Interaction Between Potassium and Calcium in Their Absorption by Intact Barley Plants. II. Effects of Calcium and Potassium Concentration on Potassium Absorption

Increasing concentrations of K (20, 200, 2000 μm) in the nutrient solution depressed Ca content and concentration in barley plants growing in nutrient solutions of low Ca concentrations (250 and 2500 μm). Increasing K from 20 to 200 μm depressed Ca absorption more than increasing K from 200 to 2000 μm K.     

Influence of calcium on sodium and potassium absorption by fresh and aged bean stem slices

The influence of Ca on the aging processes of bean stem (Phaseolus vulgaris) slices and on the absorption of K and Na by fresh and aged slices was investigated. In the presence of Ca, fresh tissue showed a preferential Na uptake. The preference for Na over K resulted from a differential depressive effect of Ca on absorption of these two ions. In aged tissue Na uptake was also depressed, but K absorption was accelerated, with a net result of a much greater absorption of K than Na.     

The distribution of potassium,calcium and magnesium in young tomato plants grown in water culture

Tomato seedlings, cv. Moneymaker were grown in water culture at a low [half] level of K, Ca of Mg as well as in a control in which the three nutrient elements were present at a higher [full] concentration. At weekly intervals, plants were harvested and partitioned. The dry weight and the K, Ca and Mg concentrations of each part were determined. In all treatments characteristic concentration gradients of each element were apparent within the plant, and in the case of K, leaf concentration changed with age. The possibility of internal re-distribution of nutrients seemed greatest in the case of K.Comparison of nutrient concentration in equivalent leaves from high and low treatments suggests that choice of leaf is not critical in assessing Ca and Mg status, but that the lower leaves during their sixth and seventh weeks of development are most sensitive to K supply. re]19760917     

Nitrogen and potassium fertilization and environmental factors affecting the grass tetany hazard of wheat forage

Summary The effects of temperature and soil moisture levels on the chemical composition of wheat forage grown in growth chambers were studied. In addition to the environmental variables, K and N fertilization effects were studied. In all the studies, increasing levels of K fertilization depressed the Mg and Ca concentration of the shoots. Nitrogen fertilization increased the Mg concentration but had no effect on the Ca concentration of the plants. N fertilization depressed the K concentration in the soil moisture experiment, but had no effect on K concentration in the temperature experiment. Increasing the temperature from 10 to 20°C did not affect the Mg and Ca concentration of the shoots, but the K concentration declined due to dilution effects caused by the greater yield at the higher temperature. In the soil moisture level experiment the K, Mg and Ca concentration in wheat tended to decline with soil moisture level due to dilution effects. Calculations showed that uptake of K was regulated primarily by diffusion of K from the soil to the plant root and that the uptake of Mg was regulated by the uptake process of the plant root and not by the nutrient transport process through the soil.This study was part of the program of the Center for Root-Soil Research. Dept. of Agronomy paper #1532.     

Effect of sulfur and potassium on zinc absorption by barley

Summary Maximum uptake of Zn in barley (Hordeum vulgare L.) seedlings occurred from nutrient solutions containing SO₄−S at 3.5 ppm and K at 6 ppm. Decreased translocation of Zn from roots to tips was observed when plants were grown with lower levels of S and K. Cysteine substituted for SO₄-ion as a source of S in Zn absorption, and more Zn was absorbed with cysteine than with sulfate. The effect of K on Zn absorption seems to be influenced by S nutrition in plants.     

