[Show abstract][Hide abstract] ABSTRACT: European white elm (Ulmus laevis Pallas) populations are scarce, small and fragmented in the Iberian Peninsula. Due to these characteristics the indigenous status of the species in the region has been questioned, whilst the species’ role in Iberian riparian forest ecology has been neglected. Herein we
review past studies regarding this species’ distribution and ecology in the Iberian Peninsula, with special emphasis on the establishment of conservation priorities. We first present a collection of palaeogeographic, historic and genetic data suggesting that the Iberian Peninsula was a glacial refuge for U. laevis. Secondly, we analyse U. laevis distribution in relation to soil physicochemical properties and water availability in Spain. Following this, we focus on the reproductive biology of the species, and investigate the effect of masting
and empty seed production on predation and regeneration establishment. Finally, based on this knowledge, we propose conservation policies for U. laevis in the Iberian Peninsula.
iForest - Biogeosciences and Forestry 01/2014; · 1.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The calcifuge and calcicole character of wild plants has been related to nutrient availability shortages, including iron (Fe)-deficiency. Surprisingly, just a few studies examined the relation between root Fe uptake and plant distribution in different soil types. We assessed the root Fe acquisition efficiency of two Ulmus species with calcareous (Ulmus minor) and siliceous (U. laevis) soil distribution patterns in the Iberian Peninsula. Seedlings of both elm species were grown hydroponically with different Fe concentrations during 6 weeks. Plant physiological responses to Fe-limiting conditions were evaluated as were the ferric reductase activity and proton (H(+)) extrusion capacity of the roots. Iron deprived elm seedlings of both species were stunted and suffered severe Fe-chlorosis symptoms. After Fe re-supply leaf chlorophyll concentrations rose according to species-dependent patterns. While U. minor leaves and seedlings re-greened evenly, U. laevis did so along the nerves of new growing leaves. U. minor had a higher root ferric reductase activity and H(+)-extrusion capability than U. laevis and maintained a better nutrient balance when grown under Fe-limiting conditions. The two elm species were found to have different Fe acquisition efficiencies which may be related to their natural distribution in calcareous and siliceous soils of the Iberian Peninsula.
Frontiers in Plant Science 01/2014; 5:104. · 3.60 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Commercial fertilizers containing synthetic manganese (Mn) chelates and complexes are currently used to alleviate Mn deficiency in crops. However, studies conducted on Mn sources in order to evaluate their behavior maintaining Mn soluble in nutrient solution and soil have not been done. In this work, representative commercial Mn fertilizers based on chelates and complexes were characterized and their chemical stability in solution and interaction with soils has been evaluated. Fertilizers studied were two ethylene diamine tetraacetic acid (EDTA) Mn chelates, one N-(1,2-dicarboxyethyl)-D,L-aspartic acid (IDHA) Mn chelate, two lignosulfonates, one carboxylate, one fulvate, one gluconate, and one heptagluconate-based Mn complex. Characterization consisted of the determination of the soluble and chelated or complexed Mn, and the ligand identification by nuclear-magnetic resonance (NMR). Stability study included batch experiments in Ca solution at different pH and three batch experiments with soil comparing with MnSO4. Results indicate that most of the Mn fertilizers comply with the declared “soluble and chelated or complexed” metal content. At a usual pH range of calcareous soils (7.5–8.5), both chelates and complexes maintain more Mn in solution than MnSO4 in the presence of Ca. Several factors affect the Mn remaining in solution after the interaction with the soil, especially, the soil-to-solution ratio. All chelates and complexes are better alternatives to the use of MnSO4 in agronomical practices such as fertigation and soil application. Mn-IDHA as chelate and Mn-HGl or Mn-Carb as complexes can be efficient, economical, and environmental friendly fertilizers for foliar application and hydroponic cultures. In soil application, Mn-EDTA or Mn-LS would be the best options. In this case, lignosulfonic acid represents a sustainable and low-cost solution.
