Toxicity of copper and zinc in seedlings of Mung bean and inducing accumulation of polyamine

A solution culture was conducted to investigate the effects of copper (Cu) and zinc (Zn) toxicity on growth of mung bean (Phaseolus aures Roxb. cv VC‐3762) and accumulation of polyamine. Eight‐day‐old seedlings were grown in diluted nutrient solution with different concentrations of Cu and Zn for 6 days. Results showed that elongation of epicotyl and fresh weight of plants were decreased by 10 μM Cu and 100 μM Zn significantly compared to control (0.03 μMCu and 0.1 μMZn). Accumulation of polyamine, especially putrescine (Put) was found in the epicotyl of mung bean seedlings. Addition of 5 mM calcium (Ca) into nutrient solution improved the growth of 10 μM Cu‐treated seedling, and decreased the concentration of Put and increased concentrations of spermine and spermidine in epicotyl of plants. Moreover, supplying Put did not increase tolerance of plant to Cu or Zn. It was suggested that Put accumulation resulting from toxicity of Cu and Zn might merely be a symptom of stress injury.     

Aluminum toxicity in tomato. Part 1. growth and mineral nutrition

Aluminum (Al) toxicity was studied in two tomato cultivars (Lycopersicon esculentum Mill. ‘Mountain Pride’ and Floramerica') grown in diluted nutrient solution (pH 4.0) at 0, 10, 25, and 50 μM Al levels. In the presence of 25 and 50 μM Al, significant reduction was found in leaf area, dry weight, stem length, and longest root length of both cultivars. Growth of ‘Floramerica’ was less sensitive to Al toxicity than growth of ‘Mountain Pride’. Elemental composition of the nutrient solutions were compared immediately after the first Al addition and four days later. The uptake of micronutrients copper (Cu), manganese (Mn), molybdenum (Mo), zinc (Zn), boron (B), and iron (Fe) from the nutrient solution was reduced in both cultivars with increasing Al levels. Nutrient solution Al gradually decreased in time for every treatment; less in cultures of ‘Floramerica’ than in ‘Mountain Pride’. Aluminum treatments decreased the calcium (Ca), potassium (K), magnesium (Mg), Mn, Fe, and Zn content in the roots, stems, and leaves. Aluminum treatment promoted the accumulation of P, Mo, and Cu in the roots, and inhibited the transport of these nutrients into stems and leaves. At 25 and 50 μM levels of Al, lower Al content was found in the roots of cv. “Floramerica’ than in the roots of cv. ‘Mountain Pride’.     

Effects of Nickel on Growth and Composition of Metal Micronutrients in Barley Plants Grown in Nutrient Solution

Abstract

A hydroponic experiment was conducted in a phytotron at pH 5.5 to study the effects of nickel (Ni) on the growth and composition of metal micronutrients, such as copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), of barley (Hordeum vulgare L. cv. Minorimugi). Four Ni treatments were conducted (0, 1.0, 10, and 100 μM) for 14 d. Plants grown in 100 μM Ni showed typical visual symptoms of Ni toxicity such as chlorosis, necrosis of leaves, and browning of the root system, while other plants were free from any symptoms. Dry weights were the highest in plants grown in 1.0 μM Ni, with a corresponding increase in the chlorophyll index of the plants, suggesting that 1.0～10 μM Ni needs to be added to the nutrient solution for optimum growth of barley plants. The increase of Ni in the nutrient solutions increased the concentrations of Cu and Fe in roots, while a decrease was observed in shoots. The concentrations of Mn and Zn in shoots and roots of plants decreased with increasing Ni supply in the nutrient solution. Shoot concentrations of Cu, Fe, Mn, and Zn in plants grown at 100 μ M Ni were below the critical levels for deficiency. Plants grown at 1.0 μ M Ni accumulated higher amounts of Cu, Fe, Mn and Zn, indicating that nutrient accumulation in plants was more influenced by dry weights than by nutrient concentrations. The translocation of Cu and Fe from roots to shoots was repressed, while that of Mn and Zn was not repressed with increasing Ni concentration in the nutrient solution.     

