Total Ca Uptake Research Articles

How nitrogen form and concentration affect growth, nutrient accumulation and photosynthetic performance of Olea europaea L. (cv. ‘Kalamon’)

A greenhouse experiment was conducted, in order to study the effect of nitrogen (N) form (NO3−, NH4+, urea, NH4++NO3−) and concentration (1, 8 and 16mM) on growth, mineral nutrition and photosynthetic performance of olive plants (Olea europaea L., cv. ‘Kalamon’). Our data indicate that when plants at high supply (16mM) received urea as N source better growth performance was recorded, compared to the cases olive plants received other N forms; however, at low to medium N supply (1 or 8mM) better plant growth performance observed when they were fertilized with NO3−–N. Total N uptake at 16mM was significantly lower when plants received NO3−–N, in comparison to the other N forms. NO3− form at 16mM resulted in lower total uptake of P, Fe, Mn and Zn, compared to the other treatments. On the other hand, NH4+-N at high N supply (16mM) resulted in lower total uptake of Ca and Mg. However, significantly higher K uptake was found when plants were treated with NH4+, at high N rate (16mM). High N supply in the form of NH4+-N significantly inhibited net photosynthetic rate (A), although the chlorophyll fluorescence (as an indicator of the function of PSII) did not significantly differ among the N treatments. In conclusion, urea-N proved to be the most appropriate N form for the mineral nutrition of the olive cultivar ‘Kalamon’; thus, it should be preferred as a source of N in olive groves receiving high N fertilizations.

Calcium Toxicity and Tolerance in Lichens: Ca Uptake and Physiological Responses

Although differential sensitivity of lichens to calcium excess has been documented previously at the community level, ecophysiological studies, which would shed light on the calcifuge or calcicole nature of lichens, are virtually absent. In the present study, we compared physiological responses of two morphologically similar foliose lichens, Dermatocarpon miniatum (calcicole lichen) and Umbilicaria hirsuta (calcifuge lichen) to Ca excess (up to 100 mM). The degree of total Ca uptake by the lichens after 24-h prolonged exposure was compared with selected physiological markers including levels of assimilation pigments, chlorophyll a fluorescence, soluble proteins, ergosterol, TBARS, and hydrogen peroxide. Both tested lichens accumulated Ca from the applied solutes of CaCl2 by a dose-dependent manner, although excess of Ca did not change content of assimilation pigments in both tested lichens, as well as integrity of lichen symbiont membranes (tested as TBARS, K content, and ergosterol content) when compared to respective controls. However, we observed significant, concentration-dependent decrease of chlorophyll a fluorescence, content of soluble proteins, and hydrogen peroxide production in U. hirsuta, while in D. miniatum were all these parameters stable through all tested Ca concentrations.

OPTIMUM RATIO OF CALCIUM AND BORON IN THE NUTRIENT SOLUTION OR IN CASTOR BEAN SHOOT FOR FRUIT YIELD AND SEED OIL CONTENT

Calcium (Ca) and boron (B) have been reported as the major macro- and micronutrient required for castor bean plant yield. The objective of this study was to determine the Ca:B ratios (in the growth media and plant tissue) for fruit yield and shoot dry weight of the castor bean (Ricinus communis L.), grown in a nutrient solution, and to evaluate Ca and B supply on concentration and total uptake of Ca, potassium (K), magnesium (Mg), and B, as well on the seed oil content. The treatments were arranged in a 3 × 3 factorial fashion, consisting of three rates of Ca (40, 80, and 160 mg L−1) and three of B (0.32, 0.96, and 1.60 mg L−1). Calcium and B rates increased the shoot and root dry weight and fruit yield at a Ca:B ratio in the nutrient solution of 166 and 100, respectively. Symptoms of B deficiency were observed in plants supplied with 0.32 mg B L−1, regardless of the Ca concentration in the nutrient solution. Plants which showed visual symptoms of Ca deficiency cultivated with 40 mg Ca L−1 presented concentration of Ca in plant tissue up to 10 g kg−1. The concentration and total Ca and B uptake increased with the rates of them. Notwithstanding, the shoot Ca accumulation was improved by B rates. In addition, there were no decreases in K and Mg uptake due to Ca rates. Furthermore, addition of 80 mg L−1 of Ca and 1.60 mg L−1 of B in the growth media increased the seed oil content. The Ca:B ratio in the diagnostic leaf associated with the highest plant dry weight (shoot and root) and fruit yield, was 500 (16 to 20 g kg−1 of Ca, and for 30 to 40 mg kg−1 of B).

