Effect of sodium in the nutrient medium on the incidence of potassium-deficiency symptoms in tomato plants

Summary Tomato plants (Lycopersicon esculentum cv. Amberley Cross) were grown in sand culture and were fed with four concentrations of potassium nitrate in combination with two levels of sodium nitrate. After six weeks the plants were scored for the presence and absence of a symptom of potassium deficiency, namely, marginal chlorosis and/or necrosis in the young, fully-expanded leaves. These leaves were also analysed for K and Na. Marginal chlorosis and/or necrosis occurred in plants given a nutrient solution containing 0.5 meq K/I or less and supplied with either of the sodium nitrate levels. However, the symptoms occurred more frequently in plants receiving the lower level of sodium nitrate. The laminae on plants receiving the lower concentration of sodium nitrate had a 50 per cent incidence of chlorisis and/or necrosis when the tissue potassium content was 0.74 per cent of the dry wt, while those laminae on plants receiving the higher level did not show a 50 per cent incidence until their potassium fell to 0.64 per cent of the dry wt.     

The composition of the leachate through cropped and uncropped soils in lysimeters compared with that of the rain

Summary The composition of the leachate from undisturbed monolith lysimeters cropped with white clover or meadow fescue or maintained bare was compared with that of the rain falling on them. No nitrogen fertilizer was applied only an initial dressing of phosphorus and potassium. The grass received much more nitrogen from the rain than it lost by leaching whereas the clover lost more than it received. Most of the leached nitrogen was NO₃-N - 92 per cent on the bare soil and 90 per cent on the clover. About 27lb nitrogen per acre (30 kg/ha) per year was drained from the actively growing clover sward rising to about 117lb N/acre/year (131 kg/ha) when the clover died or was removed. Only 2.3lb/ac (2.5 kg/ha) was drained from the actively growing grass sward. It was estimated that the clover fixed at least 270lb N/ac/year (303 kg/ha/year. The rates of leaching of potassium from a grass sward was about 1.7lb/ac/year (1.9 kg/ha) and 0.8 lb (0.9 kg) phosphorus. The quantities were similar for clover. The grass received from the rain more phosphorus and potassium than was leached but only 60 per cent of the calcium and 13 per cent of the magnesium, similar results being obtained with white clover. During the year of establishment of the grass sward there was evidence of loss of gaseous nitrogen (elemental and/or compound) from the soil: subsequently the nitrogen content of the soil slowly increased. Calcium loss from the bare soil with an average rainfall of 26″ (650 mm) was about 100 lb Ca/ac/year (112 kg/ha).     

The supply of nutrient ions by diffusion to plant roots in soil

Summary Observation of soil grown roots of rye-grass shows that an approximately cylindrical volume of soil, the root hair cylinder, is densely occupied by root hairs. Estimates are given of the concentration of labile and solution potassium within the root hair cylinder during experiments measuring potassium uptake from two soils by single roots. Calculations, using a diffusion model, suggest that labile potassium concentrations may be reduced to between 99.3 and 53 per cent of the initial, depending on the diffusion characteristics of the soil and nutrient demand by the root. Of the total potassium absorbed by a root in 4 days, the proportion which is supplied from within the root hair cylinder is small (0.8 to 6.3 per cent) indicating that diffusion to the root from the soil outside the root hair cylinder is of paramount importance. When root demand is high, diffusion appears to limit uptake to between 71 and 59 per cent of that which roots of comparable physiology would be expected to absorb from stirred solution of the same concentration. Nevertheless, the presence of root hairs is calculated to have enhanced uptake by up to 77 per cent compared with roots without hairs because they virtually increase the root diameter. Diffusion does not appear to be a limiting factor when root demand is low and hairs can then add little to the efficiency of the root system in potassium absorption.     