Effects of sulfur supply on soybean plants exposed to zinc toxicity

Application of most waste or by‐product material increases the zinc (Zn) concentration in soils markedly. This investigation was conducted to determine if enhanced sulfur (S) supplied as sulfate (SO₄) would modify the toxic effects of excess Zn. Soybean (Glycine max [L.] Merf. cv. Rarisorri) was grown for two weeks in nutrient solutions containing ranges in Zn (0.8 to 80 μM) and S (0.02 to 20 mM). Root and shoot conditions were observed, dry weights measured, and Zri concentration determined. Zinc‐toxicity symptoms started about one week after transplanting young plants to nutrient solutions. Symptoms including chlorosis, especially in the trifoliate leaves, and change in orientation of unifoliate leaves were mild in 20 μM‐, intermediate in 40 μM‐, and severe in 80 μM Zn‐containing solutions. Dry weight was reduced in plants exposed to 20, 40, and 80 μM Zn. Plants grown in 40 μM Zn and 20 mM S survived longer than those grown in lower S concentrations and showed alleviation of the chlorosis in trifoliate leaves. The change in the orientation of the unifoliate leaves due to Zn toxicity, however, was not affected by S. Zinc contents in shoots grown at toxic Zn levels were higher in 20 mM‐ than in lower S‐containing nutrient solutions. High S supply (20 mM) increased Zn translocation from roots to shoots. Besides increasing the Zn translocation from roots to shoots, it seems that S nutrition may also be a factor helping the plants to cope with high levels of Zn in their tissues.     

Some effects of fly ash (from coal burning) on bush bean plants grown in solution culture

Abstract

Bush bean plants (Phaseolus vulgaris L. C. V. Improved Tendergreen) were grown for 14 days in 3700‐ml solution cultures with varying application rates of fly ash from a coal burning plant in California. Plants were also grown in a solution culture experiment in the presence of tiie chelating agent DTPA (diethylene triamine pentaacetic acid) and also in solutions acidified with HCl. The latter treatments were to determine if metals in the fly ash could be made more available to plants. The higher levels of fly ash (5 to 10 g/3700 ml) resulted in increased Ca, B, Si, Sr, and Ba in leaves, stems, and roots. No plants, however, appeared to have an excess of trace metals. In another experiment DTPA and HCl amendments failed to increase greatly the availability of trace metals from the fly ash in solution culture except for Zn. In this experiment the fly ash was the sole source of Ca and plants were deficient in Ca because insufficient fly ash was added. The fly ash resulted in increased Zn, Ca, Fe, Mn, B, Al, Si, Ti, Mo, Li, Sr, Ba in leaves, stems, and roots and increased V, Co, and Ni in roots. There was 3 to 4 μg/g Sn and 0.6 μg/g Be in the roots of plants grown with fly ash. In another experiment, fly ash supplied all the Ca necessary for plant growth without decreased yields resulting from any trace metal.     

Effect of aluminum on growth and chemical composition of marigolds

Marigold (Tagetes erecta L. cv. ‘Discovery Yellow’, “Perfection Yellow’, ‘Inca Yellow’, and ‘Merrymum Yellow') were grown in aluminum (Al) solution culture concentrations of 0, 1, or 4 mg/L. Aluminum increased root length and weight, but had no effect on stem and leaf weight. Uptake and stem and leaf tissue nutrient concentration of phosphorus (P), calcium (Ca), and magnesium (Mg) were reduced by the Al treatments. The Al treatments increased stem and leaf concentrations of potassium (K) and decreased the concentrations of manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn). No typical Al‐toxicity symptoms were observed in the roots. Root stunting caused by Fe toxicity was alleviated by the Al treatments.     