Extração de nutrientes e produtividade de genótipos de milho afetados por níveis de palha

In a clayey Red Latosol, located in Ponta Grossa – Paraná State, the nutrient uptake and yield of corn genotypes was evaluated, affected by levels of black oat crop residues in no-tillage. The experimental design was a randomized block design arranged in split-plot with three replications. The plot consisted of three levels of black oat crop residues maintained on the soil surface (without straw, 5.0 and 10.0 ton. Ha-1), and the sub-plots comprised of 13 corn genotypes. The order of the gain on the total uptake of nutrients compared to 5.0 and 10.0 ton. Ha-1 straw was K> P> N, with values of 30.4 and 47.1, 17.6 and 26.4, and 5.4 and 11.3%, respectively. The genotypes differed significantly for nutrient uptake and grain yield, due to the added amounts of black oat crop residue on soil surface in no-tillage system in the initial phase. The increase of crop residue amount on the soil surface did not affect the mean yield of the experiment. The increase in the amount of crop residue on the soil surface resulted in greater total uptake of N, P and K, but did not affect the total uptake of Ca, Mg and S by corn plants. The order in nutrient uptake by the genotypes because affected by crop residue addition was: K> P> N> S> Ca = Mg.

Effect of ancymidol in combination with temperature regime, calcium nitrate, and cultivar selection on calcium deficiency symptoms during hydroponic forcing of tulip

Experiments were conducted to determine the effect of ancymidol, as impacted by temperature, Ca(NO 3) 2, and cultivar, on the prevention of Ca deficiency symptoms during hydroponic forcing of tulip ( Tulipa gesneriana L.). In all treatments where tulips were forced in distilled water, Ca deficiency symptoms occurred. Symptoms included scape topple; flower abortion; and chlorosis, water soaking, cracking, exudation, and purple pigmentation of the lower leaves. All symptoms except topple were avoided when tulips were forced in 5 mM Ca(NO 3) 2 solution. Topple was prevented by Ca(NO 3) 2 in a low temperature regime (21°C day–18°C night) in two of three experiments. Ca deficiency was not prevented in a high temperature regime (24°C day–21°C night). Plants forced in Ca(NO 3) 2 were too tall for commercial use. When forced in a solution of ancymidol, topple was prevented but all other symptoms of Ca deficiency persisted. An ancymidol rate of 0.25 mg per 650 ml pot containing five bulbs caused abortion, unrelated to Ca deficiency, in the cultivar Oscar. Forcing in a combination of 5 mM Ca(NO 3) 2 plus ancymidol prevented all symptoms of Ca deficiency in all experiments except in the high temperature regime of one. Ancymidol rates of 0.0625 and 0.125 mg per pot did not always provide adequate height control. A rate of 0.18 mg per pot in combination with 5 mM Ca(NO 3) 2 was sufficient to prevent Ca deficiency symptoms and provide adequate height control in all but one cultivar. `Jingle Bell' required an ancymidol rate of 0.24 mg for adequate height control. Prevention of topple by ancymidol did not appear to be due to the correction of Ca deficiency since ancymidol added to Ca(NO 3) 2 resulted in lower total Ca uptake per shoot. It was likely due to shorter, stronger scapes masking this Ca deficiency symptom.