Cation exchange in mammalian erythrocytes. III. The prolytic effect of x-rays on human cells

Freshly drawn heparinized human whole blood is exposed to x-rays in amounts up to 54,000 r in vitro and then equilibrated under a controlled atmosphere at 24 or 38°C. For as long as 26 hours following exposure, potassium is progressively lost from the cells and quantitatively replaced by sodium with little, if any, osmotic disturbance. The mean rate of loss at 20,000 r and 24°C. is about 0.4 per cent of the initial cell potassium per hour and approximately doubles for a 20,000 r increase. It is accentuated if blood is stored at low temperature (5°C.) following radiation exposure. Isotope experiments show that the rate of entrance of potassium into the cells is practically unaltered, the principal effect being an acceleration of the rate from cells to plasma. This suggests that radiation may have interfered with a mechanism of selective potassium accumulation based on preferential retention of the element. The sodium which enters the cells following irradiation contributes to the rapidly exchanging portion of the cellular sodium, suggesting that this fraction is ionic sodium.     

Potassium Uptake and Transport in Roots of Ricinus communis

The uptake, accumulation, and transport of potassium by excisedroots of Ricinus communis were investigated. It was found that: 1. The transport of potassium to the vessels was closely dependenton the supply of the ion in the medium. 2. The flux of potassium to the vessels was only a fractionof the total potassium taken up and 99 per cent, of that absorbedwas accumulated in the root tissues. Once retained in this waypotassium appeared to become unavailable for transport to thevessels. 3. There was a fixed relationship between the potassium concentrationsof the medium and the exudate when potassium was supplied aspotassium nitrate in the medium at a range of concentrations.This relationship was altered by the presence of other ionsin the medium.     

Effects of Chemical Antitranspirants on Transpiration and Growth of Grass

The effects of foliar sprays of the metabolic inhibitors dodecenylsuccinicacid (DSA) and phenylmercuric acetate (PMA), as antitranspirants,were tested on grass grown outdoors (in lysimeters), but moreaccurate tests were made with PMA in growth rooms, using smallweighable transpirometers. Concentrations of PMA which wereweaker than 10^-3.8 M resulted in only slight reductions in transpiration,whereas concentrations stronger than 10^-3.2 M were phytotoxic,though water losses were reduced by about 30 per cent. PMA at10^-3.5 M gave the greatest decrease in transpiration (about20 per cent) without reducing growth, but its effectivenessdepended on the amount applied per unit area of vegetation.The effects of PMA also differed with plant species and withenvironment, being greatest under conditions of low soil moisturestress and temperature. The antitranspirant reduced stomatalapertures and increased leaf temperatures.     

Gas exchange of a desert shrub (Zygophyllum dumosum Boiss.) under different soil moisture regimes during summer drought

The effects of soil water potential on photosynthesis and transpiration of whole Zygophyllum dumosum Boiss. shrubs were examined with a field IRGA system during a rainless summer. Daily photosynthesis and transpiration activities were not notably different on a unit phyllode area basis among shrubs at naturally differing soil water potentials. Irrigation of shrubs caused phyllodes to increase significantly in water content and new leaflets to appear. Leaflets had three times as many stomata per unit area (23000 stomata cm^-2) as phyllodes (7100 stomata cm^-2) but photosynthesis and transpiration rates were not measurably different between irrigated and non-irrigated shrubs on a unit area basis. This finding suggests that sufficient soil moisture will lead to increased carbon uptake of the entire shrub simply because the total area of photosynthesizing tissue increases. Gas exchange rates appear to be controlled solely by atmospheric conditions under the stresses of summer.     

Exploratory pot experiments on sensitiveness of different crops to sodium: D. Barley

Summary The effect of sodium on barley has been investigated by means of three pot experiments, of which one was on a humic sandy soil and two on an artificial soil complex (dusarit/quartz-sand mixture).In two of these experiments the effect of sodium — as nitrate of soda — was studied by comparison with calcium nitrate. At low potassium levels sodium was found to excercise a positive effect, but with an ample supply of potassium no differences between the effects of the two nitrate fertilizers were observed.In the third experiment a wide variation in the potassium and sodium levels was introduced by the application of these elements adsorbed to dusarit, all treatments receiving nitrogen in the form of calcium nitrate. Little influence was exercised by the total level of monovalent ions (10, 20 and 40 per cent respectively, of the adsorbed bases). Three-quarters, or possibly seven-eights of the potassium was found to be replaceable by sodium without causing significant changes in the yields of grain and straw.From a survey of the available literature it cannot yet be concluded whether the importance of sodium for barley is limited to a beneficial effect resulting from its mere replacement of potassium, when too little of the latter is available, or whether this importance may be regarded as essential in the sense that sodium has a yield-increasing effect, even in the presence of a sufficiency of potassium.     