Differential response of citrus rootstocks to aluminum levels in nutrient solutions: II. Plant mineral concentrations 2

The objective of this study was to determine relations between Al effects and mineral concentrations in citrus seedlings. Six‐month‐old seedlings of five citrus rootstocks were grown for 60 days in supernatant nutrient solutions of Al, P, and other nutrients. The solutions contained seven levels of Al ranging from 4 to 1655 μM. Al and similar P concentrations of 28 μM P. Aluminum concentrations in roots and shoots increased with increasing Al concentration in the nutrient solution. Aluminum concentrations in roots of Al‐tolerant rootstocks were higher than those of Al‐sensitive rootstocks. When Al concentrations in nutrient solution increased from 4 to 178 μM, the K, Mg, and P concentrations in roots and the K and P levels in shoots increased. Conversely, Ca, Zn, Cu, Mn, and Fe in the roots and Ca, Mg, Cu, and Fe in the shoots decreased. The more tolerant rootstocks contained higher Fe concentrations in their roots than did the less tolerant ones when Al concentrations in solution were lower than 308 μM. Concentrations of other elements (Ca, K, P, Mg, Zn, and Mn) in roots or shoots exhibited no apparent relationship to the Al tolerance for root or shoot growth of the rootstocks. Calcium, K, Zn, Mn, and Fe concentrations in roots and Mg and K concentrations in shoots of all five rootstocks seedlings had significant negative correlations with Al concentrations in corresponding roots or shoots.     

Base cations ameliorate Zn toxicity but not Cu toxicity in sugar beet (Beta vulgaris)

Seedlings of sugar beet (Beta vulgaris) were grown in nutrient solutions containing a range of Cu and Zn concentrations. Based on measurements of shoot and root length and dry weight, copper was found to be already toxic at 10 μM, while Zn became toxic at 100 μM. At Cu and Zn levels found to induce a similar level of growth inhibiton, the influence of increasing the supply of K, Ca and Mg was investigated. Increasing the concentration of both Ca and Mg in the nutrient solution attenuated the degree of inhibition of root growth by Zn, but not Cu. Potassium did not affect the toxicity of either Cu or Zn. An increase in Ca decreased the level of both Cu and Zn in roots. Magnesium ameliorated the toxicity effects of Zn without effecting the Zn concentration in the roots. Treatment with Zn significantly decreased the concentration of Mg in the roots. An increased supply of Mg lowered the percentage decrease in root Mg concentration due to Zn toxicity. The maintenance of an adequate Mg level in the roots may be critical to prevent Zn induced inhibition of root growth.     

Zinc and Sulfur Effects on Growth and Nutrient Concentrations in Rocket

This study was conducted to determine how the range of sulfur (S) supply (from deficient to luxuriant) interacted with possible toxic zinc (Zn) levels. Rocket seedlings were grown for 30 d at three Zn (1, 75, and 150 μM) and three S (0.03, 0.5, and 1.5 mM) concentrations in nutrient solution under controlled conditions. Plant leaves did not show symptoms of S deficiency or Zn toxicity, which was confirmed by pigment determination. Treatments affected only leaf area and shoot dry-weight percentage. The accumulation of Zn was greater in roots than in shoots and increased linearly with Zn supply. Shoot S concentration was affected by S deficiency, whereas nitrogen concentration was least at the greatest S and Zn concentrations.     

Boron amelioration of aluminum toxicity in mungbean seedlings

Boron (B) amelioration of aluminum (Al) toxicity was studied for growth of mungbean (Phaseolus aureus Roxb.) seedlings and cuttings (without roots) in a growth chamber. Mungbean seedlings and cuttings were grown in the solution with combinations of three concentrations of B (0,5, and 50 μM) and three concentrations of Al (0, 2, and 5 mM) in randomized complete block design experiments for 16 days. Results showed that B significantly promoted elongation of epicotyls and hypocotyls, and increased height of seedlings grown under Al stress. Boron also increased fresh weight of seedlings in high Al solution. Treatment of plants grown with high B and Al stress had no apparent effect on fresh and dry weights of seedling roots. Seedling dry weight increased significantly by adding high B to solutions with 2 mM or 5 mM Al. No significant differences were observed between the high B treatment and the control (normal B, 5 μM) in lengths of epicotyls and fresh and dry weights of mungbean cuttings grown under Al stress. High concentrations of B decreased soluble protein and increased chlorophyll in seedlings treated with 2 mM Al. Boron had no amelioration effect on cuttings grown with Al, although Al increased soluble protein. Our results suggested that B alleviation of Al toxicity was related to root function and Al toxicity may possibly be due, in part, to B deficiency.     

