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1.
Fresh Fe(ClO4)3 solutions, 0.01 M or 0.001 M in iron (III), were seeded with iron (III) hydroxide brown sols and the reaction processes were investigated. In two experiments, HC1O4 was added to fresh Fe(ClO4)3 solutions to lower their degrees of super saturation with respect to iron (III) hydroxide. Depending upon the quantity of seeding solution added, it was found that samples differed greatly in appearance and in the stability during ageing. With a small amount of seeding solution added and following a relatively long induction period, the sample rapidly developed to a dense, cloudy yellow suspension with FeOOH precipitate settled shortly afterwards. With an increased amount of seeding solution added, the sample gradually became more brownish and less turbid and eventually a clear brown sol was observed. Although α-FeOOH was the major hydrolysed species in all samples, a yellow precipitate which settled under gravity was found only in those containing a small quantity of seeding solution. The above results provide experimental evidence supporting the hypothesis (Hsu and Ragone, 1972) that the initial number of nuclei relative to the concentration of mono-meric species is the key factor governing the appearance and the stability of an hydrolysed iron (III) solution. In another experiment, varying amounts of a seeding solution were added to a fresh, pure 0.001 M Fe(ClO4)3 solution to which no HC1O4 was added. All samples rapidly hydrolysed to clear brown sols in less than 6 hours and no noticeable seeding effect was observed. It is suggested that a pure 0.001 M Fe(ClO4)3 solution is highly supersaturated with respect to iron (III) hydroxide and a large number of nuclei spontaneously form in situ shortly after preparation.  相似文献   

2.
In comparison studies (11, 12), monocotyledonous corn (Zea mays L.) and oats (Avena byzantina C. Koch) did not respond to Fe stress as effectively nor to the same degree as the dicotyledonous soybeans (Glycine max (L.) Merr.) or tomatoes (Lycopersicon esculentum Mill.). Both the Fe‐inefficient and Fe‐efficient corn and oats developed Fe chlorosis; the Fe‐efficient dicotyledonous plants were green. In the present study, the method of inducing Fe stress was changed to make it less severe. Instead of using only NO3‐N and no Fe to induce Fe stress (11, 12), both NH4‐N and NO3‐N were used along with varied concentrations of Fe. Iron stress was induced with BPDS (4,7‐diphenyl‐l, 10‐phenan‐throline disulfonic acid) and phosphate; both competed with the plant for Fe. Phosphate also inhibits reduction of Fe3+ to Fe2+ (12). This method of inducing Fe stress in the plants was less severe than using only NO3‐N and no Fe in the nutrient solutions and we were able to measure a difference in Fe‐stress response for all four plant species (Fe‐inefficient and Fe‐efficient). At the lower Fe treatments, the roots of Fe‐efficient plants usually reduced more Fe3+ to Fe2+ than did the roots of Fe‐inefficient plants. The ‘inefficient’ ys1 corn and TAM 0–312 oat roots did not compete with BPDS or phosphate for Fe as effectively as did the ‘efficient’ WF9 corn and Coker 227 oat roots. The same type mechanism for solubilization, absorption, and transport of Fe seems to function in both monocotyledenous and dicotyledenous plants but it is more effective and more readily detected in the dicot than in the monocot plants. The reactions involved in reduction of Fe3+ to Fe2+ seemed to be confined inside or at the root surface for the inefficient genotypes; the efficient genotypes alter the ambient medium to a greater degree.  相似文献   

