macronutrient and water uptake by melon (Cucumis melo) grown in recirculating nutrient solution

The aim of the present study was to determine uptake ratios between macronutrients and water for melon (Cucumis melo L. cv. Dikti) grown in a closed soilless cropping system. The obtained data can be used to establish standard nutrient solution compositions for melon crops grown in closed hydroponic systems under Mediterranean climatic conditions. Nutrient and water uptake by plants in the closed hydroponic system was compensated for by supplying replenishment nutrient solutions (RNS) differing either in the concentrations of K⁺, Ca²⁺, and Mg²⁺ or in their mutual ratio. The RNS, used as control treatment, had an electrical conductivity (EC) of 1.74 dS m^?1 and contained 6.5 mM K⁺, 2.8 mM Ca²⁺, and 1.0 mM Mg²⁺ (K⁺ : Ca²⁺ : Mg²⁺ = 0.63 : 0.27 : 0.10). Control RNS was compared with two other RNS, both with a high Ca²⁺ level (4.2 mM). The K⁺ and Mg²⁺ levels in these two RNSs were: (1) not altered (corresponding to a ratio of K⁺ : Ca²⁺ : Mg²⁺ = 0.55 : 0.36 : 0.09; EC = 2.0 dS m^?1) or (2) increased to maintain the same K⁺ : Ca²⁺ : Mg²⁺ ratio as in the control RNS (EC = 2.45 dS m^?1). Nutrient to water uptake ratios, commonly termed uptake concentrations (UCs), were assessed by two alternative methods, i.e., (1) estimating the ratio between nutrient and water removal from the system or (2) estimating the ratio between the mass of the nutrient that was recovered from plant biomass and the water consumption. Over the two methods, mean UCs for N, P, K, Ca and Mg were 15.4, 1.31, 5.47, 3.78, and 1.02 mmol L^?1, respectively, and tissue analysis resulted in a K : Ca : Mg molar ratio of = 0.55 : 0.34 : 0.11 in the whole plant. Moreover, the UCs tended to decrease as the crop aged although, in absolute values, the mass of nutrients absorbed increased following dry‐weight accumulation. Based on the obtained results, adapting the composition of the nutrient solution at least three times during the cropping period of melon is recommended. Further, the results revealed that the damage caused by the increase of the EC when attempting to maintain a target K⁺ : Ca²⁺ : Mg²⁺ ratio in the replenishment NS is higher than the benefits from the optimal cation ratio. Increasing K⁺ and Mg²⁺ concentration in addition to that of Ca²⁺ to maintain a standard K⁺ : Ca²⁺ : Mg²⁺ ratio raises the EC in the root zone (4.62 dS m^?1), due to increased accumulation of nutrients, thereby reducing the mean fruit weight and concomitantly the total fruit yield (20% decrease). Leaf gas exchange, chlorophyll parameters and fruit taste quality were not influenced by the differences in macronutrient cation concentrations or ratios in the RNS, whereas phenolics and antioxidant capacity in melon fruit were enhanced by the increased root‐zone EC.     

The Effect of Chloride on Yield and Nutrient Interaction in Greenhouse Tomato (Lycopersicon Esculentum Mill.) Grown in Rockwool

The effect of increasing chloride content in nutrient solution on nutrient composition in root environment, interaction of nutrients in leaves and yield of greenhouse tomato cv. ‘Grace F₁’ grown in rockwool were searched. In Experiment I (2004–2005) the levels of 15, 30, 60, and 90 mg Cl·L^?1 but in Experiment II (2006) 30, 60, 90 and 120 mg Cl·L^?1 of nutrient solution were tested. The sources of chloride were water (9.6–10.7 mg Cl·L^?1) and calcium chloride (CaCl₂·2H₂O) but the rest of nutrients and sodium in all treatments were on the same levels. It was found that increasing content of chloride from 15 to 60 mg Cl·L^?1 enhanced the total and marketable fruit yield. Within the range of 60 to 90 mg Cl·L^?1 the yield was on the optimum level but the content of 120 mg Cl·L^?1 declined it. Increasing chloride content in the nutrient solutions was reflected in rising of chlorine content in leaves. The concentration of chloride above 60 mg C·L^?1 reduced the content of nitrogen but above 90 mg C·L^?1 declined the content of calcium, sulfur and zinc in leaves. The antagonism between Cl:N, Cl:Ca: Cl:S and Cl:Zn was appeared. More variable interaction were between Cl:K and Cl:B. At the low levels of chloride, from 15 to 60 mg Cl·L^?1, potassium and boron content were decreased but at the higher ones, from 90 to 120 mg·L^?1, these nutrients had increasing course. It was not found out the effect of chloride contents on macro and microelement contents in nutrient solution emitted from drippers however their content upraising in root medium (rockwool). The highest increase was found out for Na 95.1 and 64.9 % (Exp. I and II - respectively), next for Ca (76.0, 70.1 %), Cu (62.5 and 71.0 %), Cl (43.6, 24.4), B (33.3, 21.0 %), N-NO₃ (30.4, 49.6 %), Zn (29.5, 32.8 %), S-SO₄ (25.9, 25.5 %), K (24.5, 24.1 %), Fe (19.8, 19.2 %), Mn (17.5, 21.3 %) and Mg (14.9, 11.7). Advantageous effect of chloride on tomato yield justified the need to introduce for the practice adequate chlorine nutrition, and recommend to maintain 60 to 90 mg Cl·L^?1 in nutrient solution. The best yield appeared when content of chlorine in leaves (8th or 9th leaf from the top) was in the range 0.48-0.60 % of Cl in d. m.     

