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1.
The short-term effectiveness of soil-applied humic acid–like substances [naturally complexed or uncomplexed with iron (Fe)] extracted from composted poultry (HLSP) and sheep (HLSS) manures in preventing lime-induced Fe chlorosis in Eureka lemon (Citrus lemon L.) cuttings grafted on sour orange (Citrus aurantium L.) was investigated and compared with the commonly applied ethylenediamine di-2-hydroxyphenyl acetate ferric (FeEDDHA). Treatments were untreated plants and plants fertilized with FeEDDHA, HLSP, and HLSS injected into the soil at a total rate of 25 mg Fe per plant each. Chlorophyll concentration index (CCI) of the youngest fully expanded leaves, growth vigor, and leaf Fe concentration were measured. HLSP and HLSS, similar to FeEDDHA, resulted in significantly greater CCI values, growth vigor, and leaf Fe concentration compared to untreated plants. HLSP and HLSS offer potential alternative to FeEDDHA to prevent lime-induced Fe deficiency in Eureka lemon. Concentrates of HLSP and HLSS can be commercially prepared to offer an inexpensive and environmentally safe product.  相似文献   

2.
The main objective of this work was to study the influence of humic substances (HS) on the effectiveness of Fe sulfate and Vivianite in preventing Fe chlorosis in white lupin with a view of performing cost-effective methods to overcome the problem. Two consecutive crops were performed using calcareous sand treated with different Fe sources (FeSO4·7H2O and Vivianite, at three different rates, and Fe-EDDHA) and five HS rates. Vivianite was more effective and persistent than Fe sulfate in increasing Soils and Plant Analysis Development (SPAD) readings and lupin yield expressed as dry matter (DM), probably due to the type of alteration products formed upon Vivianite oxidation. The effect of Fe sulfate and Vivianite in preventing Fe chlorosis was significantly increased by HS, and the best results were obtained with Vivianite and HS applied at 0.32 g Fe kg−1 and 0.06 g kg−1 growing media, respectively. SPAD readings with this treatment accounted for 85% and 70% of those obtained with Fe-EDDHA in the first and second crop, respectively, whereas DM production was greater with the Vivianite + HS treatment than with Fe-EDDHA. These results showed the potential effectiveness of treatments based on the application of Vivianite and HS in overcoming Fe chlorosis. However, HS applied with Fe sources at rates of 0.5 and 1 g kg−1 growing media decreased SPAD readings and plant yield. These positive and negative effects of HS in preventing Fe chlorosis were more evident with Fe sulfate and Vivianite than with chelated Fe, probably due to the effect of HS on the solubility of Fe forms of the growing medium.  相似文献   

3.
Abstract

Iron (Fe) chlorosis is a common symptom in many soybean (Glycine max L. Merr.) producing areas throughout the United States. On the Blackland soils found in northeast Texas, Fe chlorosis occasionally appears during vegetative growth, but often abates by the time plants flower. However, it is not clear whether preplant additions of Fe will enhance soybean growth or yield on this soil or whether different sources of Fe give different responses. In a greenhouse study, soil from a pH 8.4 Houston Black clay (fine, smectitic, thermic Udic Haplusterts), with a DTPA‐extractable concentration of 11.7 mg Fe kg?1, was treated with FeSO4 (0, 3, 10, 30, and 100 ppm Fe), sodium ferric diethylenetriamine pentaacetate (FeDTPA) (0, 0.3, 1.0, 3, and 10 ppm Fe) or sodium ferric ethylenediamine‐di (o‐hydroxyphenylacetate) (FeEDDHA) (0, 0.3, 1.0, 3, and 10 ppm Fe). Pot size was 19 L and soil dry mass was 10 kg. Soybean (cv. Hutcheson) seed were planted in November 2000 and seedlings were thinned to three per pot at the first true leaf stage. The third uppermost fully expanded leaf of each plant was harvested at growth stage R3 for nutrient analysis. Between 20 and 100 days after planting, six nondestructive leaf chlorophyll readings were obtained from the third uppermost fully expanded leaf. Entire plants were harvested at R6 (mid podfill) for nutrient and biomass yield determination. Leaf blade Fe concentration ranged from 79 to 87 mg kg?1 in the untreated check plants to a high of 109 mg kg?1 for the 10 ppm FeDTPA‐Fe treatment, all of which were greater than the acknowledged critical level of 60 mg kg?1. No visible Fe‐deficiency symptoms appeared during the study. Chlorophyll (SPAD 502) values during the R3 to R5 growth stages were greater for all of the FeSO4 treatments than for the 0 ppm treatment. The 10 ppm FeDTPA‐Fe treatment and the 3 ppm FeEDDHA‐Fe treatment exhibited higher leaf chlorophyll readings than the untreated checks during the R3 to R5 growth stage. The average seed yield from the 12 Fe fertilized treatments at growth stage R6 was only 12% greater (not significant) than the untreated check. Total biomass (root plus shoot) was not affected by the treatments. There was no evidence that the higher rates of Fe caused reduced growth. Overall, our results do not suggest that soil‐applied Fe will consistently stimulate soybean growth or yield on this soil, at least when DTPA‐extractable soil Fe is at 12 mg kg?1 or higher. However, because of the trends for increased seed yield in some of the Fe treatments, field studies using soil‐ and/or foliar‐applied Fe are warranted.  相似文献   