Journal of Plant Nutrition and Soil Science 12/2013; · 1.66 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Water soluble humic substances (denoted further by LN) extracted at alkaline pH from leonardite are proposed to be used as complexing agents to overcome micronutrient deficiencies in plants such as iron chlorosis. LN presents oxidized functional groups able to bind Fe2+ and Fe3+. The knowledge of the environment of Fe in the Fe-LN complexes is a key point in the studies on their efficacy as Fe fertilizers. The aim of this work was to study the Fe2+/Fe3+ species formed in Fe-LN complexes with 57Fe Mössbauer spectroscopy under different experimental conditions in relation to the Fe-complexing capacities, chemical characteristics and efficiency to provide iron in hydroponics.. A high oxidation rate of Fe2+ to Fe3+ was found when samples were prepared with Fe2+, although no well crystalline magnetically ordered ferric oxide formation could be observed in slightly acidic or neutral medium. It seems to be that the formation of Fe3+-LN compounds are favored compared to Fe2+, although at acidic pH no complex formation occurred between Fe+3 and LN. The Fe2+/Fe3+ speciation provided by the Mössbauer data has shown that Fe2+-LN could be efficient in hydroponics while Fe3+-LN is suggested to be used more effectively at calcareous soil conditions. However, according to the biological assay, Fe3+-LN proved to be effective as chlorosis corrector applied to iron deficient cucumber in nutrient solution.
Journal of Agricultural and Food Chemistry 11/2013; · 3.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Silicon is considered an essential element in several crops enhancing growth and alleviating different biotic and abiotic stresses. In this work, the role of Si in the alleviation of iron deficiency symptoms and in the Fe distribution in iron deficient plants has been studied. Thus, soybean and cucumber plants grown in hydroponic culture under iron limiting conditions were treated with different Si doses (0.0, 0.5 and 1.0 mM). The use of a strong chelating agent such as HBED avoided Fe co-precipitation in the nutrient solution and allowed for the first time the analysis of Si effect in iron nutrition without the interference of the iron rhizospheric precipitation. SPAD index, plant growth parameters and mineral content in plant organs were determined. For soybean, the addition of 0.5 mM of Si to the nutrient solution without iron, initially or continuously during the experiment, prevented the chlorophyll degradation, slowed down the growth decrease due to the iron deficiency and maintained the Fe content in leaves. In cucumber, Si addition delayed the decrease of stem dry weight, stem length, node number and iron content in stems and roots independently of the dose, but no-effect was observed in chlorosis symptoms alleviation in leaves. The observed response to Si addition in iron deficiency was plant-specific, probably related with the different Fe efficiency strategies developed by these two species.
Plant Physiology and Biochemistry 06/2013; 70C:455-461. · 2.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Synthetic chelates such as ethylenediamine-N,N′-bis(2-hydroxyphenylacetic acid) (EDDHA) have shown their efficacy in correcting iron (Fe) chlorosis on crops grown on calcareous soils. Several parameters, such as Fe concentration, soil and plant analyzer development (SPAD) index, yield, and fruit size, have been previously described to evaluate their efficacy. However, the relationships among them and the method variability are little known. The aim of this study was to examine both relative standard deviations and coefficients of correlation when several nutritional status indexes are compared. Three Fe chelates plus additional treatment without any exogenous Fe source were applied on a commercial nectarine grove during two consecutive growing cycles. Data from 12 nutritional status indexes were compared (related to Fe concentrations in leaf and flower, SPAD index, Fe / manganese (Mn) ratio, yield, and size of fruit). Relative standard deviations (RSD) (as dimensionless parameter) were statistically compared. Additionally, Pearson's correlation coefficient was analyzed by comparing mean values from all pairs of nutritional status indexes. Statistical analyses, analysis of variance, and Pearson's correlation coefficient were performed. Because several methods are used for nutritional status assessment, statistical methodology is necessary to know their dispersion and the relationships between these methodologies. In this experiment, relative standard deviations of all nutritional status indexes were less than 30%, which is associated with acceptable experimental variability. In conclusion, SPAD index in fruit-bearing branches seems to be one of the most adequate nutritional evaluation method because low RSD and no variation throughout sampling time and growing cycle were found. However, Fe content in leaves at 77 DAFB (days after full bloom) was correlated with yield and quality fruit parameters having relevant significance as prognosis parameters. In addition, Fe contents in leaves show low relative standard deviations.