Sodium in the mineral nutrition ofAvena Sativa

Summary In pot experiments with oats on sandy soil poor in sodium and potassium a study was made of the effect of the addition of Na₂SO₄ and K₂SO₄ on the mineral composition of the straw.The addition of sodium at 200 ppm Na significantly increased the phosphorus content of the straw and there was a slight further increase with 200 ppm Na plus 200 ppm K, but the phosphorus content never exceeded 0.13 per cent.Sodium and potassium caused a highly significant decrease in the silica content of the straw. Decreased lodging in soils inundated with sea water can therefore not be ascribed to an increase of silica content.The calcium and the cellulose contents of the straw were both significantly reduced by sodium and potassium.     

The effect of ferrous sulphate on the yield and manganese uptake of oats on sandy soil fertilized with natural pyrolusite

Summary The effects of soil treatments with ferrous sulphate and an equivalent amount of hydroquinone on the yield of dry matter and the manganese uptake of oats were investigated in pot experiments using a sandy soil deficient in manganese, with and without additions of finely ground, natural pyrolusite containing some manganite.In soil not fertilized with pyrolusite an application of hydroquinone gave a higher yield of dry matter and a considerably higher manganese uptake than an application of the equivalent quantity of ferrous sulphate.In soil fertilized with hydroquinone an increase of 23 per cent in the yield of dry matter and an increase of 50 per cent in the manganese uptake per pot were found when the soil was fertilized with 100 g of natural pyrolusite <50µ per pot. In soil fertilized with a quantity of ferrous sulphate equivalent to hydroquinone, an increase of 21 percent in the yield of dry matter and an increase of about 200 per cent in the manganese uptake per pot were found when the 100 g of pyrolusite was applied.     

Studies on potassium release in an inceptisol soil (Holambi Series) at the minimum level of exchangeable potassium

Summary Ammonium acetate extractable potassium in the soil reached a minimum value of 6.8 mg K/100g soil after 14 crops of wheat and pearl millet in the field without applying any potassium fertilizer. At this level of ammonium acetate extractable K both wheat and pearl millet utilized about, 90 per cent of the total K from non-exchangeable sources. Wheat and pearl millet were grown in this soil in the greenhouse at different levels of K. At K₀ level wheat utilized 86 per cent of the total K uptake from the non-exchangeable source and pearl millet, 95 per cent. At K₁ level, wheat utilized only 19 per cent but at higher levels of K, there was build up in the K status of soils. In the case of pearl millet at K₁, K₂ and K₃ levels 59, 13 and 22 per cent of total uptake were contributed by non-exchangeable forms. The total K uptake by pearl millet was more than double that by wheat. Plant analysis showed that 83 per cent of the total K in wheat was contained in the shoot portion and the rest in the roots. The corresponding figures for pearl millet were 94 and 6 per cent.     

EFFECTS OF POTASSIUM ON INDICATOR SPACES AND FLUXES IN SLICES OF BRAIN CORTEX FROM ADULT AND NEW-BORN RATS

—Inulin, sucrose and chloride spaces were measured in slices of brain cortex from adult and from new-born rats incubated in‘balanced', potassium-rich and sodium-rich media. The efflux of the radioactive markers was followed in the two first media and the following results were obtained: (1) In brain slices from new-born rats inulin and sucrose spaces were of identical magnitude (35 per cent). The space magnitude was essentially unaffected by excess potassium. The chloride space was somewhat larger than the inulin (sucrose) space, and the difference increased continuously but relatively slightly with the external potassium concentration. By far the largest amount (i.e. about 90 per cent) of the efflux of radioactive inulin, sucrose and chloride occurred from a rapidly exchanging compartment during incubation in both ‘balanced’ and potassium-rich media. (2) In brain slices from adult rats the inulin space (35 per cent) was significantly smaller than that of sucrose (50 per cent) and of chloride (65 per cent); it seemed to represent the extracellular space relatively well although 10 per cent of the efflux occurred from a slowly exchanging (probably intracellular) compartment. High concentrations of potassium led to a reduction of the inulin space which was probably a result of the concomitant intracellular swelling. The hyperosmolarity per se did not affect the space magnitude, but an increase of the sodium concentration exerted a competitive inhibition of potassium effects on the inulin space. Of the sucrose efflux, 20 per cent occurred from a slowly exchanging compartment in both ‘balanced’ and potassium-rich media, and 30 per cent of the chloride exchanged with this compartment when the tissue was incubated in a ‘balanced’ medium. An increase of the external potassium concentration caused a drastic increase of the chloride space and a reduction of the slowly exhanging fraction of chloride efflux to less than 10 per cent.     