Changes in Chemical Properties of an Oxisol Due to Gypsum Application

The increasing demand for fertilizers and the fact that the world reserves of phosphorus (P) and potassium (K) are depletable make appropriate soil management a critical factor in agriculture. Techniques for the fertilizer use and soil acidity corrective are becoming increasingly necessary to minimize the cost of yield and increase the nutrient efficiency. In view of the aforementioned, the present study aimed to assess the effects of gypsum application on the leaching of cations in the soil profile. A completely randomized design in a 5 × 4 factorial arrangement, with five replicates, was used. The treatments corresponded to five gypsum rates (0, 1, 2, 4, and 8 magnesium (Mg) ha^?1) applied on broadcast of soil and at four depth sampled (0–5, 6–10, 11–15, and 16–20 cm). Gypsum application increased the fertility in depth, with the leaching of cations. There was an increase in soil pH, exchangeable K⁺ and calcium (Ca²⁺), sulfur (S–SO₄^2?), P, boron (B), and manganese (Mn) concentration, cation exchange capacity (CEC), K⁺ and Ca²⁺ saturation, Ca²⁺/Mg²⁺, Ca²⁺/K⁺, and K⁺/(Ca²⁺ + Mg²⁺) ratios, and electrical conductivity in soil depth. On the other hand, there was a decrease in exchangeable Mg²⁺ and potential acidity hydrogen and aluminum (H⁺ + Al³⁺), available silicon (Si), Mg²⁺ saturation, and Ca²⁺/K⁺ and Mg²⁺/K⁺ ratio. These results demonstrate that the gypsum application in an Oxisol with 690 g kg^?1 of clay improves the root system with a significant increase in the soil fertility in the profile.     

Relationship between Callus Growth and Mineral Nutrients Uptake in Salt-Stressed Indica Rice Callus

ABSTRACT

One month old rice calli were exposed to 0, 50, and 100 mol m^?3 sodium chloride (NaCl) in the liquid LS basal medium supplemented with 2.5 mg L^?1 2,4-dichlorophenoxy acetic acid (2,4-D) and 0.5 mg L^?1 kinetin. Callus relative growth rate (RGR; fresh) of both cultivars indicated a progressive decrease; however, callus dry weight increased as the NaCl level increased in the culture medium. Salinity stress increased the callus sodium (Na⁺), manganese (Mn²⁺), and magnesium (Mg²⁺) contents while potassium (K⁺), calcium (Ca²⁺), and iron (Fe²⁺) contents decreased. ‘Basmati-385’ showed less reduction in callus RGR, K⁺, and Ca²⁺ contents and a larger increase in callus dry weight, Na⁺, Mn²⁺, and Mg²⁺ contents as compared to ‘Basmati-Karnal’. However, the reverse was true for Fe²⁺ contents. K⁺/Na⁺ and Ca²⁺/Na⁺ ratios generally decreased under salt stress. Overall, reduction in callus relative growth rate was found to be inversely correlated with decrease in K⁺, Ca²⁺, and Fe²⁺ uptake and directly correlated with increased Na⁺ and Mg²⁺ concentration in callus tissue.     