Phytosiderophore release from manganese‐induced iron deficiency in barley

An experiment was conducted in the phytotron with barley (Hordeum vulgare L. cv. Minorimugi) grown in nutrient solution to compare iron (Fe) deficiency caused by the lack of Fe with manganese (Mn)‐induced Fe deficiency. Dark brown spots on older leaves and stems, and interveinal chlorosis on younger leaves were common symptoms of plants grown in either Mn‐toxic or Fe‐deficient treatments. Dry matter yield was affected similarly by Fe deficiency and Mn toxicity. The Mn toxicity significantly decreased the translocation of Fe from roots to shoots, caused root browning, and inhibited Fe absorption. The rate of Fe translocated from roots to shoots in the 25.0 μM Mn (toxic) treatment was similar to the Fe‐deficient treatment. Manganese toxicity, based on the release of phytosiderophore (PS) from roots, decreased from 25.0>250>2.50 uM Mn. The highest release of PS from roots occurred 7 and 14 days after transplanting (DAT) to Mn‐toxic and Fe‐deficient treatments, respectively; but was always higher in the Fe‐deficient treatment than the Mn‐toxic treatments. The release of PS from roots decreased gradually with plant age and with severity of the Mn toxicity symptoms. The PS content in roots followed the PS release pattern.     

Micronutrient toxicity in buffalograss

The growth responses of buffalograss [Buchloe dactyloides (Nutt.) Engelm.] to elevated micronutrient levels in the fertilizer solution were investigated. Seedling plants established in peat‐lite mix in 11‐cm (0.6 L) pots in the greenhouse were irrigated with solutions containing 0.5, 1, 2, 4, 6, 8, or 12 mM of boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), or zinc (Zn). The control solution contained (in μM): 20 B, 0.5 Cu, 40 Fe, 10 Mn, 0.5 Mo, and 4 Zn. A standard macronutrient concentration was used for all treatment solutions. Boron and Mo induced visual toxicity symptoms more readily than other micronutrients. Boron toxicity was characterized by chlorosis often accompanied by bleached leaf tips, while Mo toxicity resulted in leaf necrosis. The lowest levels that induced visual foliar toxicity were 0.5 mM B, 2 mM Cu, 4 mM Fe, 6 mM Mn, 1 mM Mo, and 4 mM Zn. Chloride did not induce foliar abnormalities in the concentration range tested. Biomass yield was reduced when the nutrient solution contained 2 mM B, 6 mM Cu, or 2 mM Mo. Elevated levels of Cl, Fe, Mn, and Zn did not alter dry matter yield. The relationship between the nutrient and tissue concentrations was determined for each microelement.     

Absorption of various types of chelated copper in a low concentration range by cucumber

Two experiments were conducted to compare absorption of copper (Cu) from cupric chloride (CuCl₂) and various types of chelated Cu in a low concentration range by cucumbers. In the first experiment, two varieties of cucumber were grown on rockwool for 40 days in a glasshouse with standard nutrient solution which contained six different concentrations of CuCl₂ (0, 0.05, 0.10, 0.20, 0.40, and 0.80 μmol/L). Copper deficiency symptoms were examined during the growing period, and the total nitrogen (N), iron (Fe), manganese (Mn), zinc (Zn), and copper contents of young fully grown leaves were measured. There were no differences among treatments in the leaf contents of N and Mn. Copper contents increased and Zn decreased with increasing Cu levels. The content of Cu at the three low Cu treatments (including no Cu addition) were in the deficient range (48–65 μmol/kg dry matter). The zero Cu level had paler green leaves than other treatments. No differences were apparent between varieties. The second experiment was carried out under exactly the same conditions as the first, but on the basis of the results of the first experiment, Cu treatments were 0, Cu‐EDDHA at 0.4, Cu‐DTPA at 0.4, Cu‐EDTA at 0.4, Cu‐NTA at 0.4, CuCl₂ at 0.4 μmo/L as Cu²⁺. After the experiment, the total N, Fe, Mn, Zn, and Cu contents of young, fully grown leaves were measured. There were no differences between treatments in the leaf contents of Cu except zero Cu level. They were in the range of 101–119 μmol/kg dry matter. At no Cu addition treatment, the Cu content was only 31 μmol/kg dry matter which is considered to be the deficiency level. For the other examined elements, there were no differences among the treatments and varieties. From these data it was concluded that the availability of these chelated Cu types were the same as CuCl₂ under the conditions of the experiments conducted.     