Communications in Soil Science and Plant Analysis 01/2013; 44. · 0.42 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Iron (Fe) chlorosis is a widespread nutritional disorder in grapevine, particularly in vineyards developed on calcareous soils. Despite the effective application of highly efficient Fe chelates such as Fe–ethylenediamine di-o-hydroxyphenylacetic acid (EDDHA) to the soil to solve the problem, the cost of the treatments and the loss of effectiveness of the chelate in the soil in rainfed crops limit their use. An alternative could be the utilization of Fe fertilizers directly supplied through foliar spray. Two Fe chelates [Fe–ethylenediaminetetraacetate (EDTA) and Fe–ethylenediamine disuccinic acid (EDDS)], an Fe complex (Fe-lignosulfonate), and an Fe salt (Fe-sulfate) were foliarly applied to mature Tempranillo tinto (Vitis vinifera L.), grown on a soil with a high active lime (most reactive calcium carbonate phase in soils) content (92.5 g kg−1 at 30–60 cm deep), and compared to an untreated control. Three shoots per vine and five vines per treatment were selected. One hundred mL of each Fe treatment (5 mM) were sprayed on mature leaves (treated), and young leaves (covered) were covered so Fe translocation could be studied. Treatments were repeated once after 2 weeks. Leaf blades were sampled before the first spray application and at the end of the assay, 4 weeks later, and 2 weeks after the second spray application. Micronutrient content [(Fe, manganese (Mn), copper (Cu), and zinc (Zn)] in leaf blades was determined and Fe/Mn ratio was calculated as a Fe nutrition index. Leaf chlorophyll content was measured weekly using a noninvasive Minolta SPAD chlorophyll meter. As expected, all Fe treatments resulted in greater leaf Fe concentration than in the untreated control; however, leaves sprayed with Fe-EDTA and Fe-sulfate showed the greatest Fe concentration. As consequence, the largest Fe/Mn ratio was found for Fe-EDTA and Fe-sulfate treatments, although no differences with Fe-EDDS treatment were found. Leaves sprayed with Fe-EDTA chelate showed not only the greatest SPAD readings at the end of the field experiment but also the greatest SPAD readings when measured on covered leaves from the 15th day after treatment application when compared to untreated control. Covered leaves from all vines sprayed with Fe treatments showed greater Fe concentrations than untreated control but only the Fe/Mn ratio for Fe-EDTA was significantly greater than that of untreated control. The inconsistency between total Fe concentration from the sprayed leaves and SPAD readings in both sprayed and covered leaves suggests that the proposed methodology is valid for assessing the Fe translocation rate from mature to young leaves when foliar fertilization was applied.
Communications in Soil Science and Plant Analysis 01/2013; 44. · 0.42 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Strawberry production is usually carried out in Spain on sand substrate under fertigation. Micronutrient chelates are frequently applied as ethylenediaminetetraacetic acid (EDTA) chelates; EDTA is a recalcitrant chelating agent so the concern about the environmental fate of EDTA applied in agriculture has risen. In this work, the efficacy of iron, manganese, zinc, and copper in two alternative chelating agents has been evaluated: the biodegradable N-(1,2-dicarboxyethyl)-D,L-aspartic acid (IDHA) and a combination of the regioisomers ethylenediamine-N,N´-bis(2-hydroxyphenylacetic) acid (o,o-EDDHA) and ethylenediamine-N-(2-hydroxyphenylacetic)-N´-(4-hydroxyphenylacetic) acid (o,p-EDDHA) (called EDDHA mix). Doses were split according to the stability of the chelates in three or six weekly applications. Experiment started 2 January 2010. Leaf samples were taken 6, 12, and 17 weeks after the first application. Foliar analysis, in comparison with chlorophyll indices based on Soil Plant Analysis Development (SPAD) measurement, was used to evaluate chelate efficacy. No differences between treatments were found for the SPAD index, but the SPAD increment was greater for the IDHA treatment during the whole assay. However, foliar analysis was the most adequate method for evaluating differences among the three chelates. The treatment based on EDDHA mix and the IDHA chelates showed greater Fe content in leaves in the first and last periods respectively. The EDDHA mix and EDTA were better alternatives for Zn nutrition than IDHA. Manganese content in leaf was sufficient and not affected by the treatment used. Copper content in leaf showed similar results for all treatments. The Fe/Mn molar ratio showed results similar to those obtained for Fe contents in leaf. The IDHA and EDDHA mix treatments produced similar quality parameters in fruits as EDTA. As conclusion, IDHA and EDDHA mix could be good alternatives for recalcitrant EDTA to apply micronutrient chelates in strawberry plants in fertigation.