Potassium Loss during Galvanotaxis of Slime Mold

The posterior reticulated regions of the plasmodia of the slime mold, Physarum polycephalum, whose migration has been oriented by direct current (3.0 to 5.0 µa/mm² in the agar substrate), contain 30 per cent less potassium than the advancing non-reticulated region. The anterior regions have the same potassium concentration as that of the controls, approximately 32 meq/kg wet weight. Differences in potassium concentration between anterior and posterior regions of control plasmodia, not oriented by electric current, are less than 5 per cent. Sodium, in contrast to potassium, is generally less concentrated in the anterior than in the posterior regions of electrically oriented plasmodia, but sodium concentrations are extremely variable. No significant difference in protein concentration was found between oriented and control plasmodia. Thirty-five per cent of the total potassium, but none of the sodium, is found in acidified ethanol precipitates from plasmodial homogenates. Potassium, but not sodium, appears to be closely associated with processes which differentiate anterior from posterior in an oriented plasmodium.     

温带荒漠灌丛和藓类结皮对土壤养分的贡献

灌丛与生物土壤结皮镶嵌分布是温带荒漠常见的地表景观之一,二者的发育均显著影响了地表土壤养分的空间分布特征及循环过程。然而,灌丛和生物土壤结皮对荒漠土壤表层养分的影响存在怎样的差异,二者对养分变化的贡献度如何尚不清楚。因此,选择中国北方典型温带荒漠古尔班通古特沙漠为研究区,以荒漠中的优势灌丛膜果麻黄(Ephedra przewalskii)灌丛和生物土壤结皮发育高级阶段的藓类结皮的结皮层及结皮下层土壤为研究对象,采集不同微生境(裸露地、灌丛下)的裸沙与藓类结皮的土壤样品。为探究不同微生境下不同土层碳、氮、磷和钾养分变化特征,测定了不同土层土壤有机碳(SOC)、全氮(TN)、全磷(TP)、全钾(TK)、速效氮(AN)、速效磷(AP)和速效钾(AK)含量。结果表明:(1)相较于裸露地,灌丛显著提高了藓类结皮不同土层有机碳、全氮和全钾的含量和裸沙全磷的含量,降低了灌丛下藓类结皮土壤全磷的含量。(2)对于速效养分而言,与裸沙相比,裸露地藓类结皮覆盖降低了土壤速效氮含量,增加了速效磷和速效钾含量;而灌丛下藓类结皮覆盖提高了土壤速效氮和速效钾的含量,但降低了速效磷的含量。 (3) 相关性分析显示,在0-2 cm土壤中速效磷与速效氮呈现显著负相关,而在2-6 cm速效磷与速效氮呈现显著正相关(P<0.01)。(4)贡献度分析表明,土壤中灌丛效应对养分的贡献(42.54%)要远大于藓类结皮的贡献(2.43%),但二者交互作用却降低了除速效氮以外的其他土壤养分含量。综上,灌丛、藓类结皮覆盖和土层深度变化对土壤碳、氮、磷和钾养分均具有显著影响(P<0.05),但三者间的交互效应对养分的影响不显著(P>0.05)。相对于裸露地,灌丛与藓类结皮的覆盖均对表层土壤碳、氮、磷和钾养分具有促进作用,且随着土层深度的下降,土壤养分含量呈现显著的下降趋势(P<0.05)。因此,在荒漠生态系统中耐旱灌丛与生物土壤结皮这两个最重要的斑块单元联合调控了微尺度土壤养分的空间异质性变化。     