4.
Studies were conducted to determine the efficacy of K salts in alleviating lime‐induced chlorosis. Greenhouse studies using a Gibbon silt loam [fine‐silty, mixed (calcareous), mesic Typic Haplaquoll] and a 1: 1 mixture of Gibbon soil and washed sand were conducted with KCl, KNO3, K2SO4, K2HPO4, or KHCO3 applied at rates of 0, 250, and 500 mg K/kg soil. An FeEDDHA treatment was included for comparison. Similar studies were conducted at two field sites known to produce lime‐induced chlorosis. Potassium salts were applied at 0, 20, and 40 g K/m of row. In the greenhouse, plants treated with KCl, KNO3, and K2SO4 on Gibbon soil were less chlorotic than controls or plants treated with K2HPO4, or KHCO3. No K treatment totally alleviated chlorosis except FeEDDHA. Chlorophyll correlated positively with chlorosis rating. No relationship was found between leaf Fe uptake and chlorosis. Plants grown in soil/sand exhibited no chlorosis and had lower Fe uptake than plants grown in Gibbon soil. Thus chlorosis was not due strictly to low soil‐Fe availability or inadequate Fe uptake. Bicarbonate in the soil solutions of both growth media treated with KCl was lower than controls which may explain the reduced chlorosis associated with this treatment.

One field site showed positive effects of K treatments on chlorosis rating, chlorophyll concentration, and seed yield. No treatment was as effective as FeEDDHA in influencing plant growth or yield. Total leaf Fe concentration was unrelated to leaf chlorophyll concentration. Inorganic cation/anion ratios in the plant were from 4.4–8.4 which could cause net H+ efflux by the plant and alkalinization of plant tissues. One possibility is that H+ efflux solubilizes P in the rhizosphere, which after uptake could immobilize Fe in the plant. Application of KCl, KNO3, and K2SO4 generally lowered HCO3 content of the upper 15 cm of both soils. High bicarbonate could increase rhizosphere P availability and increase immobilization of Fe in the plant.  相似文献   

