Plant Zn Uptake Research Articles

Alkaline sewage sludge solids affect the chemical speciation and bioavailability of Cu and Zn in the rhizosphere soil solution

Perennial ryegrass (Lolium perenne cv. Magella) was grown in a glasshouse experiment in which nylon mesh bags separated the soil into ‘rhizosphere’ and ‘non-rhizosphere’ zones. The soil was mixed with four application rates of an organic fertiliser made by mixing sewage sludge cake with cement kiln dust and composting. Soil solution was obtained by low speed centrifugation and filtration after addition of water (1:1 soil:solution ratio). A resin exchange method was used to distinguish between labile and non-labile forms of dissolved copper (Cu) and zinc (Zn). Soil solution pH, electrical conductivity (EC), absorbance at 360 nm (A360) and Cu and Zn were determined, together with plant (shoot + root) Cu and Zn concentration and uptake.Sludge cake application increased total soluble Cu but decreased total soluble Zn in the soil solution compared to unamended controls and these effects were associated with increased soil solution pH, EC and AMI. Soluble Cu accumulated while soluble Zn was depleted in the rhizosphere compared to the bulk soil. Cu occurred mainly in non-labile form, probably as stable organic complexes, while Zn was mostly in labile form, possibly as free ions and weak complexes. Sludge cake decreased the labile form of each metal and increased the non-labile form in the rhizosphere. It increased plant yield and uptake of Cu and Zn but did not change the plant concentrations of the two metals. The strong influence of the organic fertiliser on plant Cu and Zn uptake by promoting plant growth and by changing the solubility and distribution of the metals in the rhizosphere soil solution is discussed.

Leucaena + maize alley cropping in Malawi. Part 2: Residual P and leaf management effects on maize nutrition and soil properties

Agroforestry systems involving leaf removal for animal fodder may result in rapid depletion of soil fertility. The purpose of this research was to determine if the effects of leaf removal on soil fertility parameters and maize yield in a Leucaena leucocephala alley cropping system could be reversed. Three leaf management strategies in a Leucaena alley cropping trial that had been in effect from 1987 to 1991 were investigated: 1) leaves returned, 2) leaves removed, and 3) leaves removed, with 100 kg inorganic N ha−1 added. In the 1990/91 season, a 34 confounded factorial design was utilized to investigate the effects of leaf management strategy, N rate (0, 30 and 60 kg N ha−1); maize plant population (14,800, 29,600, and 44,400 plants ha−1); and P rate (0, 18, and 35 kg P ha−1). In the 1991/92 and 1992/93 seasons, leaves were applied equally to all plots, and no P was applied. The N rate and plant population treatments were continued, and the same confounded factorial design was implemented to investigate residual leaf management strategy, residual P rate, n rate, and plant population. The yield gap between the plots where leaves had been returned vs. removed narrowed each season due to uniform leaf application. Application of N improved yields during both seasons. Residual effects of the initial P application decreased to only 10% of the total yield in 1992/93. Plant population affected yields only during the season of very good rainfall. Leaf additions resulted in a relative increase in soil pH, total N,and exchangeable Ca, Mg, and K and a decrease C/N ratio in plots that had not previously received leaves. Leaves supplied more K and Zn to the upper 15 cm of soil than were being extracted by the maize crop, but uniform leaf additions eliminated differences in K and Zn uptake. Plant Zn uptake decreased with increasing P rate and plant population, and increased with increasing N rate and a history of leaf return. The results show that applying leaves equilibrated yields within two seasons, and resulted in a relative improvement of several soil properties. The residual effect from P applications was not adequate to maximize yields.

Effects of chelated zinc, soluble and coated fertilizers, on soil zinc status and zinc nutrition of maize

Abstract Maize (Zea mays L.) was greenhouse cultivated with doses of 5, 10, and 15 ppm of zinc (Zn) in order to test the effectiveness of laboratory‐prepared coated and uncoated Zn fertilizers with commercial Zn‐EDTA and Zn‐ligno‐sulphonate (LS). Large increases were achieved both in crop yield and in Zn uptake in all cases while a large part of the Zn applied remained in the soil in easily plant‐available forms. Positive significant correlations were obtained between available Zn and the first three sequentially extracted fractions (water soluble plus exchangeable, organically complexed and that associated to amorphous sesquioxides) and also between the variables, yield, Zn concentration, and plant Zn uptake. Zinc uptake by the maize plants can be fairly accurately predicted from its sequential fractioning in the soil using an equation obtained by multiple regression analysis. Consideration of the amounts of Zn remaining as available (DTPA extractable) in the soil and results of a plant analysis let us c...