Uptake and distribution of potassium in tomato plants

Summary The uptake and distribution of potassium was examined in tomato plants, cv. Amberley Cross and Moneymaker, grown in peat/loam and given a nutrient feed either adequate or deficient in potassium.Detailed studies were also made of the distribution of potassium in various parts of tomato plants, cv. Amberley Cross, grown in sand and supplied with nutrient feeds containing four and seven concentrations of potassium. In these plants the concentration of potassium in stem, petiole and laminar tissue increased from the base to the apex of plants, irrespective of the potassium concentration in the nutrient feed. There was also a gradient of decreasing potassium concentration along leaves, from proximal to distal laminae. The concentration of potassium in all plant parts increased with increasing nutrient supply of potassium, petioles showing a greater response to nutrient potassium than laminar tissue.Marginal chlorosis and/or necrosis were observed when the potassium concentration in fully expanded leaves fell below 1.2 per cent of the dry weight for cv. Amberley Cross or 1.5 per cent for cv. Moneymaker. A 50 per cent incidence of chlorosis and/or necrosis occurred in leaf laminae containing 0.74 per cent potassium.Leaves rarely showed deficiency symptoms when the concentration of potassium in the petioles was higher than that in adjacent laminar tissue. However, chlorosis and/or necrosis occurred when the potassium concentration in petioles fell below that in laminae. In the diagnosis of the potassium status of tomato plants, the most suitable tissue for sampling for potassium analysis is considered to be the petioles of young fully expanded leaves.     

A method of sodium and potassium determination in red cells with a simple cell separation technique

Heparinized blood was centrifuged repeatedly in Eppendorf's test tubes at 7,500 g in the Unipan microcentrifuge type 320. Packed red cells were hemolysed, then sodium and potassium were determined by means of the flame photometer. The percentage of trapped plasma determined with indocyanine green amounted to on average 1 per cent. There was a good precision of the method controlled on 20 aliquots of the same blood sample. Results of red cell sodium and potassium in 80 healthy volunteers were 10.42 +/- 1.56 mmol/l and 87.8 +/- 4.03 mmol/l respectively. No significant changes in the red cell sodium and potassium concentration were observed in heparinized blood during 5 hours storage at room temperature. The method cannot be used interchangeably with the method of Helbock and Brown, since the correlation coefficients were too low in parallel examinations.     

POTASSIUM EFFECTS ON ION TRANSPORT IN BRAIN SLICES

—(1) Fluxes of sodium, potassium, chloride and glutamate ions were studied in brain slices by aid of radio-isotopes. Desaturation curves showed the efflux to occur from at least two compartments with widely different kinetics. (2) The slowly exchanging component comprises from about 10 (sodium, potassium, chloride) to about 30 (glutamate) per cent of the radioactivity in the tissue. An energy-requiring uptake of potassium and extrusion of sodium seems to occur in this compartment, which probably includes the nerve cells. (3) A rather slow efflux of especially potassium ions from the rapidly exchanging fraction indicates that this component may not be purely extracellular, but also seems to include cells, which possibly are neuroglial. The hypothesis of a cellular origin is supported by the demonstration of an increase in the rate constant of the potassium efflux evoked in the presence of oxygen by high concentrations of potassium. (4) Evidence is presented that the increase in the rate constant of the potassium efflux is due to a potassium-induced stimulation of active transport. No coupling seems to occur between the stimulated potassium transport and movements of sodium, but potassium ions may be accompanied by glutamate ions.     

Effect of potassium deficiency on carbon dioxide,cation, and phosphate content of muscle,with a note on the carbon dioxide content of human muscle