3.
No‐tillage management can increase soil surface layer organic C (OC) levels compared with conventional tillage. The mechanisms underlying this increase in highly weathered tropical soils, such as Ferralsols, are not well established. The objective of this study was therefore to evaluate the influence of mineralogy on aggregation and the apportionment of OC across aggregate size fractions in a Brazilian Ferralsol under native vegetation (NV) and no‐tillage management for 10 (NT10) or 20 (NT20) yrs. Under native vegetation, soil OC generally increased with increasing aggregate size while, in response to changing management, soil OC increased in the order NT10 (8.8 g/kg) < NT20 (12.7 g/kg) < NV (19.1 g/kg). There were no significant differences in the mineralogy of the clay size fractions among the three treatments, with the notable exception of the CBD‐extractable Fe oxide fraction (FeCBD). The FeCBD fraction comprises various pedogenic Fe(hydr)oxides and increased from NT10 (33.9 g/kg) to NT20 (64.2 g/kg). The OC/FeCBD mass ratio within aggregates increased in the order NT10 <  NT20 <  NV while R2 values for OC and FeCBD occurrence follow this same trend, with the NT10 soil showing a weaker correlation (R2 = 0.178) compared with the NV soil (R2 = 0.533). We propose that formation of organo‐Fe(III) oxide associations is promoted with implementation of NT management and the consequent reduction in macroaggregate turnover. The development of the OC‐Fe(III) oxide associations and their evolution over time within aggregates to more thermodynamically stable entities will strongly influence the long‐term preservation of soil OC.  相似文献   

4.
A sodium bicarbonate (NaHCO3)‐buffered hydroponic growth system was developed that simulates alkaline soil growth conditions necessary to screen sugar beet genotypes for iron (Fe) efficiency character. Three genotypes (NB1, NB4, and F, hybrid, NB 1xNB4) with differing capacities for Strategy I Fe responses were phenotyped successfully using this system. Genotypes NB1 and NB1xNB4 are Fe efficient, while NB4 is Fe inefficient. It was demonstrated that 5 mM NaHCO3 provided buffering within an optimal range (pH 7.3 ‐ pH 6.3) for the duration of ‐Fe treatments, promoted enhanced H+ extrusion, and increased the in vivo capacity for Fe3+‐chelate reduction (Fe3+‐chelate reductase [FCR] activity), especially in the roots of the Fe efficient genotypes. The same concentrations of NaHCO3 did not interfere with Fe supply to +Fe control plants of any genotype. The in vivo capacity for Fe3+‐chelate reduction increased over fivefold in both Fe efficient genotypes (NB1 and NB 1xNB4), but just under twofold in the Fe inefficient genotype (NB4). Localization and duration of enhanced Fe3+‐chelate reduction capacity were dependent upon the Fe efficiency character of each genotype.  相似文献   

5.
Abstract

Iron‐inefficient TAM 0–312 and Fe‐efficient Coker 227 oats (Strategy II plants) differ in their release of phytosiderophore in response to iron‐deficiency stress—the Fe‐efficient Coker 227 releases a phytosiderophore whereas the Fe‐inefficient TAM 0–312 does not. The phytosiderophore released by Coker 227 oats in response to Fe‐deficiency stress does not appear to transport Fe into the plant as Fe phytosiderophore. When the Fe‐inefficient TAM 0–312 and Fe‐efficient Coker 227 oats were subjected to Fe supplied as Fe2+(BPDS)3, Fe3+HEDTA, as Fe3+EDDHA, Coker 227 utilized the Fe more efficiently than TAM 0–312 in every case. Both cultivars reduced Fe3+ as FeCl3 to form Fe2+(BPOS)3 and responded better to this form of Fe than Fe supplied as the ferric chelate. Reduction of Fe3+ at the root appears to be a factor that facilitates iron uptake by Coker 227 oats and the release of a phytosiderophore appears to make more Fe available at the root that can be reduced and transported to plant tops.  相似文献   