Flow Rate as an Important Physiological Factor Associated to Calcium Concentration in Pods of Snap Bean (Phaseolus vulgaris L.) Plants Grown Aeroponically

To understand physiological factors associated with genetic differences for pod Ca concentration between snap bean genotypes, flow rate and Ca uptake of sieve sap were measured, as well as pod Ca concentration. Measurements for flow rate and Ca uptake were done at three developmental stages (fl owering and 1 and 3 weeks after) in two commercial snap bean cultivars (Hystyle and Labrador) grown aeroponically. Pods were collected 2 weeks after flowering only. Flow rate and Ca uptake sampling began 4 weeks after transplanting and consisted of: 1) decapitation of the plant at the first node; 2) covering the stem with pre-weighed dry cotton; and 3) removing the cotton, reweighing it, and saving it for Ca determination. Flow rate was defined as the difference in cotton weight (expressed as ml) per 17 hr divided by foliage mass. Ca uptake was defined as mg of Ca per total volume of sieve sap after 17 hr divided by foliage mass. Ca determinations were made using an atomic absorption spectrophotometer. A positive correlation between flow rate and total Ca uptake of sieve sap (R2 = 0.90), flow rate and pod Ca concentration (R2 = 0.47), and Ca uptake and pod Ca concentration (R2 = 0.42) were found. Hystyle reflected 1.5 times more flow rate and pod Ca concentration than Labrador. Significant differences between genotypes for pod Ca concentration, Ca uptake, and flow rate were observed. Results were consistent across developmental stages.

Effects of proteoglycan modification on mineral formation in a differentiating chick limb-bud mesenchymal cell culture system.

In the presence of 4 mM inorganic phosphate, differentiating chick limb-bud mesenchymal cells plated in micromass cultures form a mineralized matrix resembling that of chick calcified cartilage. To test the hypothesis that cartilage proteoglycans are inhibitors of cell mediated mineralization, the synthesis, content, and turnover of proteoglycans were altered in this system, and the extent of mineralization and properties of the mineral crystals examined. In all cases where the proteoglycan synthesis or proteoglycans present were modified to provide fewer or smaller molecules, mineralization was enhanced. Specifically, when proteoglycan synthesis was blocked by treatment with 10(-10) M retinoic acid, extensive mineral deposition occurred on a matrix devoid of both proteoglycans and cartilage nodules. The crystals, which formed rapidly, were relatively large in size based on analysis by X-ray diffraction or FT-1R microspectroscopy, and were more abundant than in controls. When 2.5 or 5 mM xylosides were used to cause the synthesis of smaller proteoglycans, the extent of mineral accretion was also increased relative to controls; however, the matrix was less affected, and the extent of mineral deposition and the size of the crystals were not as markedly altered as in the case of retinoic acid. Modification of existing proteoglycans by either chondroinase ABC or hyaluronidase treatment similarly resulted in increased mineral accretion (based on 45Ca uptake or total Ca uptake) relative to cultures in which the proteoglycan content was not manipulated. Crystals were more abundant and larger than in control mineralizing cultures. In contrast, when proteoglycan degradation by metalloproteases was inhibited by metal chelation with o-phenanthroline, the Ca accretion at early time points was increased, but as mineralization progressed, Ca accumulation decreased. These data provide evidence that in this culture system, proteoglycans are inhibitors of mineralization.

Responses of Ca-efficient and Ca-inefficient tomato cultivars to salinity in plant growth, calcium accumulation and blossom-end rot

SummaryGrowth responses of tomato plants to salinity in relation to blossom-end rot (BER) in two Ca-efficient (E1 and E2) and two Ca-inefficient (I1 and I2) cultivars, together with a modern cv. Counter (C) were studied at 5 and 12 mS cm-1. E-type plants were leafy and had the heaviest plant dry weight. They accumulated more dry matter than I-type plants in the leaves but less in the fruit, which were small. E-type plants had higher water and Ca uptakes and thus higher plant Ca than I-types, but with a lower proportion of the Ca in the fruit. E-types suffered less reduction in Ca accumulation at high salinity. The higher uptake of Ca in E-type plants may be due mainly to greater canopy transpiration as well as to possibly higher potential root absorption of water, as the Ca concentration of the root exudate was similar between the E- and I-type plants. The proportion of the total Ca uptake attributed to potential root absorption was lower for E-types than for I- types. The modern cultivar (C) had a modera...