Albino rats weighing 160 to 175 gm. were fed a complete synthetic diet containing 0.003 per cent potassium and 0.7 per cent sodium for 40 days. Controls were given the same diet plus adequate added potassium. 1. Data from analyses of serum and skeletal muscle showed (a) a fall in serum chloride concentration and an increase in serum carbon dioxide concentration and pH in the potassium-deficient rats; (b) increases of sodium, magnesium, and calcium and a decrease of potassium in the muscle of the potassium-deficient rats; (c) no change of muscle chloride or carbon dioxide concentrations in the potassium-deficient rats. (2) Application of the Wallace-Hastings calculations to these data revealed (a) intracellular pH of the skeletal muscle of the normal rat to be 6.98 +/- 0.08; (b) an increase in serum partial pressure of carbon dioxide (pCO(2)) in potassium deficiency, together with increases in concentrations of [H(2)CO(2)] and [HCO(3) (-)] per kg. extracellular water and [H(2)CO(3)] per kg. cell water; (c) a decrease in values for [CO(2)] and [HCO(3) (-)] per kg. intracellular water; (d) a fall of intracellular pH in potassium deficiency to 6.42 +/- 0.05. (3) Analyses of sacrospinalis muscle from five men undergoing operation for ruptured intervertebral disc showed a mean value of 9.46 +/- 1.31 mM carbon dioxide per kg. blood-free tissue. Some problems of interpretation of data are briefly discussed.     

Evidence for the presence of separate mechanisms regulating potassium and sodium distribution in Ulva lactuca

1. The methods employed in these and preceding (25-27) studies were shown to allow analysis of true cellular sodium and potassium concentrations. 2. The rate of reaccumulation of potassium by potassium-deficient cells is independent of the presence or absence of sodium in the external medium. 3. Phenylurethane (10(-3)M), a photosynthetic and metabolic inhibitor, causes a marked progressive loss of potassium and gain of sodium, both of which changes are completely reversible on transferring the samples to running sea water. 4. Iodoacetate, while not effective in causing potassium and sodium shifts in the light, effects a loss of potassium and a gain of sodium in the light in the presence of phenylurethane. 5. Arsenate (5 x 10(-3)M) completely protects Ulva against the potassium loss usually observed with iodoacetate in the dark while it affords no protection against the sodium influx under the same conditions. Arsenate given after 18 to 20 hours in iodoacetate gives significant protection against potassium loss in the dark, and allows a slight net reaccumulation of potassium in the light. Arsenate in the dark after iodoacetate affords no protection against the sodium uptake caused by iodoacetate in the dark, while in the light under the same conditions sodium is rapidly secreted to the control level within a few hours. This resecretion of sodium is thought to be primarily an effect of light, the presence of arsenate being incidental. 6. The "decoupling agent" 4,6-dinitro-o-cresol causes a marked progressive increase in cellular sodium and a drop in cellular potassium, though the kinetics of these two movements are distinctly different from each other. 7. Pyruvate (50 mg. per cent) given with iodoacetate (2 x 10(-3)M) for 5 hours in the dark completely prevents the sodium increase caused by iodoacetate, while affording less protection against the potassium loss. Phosphoglycerate, on the other hand, offers more protection against potassium loss, and essentially none against the sodium gain. 8. ATP added in small amounts at short intervals to samples maintained in 10(-3)M iodoacetate in the dark affords significant protection against the potassium loss observed in iodoacetate. Cellular sodium is somewhat higher in the ATP-iodoacetate samples than in the iodoacetate samples. 9. In the discussion of the data presented two major points are emphasized: (1) the close correlation between cellular metabolism and normal cation control; (2) two mechanisms must be operative in cation regulation in this organism: one for moving potassium inwards and the other for transporting sodium outwards. These mechanisms are independent of each other.     

基于土芯法的亚热带常绿阔叶林细根空间变异与取样数量估计

树木细根具有高度空间异质性,确定合理的细根取样策略是林木细根研究的前提。通过在福建省三明米槠天然常绿阔叶林内随机钻取96个土芯,分析细根生物量和形态特征的空间变异特征,并估计各指标所需的取样数量。结果表明:(1)随着径级增加,细根各指标变异系数增大,相应的取样数量增加;(2)随着土壤深度增加,单位面积细根生物量变异程度和相应的取样数量均增加。在置信水平为95%、精度为80%的条件下,直径为0-1 mm和1-2 mm的细根,分别采集16和42个样品可以满足测定单位面积细根生物量,采集17和31个样品可以满足测定单位面积细根长度,采集25和33个样品可以满足测定单位面积细根表面积。Shapiro-Wilk检验表明,除表层土壤0-1 mm细根单位面积生物量符合正态分布外,其余细根生物量和形态指标数据均不符合正态分布。研究结果为亚热带常绿阔叶林细根的合理取样提供了科学依据。