6.
刘慧  董颖  王玉军  俞元春  姜军  徐仁扣 《土壤》2021,53(5):1040-1047
Mehlich 3（M3）方法可同时提取土壤中磷、钾、钙、镁、铝、铁、锌、锰、铜等多种元素的有效态，提高土壤检测的效率；另外，M3法适用于钙质土、火山灰土、高度风化土等各类土壤，可作为一个“通用”型土壤有效元素提取试剂。但是硝酸铵（NH4NO3）由于管制不易获取，应用M3方法测定土壤有效元素含量时受到极大限制。因此，本研究用另一种易获取的惰性电解质氯化铵（NH4Cl）替代硝酸铵（NH4NO3），评价氯化铵替代硝酸铵M3法的适用性。Pearson相关分析结果表明，用氯化铵替代硝酸铵M3法测得的30种土壤有效磷、钾含量与M3法测定结果呈极显著正相关，其决定系数（R2）分别为0.99（P=2.31×10-55，n=60）和0.98（P=1.52×10-49，n=60）。同时，氯化铵替代硝酸铵M3法和M3法测定的有效钙、镁、铝、铁、锌、锰和铜含量极显著相关，R2值分别为0.98，1.00， 0.99，0.96，0.99，0.95和0.94。氯化铵替代硝酸铵M3–P与酸性、中性和碱性土壤的 Bray–P和Olsen–P极显著相关，R2分别为0.97和0.91 （P=1.42×10-15和1.00×10-21，n=20和40）。同时，利用氯化铵替代硝酸铵M3法测定酸性改良土壤有效磷含量，发现其得到显著提高。因此，氯化铵替代硝酸铵M3法可作为测定各种土壤，以及改良土壤中有效磷、钾和其他金属元素有效态含量的通用方法。  相似文献   

7.
The excretion of phytosiderophores by barley (Hordeum vulgare L.) has recently been documented and a major difference in the Fe‐stress response of gramineous species and dicotyledonous species proposed. However, currently used methods of quantifying and measuring phytosiderophore are tedious or require specialized equipment and a cultivar easily accessible to U.S. scientists is needed. The objectives of this study were (a) to determine if “Steptoe”; and “Europa”; (used as a control cultivar) barleys would release Fe3+ solubilizing compounds in response to Fe‐deficiency stress and (b) to develop a technique to determine the efficiency of solubilization of Fe(OH)3 by the released chelating substances. Two cultivars of barley were place under Fe‐stressed (‐Fe) and nonstressed (+Fe) conditions in modified Hoagland solutions (14 L). The solutions were periodically monitored for H+ and reductant release from the roots and plants were rated daily for chlorosis development. Periodic (6 or 7 harvests) evaluation of the release of Fe3+ solubilizing substances was performed as herein described. Neither H+ nor reductant extrusion occurred with either cultivar during Fe stress. However, Fe3+ solubilizing substances were released by both cultivars at relatively high levels under Fe‐stress conditions compared to the nonstressed plants. A convenient technique was developed to measure the release of Fe solubilizing substances released by barley roots.  相似文献   

8.
The distribution of iron‐cyanide complexes between ferrocyanide, [FeII(CN)6]4–, and ferricyanide, [FeIII(CN)6]3–, in soils on contaminated sites depends on the redox potential, EH. We carried out microcosm experiments in which ferrocyanide (20 mg l?1) was added to an uncontaminated moderately acidic subsoil (pH 5.2), and varied the EH of the soil suspension between 200 and 700 mV over up to 109 days. Ferrocyanide and ferricyanide were analysed by capillary isotachophoresis. At redox potentials ranging from 400 to 700 mV, small amounts of iron‐cyanide complexes were adsorbed, and ferrocyanide was almost completely oxidized to ferricyanide. Decreasing EH to 200 mV led to nearly complete removal of iron‐cyanide complexes from solution, and the complexes were not mobilized after subsequent aeration (EH > 350 mV). Under weakly to moderately reducing conditions (EH ≈ 200 mV), iron‐cyanide complexes were removed from solution by precipitation, which occurred, presumably in the form of e.g. Fe2[FeII(CN)6], Fe4[FeII(CN)6]3 or Mn2[FeII(CN)6], after reductive dissolution of Mn and Fe oxides. Four different sets of geochemical model calculations were carried out. The species distribution between ferrocyanide and ferricyanide in solution was predicted reliably under varying pH and redox conditions when iron‐cyanide complex concentrations and Fe concentrations, excluding Fe bound in iron‐cyanide complexes, were used in model calculations. In model calculations on the fate of iron‐cyanide complexes in soil, adsorption reactions must be considered, especially under oxidizing conditions. Otherwise, the calculated iron‐cyanide complex concentrations are larger than those actually measured.  相似文献   