Effects of copper concentration on mineral nutrient uptake and copper accumulation in protein of copper-tolerant and nontolerant Lotus purshianus L.

One copper-tolerant and one copper-sensitive inbred line of Lotus purshianus L. derived from a copper mine waste site in Northern California and one inbred line of the same species derived from a pasture next to the mine waste were examined for the effects of excessive copper concentrations on mineral nutrient uptake and accumulation of copper in protein fractions. Plants were grown from seeds for a period of 24 days in a modified Hoagland nutrient solution culture supplemented with 3, 6, and 10 μ M copper as copper sulfate. The basal nutrient solution without copper amendment was used as the control treatment. The uptake of Cu found in the roots was 100 times or more than that in the leaves. The root tissue copper concentrations reached a plateau under 6 μ M copper treatment. The leaf tissue copper concentrations increased with the increase of copper concentration in the solution culture. No difference in pattern of copper uptake was detected between the copper-tolerant and nontolerant plants. The effects of excessive copper concentrations caused reduction of Ca uptake in the leaf tissue and P uptake in both the root and leaf tissues, and no difference was found between the copper-tolerant and nontolerant plants. Increased tissue copper concentration caused greater reduction of Fe, Mn, and Zn uptake in the nontolerant plants than in the tolerant plants; this difference may be important for the growth of the tolerant plants under conditions of excessive copper concentrations. Protein extracted from the roots and leaves of both the copper tolerant and nontolerant plants was subjected to Sephadex G-75 column separation. Two major peaks of protein fractions were detected. Under low (normal level) copper concentration treatment, the copper-tolerant and nontolerant plants had similar Cu/protein ratios. However, under higher copper concentration challenged conditions the copper-tolerant plant had a considerably greater Cu/protein ratio (peak II protein) than the nontolerant plants. The amino acid composition of the copper-rich protein fraction (peak II) extracted from both the tolerant and nontolerant plants demonstrated a high asparate (about 25%) content. The contents of glutamate, cystine, and glycine were about 11, 2.5, and 10%, respectively, and the rest of the amino acids were in a range of 2 to 6%. This pattern of amino acid composition is different from the amino acid composition of the phytochelatin metallothionein-like proteins found in copper-tolerant plants which are very high in cysteine. Instead, the copper rich protein found in the L. purshianus resembles the copper-binding protein found in spinach which has high acidic amino acids and asparate content. More studies are needed to characterize this copper-binding protein and discover its possible role in copper tolerance of L. purshianus.

The extraction by soil and absorption by plants of applied zinc and cadmium

In five consecutive years lettuce, spinach, spring wheat, endive and maize were grown in pots and the effects of ‘native’ and soil-applied Zn and Cd on plant Zn and Cd concentrations were studied. The normal interactive pattern was antagonistic, Zn reducing plant Cd uptake, and conversely, but less so. Only in loam soil Zn and Cd were synergistic to some extent, plant Zn uptake increasing with applied Cd. When relating total soil Cd/Zn to plant Cd/Zn separate sets of data could be distinguished for loam and sandy soil, each fitting a straight line. The use of 0.1 M CaCl2 instead of ‘total’ extractable soil Cd/Zn makes the two sets of data to coalesce around a single straight line. All crops were found to show a positive linear relationship between 0.1 M CaCl2-extractable soil Cd/Zn and plant Cd/Zn.