Growth, Net Photosynthetic Rate, Nutrient Status and Secondary Xylem Anatomical Characteristics of Fagus Crenata Seedlings Grown in Brown Forest Soil Acidified with H2SO4 Solution

Dry matter production, net photosynthetic rate, leaf nutrient status and trunk anatomical characteristics of Fagus crenata seedlings grown in brown forest soil acidified by adding H₂SO₄ solution were investigated. The soil acidification leaded to decreased (Ca+Mg+K)/Al molar ratio in the soil solution. Dry mass per plant of the seedlings grown in the soil treated with H⁺ at 120 mg·L^?1 was significantly reduced compared with the control value at 0 mg·L^?1. When net photosynthetic rate was reduced in the seedlings grown in the soil treated with H⁺ at 120 mg·L^?1, the carboxylation efficiency and maximum net photosynthetic rate at saturated CO₂-concentration were lower than the control values. The addition of H⁺ to the soil at 120 mg·L^?1iinduced a reduction in the concentration of Ca in the leaf. By contrast, the concentration of Al in the leaf was increased with increasing the amount of H⁺ added to the soil. The annual ring formed in the seedlings grown in the soil treated with H⁺ at 120 mg·L^?1 was significantly narrower than that at 0 (control), 10, 30, 60 or 90 mg·L^?1. Based on the results obtained in the present study, we conclude that Fagus crenata is relatively sensitive to a reduction in the (Ca+Mg+K)/Al molar ratio of soil solution compared with Picea abies.     

EFFECT OF PACLOBUTRAZOL AND PUTRESCINE ON ANTIOXIDANT ENZYMES ACTIVITY AND NUTRIENTS CONTENT IN SALT TOLERANT CITRUS ROOTSTOCK SOUR ORANGE UNDER SODIUM CHLORIDE STRESS

The effects of paclobutrazol (PBZ) and putrescine (Put) on antioxidant enzymes activity, proline contents and nutrients uptake were studied on salt tolerant citrus rootstock sour orange. Six-month-old nucellar seedlings grown in pots and subjected to three levels of PBZ and two levels each of salinity and Put for 90 days. Seedlings treated with PBZ or Put alone or in combination had higher anti-oxidant enzymes activities, accumulation of proline and nutrients contents like potassium (K⁺) and calcium (Ca²⁺) under both saline and non-saline conditions. Further, application of PBZ or Put alone or in combination also reduced the accumulation of both Na⁺ and Cl^? ions in leaves and roots in NaCl stressed seedlings. A combined application of 250 mg L^?1 PBZ and 50 mg L^?1 Put proved to be more effective in improving proline and Ca²⁺ content and restricting accumulation of Na⁺ ions in leaf tissues.     

Growth and ion uptake of four Brassica species as affected by Na/Ca ratio in saline sand culture

The influence of supplemental Ca² in saline nutrient solutions on germination, growth, and ion uptake of four Brassica species, B. campestris L., B. carinata, A.Br., B. juncea (L.) Czern. and Coss., and B. napus L. was studied in sand culture. The addition of 11.25 mM CaC1² to nutrient solution containing 225 mM NaC1 improved percentage of germination of B. napus and B. juncea, but had no significant effect on the germination speed of the four species. There was no significant effect of additional amount of Ca² in the saline medium (150 mM NaC1) on the shoot biomass and seed yield of B. carinata and B. campestris. By contrast, shoot dry matter of B. napus and B. juncea increased significantly with the increased in Ca² concentration of the growth medium, but their seed yield remained unaffected. Decreased Ca² concentrations of the saline growth medium reduced percent oil content in B. carinata, B. juncea, and B. campestris. Increasing Na/Ca ratio of the external medium affected ion uptake differently in different species. In B. carinata, a relatively salt-tolerant species, the concentrations of Na⁺ and K⁺ in the shoots remained unaffected, but the C1 concentration was reduced linearly with the increase in external Na/Ca ratios. Root K⁺ and Ca²⁺ of the species decreased with the decrease in Ca²⁺ supply. In B. campestris increasing Na/Ca ratios of the saline medium had no effect on the concentrations of Na⁺, C1, and Ca²⁺ in the shoots and Na⁺, C1, and K⁺ in the roots. Only shoot K⁺ and root Ca²⁺ decreased consistently. In the highly salt-sensitive species, B. napus, the shoot Na⁺ was reduced by the addition of Ca²⁺ in the salt treatment, whereas the C1 and Ca²⁺ uptake was promoted by supplemental Ca²⁺. The root K⁺ concentrations decreased with the increase in Na/Ca. In B. juncea, which was similar to B. napus in biomass production, high Ca²⁺ concentration in the salt treatment reduced the shoot Na⁺ and root C1 concentrations and promoted the K⁺ uptake. Shoot Na/Ca and Na/K ratios were increased in B. napus and B. juncea at the highest Na/Ca ratio of the growth medium. Shoot K⁺ selectivity, S^K,Na (determined as molar ratio of K: Na in tissue to molar ratio of K:Na in external medium) of all species remained unaffected except for B. juncea in which it decreased significantly at the highest Na/Ca ratio. The root K⁺ selectivity increased in B. carinata.     