Communications in Soil Science and Plant Analysis 01/2013; 44. · 0.42 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Polyaminocarboxylate and polyaminophenolcarboxylate chelating agents, of which EDTA and o,o-EDDHA are
the most representative, are being profusely studied by our research team for 25 years due to their importance as
micronutrient fertilizers used to correct nutritional disorders, and based on their level of impact on crop yields in
Mediterranean regions. Recently, new chelating agents have been designed and synthesized; it has been suggested
that these agents be included in the current European Directive on Fertilizers. Overall chelating agent properties,
including equilibrium in soil based on modeling studies, should be considered when evaluating iron chlorosis correction
ability. Chemical speciation programs such as MINTEQA2, and most recently VMinteq, have been successfully used as
tools for predicting the behaviors of novel chelating agents in soil-plant systems. Currently, only one
polyaminophenolcarboxylate chelating agent (o,o-EDDHA) is available in the VMinteq-compatible database (Lindsay’s
database), although more than seven have been approved as European fertilizers, which can be used as micronutrient
fertilizers. Therefore, the aim of this project was to update the database to include all chelating agents related to o,o-
EDDHA and EDTA, whose complete characterization has been performed and is published elsewhere. Once the
database is updated, further modeling studies, such as equilibrium studies and adsorption isotherm studies based on
solid phase analysis, can be performed to determine fundamental information about and understand the reactivity of
these recalcitrant polyaminophenolcarboxylates in soils.
Journal of Applied Solution Chemistry and Modeling. 10/2012; 1:46-64.
[Show abstract][Hide abstract] ABSTRACT: Mineral, complex and chelated micronutrient fertilisers are widely used in agriculture. However, there have been few studies on manganese and zinc fertilisers. In fact, specific chelating agents to provide these micronutrients to plants have not been found, in contrast to iron. This work considers the interactions of novel and traditional ligands in micronutrient mixtures used in hydroponics and fertigation. Theoretical speciation studies comparing the stability in solution have been carried out to
simulate the possible interactions that can affect Fe, Mn and Zn in aqueous formulations containing these micronutrients. Unknown stability constants of ligands with Zn and Mn have been determined. Also, theoretical speciation investigations in hydroponic conditions have been carried out. It has been found that the new chelating agents, IDHA and EDDS, and the poorly studied o,p-EDDHA, can be good alternatives to the traditional sources such as EDTA, HEEDTA and DTPA principally
for Zn fertilisers. The Mn and Zn chelates with o,p-EDDHA and complexes with lignosulfonate and gluconate have also shown high stability in a hydroponic nutrient solution, maintaining more than 80% Mn in solution until pH 10. The presence of o,o-EDDHA/Fe3+ and o,p-EDDHA/Fe3+ enhances the stability of Zn in solution in the mixed fertilisers. More studies with substrates are necessary to confirm these results and to extend them to other agronomic conditions
Chemical Speciation and Bioavailability 08/2012; · 0.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Aims The efficacy of N,N′-bis(2-hydroxybenzyl)ethyl-enediamine-N,N′-diacetic acid (HBED) as an Fe source in plant nutrition for soybean (Glycine max) plants grown in calcareous soil under controlled con-ditions was studied. Methods The ability of ethylenediamine-N,N′-bis(o-hydroxyphenylacetic) acid (o,oEDDHA/ 57 Fe 3+) and HBED/ 57 Fe 3+ at increasing concentrations and the long lasting effect were evaluated. In addition, iron nutrition was studied considering the Fe uptake from the chelates prepared with the isotope 57 Fe. Further, the SPAD index, total Fe and 57 Fe content in plant were analyzed and soluble and available 57 Fe fractions in soil were deter-mined over time. Results Doses experiment indicated that a higher con-centration of HBED/ 57 Fe 3+ as compared to o,oED-DHA/ 57 Fe 3+ is necessary for obtaining the same 57 Fe absorption by the plant; however, these differences were found to be lower in the second sampling time as com-pared to the first one. This long lasting effect of HBED/ Fe 3+ was corroborated in the long term experiment. Moreover, it was found that the load of Fe in the pods was higher when using HBED/ 57 Fe 3+ than when o,oED-DHA/ 57 Fe 3+ was used. The soil extract analysis for each sampling time indicated that HBED/ 57 Fe 3+ presented a higher stability in soil than o,oEDDHA/ 57 Fe 3+ over time. Conclusion The HBED/Fe 3+ could be a long lasting alternative to EDDHA/Fe 3+ for correcting the iron chlorosis of dicotyledonous plants grown on calcare-ous soils.