Uneven distribution of nutrients in the root zone affects the incidence of blossom end rot and concentration of calcium and potassium in fruits of tomato

Tomato plants (Lycopersicon esculentum Mill. var. DRK) were grown hydroponically to determine the effect of an uneven distribution of nutrients in the root zone on blossom end rot (BER) and Ca and K concentrations in the fruits. The plants were grown in rockwool with their root system divided into two portions. Each portion was irrigated with nutrient solutions with either the same or the different electrical conductivity (EC) in the range 0 to 6 dS m^–1. Solutions with high EC supplied to both sides of the root system significantly increased the incidence of BER. However, when only water or a solution of low EC was supplied to one portion, BER was reduced by 80%. Fruit yields were significantly higher (P<0.01) for plants that received solutions of the uneven EC treatments (6/0 or 4.5/0 EC treatment). Plants supplied with solutions of uneven EC generally had higher leaf and fruit concentrations of Ca but lower concentrations of K than those supplied with solutions of high EC. There was no difference in Ca concentration at the distal end of young fruits of the uneven EC treatment but it was reduced in the high EC treatments. The concentration of K in the mature fruits of the uneven EC treatments was lower than that of the high EC treatments and higher or similar that of the 3/3 or 2.5/2.5 EC treatments (controls). A clear relationship was found between the incidence of BER and the exudation rate. High rate of xylem exudation was observed in the uneven EC treatments. Reduction of BER in the uneven EC treatments is most likely to be the effect of high exudation rate on Ca status in the young fruits. It was concluded that high EC of solution had positive effects on Ca concentration and incidence of BER provided that nutrient solution with low EC or water is supplied to the one portion of the root system.     

Uptake of potassium and its influence on growth and magnesium uptake by groundnut (Arachis hypogaea L.) plants

Groundnut (Arachis hypogaea L.) plants were grown for 55 days in dilute nutrient solution at varying concentration of potassium. Data are recorded for the rate of uptake of potassium, magnesium and growth response. Over the concentration range studied, the rate of absorption of potassium followed Michaelis-Menten kinetics with a Michaelis constant (K_m) of 0.06×10^?3M. Identical response curves were observed for either total growth or total uptake. Maximum yield was obtained at a concentration of about 200 μM potassium. Increasing concentrations of potassium depressed the uptake of magnesium.     

Interaction of rubidium or sodium with potassium in absorption by intact sugar beet plants

This study concerns the selective absorption of K and Rb or of K and Na by intact sugar beet (Beta vulgaris) plants from modified conventional nutrient solutions over an extended period of plant growth. Long term results agreed with those of short term experiments by other investigators using excised root systems and simple salt solutions. Potassium and Rb were mutually competitive in their absorption. High selectivity of K relative to Na absorption was observed. Sodium was excluded during the early growth period of sugar beets.     

Sodium and potassium absorption by bean stem tissue

The effect of various periods of pretreatment in CaSO₄ solutions (aging) on the absorption of Na and K by bean stem slices was investigated. Freshly sliced tissue absorbed Na over the entire range of concentrations studied (0.02-50 mm). Potassium absorption by fresh tissue was nil at concentrations below 0.5 mm but at higher concentrations was similar to that of Na. When tissue was aged by aerating slices for 20 hr in 0.5 mm CaSO₄, K absorption was substantial over the entire range (0.01-50 mm), with evidence of a dual mechanism of absorption, whereas Na absorption was nil at concentrations below 0.2 mm. The formation of K-absorbing capacity with aging, and the loss of Na-absorbing capacity at low concentrations, were temperature-dependent and did not result from significant changes in rates of efflux of either ion. The absorption of Na by fresh tissue and K by aged tissue was sensitive to antimetabolites, with K uptake the more sensitive. Benzyladenine, an analog of kinetin, suppressed the formation of K-absorbing capability in aged tissue but did not prevent the loss of Naabsorbing capacity. Possible mechanisms for this alteration in ion-specificity of transport mechanisms are discussed.     

Effect of calcium on transport of cations to the xylem exudate of tobacco

Summary Roots of detopped tobacco plants (Nicotiana tabacum var. Virginia Gold) were exposed to Na, K, and Ca salts or to water, and cation transfer to xylem vessels was measured. In some cases plants had been exposed to Na in addition to regular nutrient solutions before detopping. Calcium in the external medium greatly depressed the transport of Na from the external medium to the xylem vessels and it often stimulated the transfer of K from the external medium to the xylem vessels. The K/Na ratio in the exudate thus was dependent upon the Ca content of the external medium under these conditions. In contrast, externally applied Ca or Ca deficiency had very little effect on the transfer of preaccumulated K and Na from compartments within roots to the xylem vessels. The K/Na ratio in the exudate under these conditions was not related to Ca levels nor to mild Ca deficiency. The ratios decreased with time after detopping regardless of Ca level. Intact plants accumulated more Na than did root systems of detopped plants in a 6-day period.Riverside University of CaliforniaSoil Science and Agricultural Engineering     