5.
《Journal of plant nutrition》2013,36(10-11):2031-2041
Abstract

In this study we have tested the hypothesis that lime‐induced Fe deficiency chlorosis of kiwifruit may be prevented by the application of a synthetic iron(II)‐phosphate analogous to the mineral vivianite [(Fe3(PO4)2·8H2O)]. Two experiments, under greenhouse and field conditions, were performed. In the greenhouse, 1‐year old micropropagated plants (Actinidia deliciosa, cv. Hayward), grown in 3‐L pots on a calcareous soil, were treated in early autumn with soil‐applied: (1) synthetic vivianite (1.35 g plant?1) and (2) Fe‐EDDHA (24 mg Fe plant?1). The synthetic vivianite suspension, prepared by dissolving ferrous sulfate and mono‐ammonium phosphate, was injected into the soil as a sole application whereas the Fe‐EDDHA solution was applied four times at weekly intervals. The field experiment was conducted in a mature drip‐irrigated kiwifruit orchard located on a calcareous soil in the Eastern Po Valley (Italy). Treatments were performed in early autumn by injecting synthetic vivianite (1.8 kg tree?1) and Fe‐EDDHA (600 mg Fe tree?1) into four holes in the soil around each tree, at a depth of 25–30 cm. The Fe‐chelate application was repeated at the same rate in the following spring. Untreated (control) plants were used in both experiments. Autumn‐applied Fe fertilisers significantly prevented development of Fe chlorosis under greenhouse conditions whereas in the field only vivianite was effective. In conclusion, these 1‐year results show that vivianite represents an effective alternative to soil‐applied Fe chelates for preventing Fe chlorosis in kiwifruit orchards.  相似文献   

6.
Response of five citrus rootstocks to iron deficiency   总被引：1，自引：1，他引：0  
Citrus established in calcareous soils can be affected by iron (Fe)‐deficiency chlorosis which limits yield and the farmers' income. The degree of deficiency depends on the rootstock, but the resistance to Fe chlorosis still requires further investigation. To study physiological parameters of citrus rootstocks that could be used to evaluate resistance to Fe deficiency, plants of Troyer citrange (Citrus sinensis L. Osb. × Poncitrus trifoliata L. Raf.), Carrizo citrange, Volkamer lemon (Citrus volkameriana Ten. & Pasq.), alemow (Citrus macrophylla Wester), and sour orange (Citrus aurantium L.) were grown in nutrient solutions with 0, 5, 10, 15, or 20 μM Fe. For each rootstock, plant height, root and shoot dry weights, and concentration of Fe in the shoots and roots were measured at the end of the experiment. Chlorophyll (CHL) concentration was estimated throughout the experimental period using a portable CHL meter (SPAD‐502) calibrated for each rootstock. At the end of the experiment, CHL fluorescence parameters were measured in each rootstock with a portable fluorimeter. Maximal and variable fluorescence values indicated that the photochemistry of Troyer was more affected by a low concentration of Fe in the nutrient solution than that of other rootstocks. To compare rootstocks, the absolute CHL concentration was converted into relative yield by employing a scaling divisor based on the maximum value of total CHL in plants without Fe‐deficiency symptoms. Exponential models were developed to determine the minimum Fe concentration in nutrient solution required to maintain leaf CHL at 50% of the maximum CHL concentration (IC50). Models were also developed to assess the period of time the rootstocks were able to grow under Fe‐stress conditions before they reached IC50. Volkamer lemon and sour orange needed the lowest Fe concentration (between 4 and 5 μM Fe) to maintain IC50, and Troyer citrange had the highest Fe requirement (14 μM Fe). Citrus macrophylla and Carrizo citrange required 7 and 9 μM of Fe, respectively. Similarly, Volkamer lemon and sour orange rootstocks withstood more days under total Fe depletion or with a low concentration of Fe (5 μM Fe in nutrient solution) until they reached IC50, compared to the other rootstocks. The approach used led to a classification of the rootstocks into three categories, regarding their internal tolerance to Fe chlorosis: resistance (sour orange and Volkamer lemon), intermediate resistance (C. macrophylla and Carrizo citrange), and reduced resistance (Troyer citrange).  相似文献   