9.
Grapevine is considered a ‘Strategy I’ plant because it performs some peculiar biochemical and physiological responses when grown under iron (Fe) deficiency stress conditions. Callus cultures were started from leaf and internode cuts of micropropagated plantlets of two grapevine genotypes well known for their Fe‐chlorosis characteristic: Vitis riparia a very susceptible genotype and Vitis berlandieri a resistant one. Modification of NADH: ferric (Fe3+) reductase activity was spectrophotometrically evaluated by following the formation of the complex ferrous (Fe2+)‐(BPDS)3, while the malic and citric acid production were determined in callus cultures grown both in the presence (+Fe) and absence (‐Fe) of Fe. Moreover, a microsomal fraction was isolated from the calli to evaluate the H+‐ATPase and the Fe3+‐EDTA reductase activities. As expected, calli of the Fe‐efficient genotype (V. berlandieri) was able to enhance Fe3+‐EDTA reductase activity when growing under Fe deficiency while the Fe‐chlorosis susceptible V. riparia could not or did it with lower efficiency. Therefore, the H+‐ATPase assay showed a higher enzymatic activity in the microsomal fraction isolated from Vitis berlandieri grown without Fe with respect to its control (+Fe). Organic acid determination gave quite contradictory results, specially regarding malic acid which, under our study conditions, seemed not to be linked with the strategies of response to Fe deficiency.  相似文献   

10.
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11.
Indirect assays are commonly used to measure phytosiderophore (PS) concentrations in the root exudates of grasses. The Cu‐mobilizing, Cu‐CAS and Fe‐binding assays are three commonly used assays but there have been few published attempts to validate or calibrate them rigorously. Thus, we undertook to compare, validate and, where appropriate, to improve and/or optimize each assay. Ethylenediamine‐N,N′‐diacetic acid (EDDA) and N‐2‐hydroxyethylethylenediamine‐N,N′,N′‐triacetic acid (HEDTA) bracket deoxymugineic acid for binding strength with both Fe and Cu and were thus used as model ligands. For the Cu‐mobilizing assay, reasonable regressions (as R2) were obtained between measured and known ligand concentrations for all resin combinations tested. However, the relationship was non‐stoichiometric; less than 5% of the ligand present was recovered as a Cu‐complex. Testing of the Cu‐CAS assay yielded good 1:1 stoichiometric relationships (slopes of 0.97 and 1.08 for EDDA and HEDTA, respectively) with little scatter (R2= 0.97). However, the limits of quantification were approximately 30 μm , which is greater than concentrations generally found in root‐exudate collections. Thus, the Cu‐CAS assay is best suited to situations where large concentrations of PSs are expected. Results from the original Fe‐binding assay indicated a lack of linearity and considerable scatter (R2= 0.57 for EDDA; R2= 0.28 for HEDTA). Thus, as published, use of the original Fe‐binding assay is not recommended. The effects of filter paper, FeCl3 reagent concentration and increase in the reduction time were tested and a revised Fe‐binding assay developed with both good stoichiometry and great precision (R2≥ 0.99). We suggest the use of the revised Fe‐binding assay in most situations where PS concentration would be expected to be < 30 μm .  相似文献   

12.
The iron‐cyanide complexes ferrocyanide, [FeII(CN)6]4–, and ferricyanide, [FeIII(CN)6]3–, are anthropogenic contaminants in soil. We investigated their sorption on goethite, α‐FeOOH, in batch experiments in a time range from 1 d to 1 yr, their desorption by phosphate and chloride as well as their surface complexes on goethite by Fourier‐transform infrared spectroscopy (FTIR). The sorption of both complexes continued over the whole time range. Percent desorption of ferricyanide by phosphate decreased, whereas that of ferrocyanide increased until it amounted to approximately 87% for both complexes. By FTIR spectroscopy inner‐sphere complexation of both complexes on the goethite surface was indicated. With both complexes, a Berlin‐Blue‐like layer (Fe4[Fe(CN)6]3) was formed initially on the goethite surface which disappeared with increasing reaction time. After at least 30 d reaction time, ferricyanide was the only sorbed iron‐cyanide complex detected even when ferrocyanide was initially added. This resulted from slow oxidation of ferrocyanide, most probably by dissolved oxygen. Based on all results, we propose that ferricyanide forms monodentate inner‐sphere complexes on the goethite surface.  相似文献   

