Influence of level and source of Fe on growth and nutrient content of Euglena gracilis

Abstract

Growth parameters and Fe, Cu, Mn and N status of Euglena gracilis cells were determined as a function of level and source of Fe supply in the nutrient environment. Use of FeEDDHA promoted cell division while FeSO₄·lb7H₂O promoted cell enlargement after 7 days. Greatest N content was present in rapidly dividing as compared to enlarging cells. Copper content was directly related to cell size with larger cells containing more Cu than smaller cells. Manganese uptake was inversely related to Fe supply with FeSO₄·lb7H₂O inhibiting Mn uptake to a greater extent than chelated Fe. Iron uptake increased significantly with the addition of iorganic or chelated Fe. The Fe uptake was comparable from both sources at the 1 ppm Fe level of supply, but much greater amounts of Fe were accumulated from inorganic supply at the 10 ppm Fe level.     

Response of date palm to iron fertilization by trunk injection and soil application

To study the response of date palm trees to Fe fertilization, two date palm cultivars, Khlas and Ruzaiz, were fertilized with different levels of FeEDDHA (trunk injected and through soil) and FeSO₄ · 7H₂O(trunk injected). Leaves were collected 100 days after iron application and analyzed for micronutrients. The injection with 100 g FeSO₄ · 7H₂O/tree increased the Fe contents in the leaves of both cultivars, and with 100 g FeEDDHA/tree in the leaves of Ruzaiz cultivar. Soil application of FeEDDHA was not effective. The contents of Cu, Mn and Zn in the leaves were not affected by Fe fertilization.     

DIFFERENTIAL TRANSLOCATION OF 59IRON IN IRON SUFFICIENT AND DEFICIENT SORGHUM PLANTS

Radioactively labeled iron (⁵⁹Fe) was used to study differential uptake in sorghum plants in the recovery stage of chlorosis. Radio-labeled ⁵⁹Fe was supplied through root feeding in nutrient solution experiment (48 hrs, pH 6.2) to non-chlorotic and chlorotic plants. Chlorotic plants were further treated with foliar spray [ferrous sulfate (FeSO₄), FeSO₄ + thiourea (TU), FeSO₄ + citric acid (CA), FeSO₄ + thioglycollic acid (TGA)] to study the uptake of radio-labeled ⁵⁹Fe through root feeding during recovery process of chlorosis. Under iron deficiency, the differential uptake of ⁵⁹Fe was markedly increased in leaves and stem of chlorotic control (-Fe) sorghum plants as compared to non-chlorotic control (+Fe) and foliar sprayed (FeSO₄, FeSO₄ + TU, FeSO₄ + CA, and FeSO₄ + TGA) plants. The lowest uptake of ⁵⁹Fe was observed in younger leaves (24.33 nmol, g^?1 fresh weight h^?1) and stem (1.98 nmol, g^?1 fresh weight h^?1) of non-chlorotic control followed by foliar sprayed plants in comparison to chlorotic control, respectively. Similarly less ⁵⁹Fe uptake was observed in the older leaves of FeSO₄ + CA sprayed (21.70 nmol, g^?1 fresh weight h^?1) plants in comparison to chlorotic control (35.60 nmol, g^?1 fresh weight h^?1). The highest differential ⁵⁹Fe uptake through nutrient medium was in the roots of plants, which were foliar sprayed with FeSO₄ along with TU. The role of iron alone and along with citric acid and thiol compounds is discussed in recovery of chlorosis.     

Evidence for the existence of different uptake mechanisms in soybean and sorghum for iron and manganese

A greenhouse experiment was conducted in which four varieties of soybean (Glycine max L.) and three varieties of sorghum (Sorghum bicolor L. Moench) were grown in a calcareous soil with and without soil applied FeEDDHA (0 and 2 mg Fe/kg soil). Soil applications of FeEDDHA increased Fe concentrations and reduced Mn concentrations in all varieties of soybean and eliminated Mn toxicity symptoms in Corsoy soybeans. Soil applications of FeEDDHA did not increase Fe uptake or affect Mn uptake into sorghum leaves. This study tends to support the hypothesis that there are distinct plant mechanisms between dicots and graminaceous species for the uptake of Fe, and that these mechanisms have a direct effect on Mn availability for plant uptake.     

Iron Sources Effects on Growth,Physiological Parameters and Nutrition of Cacao

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 P_N. 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.     