7.
Productivity and sustainability of cacao (Theobroma cacao L.) in tropical soils are affected by levels of iron. Information is lacking on the cacao response to various sources of iron (Fe). A greenhouse experiment was conducted to evaluate the effects of five iron sources iron sulfate heptahydrate, ferric ethylenediamine-N,N’-bis(2-hydroxyphenylacetic acid), ferric diethylenetriaminepentaacetic acid, ferric ethylenediaminetetraacetic acid, fiesta herbicide (FeSO4 · 7H2O, FeEDDHA, FeDTPA, FeEDTA,) at 10 mg Fe kg?1 soil on growth, photosynthesis, content of photosynthetic pigments and starch and macro- and micronutrient nutrition of cacao. The various iron sources had significant effects on shoot and root dry biomass accumulation, leaf chlorophyll a and b content, carotenoid levels, SPAD index and PN. These parameters were significantly correlated with concentration, uptake, influx, and transport and use efficiency of Fe. In cacao net photosynthesis, stomatal conductance, internal carbon dioxide (CO2), and transpiration in leaf level responded differently to the sources of Fe. Invariably, macro and micronutrient uptake, influx, transport, and use efficiency showed differential responses to sources of iron but significant effects were only observed for copper (Cu), Fe, manganese (Mn), and zinc (Zn). Overall, FeDTPA, FeEDTA and FeHEDTA could be the best sources of Fe in improving, growth, photosynthesis and macro and micro nutrition of cacao.  相似文献   

8.
Humic substances improve the efficiency of different iron (Fe) sources overcoming Fe deficiency chlorosis of plants. However, applied at high rates, they can promote negative effects on plants. The main objective of this work was to study the potential adverse effect of three humic acids from different origin when they were applied with two effective Fe sources for plants: Fe- ethylenediaminedihydroxyphenylacetic acid (EDDHA) and Vivianite. To this end, an experiment with lupin (Lupinus albus L.) was performed involving two factors: (i) Fe source, and (ii) humic substances from three different origin (composted cork, leonardite, and compost obtained from a mixture of olive husk with cotton gin trash) applied at 0, 0.1, and 0.5 g organic carbon (C) kg?1 of growing media. At the rates used, humic substances promoted adverse effects on plant development, chlorophyll meter readings, and Fe content in lupin grown in calcareous media. Overall, the effect on dry matter and Fe content in plants was more relevant when Fe was supplied with Vivianite, the effect on chlorophyll meter readings being more significant when Fe was applied as Fe-EDDHA. Differences were also observed depending on the source of humic substances, those from leonardite promoting the greatest decrease in dry matter in roots and shoots. These humic substances possessed the highest values of spectroscopy index for aromaticity (A254 ). On the other hand, the application of humic substances from olive husk compost, which exhibited the lower aromaticity index, resulted in the smallest decrease in dry matter production and chlorophyll meter readings. Dry matter in roots decreased logarithmically with increased values of the estimates of the amounts of aromatic compounds accumulated in the growing media (R2 = 0.92; P < 0.01) with Vivianite as Fe source. Thus, the effects decreasing dry matter production, particularly in roots, and chlorophyll meter readings can be ascribed at least partially to the presence of phytotoxic aromatic compounds in humic substances.  相似文献   

9.
It has been proposed that glutathione can relieve the effects of Fe deficiency. This study tested the effects of glutathione foliar treatments to prevent Fe chlorosis, using as positive controls soil and foliar Fe fertilisation. Medicago scutellata plants were grown in soil (5.7% CaCO3) supplemented or not with 4 and 8% CaCO3. Two Fe(III)‐EDDHA soil treatments (5 and 10 mg Fe kg?1), and three foliar treatments (three applications each of 2.14 mM Fe(III)‐EDDHA, 1 mM glutathione, and the previous two combined) were applied. Measurements include leaf chlorophyll and Fe concentrations, biomass, leaf enzymatic and non‐enzymatic antioxidant systems and carboxylates. The addition of CaCO3 caused typical Fe deficiency symptoms, including changes in chlorophyll, Fe, antioxidant systems and carboxylates, which were prevented by soil and foliar Fe fertilisation. The foliar treatment with glutathione also led to higher chlorophyll, leaf extractable Fe and root Fe, as well as decreases in some antioxidant systems, whereas leaf Fe concentrations decreased. The combined foliar application of glutathione and Fe was even more efficient in preventing chlorosis. Including glutathione in foliar fertilisation programs should be considered as an option for Fe chlorosis prevention, especially when relatively large leaf total Fe concentrations occur in the so called chlorosis paradox.  相似文献   