13.
Bao  Yanyu  Ma  Chuanxin  Hu  Lu  Xing  Baoshan 《Journal of Soils and Sediments》2019,19(5):2459-2471
Purpose

It has been reported the bioaccumulation of γ-ferric oxide nanoparticles (Fe2O3 NPs) or oxytetracycline (OTC) in crops. However, there have been little references investigating their uptake and bioaccumulation in crops after the combined exposure. The present study focused on Fe2O3 NPs and OTC accumulation on root surface and in the tissues of rice (Oryza sativa L.) seedlings under combined exposure. And, the interactive influence mechanism was also discussed.

Materials and methods

Hydroponic experiments were conducted to investigate the Fe and OTC accumulation on root surface and in rice tissues under individual and combined exposure of Fe2O3 NPs and OTC. The dynamic change of particulate Fe, ionic Fe, and Fe plaque concentrations on root surface was determined under the influence of OTC from Fe2O3 NPs and Fe-EDTA exposure. Fe2+ from Fe-EDTA was selected in order to compare the Fe bioaccumulation from ionic Fe and nanoparticle Fe exposure. Hydrodynamic diameter and ζ-potential of Fe2O3 NPs in solution were investigated when OTC was present or not, and the changes of OTC concentrations were also determined during hydroponic culture. SEM, XRD, and TEM were used to analyze Fe2O3 NP distribution on root surface and inside root under the influence of OTC.

Results and discussion

OTC promoted surface-Fe and shoot-Fe accumulation in Fe2O3 NPs treatments, which was just an opposite result from Fe-EDTA treatments. Upon Fe2O3 NP exposure, Fe plaque was formed through the direct adsorption of NPs on the outside root surface and then incorporated into plaque as its crystalline components. OTC elevated notably surface-Fe accumulation mainly through increasing adsorption and precipitation of Fe2O3 NPs on the root surface due to low repulsive electrostatic interaction between NPs and the root surface after adding OTC. Fe2O3 NPs increased surface-OTC and root-OTC levels. Compared to Fe-EDTA, surface-Fe from NP treatments can hold strongly OTC due to Fe2O3 particle precipitated on root surface with high specific surface area. NPs reduced shoot-OTC under 25 mg L?1 OTC, but not under 100 mg L?1 OTC.

Conclusions

This study clearly demonstrates that Fe/OTC accumulation in rice was always in the order root surface > shoot > root, whether Fe2O3 NPs/OTC was individual or combined exposure. The combined exposure will increase their root surface distribution comparing with individual exposure, and Fe2O3 NPs increased also root-OTC levels, which could pose a potential risk to food safety in subsequent growth of rice.

  相似文献   

14.
This study addressed some complementary aspects related to plant Fe nutrition. A field and a greenhouse experiment were conducted to monitor changes in chlorophyll, Fe3+, Fe2+, Ca2+ and K+ along with the progressive evolution of lime‐induced chlorosis, and following soil (Fe‐EDDHA, Fe‐EDTA, Fe‐DTPA, DTPA) and foliar (Fe‐EDDHA, FeSO4, “Fe‐Metalosate") treatments, in a chlorosis‐susceptible ornamental plant, Hydrangea macrophylla, over a year's growing period. Though soil Fe‐EDDHA was the most effective compound in alleviating chlorosis symptoms, it became less so with time and was only partly effective as a foliar spray. Leaf analysis showed that as chlorosis intensified and chlorophyll content decreased, phenanthroline ‐ Fe (Fe2+) decreased with corresponding increases in total iron (Fe3+) and K+ concentrations. The reliability of these chlorosis‐indicators was confirmed as the reverse changes occurred upon chlorosis plant recovery.  相似文献   