Phosphorus and Temperature Effects on Magnesium, Calcium, and Potassium in Wheat and Tall Fescue Leaves

AbstractHigh K fertilization often reduces leaf Mg and Ca concentration, increasing the incidence of grass tetany, while increased P treatment increases uptake and leaf concentrations of Mg and Ca in winter wheat (Triticum aestivum L.). Since P availability and uptake are often reduced at low soil temperatures, the effects of P and K nutrition on mineral element composition of wheat at two root‐zone temperatures were determined. The effects of P and NPK + Mg fertilization on leaf elemental concentrations of tall fescue (Festuca arundinacea Schreb.) grown in the field near Mt. Vernon, MO, on a Creldon silty clay loam (fine, mixed, mesic Mollic Fragiudalf) were determined. Concentration of Mg in wheat shoots was 20% higher when treated with 400 μM P than 50 μM P, and only 9% higher when root‐zone temperature was 25°C rather than 15°C. Similarly, shoot Ca concentration was 11% higher with the high P treatment. Total plant Mg uptake was 60% greater and total Ca uptake was 51% greater with high P. The higher root‐zone temperature increased total plant Mg uptake 38% and total plant Ca uptake 36%. Increasing K treatment from 400 to 800 μM decreased shoot Mg concentration 13% and shoot Ca concentration 7%. In the field, at soil temperatures <15°C, treatments of 20 or 28 kg ha−1 P increased both Mg and Ca leaf concentration of tall fescue. When leaf Mg and Ca concentrations in control plots were below 2.0 and 4.0 g mg−1 respectively, P fertilization increased Mg and Ca concentration above those thresholds considered likely to cause grass tetany. Fertilization with Mg increased leaf Mg concentration only when P fertilizer was added, but caused a decrease in leaf Ca concentration when no P fertilizer was applied. Leaf concentration and total plant uptake of Mg and Ca were more dependent on P nutrition than root temperature.

Effects of environment on the uptake and distribution of calcium in tomato and on the incidence of blossom-end rot

Studies of Ca uptake and distribution in relation to environmental variables were used to relate Ca status of tomato fruit to blossom-end rot (BER) incidence. Ca uptake was highly correlated with solar radiation and root temperature. The rate of Ca uptake decreased linearly with increasing salinity. High humidity reduced Ca import by the leaves but increased that by the fruit. While total plant dry weight was reduced more than fruit dry weight by salinity, total Ca uptake and the Ca content of the fruit were decreased similarly. Thus, the concentration of calcium in the fruit was substantially reduced by salinity. The distal half of the fruit contained less Ca than the proximal half. The lowest % Ca was found in the distal placenta and locular tissues, where BER first develops. The incidence of BER was often stimulated more by high salinity achieved with the addition of major nutrients than with NaCl. The cause of BER is usually an interaction between the effects of irradiance and ambient temperature on fruit growth and the effects of environmental stress on calcium uptake and distribution within the whole plant.