Effect of calcium on the absorption and translocation of heavy metals in excised barley roots: Multi-compartment transport box experiment

Summary The effect of Ca on the absorption and translocation of Mn, Zn and Cd in excised barley roots was studied using a multi-compartment transport box technique. A radioisotope (⁵⁴Mn,⁶⁵Zn or^115mCd)-labelled test solution was supplied to the apexes of excised roots and the distribution pattern in the roots was examined in the absence or presence of Ca. Results obtained were as follows. Addition of Ca to the test solution reduced the absorption of Mn and inhibited drastically its translocation in excised roots. With increasing concentrations of Ca in test solutions, its inhibitory effects on the absorption and translocation of Mn became severe. Similar results were observed for the absorption and translocation of Zn. Ca in the test solution decreased the absorption and inhibited drastically the translocation of Zn; as in the case of Mn, higher concentrations of Ca had severe effects on these functions. It was also evident that the addition of Ca to the test solution reduced the absorption of Cd at all levels of Cd concentration (1, 10, and 100 μM). Cd absorption decreased with increasing concentrations of Ca in the test solution. However, Ca accelerated the translocation of Cd in excised roots supplied with test solutions containing up to 10μM Cd. At 100μM Cd, addition of Ca caused a negligibly small acceleration of Cd translocation. The accelerating effect of Ca on Cd translocation, especially “xylem exudation”, decreased markedly with the addition of 2,4-dinitrophenol, but not with the addition of chloramphenicol or p-chloromercuribenzene sulphonic acid. When barley plants were supplied with only CaSO₄ during the entire growing period, that is, plants were not supplied with nutrient solution on the last day of this period, Ca had no accelerating effect on Cd translocation in excised roots.     

Influence of potassium and manganese on growth and uptake of magnesium by soybeans (Glycine max (L.) Merr. cv. Bragg)

Summary Soybean (Glycine max (L) Merr. cv. Bragg) seedlings were grown in nutrient solutions to evaluate the response to manganese nutrition as affected by potassium supply. In solutions containing 275 M manganese, increasing the solution concentration of potassium from 1 mM to 10 mM alleviated symptoms of manganese toxicity, decreased manganese concentrations in the leaves and increased dry matter yields of the plants. The reduction in manganese toxicity was brought about by a reduced rate of root absorption of manganese at high potassium supply levels.Increasing the supply of either potassium or manganese decreased the leaf concentration of magnesium although there were no apparent symptoms of magnesium deficiency in any treatment. The reduced concentration of magnesium in the leaves was due to effects of potassium and manganese on the rate of root absorption of magnesium.Under manganese deficiency conditions, growth was reduced and manganese concentrations in plant parts were very low; there was no effect of potassium supply when manganese was absent from the nutrient solution.     

The influence of ionic strength on potassium contractures and calcium movements in frog muscle

Frog toe muscles were bathed in isotonic, sodium-free Tris chloride, methanesulfonate, or sulfate solutions containing sucrose or mannitol and varying in ionic strength from 0.006 to 0.291. By decreasing the ionic strength the curve relating the peak tension of the K contractures to the log [K] was reversibly shifted to lower [K]. Increasing the [Ca] from 1 to 4 mM almost abolished this effect. The resting uptake of ⁴⁵Ca was increased more than two times by decreasing the ionic strength from 0.125 to 0.039. It was not increased significantly by raising [Ca] from 1 to 4 mM at low or normal ionic strength. The additional uptake of ⁴⁵Ca during contractures provoked by 120 mM K was not significantly different at the two levels of ionic strength. The rate of emergence of ⁴⁵Ca from muscles loaded with ⁴⁵Ca at reduced ionic strength, was decreased. The effects of low ionic strength are discussed in terms of changes in the potential difference across a membrane with fixed negative charges on the outer surface.     