Calcium-Ammonium Selectivity of Two Benchmark Soils from Botswana as Assessed by Competing Semi-empirical Ion Exchange Equations

The effectiveness of lime-ammonium-nitrate (LAN) as a nitrogen (N) fertilizer in weathered soils depends on the respective selectivity for ammonium (NH₄) and calcium (Ca) by the soils. The study assessed Ca²⁺/NH₄⁺ exchange selectivity of two benchmark soils from Botswana and examined the soil fertility management implications. Surface horizons (0–20 cm) of Pellustert and Haplustalf were equilibrated with 50 ml stock solution containing variable concentrations of Ca²⁺ and NH₄⁺. The Ca²⁺/NH₄⁺ exchange data were fitted into the Vanselow (K_V), Gaines and Thomas (K_GT), Davies (K_D), and the regular solution (K_RS) equations. The selectivity coefficients for the Ca²⁺/NH₄⁺ exchange reactions varied widely with the soil exchanger composition except for the relatively stable K_RS. The selectivity coefficients indicated strong preference for NH₄⁺ to Ca²⁺. The thermodynamic exchange constant, K_ex, was 5.75 ± 1.24 in the Pellustert, indicating preferential adsorption of NH₄⁺, but not in the Haplustalf with K_ex = 0.92 ± 0.27. The free energy for Ca²⁺/NH₄⁺ exchange (ΔG°_ex) was negative (?4.26 ± 0.59 kJ mol^?1) in the Pellustert but slightly positive in the Haplustalf (0.34 ± 0.87 kJ mol^?1). In conclusion, the soil-NH₄ complex was more stable than soil-Ca complex in the Pellustert, indicating LAN as a N fertilizer would have greater potential effectiveness in the Pellustert than in the Haplustalf.     

Use of Potassium Fertilization to Ameliorate the Adverse Effects of Saline-sodic Stress Condition (ECw: SARw Levels) in Rice (Oryza Sativa L.)

ABSTRACT

Salt-affected soils expand around the world and become a critical handicap for high crop yield. Saline-sodic soil contributed a major portion in salt-affected soils. Such types of soils have a sizable amount of Na⁺ in nutrient medium and that reduce the K⁺ uptake in plants. A hydroponic experiment was performed to investigate the ameliorative effect of different doses of potassium fertilizer (K₁ = 0.3, K₂ = 0.6 and K₃ = 1.2 mM L^?1) on rice (Oryza sativa L.) under different EC_w (6 dS m^?1) and SAR_w [12 and 24 (mmol L^?1)^1/2] levels. Application of K⁺ at elevated levels under saline-sodic conditions improved the concentration of anti-oxidant enzymes, plant physiological, and biochemical attributes by improving the K⁺: Na⁺ ratio in plant tissues. Total phenolic content, total soluble protein, and soluble sugar content of rice plant were increased with an increase in potassium dose and saline-sodicity. Maximum K⁺: Na⁺ ratios, 4.13 and 2.0 were observed in shoot and root, respectively upon application of K⁺ at 1.2 mM L^?1 in a solution having EC_w: SAR_w level of 6: 12. This study suggested that application of potassium at elevated levels (1.2 mM L^?1) has enhanced the rice growth by reducing the harmful effect of Na⁺ salts on plant physiology, biochemical attributes, and anti-oxidant enzymes under specific saline-sodic conditions.     