10.
Abstract

Vivianite is a hydrated ferrous phosphate mineral that can form in reducing environments, and it was recently identified on aged paddy rice (Oryza sativa, L., cultivar Hitomebore) roots. However, the formation and dissolution of vivianite appear highly susceptible to the soil redox potential. We examined the effect of water management on the vivianite content of rice roots in three experimental micro (1 m2) paddy fields. The vivianite content of the roots was estimated using a method based on the alteration of vivianite after heating at 105°C for 48 h. This alteration steeply lowers the dissolution of phosphate from the roots in a mixed acid solution of 0.1 mol L?1 of hydrochloric acid (HCl) and 1 mol L?1 of acetic acid (CH3COOH). Efficiency of the method was confirmed regarding heating temperature and duration of heating. Using this method, we found that water management significantly influenced the vivianite content of the rice roots. The vivianite content of the rice roots was highest, i.e., 2.3 g phosphorus (P) kg?1 expressed by its estimated P content, when the paddy field was continuously flooded from May to until early September. After flooding stopped, the soil was gradually oxidized, leading to a decrease in vivianite content. In the micro plot exposed to midseason drainage, the vivianite content increased to the level of the continuously flooded plot after reflooding, and finally decreased after flooding was stopped in late August. The plots exposed to midseason drainage followed by intermittent irrigation presented the lowest vivianite contents among the three experimental paddy fields. These results confirm that increases and decreases in the vivianite contents of paddy-rice roots strongly depend on water management.  相似文献   

11.
A greenhouse pot experiment was conducted with peanuts (Arachis hypogaea L., Fabceae) to evaluate iron compound fertilizers for improving within-plant iron content and correcting chlorosis caused by iron deficiency. Peanuts were planted in containers with calcareous soil fertilized with three different granular iron nitrogen, phosphorus and potassium (NPK) fertilizers (ferrous sulphate (FeSO4)–NPK, Fe–ethylendiamine di (o-hydroxyphenylacetic) (EDDHA)–NPK and Fe–citrate–NPK). Iron nutrition, plant biomass, seed yield and quality of peanuts were significantly affected by the application of Fe–citrate–NPK and Fe–EDDHA–NPK to the soil. Iron concentrations in tissues were significantly greater for plants grown with Fe–citrate–NPK and Fe–EDDHA–NPK. The active iron concentration in the youngest leaves of peanuts was linearly related to the leaf chlorophyll (via soil and plant analyzer development measurements) recorded 50 and 80 days after planting. However, no significant differences between Fe–citrate–NPK and Fe–EDDHA–NPK were observed. Despite the large amount of total iron bound and dry matter, FeSO4–NPK was less effective than Fe–citrate–NPK and Fe–EDDHA–NPK to improve iron uptake. The results showed that application of Fe–citrate–NPK was as effective as application of Fe–EDDHA–NPK in remediating leaf iron chlorosis in peanut pot-grown in calcareous soil. The study suggested that Fe–citrate–NPK should be considered as a potential tool for correcting peanut iron deficiency in calcareous soil.  相似文献   

12.
《Journal of plant nutrition》2013,36(10):2205-2228
ABSTRACT

Chlorosis in crops grown on calcareous soil is mainly due to iron (Fe) deficiency and can be alleviated by leaf application of soluble Fe2+ or diluted acids. Whether chlorosis in indigenous plants forced to grow on a calcareous soil is also caused by Fe deficiency has, however, not been demonstrated. Veronica officinalis, a widespread calcifuge plant in Central and Northern Europe, was cultivated in two experiments on acid and calcareous soils. As phosphorus (P) deficiency is one of the major causes of the inability of many calcifuges to grow on calcareous soil we added phosphate to half of the soils. Leaves in pots with the unfertilized and the P-fertilized soil, respectively, were either sprayed with FeSO4 solution or left unsprayed. Total Fe, P, and manganese (Mn) in leaves and roots and N remaining in the soil after the experiment were determined. In a second experiment, no P was added. Leaves were either sprayed with FeSO4 or with H2SO4 of the same pH as the FeSO4 solution. Degree of chlorosis and Fe content in leaves were determined. Calcareous soil grown plants suffered from chlorosis, which was even more pronounced in the soils supplied with P. Newly produced leaves were green with Fe spray but leaves that were chlorotic before the onset of spraying did not totally recover. H2SO4 spray even increased chlorosis. This demonstrated that chlorosis was due to Fe deficiency. As total leaf Fe was similar on acid and calcareous soil, it was a physiological Fe deficiency, caused by leaf tissue immobilization in a form that was not metabolically “active”. Iron in the leaves was also extracted by 1,10-phenanthroline, an Fe chelator. In both experiments, significant differences between leaves from acid and calcareous soil were found in 1,10-phenanthroline extractable Fe but not in total leaf Fe, when calculated on a dry weight basis. Differences in 1,10-phenanthroline extractable Fe were more pronounced when calculated per unit dry weight than calculated per leaf area, whereas the opposite condition was valid for total leaf Fe.  相似文献   