15.
柑桔根系对缺铁的生理反应   总被引：1，自引：0，他引：1  
柑桔在缺铁条件下,幼苗根系分泌H+和还原Fe3+的能力增加,与植株吸收铁素营养的能力相一致。摘除缺铁失绿的新叶和顶芽,抑制根系分泌H+和Fe3+还原物;但随着新叶的重新长出,根系分泌H+和Fe3+还原物的速率逐渐提高。说明缺铁失绿的组织能调控根系分泌H+和Fe3+还原物。在营养液中加入0.1nmol/L生长素(IAA),能解除因缺少失绿组织对根系分泌H～+产生的抑制作用。此外,在缺铁条件下,吸铁能力较强的酸橙根尖发生膨胀,有利于铁的接触吸收。  相似文献   

16.
Abstract

Problems are invariably encountered when attempts are made to explain the variability in Bray percent yields or plant response in terms of soil or plant iron (Fe). To resolve this inconsistency, the present investigation was initiated to identify a combination of soil extractable Fe, soil properties and form of plant Fe that may be used as a measure of Fe deficiency. The study involved 16 diverse soils, using upland rice (Oryza sativa L.) as the test crop and Fe‐EDDHA [ferric ethylenediamine di (o‐hydroxyl‐phenyl acetic acid)] as source of Fe. The results showed that Bray percent yields were neither related to DTPA (diethylenetriamine pentaacetic acid) or EDTA (ethylenediamine tetraacetic acid) extractable Fe nor with total plant Fe. Even the inclusion of pH, lime, organic carbon and clay data in the regression equations was of no value. However, Bray percent yields were significantly and positively (r = 0.57* ) associated with ferrous Fe (Fe2+) in 40‐day‐old rice plants. The explanation concerning variability in Bray percent yields obtained on diverse soils could be increased about one and half 2 times (R2= 0.59*) if the contribution of lime and soil pH was also incorporated in the stepwise regression analysis. The individual contribution to R of lime, pi respectively. Thus, it appears that Fe2+ concentration in plants (along with soil pH) may identify Fe deficiency. The critical limit to separate Fe deficient from green rice plants was set at 45 ug Fe2+/g in the leaves.  相似文献   

17.
Physcia caesia is a foliose, saxicolous lichen commonly found on weakly acidic to alkaline rock and artificial calcareous substrata. Uptake of iron and phosphate, which are known to be significant for governing the calcifuge‐calcicole behavior of lichens (as well as vascular plants), was studied in individuals of P. caesia deriving either from variegated sandstone or concrete. Samples from either substratum originated from walls erected at the same location, i.e., lichens were exposed to the same atmospheric element load and microclimate prior to the experiments. Element uptake was investigated after short‐term incubation in the laboratory involving solutions of FeCl2, FeCl3, and KH2PO4 at pH 3 and 8. Uptake of Fe2+ was significantly higher at either pH in the thalli from concrete than in those from sandstone, whereas Fe3+ uptake was not significantly different between the two groups of lichen thalli, though there was an insignificant trend for higher Fe3+ uptake at pH 8 in the samples from concrete. Phosphate uptake also was more efficient in thalli deriving from concrete than in those from sandstone, even though the initial P content was higher in the samples from sandstone. The results suggest that the ability of P. caesia to adapt Fe and P uptake to the pH‐dependent availabilities of these nutrients is responsible for the potential of the species to grow both on weakly acidic and alkaline substrata.  相似文献   