Potassium uptake by rice plants and interaction with other cations

Summary Rice plants were grown in nutrient solutions in which the K supply was varied by stepwise substitution of Na, Mg, or Ca. Curves relating concentrations in the tissues to those in the root medium showed that K uptake depressed the transfer of Na, Mg, and Ca into the shoots even when supplies of the latter were raised at the expense of K. Only when K was depleted did the other cations substitute for K in the shoots with little change in the total cation concentration in the tissue. Uptake appears to be controlled by a single system in which the 4 cations compete for uptake sites and K was the most effective competitor. re]19730507     

Membrane effects of phenothiazines in yeasts. I. Stimulation of calcium and potassium fluxes

Application of trifluoperazine (10-50 microM) to suspensions of the yeast Saccharomyces cerevisiae induces the following effects. (1) A marked increase in the initial rate of 45Ca2+ influx into the cells, accompanied by an increase in the cellular content of calcium. This stimulation in 45Ca2+ influx (10-20-fold) is observed only in the presence of a metabolic substrate and is completely inhibited by LaCl3. The dose-response curves of the cellular accumulation of 45Ca2+ are of a bell shape, indicating a biphasic response. The concentration of the drug yielding maximal accumulation depends on the density of the cells in the suspensions. The results indicate that the stimulation of 45Ca2+ influx is mediated by an energy-dependent carrier-mediated process and not by the increase in the passive membrane permeability to Ca2+. (2) Efflux of K+ from the cells is induced. Removal of metabolic substrate abolishes the effect at concentrations of up to 35 microM and reduces it at higher concentrations. Addition of high concentrations of cations (K+, Na+, Mg2+) to the medium abolishes the stimulation of both K+ efflux and Ca2+ influx. Chloropromazine, thioridazine and chlorprothixene display similar effects, but at higher concentrations. The results are discussed in terms of two possible alternative mechanisms; (1) calmodulin-independent effects of trifluoperazine on cell membranes, or (2) inhibition of some calmodulin-dependent processes by low concentrations of trifluoperazine.     

The effect of calcium deficiency on nitrate absorption and assimilation in pumpkin plants

The absorption of nitrate and the activity of nitrate reductase were much lower in Ca-deficient plants ofCururbita pepo L., cv. ‘Kveta’ than in normal plants grown in complete nutrient solution for a period of 8 days. After the addition of nitrate to the nutrient medium, nitrate reductase activity in the roots of NO₃-deficient plants sharply rose during the first 6 h and then remained constant during the following 6 h; the content of endogenous NO₃ ^? rose slowly and continuously. These processes were depressed in (Ca, NO₃)-deficient plants independently of the addition of Ca²⁺ to the medium in the variant with NO₃ ^?. Thus it seems that the whole nitrogen metabolism,i.e. both NO₃ ^? absorption and the synthesis of nitrate reductase, is impaired in Ca-deficient plants.     

The regulation of potassium absorption in barley roots

The dynamics of changes in K(+) influx across the plasmalemma and of internal K(+) concentrations [K(+)](1) of intact barley (Hordeum vulgare) roots were examined as the roots were converted from ;high-salt' to ;low-salt' roots. Following the transfer of plants grown in 0.5 mm CaSO(4) solutions plus various concentrations of KCl to 0.5 mm CaSO(4) solutions, influx rates increased and internal K(+) concentrations declined as a function of time and the initial K(+) status of the tissue. The relationship between plasmalemma influx and [K(+)](1) was examined over a wide range of [K(+)](1) values by growing intact plants in various concentrations of KCl. Plasmalemma influx was inversely correlated with the square of [K(+)](1). A model for the regulation of plasmalemma influx by [K(+)](1) is considered.     