Uptake of Calcium and Magnesium by Cotton Grown under Dryland Conditions

AbstractThe mid‐1940s was the last time an intensive study of the Ca and Mg nutrition of cotton (Gossypium hirsutum L.) was conducted in the USA. Since that time cultivars and cultural practices have changed, thus, field studies were conducted for 2 yr to evaluate the Ca and Mg uptake characteristics of four cultivars that are representative of those now produced in the South: ‘Deltapine 90’, ‘Stoneville 825’, ‘Coker315’ and ‘Paymaster 145’. They were grown on a nonirrigated Decatur silt loam (clayey, thermic, kaolinitic, Rhodic Paleudults) and a nonirrigated Norfolk fine sandy loam (fine loamy, thermic, siliceous, Typic Paleudults) in Alabama. Plants were collected at 2‐wk intervals throughout the growing season, beginning at 15 d after emergence, partitioned into leaves, stems, burs, seed, and lint, and analyzed (except for lint) for Ca and Mg. Total Ca and Mg uptake when averaged for both soils and all four cultivars was 64 and 18 kg ha−1, respectively (or 9.3 kg of Ca and 2.6 kg Mg per 100 kg lint produced). Total Ca uptake was significantly lower on the Norfolk soil (44 kg ha−1) as compared to the Decatur soil (75 kg ha−1) which had a higher level of extractable Ca. There were no cultivar differences in total Ca and Mg uptake or uptake within a given plant part. There were no consistent differences among the cultivars for the concentration of Ca in the various plant parts. The concentration of Mg in the leaves and burs was affected by the cultivar. These cultivars accumulated similar amounts of Ca and Mg as compared to older cultivars, although previous research has shown that modern cultivars partition dry matter differently from older cultivars.

EFFECT OF FARMYARD MANURE AND AMMONIUM SULPHATE ON THE CALCIUM AND MAGNESIUM CONTENT AND UPTAKE BY RAGI (Eleusine coracana) GAERTN.

A field experiment was conducted to study the effect of FYM and (NH,),SO, on ths Ca and Mg content and uptake of Ragi. The study revealed that Ca and Mg content increased markedly by the application of N-Sources of Fertilizers. Ragi variety Co-9 recorded significantly higher content of Ca than Co. 7. Combined application of FYM @ 90 Kg N/ha and (NH),SO. @ 90 kg N/ha registered the highest total uptake of Ca. Application of 60 kg N/ha as FYM and (NH,),SO, recorded the highest content of Mg in ragi grain. The variety of Co. 7 recorded significantly higher uptake of Mg than Co. 9. The variety Co. 7 registered significantly higher uptake of Mg 'by grain as well as total uptake than Co. 9

Effect of Calcium Source and Application Method on Potato Yield and Cation Composition

AbstractCalcium applications to low Ca, sandy soils can improve potato (Solanum tuberosum L.) grade and USlA size grade, and these improvements are significantly correlated with increased periderm Ca concentrations. This study evaluated the effectiveness of several Ca sources (pelleted CaSO4, granulated CaSO4, sieved CaSO4, dolomitic lime, triple superphosphate, or CaCl2), methods of application (broadcast, sidedress, and preplant strip), and rates (84–336 kg Ca ha−1) on increasing tuber Ca on two irrigated loamy sands (Typic Udipsamments) in Wisconsin from 1983 to 1985. The addition of Ca increased the percent of grade USlA tubers, the yield of prime size (<170–370 g) USlA tubers, and periderm Ca concentrations. It also reduced the percent of USlB or cull tubers, the yield of small (170 g) USlA tubers, and the concentration of periderm Mg. Improvements of grade USlA tubers ranged from 3 to l0%, and yield of USlA prime tubers was increased from 2 to 10 Mg ha−1. Dolomitic lime, triple superphosphate, and CaCl2 did not consistently improve tuber yield or grade, whereas CaSO4 in any of the forms applied was an effective Ca source. In 1985, a vertical cross‐section of the potato hill was sampled to determine the distribution of exchangeable Ca in the hill for each application method. The accumulation and uptake of Ca in the plant tops and in tuber periderm and medullar tissue for an untreated control and each application method were determined at several times during the season. The preplant strip method concentrated more material in the central portion of the potato hill where the tubers formed, and increased Ca uptake in both periderm and medullar tissue compared to the sidedress and broadcast treatments. Calcium concentration and uptake in the plant tops was not affected by any method of Ca application. Total Ca uptake averaged 8.5 and 32.9 kg Ca ha−1 in the tuber and plant tops, respectively.