Comparison of DTPA and resin extractable soil Zn to plant Zn uptake

Abstract Extraction of soil zinc with routine chemical extractants does not always reflect differences in Zn availability as detected by plant uptake. This study was undertaken to explore and compare the use of an ion exchange resin and diethylenetriaminepentaacetic acid (DTPA) for extracting soil Zn as related to plant Zn uptake. Beans were grown in 1989 following differential cropping with corn and beans or fallow in 1988 on a Portneuf silt loam near Kimberly, Idaho. Two Zn fertilizer treatments were imposed across previous cropping treatments. A batch method for determining resin extractable soil Zn was established. Both plant Zn concentration and Zn uptake by beans in 1989 were significantly higher in Zn fertilized than unfertilized treatments regardless of previous crop; and higher in plots previously cropped with corn than beans or fallow, regardless of Zn treatment. DTPA and resin extractable soil Zn were significantly higher in Zn fertilized plots compared to unfertilized plots but did not differ between previous cropping treatments. Resin and DTPA extractable soil Zn concentrations were positively correlated. Resin extracted soil Zn correlated better with plant Zn concentration and Zn uptake throughout the growing season than DTPA extracted soil Zn, particularly in plots that had been fallowed or previously cropped with corn. Resin may be extracting labile soil Zn not extracted with DTPA and, therefore, be better simulating plant uptake. Both extraction methods correlated better with Zn uptake when evaluated within cropping treatments, emphasizing the need to consider previous crop when calibrating soil tests.

The effect of seaweed concentrate on the uptake of foliar-applied Cu, Mn and Zn by tomato seedlings

The effect the seaweed concentrate Kelpak on the uptake of foliar-applied Cu, Mn and Zn by tomato seedlings grown with and without added macronutrients was investigated. Kelpak had little effect on the uptake of Cu and Mn, but significantly stimulated Zn uptake in plants receiving no macronutrients. However, Kelpak did not increase Zn uptake in plants receiving macronutrients. Results suggested that seaweed concentrates are unlikely to be useful in promoting the uptake of foliar-applied trace elements in tomatoes grown under normal commercial conditions.

Metal uptake in plants from a birch forest area near a copper smelter in Norway

Uptake of Ca, Mg, K, Mn, Fe, Al, Rb, Ph, Cu, Zn, and Cd in vascular plants from a birch forest area near a Cu smelter in northern Norway was investigated. The primary objective was to study metal uptake in plants growing in a strong local acidification gradient. Decreased levels of Mn, Mg, and Ca found in Betula pubescens, Vaccinum myrtillus, and Deschampsia flexuosa near the smelter corresponded to a decrease in base saturation of the soil. This suggests that appreciable soil acidification has taken place. The level of Rb in Vaccinum myrtillus and Sorbus aucuparia increased significantly towards the smelter, probably due to the higher soil acidity. Elevated levels of Cu, Zn, Ph, and Cd in surface soil were found with values up to 2500 mg kg−1 Cu within 1 km from the smelter. These concentrations decreased significantly with distance, but metal contamination was detectable up to 27 km from the smelter along the prevailing wind direction. A corresponding decrease was detected for Cu in the four plant species analyzed. Elevated levels of Zn, Ph, Fe, and Al were found in some, but not all, species.

Measurement of plant‐available zinc in British Columbia orchard soils

Abstract Zinc availability in 20 southern British Columbia orchard soils was examined in the greenhouse. Zinc concentration, uptake and yield in navy beans (Phaseolus vulgaris) were measured and compared with soil Zn extracted by MgCl2 at three concentrations (1.0 M, 0.50 M and 0.25 M), DTPA, 0.10 M HC1 and 0.05 M HC1 + 0.0125 M H2SO4 (Mehlich No. 1). Adding Zn at the rate of 10 mg/kg did not increase yields. Available Zn varied greatly as measured by the soil tests and by plant Zn concentration and uptake. These availability indices, except for plant Zn concentration, varied directly with Bray‐P1 extractable P and organic matter content. Plant Zn uptake and concentration and MgCl2 extractable Zn also varied inversely with pH. Zinc extracted by MgCl2 was more closely related to plant zn concentration and uptake than Zn extracted by the other three extractants. Furthermore, extraction of Zn with 0.25 M MgCl2 instead of with 1 .0 M MgCl2 decreased analytical difficulties with atomic absorption spectrophotom...