Factors affecting soil acidification under legumes I. Effect of potassium supply

This study examined the effect of K (as K₂SO₄) supply on acid production under N₂-fixing plants of lupin (Lupinus angustifolius L. cv. Gungurru) and clover (Trifolium subterraneum L. cv. Dalkeith) grown in a K-deficient soil with a low pH buffer capacity for 55 days in the glasshouse at 20/12 °C (day/night). Increasing K supply up to 240 mg K kg^-1 soil markedly increased plant growth of both species but clover growth was more responsive than lupin. Growing plants for 55 days decreased soil pH by 0.65–0.85 units under lupin and 0.45–0.83 units under clover. The amounts of H⁺ produced per kg biomass (specific acid production) were the highest at the nil K supply, generally decreased with increasing K level up to 30 mg K kg^-1 under lupin and up to 120 mg K kg^-1 soil under clover and only slightly increased with further increasing K under lupin. Increasing K₂SO₄ supply proportionally increased plant uptake of K and SO ₄ ^2- but generally decreased concentrations of Ca, Mg, Na, P and Cl. Specific acid production correlated well with concentrations of excess cations and ash alkalinity, and total acid production was strongly correlated with total excess cations and total ash alkalinity in plants. These relationships were not affected by K treatment and species. Specific acid production also correlated with plant Ca concentration but not with K concentration. In addition, lupin and clover extruded similar amounts of H⁺ per kg biomass produced. It is suggested that application of K₂SO₄ does not have a significant impact on acid production by lupin and clover.     

钾与信号抑制剂对外生菌根真菌分泌乙酸的调控作用

外生菌根真菌是森林生态系统中的重要成分,参与树木养分的吸收利用。试验液体培养外生菌根真菌,设置不同供钾水平,添加钙信号抑制剂,研究了它们的有机酸和氢离子分泌,以及乙酸分泌对供钾和信号抑制剂的响应。结果表明,供试菌株的生长,氮、磷、钾含量和吸收量因菌株不同而异,生物量变化于52.91—121.72 mg/瓶之间,相差1倍以上。外生菌根真菌吸收养分的差异可能与它们对土壤养分环境的长期适应、进化、选择有关。在外生菌根真菌的培养液中,分别检测出草酸、乙酸、苹果酸、柠檬酸和丁二酸等,以及大量的氢离子,说明菌根真菌能分解土壤含钾矿物,释放钾离子,改善寄主植物的钾营养。其中,乙酸分泌量较大,具有普遍性,低钾刺激分泌乙酸,高钾时分泌减少,其分泌速率与供钾浓度和菌丝吸钾量之间呈显著负相关(r=-0.734,r=-0.617,n=60)。钾对菌根真菌分泌乙酸的调控作用具有改善森林钾素营养,防止土壤养分淋失的生理和生态意义。此外,在低钾条件下,阴离子通道和钙信号抑制剂抑制外生菌根真菌分泌乙酸。说明钙信号和阴离子通道参与了乙酸分泌,缺钾可能是刺激乙酸分泌的原初信号,通过信号转导和一系列级联反应促进乙酸分泌。     

The effect of calcium bicarbonate on iron absorption and distribution byChrysanthemum morifolium, (Ram.)

Summary Plants grown for two weeks in high-bicarbonate nutrient solution with iron became chlorotic, absorbed less iron, and translocated a lower percentage of absorbed iron than did green plants grown under low bicarbonate with iron. Chlorotic plants, pretreated in low-bicarbonate solutions lacking iron, absorbed more iron and translocated a higher percentage to leaves than the green plants. Plants induced to chlorosis by high bicarbonate absorbed less iron after transfer to low-bicarbonate solution containing iron than did chlorotic plants pretreated with low-carbonate solution lacking iron. Initial localization of iron occurred in the roots. A considerable amount of the iron initially found on the roots was translocated to developing shoots over a nine-week period unless the plants were grown in high bicarbonate solutions. More iron was translocated from roots of plants in minus-iron solutions following initial absorption than when iron was supplied in the nutrient solutions. Journal Series Paper736. University of Georgia, College of Agriculture Experiment Stations, College Station, Athens, Ga. 30601.