[Show abstract][Hide abstract] ABSTRACT: The o,oEDDHA/Fe is the most common and effective iron chelate used as
fertilizer in calcareous soils. Several authors have reported that the
anionic o,oEDDHA/Fe complex is adsorbed to soil components such as
ferrihydrite. The bicarbonate anion may be a competing ion for this
sorption, however no studies have yet identified the extent and
mechanism of this interaction. The aim of this work was to study the
carbonate (bicarbonate + carbonate) effect on EDDHA/Fe adsorption on
two-line ferrihydrite. Two-line ferrihydrite was synthetized adding NaOH
on a nitrate iron (III) solution up to a final pH to be 8.0 and allowing
to age for 22 hours at 20°C. Dialyzed ferrihydrite was characterized
by determining specific parameters such as Fe/OH ratio, BET surface,
point zero of charge and x-ray diffraction. The sorption was performed
at three pH levels (5, 7.5 and 9.5) and three initial carbonate
concentrations (from 0 to 2 mM). Initial EDDHA/Fe, ferrihydrite and
ionic strength concentrations were adjusted to 0.18 mM, 10 g L-1 and 5
mM respectively. Total dissolved FeEDDHA concentrations were quantified
at 480 nm. The o,oEDDHA/Fe isomers (rac-o,oEDDHA/Fe and
meso-o,oEDDHA/Fe) were separated and quantified by High Performance
Liquid Chromatography (HPLC) fitting a photodiode array detector (PDA).
Distribution factor (KD) and sorbed o,oEDDHA/Fe concentration were
determined. Actual carbonate concentration was determined using a multi
N/C analyzer. Ferrihydrite samples showed a typical XRD pattern of
two-line ferrihydrite, two broad peaks at about 35 and 62°
respectively. The BET surfaces (two replicates) were 259.2 ± 3.1
m2/g and 256.0 ± 2.5 m2/g. The Point Zero of Salt Effect (PZSE)
was 7.9 ± 0.2 as bibliographically supported for all fresh and
thus not rigorously de-carbonated ferrihydrite samples. The KD of the
o,oEDDHA/Fe increased from 27.4 ± 0.6 to 304 ± 6 l/kg by
decreasing pH from 9.5 and 5.0 when no carbonate was added. Increasing
equilibrium carbonate concentrations between 8.6 10-2 and 76 10-2 mM
decreased the KD about two-fold at pH 7.5. The KD values from
meso-o,oEDDHA/Fe were up to 1000 fold larger than those of
rac-o,oEDDHA/Fe at highest carbonate concentration at pH 7.5 and pH
dependency suggests that former binds as inner sphere whereas latter
binds as outer sphere. Despite the carbonate competition is unlikely to
largely affect the net sorption of the chelate in soil, clear
differences between meso-o,oEDDHA/Fe and rac-o,oEDDHA/Fe sorption rate
on ferrihydrite in presence of carbonate were found.
[Show abstract][Hide abstract] ABSTRACT: In this study we have obtained experimental evidence that confirms the high activity of aquo complexes III and IV towards the enzyme FCR, responsible for the reduction of Fe(III) to Fe(II) in the process of iron acquisition by plants. The in vivo FCR assays in roots of stressed cucumber plants have shown a higher efficiency of the family of complexes III and a striking structure-activity relationship with the nature of the substituent placed in a phenyl group far away from the metal center. The results obtained in this work demonstrate that all the aquo compounds tested interact efficiently with the enzyme FCR and hence constitute a new concept of iron chelates that could be of great use in agronomy.
[Show abstract][Hide abstract] ABSTRACT: Iron chlorosis is a very common nutritional disorder in plants that can be treated using iron fertilizers. Synthetic chelates have been used to correct this problem, but nowadays environmental concerns have enforced the search for new, more environmentally friendly ligands, such as lignosulfonates. In this paper, Fe coordination environment and speciation in lignosulfonate (LS) complexes prepared under different experimental conditions were studied by (57)Fe Mössbauer spectroscopy in relation to the Fe-complexing capacities, chemical characteristics of the different products, and efficiency to provide iron in agronomic conditions. It has been observed that the complex formation between iron and lignosulfonates involves different coordination sites. When Fe(2+) is used to prepare the iron-LS product, complexes form weak adducts and are sensitive to oxidation, especially at neutral or alkaline pH. However, when Fe(3+) is used to form the complexes, both Fe(2+) and Fe(3+) are found. Reductive sugars, normally present in lignosulfonates, favor a relatively high content of Fe(2+) even in those complexes prepared using Fe(3+). The formation of amorphous ferrihydrite is also possible. With respect to the agronomical relevance of the Fe(2+)/Fe(3+) speciation provided by the Mössbauer spectra, it seems that the strong Fe(3+)-LS complexes are preferred when they are applied to the leaf, whereas root uptake in hydroponics could be more related with the presence of weak bonding sites.