18.
Abstract

Although sunflower (Helianthus annus L.) is an Fe efficient plant, tumorous crown gall tissue development and tissue ability to reduce Fe3+ to Fe2+ were both diminished by Fe‐deficiency stress. Crown gall also develops readily on Fe‐efficient and Fe‐inefficient tomato cultivars (Lycopersicon esculentum Mill.). The objective of this study was to determine if the effect of a limited Fe supply on the growth, nutrition and reduction of Fe3+ to Fe2+ by tumorous crown gall would differ between Fe‐efficient T3238FER and Fe‐inefficient T3238fer tomato. Healthy green 25‐day‐old plants were either stem‐inoculated with Agrobacterium tumefaciens to induce tumorous crown gall tissue development or were left uninoculated for comparison. Plants were grown in modified Hoagland nutrient solutions containing 0.0, 0.15, 0.6 and 2.0 mg Fe L?1. Yield of tumorous crown gall tissue was not diminished by low solution Fe in T3238FER, but was in T3238fer. This was attributed to inability of the T3238fer tomato to make Fe available to itself. Tumor tissue from both cultivars contained more Fe, Cu and P than normal stem tissues, which confirms a modified metabolism in these tissues previously observed in sunflower. An abundant supply of Fe enhances the development and growth of the tumorous crown gall tissue, but a deficient supply of Fe retards its growth.  相似文献   

19.
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   

20.
辽西‘富士’苹果CND法营养诊断研究   总被引：3，自引：1，他引：2  
【目的】辽西地区‘富士’苹果的栽培面积和产量占辽宁省较大比例,但其施肥管理缺乏科学理论依据,本研究采用Compositional Nutrient Diagnosis(CND)法对辽西‘富士’果园的营养状况开展叶片分析研究,初步探明辽西地区‘富士’果园营养状况,指导果园施肥管理。【方法】以86个有代表性的‘富士’苹果园为研究试材,测定了果园产量,果实品质以及叶片中氮(N)、磷(P)、钾(K)、钙(Ca)、镁(Mg)、铁(Fe)、铜(Cu)、锰(Mn)、锌(Zn)元素的含量。采用CND法对高生产水平果园进行划分,并对低产水平果园进行营养诊断。采用CND法对高产果园产量划分标准临界值进行确定;对果实品质的划分标准进行确定:第一,对果实品质的6个指标进行归一化;第二,对6个指标进行主成分分析,得到6个指标的综合评价得分;第三,采用CND法对果实品质综合得分进行划分,得到果实品质的划分标准临界值;选择同时满足产量和品质划分标准临界值的果园,结合专家咨询法,确定高生产水平果园的划分标准。根据高生产水平果园的营养状况确定CND法标准参比值,并以此为基础进行叶营养诊断,得到辽西‘富士’果园的叶营养状况。针对叶营养状况进行土壤营养丰缺状况的分析,得到辽西‘富士’果园的营养状况的整体情况。【结果】根据CND法的叶分析可以得到:高生产水平果园的产量划分临界值为44.556t/hm2,品质评价综合得分的划分临界值为0.792,辽西地区满足此条件的果园有13个,占总体采样园的15.12%;不同营养元素CND法叶标准参比值为:V*N=2.776,V*P=0.212,V*K=1.884,V*Ca=2.042,V*Mg=0.814,V*Fe=-2.470,V*Cu=-5.090,V*Mn=-2.631,V*Zn=-3.867,V*R=6.330;SD*N=0.173,SD*P=0.144,SD*K=0.155,SD*Ca=0.266,SD*Mg=0.307,SD*Fe=0.189,SD*Cu=0.474,SD*Mn=0.467,SD*Zn=0.325,SD*R=0.134;辽西‘富士’苹果低生产水平果园需肥顺序为:FeMnPNCaKCuZnMg。【结论】CND法使叶分析研究可同时考虑果园产量和果实品质。以此方法进行分析,辽西地区高生产水平果园的产量划分临界值为38.451 t/hm2,品质评价综合得分的划分临界值为0.792,辽西地区满足此条件的果园有13个,仅占总体采样园的15.12%;辽西地区‘富士’苹果的树体营养状况表现为Fe、Mn、P和N元素缺乏;土壤丰缺状况表现为Fe、Mn元素含量适宜,N、P元素缺乏;建议辽西‘富士’低生产水平果园的N、P、K施用采用少量多次原则,适当增加Fe、Mn元素叶面肥的施用。  相似文献   

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