13.
Abstract

A glasshouse study employing a split-root technique was conducted to investigate the influence of intercropping with maize (Zea mays L.) in a calcareous soil on N2 fixation by peanut (Arachis hypogaea L.) at early stages of growth. In this intercropping system, competitive interactions between maize and peanut for N and improvement of Fe uptake were likely to be important factors affecting N2 fixation of peanut. The experiment was comprised of three treatments which included treatment I: peanut monocropping; treatment II: maize/peanut intercropping (the major and the minor compartments with low N, 50 mg kg?1); treatment III: maize/peanut intercropping (the major compartment with low N, 50 mg kg?1 and the minor compartment with high, N 200 mg kg?1). The minor compartment of treatment III was fertilized with 200 mg kg?1 N for reducing or eliminating the competition of N coming from intercropping maize. Intercropping with maize corrected Fe chlorosis of peanut by significantly increasing plant Fe concentration and uptake. Compared with the monocropping treatment, iron uptake increased from intercropping treatment II and III by 22 and 24% per plant, 30 and 29% shoots, 38 and 60% nodules. Iron uptake by the root nodules was especially enhanced in the intercropping system. In contrast, intercropping with maize had little effect on NO3 ?1-N concentrations in the soil rhizosphere of peanut or on N concentrations and uptake by peanut compared with plants in monoculture. The results indicate that the improvement in Fe nutrition was an important factor promoting N2 fixation by peanut in the intercropping system at the flowering stage of peanut growth, and that competition for N by intercropped maize had little effect on N2 fixation by peanut under the experimental conditions.  相似文献   

14.
The aim of this study was to evaluate the effectiveness of soil-applied aqueous extract of Amaranthus retroflexus L. in preventing lime-induced iron (Fe) chlorosis of pear trees (Pyrus communis L.). Tree growth, nutritional status, yield and fruit quality were also assessed. The aqueous extract was obtained by soaking dried and ground canopy (epigeal part) of spontaneous A. retroflexus plants in tap water. A. retroflexus extract was chosen because of its ability to solubilize Fe from calcareous soil, which was found to be 100-fold higher than deionized water alone. Two experiments were carried out (controlled environment and commercial field conditions) where soil-applied aqueous extract of A. retroflexus alone or mixed with iron sulfate (FeSO4) was compared with synthetic Fe-chelate and an untreated control. Soil-applied aqueous extract of A. retroflexus increased shoot length, leaf SPAD and total plant biomass in controlled environment. In the commercial orchard control trees showed severe leaf Fe-chlorosis symptoms effectively prevented by Fe-chelate. The supply of A. retroflexus aqueous extract improved Fe nutrition of trees, particularly when enriched with FeSO4. Fe-chelate increased tree yield but decreased fruit weight, leaf potassium (K) and manganese (Mn) concentration. At harvest, all strategies raised fruit soluble solid concentration compared to the untreated control. Results showed that soil-applied A. retroflexus aqueous extract improved Fe nutritional status of pear trees, probably because of the natural Fe chelating capacity of the compounds released by its tissues.  相似文献   