Journal of Agricultural and Food Chemistry 03/2012; 60(13):3331-40. · 3.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mineral, complex and chelated micronutrient fertilisers are widely used in agriculture. However, there have been few studies on manganese and zinc fertilisers. In fact, specific chelating agents to provide these micronutrients to plants have not been found, in contrast to iron. This work considers the interactions of novel and traditional ligands in micronutrient mixtures used in hydroponics and fertigation. Theoretical speciation studies comparing the stability in solution have been carried out to simulate the possible interactions that can affect Fe, Mn and Zn in aqueous formulations containing these micronutrients. Unknown stability constants of ligands with Zn and Mn have been determined. Also, theoretical speciation investigations in hydroponic conditions have been carried out. It has been found that the new chelating agents, IDHA and EDDS, and the poorly studied o,p-EDDHA, can be good alternatives to the traditional sources such as EDTA, HEEDTA and DTPA principally for Zn fertilisers. The Mn and Zn chelates with o,p-EDDHA and complexes with lignosulfonate and gluconate have also shown high stability in a hydroponic nutrient solution, maintaining more than 80% Mn in solution until pH 10. The presence of o,o-EDDHA/Fe3+ and o,p-EDDHA/Fe3+ enhances the stability of Zn in solution in the mixed fertilisers. More studies with substrates are necessary to confirm these results and to extend them to other agronomic conditions.
Chemical Speciation and Bioavailability 01/2012; 24(3):147-158. · 0.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The application of nuclear magnetic resonance (NMR) for the quality control of fertilizers based on Fe(3+), Mn(2+), and Cu(2+) chelates and complexes is precluded by the strong paramagnetism of metals. Recently, a method based on the use of ferrocyanide has been described to remove iron from commercial iron chelates based on the o,o-EDDHA [ethylenediamine-N,N'bis(2-hydroxyphenylacetic)acid] chelating agent for their analysis and quantification by NMR. The present work extended that procedure to other paramagnetic ions, manganese and copper, and other chelating, EDTA (ethylenediaminetetraacetic acid), IDHA [N-(1,2-dicarboxyethyl)-d,l-aspartic acid], and complexing agents, gluconate and heptagluconate. Results showed that the removal of the paramagnetic ions was complete, allowing us to obtain (1)H NMR spectra characterized by narrow peaks. The quantification of the ligands by NMR and high-performance liquid chromatography showed that their complete recovery was granted. The NMR analysis enabled detection and quantification of unknown impurities without the need of pure compounds as internal standards.
Journal of Agricultural and Food Chemistry 11/2011; 59(24):13110-6. · 3.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The improvement of Zn fertilizers requires new techniques to evaluate their efficacy. In this paper, the (67)Zn stable isotope was used as tracer of several Zn-lignosulfonate complexes to study the foliar-applied Zn uptake and distribution behavior in the plant, compared with ZnEDTA. Navy bean plants ( Phaseolus vulgaris L.) were grown hydroponically in a Zn-free nutrient solution, and six modified lignosulfonates and EDTA complexed with (67)Zn were used in foliar application in the young leaves as Zn sources. Zinc isotopes in roots, stems, and sprayed and unsprayed leaves were determined by ICP-MS, and signal interferences caused by the compounds of the digested vegetal samples were corrected. The mathematical procedure of isotope pattern deconvolution allowed the minimization of the uncertainty in the measured molar fractions of Zn from fertilizer or from natural sources. Significant differences in Zn use and distribution were observed among the fertilizers when the calculated concentrations of Zn from the fertilizer were compared, whereas they were unnoticeable attending to the total Zn in plant tissues, usually determined at the conventional studies. By foliar spray, higher Zn uptake and mobilization to leaves and stems were achieved with (67)ZnEDTA than with (67)Zn-LS complexes. The ultrafiltered LS and phenolated LS showed slightly better ability to provide Zn to the bean plants than the other LS. The foliar-applied Zn use and distribution in the plant were related with the stability of the Zn-lignosulfonates complexes. Those presenting the lower stability versus pH, but the highest complexing capacity, were slightly more suitable to supply foliar-applied Zn to navy beans.
Journal of Agricultural and Food Chemistry 08/2011; 59(16):8829-38. · 3.11 Impact Factor