Effects of boron deficiency and calcium supply on the calcium metabolism in tomato plant

Tomato plants were grown in water-culture with a different supply of Ca (10, 100 ppm) and B (0, 0.2 ppm), and the effects of B deficiency on the translocation and subcellular distribution of Ca in tomato plants were studied by using45CaCl2 as a carrier of Ca. Boron deficiency slight increased the total Ca uptake by the plant and inhibited the Ca translocation to the upper leaves. The incorporation of45Ca into the cell wall in the upper leaves was increased by B deficiency at both Ca levels. As Ca supply decreased, the distribution of45Ca in the 1N NaCl fraction of the cell wall increased only at 0.2 ppm B. As B supply decreased, the distribution of45Ca in the 0.6N HCl fraction increased at both Ca levels. These results suggest that B deficiency inhibit the translocation of Ca, and induce the abnormal changes of the Ca metabolism in the cell wall.

High-affinity calcium binding sites in luminal and basolateral renal membranes.

We evaluated Ca binding by highly purified luminal (L) and basolateral (BL) tubular membranes prepared from beef kidney. Ca binding was measured by using 45Ca and a rapid-filtration technique. After Ca uptake reached equilibrium, the vesicles were lysed and the amount of 45Ca retained in the membranes was considered the bound Ca. Ca binding in both membranes accounted for approx. 80% of total Ca uptake. Analysis of binding data by Scatchard plot revealed the presence of two distinct types of binding sites in both L and BL membranes. The high-affinity binding sites showed a similar affinity constant of 10(-5)M for both L and BL membranes, but the maximum number of binding sites was 0.75 and 1.6 nmol/mg protein, respectively. In contrast, the low-affinity binding sites were similar regarding affinity constant and maximum number of binding sites in the two membranes. In L and BL membranes, high-affinity binding sites were selective for Ca, as high concentrations of divalent cations were required to inhibit Ca binding. In both membranes Ca binding was inhibited by ruthenium red, LaCl3, and detergents, and it was stimulated by calmodulin inhibitors (trifluoperazine, calmidazolium), ionophore A-23187, and ATP. These results demonstrate that L and BL membranes possess high-affinity binding sites with different capacities but similar characteristics as regards affinity constant and stimulation and inhibition of binding. The data further demonstrate that most of Ca uptake by these membranes represents binding.

Availability of Ca from Ca45SO4 in a highly saline-sodic soil

Application of gypsum (tagged Ca45SO4.2H2O) caused a considerable increase in dry matter yield and content of Ca, Ca45, Mg and K and Ca:Na and (Ca+Mg): (Na+K) ratios and a decrease in the content of Na, N and P in dhaincha tops. There was a considerable increase in the total uptake of Ca, Mg, Na, K, N, P and Ca45 by plant tops in response to gypsum. Contribution of Ca from applied Ca45SO4 varied from 78.3 to 84.7 per cent of the total Ca in plant tops, whereas, its uptake from this source varied from 52.18 to 98.73 me per 100 g plant tops. re]19720705

Effect of farm yard manure on the availability of Ca from Ca45CO3 in a sodic soil (ESP 77.7)

Application of FYM caused a gradual increase in the dry weight of dhaincha (Sesbania aculeata Pers.) tops. It also caused a gradual increase in the content of Mg and K and a decrease in the content of Ca, Na, N and P in dhaincha tops. Increase in Ca: Na ratio was more steeper than (Ca+Mg): (Na+K) ratio. Total uptake of Ca, Mg, K, N and P increased and that of Na decreased in response to FYM. Contribution of Ca from Ca45CO3 did not differ much at different levels of FYM and it was less than 6 per cent of total Ca in plant tops in all the treatments. re]19721017

Effect of gypsum and calcium carbonate on plant yield and chemical composition and calcium availability in a non-saline sodic soil