Zinc chelate inhibited uptake of copper and manganese, or is it chelating agent inhibition? — Differential zinc accumulation in primary leaves

Abstract Zinc DTPA, but not ZnEDTA, inhibited Mn uptake by bush bean plants at high solution pH just as much as did excess DTPA without Zn in previous studies. Copper uptake was also inhibited by ZnDTPA, and to a lesser extent by ZnEDTA, but this may be explained by the unavailability of chelated Cu in solution culture. The high levels of chelated Zn applied were not greatly available for uptake except that both sources promoted large accumulation in primary leaves. It was postulated that primary leaves are a major sink for chelating agents that are taken up by plants. It is well known that Fe chelates and chelating agents do inhibit Mn uptake by plants and often induced Mn deficiency (Wallace et al., 1976; Wallace, 1980a, b). High levels of excess chelating agents, especially DTPA, inhibit plant uptake of Zn, Cu and Mn but not always of Fe (Halvorson and Lindsay, 1977). The major purpose of the experiment reported here was to determine if a high level of ZnDTPA would result in greater Zn uptake by plants...

Soil temperature and nitrogen effects on response of flooded and nonflooded rice to zinc

Response of direct seeded rice (cv. Bluebelle) to Zn was studied in flooded and nonflooded (field capacity) Crowley soil (pH 7.6) maintained at soil temperatures of 18 and 30°C. Urea and (NH4)2SO4 were compared as sources of N to determine their effect on plant uptake of Zn from ZnSO4 either mixed or surface applied to the soil. Grain yields were slightly higher from nonflooded than from flooded soil. Higher dry matter production at 30 than at 18°C was not related to Zn nutrition. Urea and (NH4)2SO4 resulted in similar yields and Zn uptake by flooded rice, but (NH4)2SO4 was superior for nonflooded rice in the absence of applied Zn. More fixation of mixed Zn by the limed Crowley soil probably caused its lower effectiveness, as compared to surface-applied Zn.

Extractability of Cadmium, Copper, Nickel, and Zinc by Double Acid Versus DTPA and Plant Content at Excessive Soil Levels

AbstractCadmium, copper, nickel, and zinc were applied as sulfate salts to samples of surface horizons of three Maryland soils in the greenhouse at rates of metals equivalent to those in 0 to 896 dry metric tons/ha of Washington, D.C., digested sewage sludge. The sludge was also applied at a rate of 224 dry metric tons/ha. Two pH regimes, approximately 5.5 and 6.5, were maintained. Metals were extracted by the DTPA (diethylenetriaminepentaacetic acid buffered at pH 7.3) double acid (0.05N HCl, 0.025N H2SO4) extractants. Correlations were determined between extractable soil metals and metal content of two crops of corn (Zea mays L.) each grown for 30 days, but at times of 1 or 13 mo after making the chemical amendments to the soils.Highly significant associations, r values ranging from 0.658 to 0.998, were obtained between the quantities of Cd, Cu, Ni, and Zn extracted by the two extractants. DTPA tended to extract smaller quantities of all metals and tended to be more indicative of reduced plant Zn and Cu uptake under limed conditions than double acid. Cadmium remained the most extractable after 14 mo by either extractant when expressed as a percent of the applied metal that was extractable. Overall metal extractability on this basis followed the order Cd > Cu > Zn > Ni, independent of soil type or extractant.Sludge‐applied metals were approximately half as extractable as sulfate salt‐applied metals at comparable rates of application, but followed the same order of relative extractability.Plant content ofCd, Cu, and Zn was significantly correlated, at the 1% level, with extractability of the respective metal for both extractants for metal salt‐amended soils. Correlations from the sludged soils were poor and generally not significant. Numerically higher and generally more significant correlations were obtained when the data were separated by lime level into two regression equations compared to a combined regression. The primary cause of this effect was the greater metal content of the plant tissue per unit of extractable metal on the low vs. the high pH soils, except for Cd, producing two distinct regression equations. This relationship was more pronounced with the first crop than with the second.