Spatio-temporal variations in nutrient concentration in soil solution under greenhouse tomato

The aim of this trial was to study the spatio-temporal variability in solution nutrient concentration under intensive greenhouse tomato production, to determine the number of suction-cups needed to obtain a representative sample and the influence by the position in the greenhouses. Twenty sampling points were selected within the greenhouse with one suction-cup per sampling point. One soil solution were sampled per point at weekly intervals to analyze for pH, electrical conductivity, chloride, nitrate, phosphate, sulfate, sodium, potassium, calcium, and magnesium (EC, Cl^?, NO₃^?, H₂PO₄^?, SO₄^2—, Na⁺, K⁺, Ca²⁺, and Mg²⁺) concentrations. The pH, Cl^?, H₂PO₄^?, and SO₄^2? concentrations showed no spatio-temporal variation but EC, NO₃^?, and K⁺ showed temporal variation. The spatial variability in EC, K⁺_, Na⁺, Mg²⁺, and Ca²⁺ can be influenced by microclimate and topography. The numbers of suction cups required for a representative sample ranged from 1 to 10 depending on nutrient.     

Effects of NaCl and silicon on ion distribution in the roots,shoots and leaves of two alfalfa cultivars with different salt tolerance

Abstract

The effects of exogenous NaCl and silicon on ion distribution were investigated in two alfalfa (Medicago sativa. L.) cultivars: the high salt tolerant Zhongmu No. 1 and the low salt tolerant Defor. The cultivars were grown in a hydroponic system with a control (that had neither NaCl nor Si added), a Si treatment (1 mmol L^?1 Si), a NaCl treatment (120 mmol L^?1 NaCl), and a Si and NaCl treatment (120 mmol L^?1 NaCl + 1 mmol L^?1 Si). After 15 days of the NaCl and Si treatments, four plants of the cultivars were removed and divided into root, shoot and leaf parts for Na⁺, K⁺, Ca²⁺, Mg²⁺, Fe³⁺, Mn²⁺, Cu²⁺ and Zn²⁺ content measurements. Compared with the NaCl treatment, the added Si significantly decreased Na⁺ content in the roots, but notably increased K⁺ contents in the shoots and leaves of the high salt tolerant Zhongmu No.1 cultivar. Applying Si to both cultivars under NaCl stress did not significantly affect the Fe³⁺, Mg²⁺ and Zn²⁺ contents in the roots, shoots and leaves of Defor and the roots and shoots of Zhongmu No.1, but increased the Ca²⁺ content in the roots of Zhongmu No.1 and the Mn²⁺ contents in the shoots and leaves of both cultivars, while it decreased the Ca²⁺ and Cu²⁺ contents of the shoots and leaves of both cultivars under salt stress. Salt stress decreased the K⁺, Ca²⁺, Mg²⁺ and Cu²⁺ contents in plants, but significantly increased Zn²⁺ content in the roots, shoots and leaves and Mn²⁺ content in the shoots of both cultivars when Si was not applied. Thus, salt affects not only the macronutrient distribution but also the micronutrient distribution in alfalfa plants, while silicon could alter the distributions of Na⁺ and some trophic ions in the roots, shoots and leaves of plants to improve the salt tolerance.     

Changes in soil solution composition and pH in urine-affected areas of pasture

Changes in soil solution composition and concentrations of exchangeable cations and mineral N in undisturbed cores of pasture soil were investigated in two experiments following applications of sheep urine to the cores. The major cations applied in the urine were K⁺ and Na⁺, and the major anions were HCO₃^? and Cl^?. Addition of urine increased concentrations of exchangeable K⁺, Na⁺ and NH₄⁺ and measured ionic strength of the soil solution throughout the surface 15 cm of soil, demonstrating that the urine moved through the core by macropore flow immediately following addition. Immediately following urine application the ionic strength in soil solution in the surface 2.5 cm of soil increased from 4–6 MM to 24–41 mM. Hydrolysis of urine-urea was extremely rapid, and in less than 1 d high concentrations of NH₄⁺-N (i.e. 270–370 mg N kg^?1) had accumulated in the surface 0–2.5 cm of the urine patch, and soil pH had risen by over one unit. Nitrification then proceeded and, after approximately 15 d, NO₃^? became the dominant form of mineral N present. During nitrification, soil pH declined and the ionic strength of the soil solution increased substantially with NO₃^? becoming the dominant anion present in solution. There were concomitant increases in the concentrations of Ca²⁺ and, to a lesser extent, Mg²⁺ in the soil solution as NO₃^? concentrations increased. After approximately 30 d, concentrations of exchangeable NO₃^? had risen to 250–330 mg N kg^?1, soil solution NO₃^? concentrations had increased to about 80 mmol, dm^?3, and ionic strength in the soil solution had increased to 130–140 mM. These results demonstrate the dominating effect of N transformations in causing large fluctuations in the pH, ionic composition and ionic strength of the soil solution in the urine patch. It was concluded that nutrient availability in the patch was affected directly by nutrient addition in urine, and also probably indirectly through the fluctuations in soil solution pH and ionic strength that occur.     