The availability of Ca from different levels of gypsum and calcium carbonate in a non-saline sodic soil has been investigated. Different levels of tagged gypsum (Ca45SO4.2H2O) and calcium carbonate (Ca45CO3) (i.e. 0, 25, 50, 75, and 100 per cent of gypsum requirement) were mixed thoroughly in 3.5 Kg of a non-saline alkali soil (ESP, 48.4; ECe, 2.68 millimhos/cm). Dhaincha (Sesbania aculeata) — a legume and barley (Hordeum vulgare L.) — a cereal were taken as test crops. Increasing levels of gypsum caused a gradual increase in the yield of dry matter, content of Ca and K in the plant tops and Ca:Na and (Ca+Mg):(Na+K) ratios in both the crops. Application of calcium carbonate caused a slight increase in the dry matter yield, content of Ca and Mg and Ca:Na and (Ca+Mg):(Na+K) ratios in barley, however, in case of dhaincha there was no such effect. Gypsum application caused a gradual decrease in the content of Na and P in both the crops. Total uptake of Ca, Mg, K, N and P per pot increased in response to gypsum application. The effect of calcium carbonate application on the total uptake of these elements was much smaller on dhaincha, but in barley there was some increasing trend.

Differential Aluminum Tolerance in Two Snapbean Varieties1

AbstractTwo snapbean (Phaseolus vulgaris L.) varieties, shown previously to differ in tolerance to acid, Al‐toxic Bladen soil, were tested more specifically for Al tolerance in nutrient cultures. The Bladen soil‐tolerant ‘Bade’ variety was much more tolerant to Al than Bladen‐sensitive ‘Romano.’ For example, with 8 ppm Al added, at initial pH 4.8, top and root yields of Dade were 94 and 107%, respectively, of those with no Al. Corresponding top and root yields of Romano were only 53 and 59%, respectively, of those with no Al.With 8 ppm Al added, the total Ca uptake values for Dade tops and roots were 98 and 131%, respectively, of those with no Al; corresponding values for Romano tops and roots were only 25 and 22%, respectively. Aluminum added at 6 or 8 ppm also reduced Ca concentrations in tops and roots of Romano by 30 to 50%, but had little effect on those of Dade. Differential Al tolerance was not related to differential pH changes in nutrient solutions or to Al concentrations of plant tops or roots. With 8 ppm Al added the P concentrations in Romano tops and roots were 60 and 14% higher, respectively, than those of Dade.Aluminum added at 4 ppm decreased stem exudate production of Romano by 66% but did not affect that of Dade. The same Al treatment reduced concentrations of Ca, Mg, K, and P in Romano exudates by 66, 42, 80, and 76%, respectively, but either decreased or failed to affect those of Dade. Lower concentrations of these elements in stem exudates of Al‐injured Romano plants were not associated with immobilization hi roots. The 4‐ppm Al treatment decreased Ca concentrations in Romano root cell walls, mitochondria, supernatant, and total roots by 55, 68, 51, and 43%, respectively. The same treatment decreased the Ca concentration hi Dade root cell walls by only 27% and that in total roots by 8%, and actually increased the Ca concentration in mitochondria and supernatant fractions by 21 and 63%, respectively.Reduced Ca uptake appears to be a good indicator of Al sensitivity in the two snapbean varieties studied.

Effects of Chromium on Growth and Mineral Nutrition of Soybeans

AbstractChromium additions [0–5 ppm Cr(VI)] to soybeans, Glycine max (L) Merrill, grown in nutrient culture resulted in decreased concentrations and total uptake of Ca, K, P, Fe, and Mn in tops and of K, Mg, P, Fe, and Mn in roots. These effects were often apparent at Cr treatments as low as 0.5 ppm.In soil culture Cr additions [0–60 ppm Cr(VI)] appeared to interfere with the accumulation of Ca, K, Mg, P, B, and Cu by soybean tops, with little or no effect on Fe, Mn, or Zn uptake. These effects were generally first observed at the 5‐ppm Cr treatment.The initial symptoms of Cr toxicity appeared as severe wilting of tops of treated plants.It could not be concluded from the results of these experiments that Cr, as the hexavalent anion, specifically interfered with uptake of Fe or P by plants, as earlier reported.