15.
Abstract

Iron (Fe) chlorosis, an Fe deficiency commonly observed in grapevines cultivated on calcareous soils, generally inhibits plant growth and decreases yield. The objective of this research was to relate the incidence of Fe chlorosis in vines of the Montilla‐Moriles area, southern Spain, to indigenous soil properties. Thirty‐five grapevines (V. vinífera L. cv. Pedro Ximenez grafted on V. berlandieri×V. rupestris 110 Ritcher) showing different degree of Fe chlorosis were selected from 13 vineyards. The leaf chlorophyll concentration (estimated by the SPAD value measured with a Minolta meter) was positively correlated with the contents in different soil Fe forms but not with alkalinity‐related soil properties (pH, calcium carbonate equivalent, and active lime). The acid NH4 oxalate‐extractable Fe (Feo) was the most useful simple variable to predict the occurrence of Fe chlorosis. A Feo/active lime ratio of 25×10–4 was found to be useful to class soils into two groups according to the probability of inducing Fe chlorosis.  相似文献   

16.
The most widely used Iron (Fe) fertilizer in calcareous soils is the synthetic chelate Fe(o,o‐EDDHA). However, humic substances are occasionally combined with Fe chelates in drip irrigation systems in order to lower costs. We investigated the effect of various mixtures of Fe(o,o‐EDDHA) and a commercially available humic substance on Fe availability in a calcareous soil from Murcia, Spain (in vitro experiment) and on leaf Fe content and fruit‐quality attributes of Citrus macrophylla (field experiment). In the in vitro experiment, a calcareous soil was incubated for 15 d with solutions of sole Fe(o,o‐EDDHA) and humic substance and of a mixture of humic substance and Fe(o,o‐EDDHA) to determine the dynamics of available Fe. While the mixture did not significantly increase the available soil Fe, it did decrease the rate of Fe retention in the surface soil compared to sole Fe(o,o‐EDDHA). In the field experiment, the substitution in the application solution of 67% of Fe(o,o‐EDDHA) by commercial humic substance increased leaf P in lemon trees from 0.19% with sole Fe(o,o‐EDDHA) to 0.30% and leaf Fe from 94 mg kg–1 to 115 mg kg–1. Some quality parameters like vitamin C content and peel thickness were also improved with a partial substitution of Fe(o,o‐EDDHA) by humic substances. We conclude that a partial substitution of commercial Fe chelates by humic substance can improve crop Fe uptake and may thus be economically attractive. The underlying physiological mechanisms and ecological implications require further studies.  相似文献   

17.
A hypothesis has been presented and tested that bicarbonate (HCO3) and nitrate (NO3) are the most important anions inducing iron (Fe) chlorosis because these anions increase the pH of leaf apoplast which in turn depresses ferric‐iron [Fe(III]) reduction, and hence, the uptake of Fe into the symplasm. Experiments with young sunflower (Helianthus annuus) plants showed that nutrition with NO3 as the sole nitrogen (N) source induced chlorosis whereas ammonium nitrate (NH4NO3) did not. Monohydrogen carbonate (bicarbonate) also favoured the development of chlorosis. The degree of chlorosis was not related to the Fe concentration in the leaves. Both anion species, NO3 and HCO3, increased the pH of the leaf apoplast which was measured by means of the fluorescence dye 5‐carboxyfluorescein. A highly significant negative correlation between leaf apoplast pH and chlorophyll concentration in the leaves (r = ‐0.97) was found. Ferric‐Fe reduction in the apoplast—measured by means of ferrocene—provided evidence that a low leaf apoplast pH, obtained with ammonium (NH4) supply, favoured the reduction of Fe(III) as compared with a higher leaf apoplast pH obtained with NO3 supply. These results support the hypothesis tested.  相似文献   

18.
Susceptible Trifolium plants often exhibit symptoms of iron (Fe)‐deficiency chlorosis when grown on high pH, calcareous soils. A greenhouse method was developed to screen seedlings for Fe‐deficiency chlorosis. ‘Yuchi’ arrowleaf (T. vesiculosum Savi.) and ‘Dixie’ crimson (I. incarnatum L.) clover seedlings were grown in “Super Cell”; Cone‐tainers in six calcareous Texas soils differing in Fe and selected other chemical characteristics. At the fourth trifoliolate leaf stage, chlorosis was induced by saturating the soil for a minimum of 2 weeks. The soils differed in their capacity to induce chlorosis in both clovers. Yuchi was more susceptible than Dixie, showing a higher percentage of chlorosis in five of the six soils. The results indicate that this screening method would be a useful tool for studying Fe‐deficiency chlorosis in Trifolium spp.  相似文献   