AVAILABILITY OF CU, ZN, AND MN AS INFLUENCED BY APPLICATION OF CU-POLYFLAVONOID

Copper, in the form of Cu-polyflavonoid, was applied at 50 or 100 ppm to surface samples of nine Wisconsin soils varying from 0.8 to 12.5% organic matter. The effects on yield and on plant uptake of Cu, Zn and Mn were evaluated using oats (Avena sativa L. cv. Lodi). Complexed Cu additions increased extractable Cu, had little effect on extractable Zn, but also increased extractable Mn. Complexed Cu decreased plant uptake of Zn, but increased uptake of Mn. Interactive effects of organic matter, clay, available phosphorus and Zn appeared to occur with respect to plant yield and Cu, Zn, and Mn uptake.

Soil tests for available copper and zinc in soils of Western Nigeria.

AbstractFour soil tests for copper and zinc were evaluated for their ability to predict Cu and Zn uptake by oats (Avena sativa, L., Lodi var.) grown on 28 soils from Western Nigeria. Statistical analyses showed that EDTA was a better extractant for predicting Cu uptake than was DTPA, 0.1 N‐HCl or 1 N‐HCl. Copper uptake was more strongly correlated with inorganic soil fractions than with organic matter and was not significantly affected by soil pH.The best prediction of Zn uptake was provided by a combination of 0.1 N‐HCl extractable Zn, pH, organic matter and the silt plus clay fraction in a multiple regression analysis. All four extractants predicted plant Zn uptake better on soils of pH less than 6.0 than on soils of pH greater than 6.0.A significant amount of Cu and Zn in the soils appeared to be associated with sesquioxides, part of which was available for plant use.

Availability of Cu, Zn and Mn in Soils: III.—Predictability of plant uptake

AbstractThe influence of various chemical soil fractions Of Cu, Zn and Mn in conjunction with plant uptake of any one or two of the elements on the variability of plant uptake of one of them was evaluated by correlation and regression analyses. Plant and soil data were obtained from divergent Wisconsin soils. Inclusion of Zn uptake and the HCl‐or EDTA‐extractable soil Cu fraction in the regression equation resulted in very high predictability of Cu uptake by oats. High predictability of Zn uptake was likewise realized by using the Mg(NO3)2 or DTP A soil Zn fraction along with plant Cu uptake as determinants. Manganese uptake was best predicted by using plant Zn uptake and Mg (NO3)2‐rextractable soil Mn as predictors. The extractant N ammonium acetate (pH 7)/0·01 M EDTA showed promise as a reliable soil test for predicting the concurrent plant availability of Cu, Zn and Mn in Wisconsin soils.

The Utilization of Applied Zinc as Affected by pH and Pyrophosphate Content of Ammonium Phosphates

AbstractLaboratory preparations of pure ammonium ortho‐ and pyrophosphates were blended to give mixtures containing 0, 20, 40, 60, 80, and 100% of the total P as pyrophosphate at pH values of 3.6, 4.0, 5.0, 6.0, 7.0, and 8.0. Each ammonium phosphate mixture was blended with ZnSO4 · H2O to yield a product containing 2 or 8% Zn, formed into a pellet, and reacted with soil solution. Residues were recovered and analyzed for chemical and mineralogical composition.The quantity and species of Zn precipitating in the residues were markedly influenced by the pyrophosphate content and pH of ammonium phosphate mixtures. At pH 3.6 and 4.0, the quantity of Zn in the residue was increased with increasing pyrophosphate content. At pH 5.0 all of the Zn precipitated when the P was 100% orthophosphate but as the pyrophosphate level was increased to 60% more Zn moved out of the pellet. The Zn content of the residues decreased as pH increased (6.0, 7.0, and 8.0) and was lowest when the mixture contained 40, 60, and 80% pyrophosphate, respectively.Two zinc ammonium orthophosphates, ZnNH4H3(PO4)2 · H2O and ZnNH4PO4, were identified in the residues. Zinc ammonium pyrophosphates identified were Zn(NH4)2H4(P2O7)2 · 2H2O, Zn3(NH4)2(P2O7)2 · 2H2O, and Zn(NH4)2P2O7 · H2O.Ammonium phosphate mixtures with pH values of 3.6, 6.0, and 8.0 containing 2% Zn as 65ZnSO4 · H2O were spot‐placed in pots and evaluated in growth chamber experiments. Plant uptake of Zn was proportional to the quantity of Zn which moved from the placement site.