Germanium accumulation and toxicity in barley

The accumulation of germanium (Ge) by barley (Hordeum vulgare cv. ‘Arivat') grown at various Ge and pH levels was investigated because Ge is an industrially important metal and bioaccumulation of Ge is a potentially useful means of concentrating this trace metal. Six‐day‐old barley seedlings were grown in perlite and nutrient solution adjusted to a pH of 4.5, 6.0, or 7.5 supplemented with 20, 40,60, or 80 μM Ge for seven days. The plants were divided into roots and shoots after harvesting; the dry weight and Ge content of the individual organs were measured, as was the peroxidase activity in the distal 1 cm of the primary leaves. Barley seedlings accumulated Ge in the roots and shoots; the shoots accumulated Ge linearly as medium Ge concentration increased. The dry weight of the organs was not affected, although necrosis was observed in the primary leaves of the seedlings treated with Ge concentrations greater than 20μM. Peroxidase activity in the primary leaves also increased as the Ge levels in the medium increased which indicated that elevated levels of Ge stimulated leaf senescence. These results demonstrate that barley plants can take up Ge and suggest that Ge is not toxic at the levels that might occur in areas where Ge is normally mined.     

Effect of nitrogen source on aluminum toxicity in nonmycorrhizal and ectomycorrhizal pitch pine seedling

The effect of elevated nitrate [(NO₃‐nitrogen (N)] or ammonium (NH₄)‐N on the response of nonmycorrhizal (NM) and ectomycorrhizal (ECM) pitch pine (Pintis rigida Mill.) seedlings to aluminum (Al) was determined in experiments in which N was increased three times above ambient levels. Seedlings with and without the mycorrhizal fungus Pisolithus tinctorius (Pers.) Coker & Couch were grown in sand irrigated with nutrient solution (pH 3.8) containing 0, 10, or 20 mg Al L^‐1 (0, 370, or 740 μM Al). The nutrient solution simulated that for the sandy, nutrient‐poor soil of the New Jersey Pine Barrens. Elevated NO₃‐N had no significant effect on Al toxicity in NM seedlings, but Al toxicity at ambient NH₄‐N was ameliorated by elevated NH₄‐N. Symptoms of Al toxicity in roots (thick and stunted) of ECM seedlings at ambient N levels were reduced by elevated NH₄‐N and absent at elevated NO₃‐N. When N was elevated by an increase in NO₃‐N or NH₄‐N, uptake of N and relative increases in total biomass were greater in ECM than in NM seedlings.     

Differences in aluminium tolerance of ryegrass and white clover plants grown from seed or propagated vegetatively

The effect of aluminium (Al) on the relative yield of plants grown from seeds of ryegrass (Lolium perenne L.) or white clover (Trifolium repens L.) and either tillers (ryegrass) or stolon tip cuttings (white clover) were investigated using a low ionic strength (2.7 x 10^‐3 M) solution culture technique. In ryegrass, plants grown from tillers had higher relative yields than plants grown from seedlings in the tops when solution Al concentrations were greater than 16 μM and in the roots when solution Al concentrations were greater than 7 μM. In white clover, relative yields in the tops and roots plants were higher in plants grown from stolon tip cuttings than from seedlings when solution Al concentrations were greater than 10 μM. There were no significant cultivar effects. The results indicate that plants used in Al‐tolerance experiments can be grown from seed or vegetatively propagated, provided solution Al rates are adjusted to reflect differences in Al tolerance.     