Mobility of Iron and Manganese within Two Citrus Genotypes after Foliar Applications of Iron Sulfate and Manganese Sulfate

Seedlings of sour orange (Citrus aurantium L.) and Carrizo citrange (C. sinensis L. cv. Washington navel x Poncirus trifoliata)] were grown in plastic pots containing a sand: perlite mixture and watered with a modified Hoagland No 2 nutrient solution throughout the experiment. Three-months-old plants were divided in three groups and sprayed with 0.018 M iron sulfate (FeSO₄ ^.7H₂O), 0.018 M manganese sulfate (MnSO₄ ^.H₂O), or deionized water. Two months later, plants were harvested and divided into top leaves that grown after the treatments, basal leaves that existed prior to the treatments, stems that partially came in contact with the spray, and roots. The manganese (Mn) spray resulted in a significant increase of Mn concentrations in top leaves, basal leaves, stems and roots of sour orange, and in top leaves, basal leaves, and stems of Carrizo citrange. The iron (Fe) spray significantly increased the concentrations of Fe in the stems and basal leaves of both genotypes. For both genotypes, transport of Mn from basal (sprayed) leaves to top (unsprayed) ones was found. However, the results of this experiment did not give any evidence neither for Mn translocation from sprayed tissues to roots nor for Fe transport from sprayed tissues to unsprayed ones (top leaves, roots). Mn and Fe were found to be relatively mobile and strictly immobile nutrients, respectively, within citrus plants after their foliar application as sulfate salts.     

Metal Extractability in Binary and Multi-metals Spiked Calcareous Soils

In the present study, a laboratory experiment was designed to compare the 0.01 M calcium chloride (CaCl₂) and diethylenetriaminepentaacetic acid (DTPA) extraction methods for their ability to predict cadmium (Cd), copper (Cu), iron (Fe), Manganese (Mn), nickel (Ni), and zinc (Zn) availability and mobility in five calcareous soils. The soils were spiked with different amounts of metals (0, 50, 100, 200, and 400 mg kg^?1) both in binary (Cu and Zn; Ni and Cd; Fe and Mn) and in multi-systems (Cd, Cu, Fe, Mn, Ni, and Zn) and incubated for 1 months at field capacity. In metal-spiked soils, both extraction methods showed a linear relationship of extractable to total metals for all soils. The fraction of total metals extracted by DTPA was much higher than the fraction extracted by CaCl₂, which was attributed to the formation of soluble metal-complexes in the complexing extracts calculated by the Visual Minteq program. DTPA extraction method showed higher selectivity for Cu over other metals both in binary and in multi-systems. Different order of metals extractability was found in binary and multi-systems for both extraction methods. Solid/solution distribution coefficient (K_d) was calculated by the ratio of the solid phase to soil solution concentration of metals extracted by CaCl₂ or DTPA extraction methods. Both in binary and in multi-systems, the average K_d (l kg^?1) of metals by soils were in the order of Mn (5398) > Fe (4413) > Zn (3376) > Cu (2520) > Ni (969) > Cd (350) in the CaCl₂-extractable metals and Fe (35) ≥ Ni (34) > Zn (18) > Mn (11.2) > Cu (6.3) > Cd (4) in the DTPA-extractable metals. Results showed that among the six studied metals, Cd had the lowest K_d, implying a relative higher mobility in these calcareous soils. The Visual Minteq indicated that in the CaCl₂-extraction method and in both binary and multi-systems the dominant species for Cu, Mn, Ni, and Zn were Cu²⁺, Mn²⁺, Ni²⁺ and Zn²⁺, respectively, while for Cd and Fe, the dominant species were CdCl⁺ and Fe(OH)²⁺, respectively.     

Agronomic evaluation of mulching and iron nutrition on productivity,nutrient uptake,iron use efficiency and economics of aerobic rice-wheat cropping system