Nitrite and Ammonium Toxicity on Lettuce Grown under Hydroponics

Abstract

Nitrite (NO₂ ^?‐N) toxicity symptoms have been observed on lettuce (Lactuca sativa) at various locations in California. The objective was to evaluate the symptoms of ammonium (NH₄ ⁺‐N) and nitrite (NO₂ ^?‐N) toxicity on Sundevil iceberg lettuce and Paragon romaine lettuce and to determine lettuce growth and biomass production under different levels of NO₂ ^?‐N. Hydroponic studies under greenhouse conditions were conducted using nutrient solutions containing nitrate (NO₃ ^?‐N) and two other forms of nitrogen (NO₂ ^?‐N and NH₄ ⁺‐N) applied at a constant concentration (50 mg NL^?1) or using different NO₂ ^?‐N levels (0, 5, 10, 20, 30, and 40 mg N L^?1) and a constant NO₃ ^?‐N level (30 mg N L^?1). Crown discoloration (brownish color) was observed for lettuce grown in both NO₂ ^?‐N and NH₄ ⁺‐N solutions approximately 3 weeks after transplanting into the hydroponic systems. Lettuce grown in NO₃ ^?‐N solution produced larger biomass and greater number of leaves per plant than lettuce grown in NO₂ ^?‐N or NH₄ ⁺‐N solutions. Increasing the concentration of NO₂ ^?‐N suppressed plant height, fresh and dry biomass yield, and number of leaves and increased the root vascular discoloration. Lettuce growth was reduced more than 50% at NO₂ ^?‐N concentrations greater than 30 mg N L^?1. Even at 5 mg NO₂ ^?‐N L^?1, growth was reduced 14 and 24% for romaine and iceberg lettuce, respectively, relative to that obtained in nitrate solution. Although concentrations between 5 and 40 mg NO₂ ^?‐N L ^?1 reduced dry biomass similarly for both lettuce types, toxicity symptoms were more severe in iceberg lettuce than in romaine.     

Effect of Calcium and Potassium Nutrition on Yield,Ion Content,and Salt Tolerance of Brassica campestris (rapa)

When plants encounter salinity, growth is reduced initially by water stress and subsequently by toxic levels of ions and by interference with nutrient acquisition and translocation. Calcium (Ca^{2 +}) in particular seems to have an important role in salt tolerance and there are reports of a beneficial effect of increasing Ca^{2 +} availability. Higher potassium (K⁺) concentrations in plants may also improve salinity tolerance as sodium (Na)⁺/K⁺ ratios have been shown to be important. Previous work with a range of Acacia species has suggested that endogenous seed Ca^{2 +} and K⁺ concentrations might influence salinity tolerance at germination, but this has not previously been tested with a single species. The objectives of this investigation were thus to determine whether (1) altered Ca^{2 +} and K⁺ nutrition of Brassica campestris (rapa) L. plants affects the yield and ion content of their seeds, and (2) seeds with different Ca^{2 +} and K⁺ contents differ in their salinity tolerance. Plants were grown in a growth room or greenhouse in (1) Gem® horticultural sand (2) Silvaperl® perlite and sand (2:1), or (3) Shamrock® Medium General Purpose Irish Sphagnum Peat and Vermiperl® vermiculite (1:1). Plants in each growth substrate were supplied with nutrient solutions based on a modified Hoagland's solution as a control, low Ca^{2 +} and low K⁺ solutions containing those elements at half the control strength, but all other mineral elements as far as possible at control strength, and high Ca^{2 +} and high K⁺ solutions containing those elements at double control strength but all other mineral elements, as far as possible, at control strength. An increase in substrate available Ca^{2 +} and K⁺ resulted in increased Ca^{2 +} and K⁺ concentration in seeds, respectively, and was accompanied by a reduction in seed K⁺ and Ca^{2 +}, respectively. The Ca^{2 +} and K⁺ concentrations of seeds affected their salinity tolerance. Increases in seed Ca^{2 +}, K⁺ or Ca^{2 +}+ K⁺ concentrations decreased salinity tolerance at germination. The results, especially in terms of Ca^{2 +} nutrition, contradict previous results of an increased salinity tolerance with increased Ca^{2 +} and/or K⁺ concentrations.