Growth and mineral content of roots and shoots of maize seedlings in response to increasing water deficits induced by peg solutions

Abstract

The effects of polyethylene glycol (PEG) solutions of increasing osmotic potentials (ψπ=?0.44 and ‐0.88 MPa) on the growth of the seedlings and on the concentrations of Mn, Cu, Pb, Zn, Ni, Co, Mo, Cr, Cl, Fe, Ca, Mg, K, Na, P, and N were determined in the shoots and roots of maize (Zea mays L. cv. Summer II) grown in Hoagland's solution in a growth chamber. Water stress was imposed for three days with PEG 4000 on six‐day‐old seedlings. Despite a reduction in the leaf water potential (ψw), which decreased with increasing PEG concentrations, and despite an increase in the water saturation deficit (W.S.D.), the pressure potentials (ψp) were maintained in both treatments at levels quite similar to that in the control seedlings.

At ψπ=?0.44 MPa of the growth medium, both the length and dry weight of the shoots and roots significantly decreased, whereas at ψπ=?0.88 MPa only the root length continued to decrease with the consequence of an increase in the total mass production of the seedlings. At ψπ=?0.88 MPa, PEG was absorbed by the seedlings in significant amounts, although the roots were undamaged.

The effects of the imposed water stress on nutrient absorption and accumulation differed in the two treatments, depending on the plant tissue and nutrient; nevertheless, the element contents generally showed their lowest values at ψπ=?0.44 MPa, as consequence of the reduction in dry matter. The water stress experienced by the maize seedlings grown at ψπ=?0.88 MPa did not induce further decreases in either the macro‐ or micronutrients.     

Effects of excess manganese on mineral uptake in mycorrhizal sorghum

Associations between vesicular‐arbuscular mycorrhizal (VAM) fungi and manganese (Mn) nutrition/toxicity are not clear. This study was conducted to determine the effects of excess levels of Mn on mineral nutrient uptake in shoots and roots of mycorrhizal (+VAM) and non‐mycorrhizal (‐VAM) sorghum [Sorghum bicolor (L) Moench, cv. NB9040]. Plants colonized with and without two VAM isolates [Glomus intraradices UT143–2 (UT1 43) and Gl. etunicatum UT316A‐2 (UT316)] were grown in sand irrigated with nutrient solution at pH 4.8 containing 0, 270, 540, and 1080 μM of added Mn (as manganese chloride) above the basal solution (18 μM). Shoot and root dry matter followed the sequence of UT316 > UT143 > ‐VAM, and shoots had greater differences than roots. Shoot and root concentrations and contents of Mn, phosphorus (P), sulfur (S), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and copper (Cu were determined. The +VAM plants generally had higher mineral nutrient concentrations and contents than ‐VAM plants, although ‐VAM plants had higher concentrations and contents of some minerals than +VAM plants at some Mn levels. Plants colonized with UT143 had higher concentrations of shoot P, Ca, Zn, and Cu and higher root Mg, Zn, and Cu than UT316 colonized plants, while UT316 colonized plants had higher shoot and root K concentrations than UT143 colonized plants. These results showed that VAM isolates differ in enhancement of mineral nutrient uptake by sorghum.     

Cadmium‐induced alterations in nutrient composition and growth of betula pendula seedlings: The significance of fine roots as a primary target for cadmium toxicity

Birch seedlings (Betula pendula) were cultivated in nutrient solution with 0–2 μM cadmium (Cd). The effects of 2–10 days of Cd exposure on root and shoot element composition [potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P), sulfur (S), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), and Cd] and growth (as percentage dry weight increase) were investigated. The element composition of fine roots and remaining root parts were analysed separately to elucidate the significance of the fine roots as a primary target for Cd toxicity. The nutrient composition of the roots was considerably altered by the Cd exposures, whereas the nutrient composition of the shoot was less affected. After eight days, the whole root (fine roots + remaining roots) concentrations of K, Ca, Mg, and Mn were reduced, whereas the opposite was found for Cu and Mo. The element distribution between fine roots and remaining roots was altered by the Cd exposures. Cadmium was accumulated in the roots and in fine roots especially. Fine roots also exhibited a capacity for Cu accumulation and a retainment of Ca and S. Total plant growth was stimulated by 0.05 μM Cd but was reduced by the 0.5–2 μM Cd treatments. Root growth was increased by the Cd exposures and growth reductions were restricted only to the shoot. Accumulation of Cd and Cu and a retainment of Ca and S in the fine roots together with a preference for root growth, imply that the explanation for the Cd effects obtained may include mechanisms for Cd tolerance.