Field experiments were carried out during rainy (kharif) and winter (rabi) seasons (June–April) of 2008–2010 at Indian Agricultural Research Institute (IARI), New Delhi, to study the productivity, nutrients uptake, iron (Fe) use-efficiency and economics of aerobic rice-wheat cropping system as influenced by mulching and Fe nutrition. The highest yield attributes, grain and straw yields (5.41 tonnes ha^?1 and 6.56 tonnes ha^?1, respectively) and nutrient uptake in rice was recorded with transplanted and puddled rice (TPR) followed by aerobic rice with Sesbania aculeata mulch. However, residual effect of aerobic rice with wheat straw mulch was more pronounced on yield attributes, grain and straw yields (4.20 and 6.70 tonnes ha^?1, respectively) and nutrient uptake in succeeding wheat and remained at par with aerobic rice with Sesbania mulch. Application of iron sulfate (FeSO₄) at 50 kg ha^?1 + 2 foliar sprays of 2% FeSO₄ was found to be the best in terms of all the yield attributes, grain and straw yield (5.09 and 6.17 tonnes ha^?1, respectively) and nutrient uptake and remained at par with 3 foliar sprays of 2% FeSO₄. Although residual effect of iron application failed to increase the yield attributes, yield and nutrient uptake nitrogen, phosphorus and potassium (N, P, K) except Fe. The highest system productivity, nutrient uptake, gross returns, net returns, B: C ratio and lowest cost of cultivation were recorded with aerobic rice with wheat straw and Sesbania aculeata mulch. Application of FeSO₄ at 50 kg ha^?1 + two foliar sprays of 2% FeSO₄ was found better in respect of system productivity, nutrient uptake, gross returns, net returns, B:C ratio and cost of cultivation in aerobic rice-wheat cropping system. The Fe use efficiency values viz. partial factor productivity (kg grain kg^?1 Fe), agronomic efficiency (kg grain increased kg^?1 Fe applied), agrophysiological efficiency (kg grain kg^?1 Fe uptake), physiological efficiency (kg biomass kg^?1 Fe uptake), apparent recovery (%) utilization efficiency and harvest index (%) of applied Fe were significantly affected due to methods of rice production and various Fe nutrition treatments in aerobic rice and aerobic rice-wheat cropping system.     

Phytotoxicity and some interactions of the essential trace metals iron,manganese, molybdenum,zinc, copper,and boron

Abstract

The essential trace elements Fe, Mn, Zn, Cu, and B in high concentrations can produce phytotoxicities. Iron toxicity resulted from 5 × 10^‐4 M and 10^‐3 M FeSO₄, but not from equivalent amounts of FeEDDHA (ferric ethylenediamine di (o‐hydroxyphenylacetic acid) ). Leaf concentrations in bush beans of 465 μg Mn/g, 291 μg B/g, and 321 μg Zn/g all on the dry weight basis resulted in 27%, 45%, and 34% reduction in yields of leaves, respectively. Zinc was concentrated in roots while Mn and B concentrated in leaves. Solution concentrations of MnS0₄ of 10^‐3 and 10^‐2 M depressed leaf yields of bush beans by 63% and 83%, respectively, with 5140 and 10780 μg Mn/g dry weight of leaves. Copper concentrations were simultaneously increased and those of Ca were decreased. Bush bean plants grown in Yolo loam soil with 200 μg Cu/g soil had a depression in leaf yield of 26% (with 28. 8 μg Cu/g leaf); plants failed to grow with 500 μg Cu/g soil. A level of 10^‐3 M H₂MoO₄ was toxic to bush beans grown in solution culture. Leaves, stems, and roots, respectively, contained 710, and 1054, and 5920 μg Mo/g dry weight.     

Aluminum toxicity in maize: Biomass production and nutrient uptake and translocation

The effect of increasing aluminum (Al) concentrations on root nutrient contents along with the concurrent translocation to the shoot of C₄ plants prompted this study. Two‐week‐old maize (Zea mays cv XL‐72.3) plants were therefore submitted for 20 days to Al concentrations ranging from 0 to 3.00 mM in a medium with low ionic strength were used as a test system. Aluminum concentrations in root tissues showed a 3‐fold increase between 0 and 3.00 mM Al treatment, and was not detected in the shoot. Root plasma membrane‐H⁺ ATPase activity decreased after the 0.33 mg L^‐1 Al treatment, while membrane permeability increased up to 1.00 mM Al treatment. Root and shoot biomass decreased after the 0.33 mM Al treatment. All elements in the roots, except potassium (K), manganese (Mn), and zinc (Zn) were highest for plants treated with 0.33 mM Al. Potassium increased continuously between 0 and 3.00 mM Al treatments, and iron (Fe) decreased above 0.33 mM. Only a slight decrease in nitrogen (N) was observed. All the measured nutrients in shoots, except N, Mn, and Fe decreased above 0.33 mM, but calcium (Ca) and magnesium (Mg) had little variation as Al varied. Data indicated that maximum net uptake for mineral nutrients, except Mn, occurred up to 0.33 mM Al. Translocation of phosphorus (P), K, Mn, and Zn decreased above 0.33 mM Al, N, and Ca decreased when any Al was added, and no clear trend was observed for Mg and Fe. Between the 0 and the 3.00 mM Al treatments, electrolytic conductance did not increased significantly indicating that the observed inhibitions of translocation from roots to shoots were not directly related to increasing membrane degradation.     