19.
The aim of the study was to examine impact of foliar titanium (Ti) sprays on vegetative and reproductive response of apple (Malus domestica Borkh.) trees under conditions of low soil availability of iron (Fe), manganese (Mn), and zinc (Zn). The experiment was conducted during 2005–2006 at a Experimental Station in Isparta region, Turkey, on mature ‘Granny Smith’ apple trees/M.9, planted at a spacing of 3.5 × 1.5 m, on fine-textured soil with neutral reaction, medium status of organic matter, high amounts of available phosphorus (P), potassium (K), and magnesium (Mg), and low availability of Fe, Mn, and Zn. The trees were sprayed with Ti-ascorbate at the green and pink bud stage, petal fall, and 3, 6, and 9 weeks after full bloom, at a rate of 3 g Ti ha?1 per spray. The efficiency of Ti sprays was compared to combined sprays of Fe, Mn, and Zn [chelated with ethylenediaminetetraacetic acid (EDTA)], applied at the same terms as Ti sprays, at rate of 36 g, 36 g and 24 g per spray, respectively. Trees unsprayed with Ti, Fe, Mn, and Zn served as the control. It was shown that summer leaf Ti concentrations of the trees untreated with Ti were high, varying from 34 to 36 mg kg?1 dry matter. Foliar Ti sprays increased leaf status of this nutrient but they had no effect on nutrition of essential macro- and microelements, tree vigor, and fruit yield. Mean apple weight, coloring, firmness, soluble solids concentration, and titratable acidity of fruit were not also influenced by Ti sprays. Foliar sprays of Fe, Mn, and Zn improved leaf status of nitrogen (N), Mg, Fe, Mn, and Zn; leaves of the trees sprayed with those micronutrients were also greener, and contained more Fe2+ than those of the control plants. Combined sprays of Fe, Mn, and Zn improved tree vigor and fruit yield.  相似文献   

20.
Abstract

Peanut (Arachis hypogaea L.) is susceptible to iron (Fe) chlorosis, however, plant analysis diagnostic criteria are lacking for determining the intensity of chlorosis in this crop. As total Fe content is a misleading index of Fe nutritional status of plants, determination of physiologically active Fe fraction (Fe2+) is suggested for the purpose. In a nutrient indexing survey of the chlorosis‐affected peanut crop grown in the rainfed Potohar plateau of Pakistan, o‐phenanthroline extractable Fe2+ concentration in plants decreased with increasing severity of chlorosis and thus proved an effective technique for determining the intensity of Fe chlorosis. Green plants contained 40.1 to 67.3 mg Fe2+/kg, mildly chlorotic 32.1 to 40.0 mg Fe2+/kg, moderately chlorotic 28.0 to 32.0 mg Fe2+/kg, and severely chlorotic <28.0 mg Fe2+/kg. The minimum Fe2+ requirement in green plants was estimated to be 40 mg/kg on dry weight basis. In rainfed field experiments on a calcareous Typic Hapludalfs soil, foliar sprays of 1% solution of sequestrene (NaFeEDDHA) proved superior to the foliar sprays of 0.5% FeSO4.7H2O in correcting Fe chlorosis in two cultivars of peanut. Maximum increase in pod yield with sequestrene was 42% in cv. BARD‐92 and 27% in cv. BARD‐699 over the respective control yields. Ferrous concentration in plants increased with both the Fe sources, however, a substantial increase was recorded only with sequestrene. As peanut is a low‐input high‐risk rainfed crop, correction of Fe chlorosis by using sequestrene may not be economically feasible. Thus, development and/or screening of peanut varieties tolerant to Fe chlorosis is suggested by employing Fe2+ analysis technique.  相似文献   

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