Salt effects on growth and mineral contents of Diplachne fusca (Kallar grass)

Effects of NaCl, KC1, and CaCl₂ alone, and in combinations of NaCl/KCl and NaCl/CaCl₂ on growth and ion uptake by ‘Kallar'grass in soil and in solution cultures were studied. In soil up to 150 mM NaCl and KCl had little effect on growth but CaCl₂ depressed growth strongly. Dry weights in 150 mM NaCl/KCl decreased but remained little affected in NaCl/CaCl₂. Plant response to Na⁺ was little affected by Ca⁺⁺ or K⁺ and no interactions between Na⁺ and Ca⁺⁺ or Na⁺ and K⁺ were observed. Plant tissue exhibited a strong selectivity for K⁺ over Na⁺ Concentrations of Na and Cl in the tops exceeded those in the roots. Leaf transections are presented providing some information on the tissue anatomy.     

Iron nutrition of sunflower(Helianthus annuus L.) as affected by various levels of p and ZN

The effects of various P and Zn levels on iron nutrition of sunflower (Helianthus annuus L.c.v. Record) were studied in two separate experiments in nutrient solution under greenhouse conditions.

In the first experiment, sunflower was grown in nutrient solutions containing four levels of P(1.5, 2.5, 3.5 and 4.5 mM/l) and three levels of Fe(0.25, 0.75, and 1.5 ppm) as FeCl₃ or FeEDDHA. In the second experiment (following the first experiment), the treatments were three P levels (0.75, 1.50 and 3.00 mM/l), three Fe levels (0.25, 0.75 and 1.5 ppm) as FeEDDHA and three Zn levels (0.1, 0.2 and 0.4 ppm).

The plants receiving Fe‐chelate, except for 0.25 ppm Fe, showed no symptoms of iron chlorosis. With inorganic Fe treatments, iron chlorosis appeared after 7–10 days depending on P level, but except for 0.25 ppm Fe which remained chlorotic, plants recovered completely within 3–4 days thereafter due to pH regulating mechanism of sunflower under iron stress condition. With both sources of Fe, chlorosis was associated with high P:Fe ratio.

Increased P and Fe levels in nutrient solution resulted in general increases in the dry weights of roots and shoots. The Fe concentration of shoots, except in few instances, was not affected by P levels, indicating that the sunflower cultivar used in this experiment could utilize inorganic Fe as well as Fe‐chelate under our experimental conditions.

Increasing P levels caused significant increases in Mn content of the shoots as 0.25 and 0.75 ppm inorganic Fe³⁺. Increased Fe levels increased shoot Mn content with inorganic Fe and decreased it with Fe‐chelate. The effects of P, Fe and Zn on sunflower indicated an antagonistic effect of Zn on 1.5 ppm Fe for all P levels. Increased Zn levels in nutrient solution generally increased Zn content of the shoots without having any marked effect on their Mn content.     

铁和不同形态氮素对玉米植株吸收矿质元素及其在体内分布的影响 Ⅱ.对铁、锰、铜、锌等营养元素的影响

用营养液培养方法研究了铁和两种形态氮素对玉米植株吸收铁、锰、铜、锌等微量元素及其在体内分布的影响。结果表明:与硝态氮(NO₃^--N)相比,铵态氮(NH₄⁺-N)显著提高了玉米对铁的吸收,降低了对锰、铜及锌的吸收。供铁也明显提高了植株地上部铁的吸收总量,降低了锰及锌的吸收量,尤其是在供应No₃^--N时这种作用更为明显。在缺铁条件下,NH₄⁺-N处理的玉米新叶中铁的含量明显高于NO₃^--N处理;而新叶、老叶、茎中锰、锌、铜含量以及根中锰、锌含量都明显低于NO₃^--N处理。但使用NH₄⁺-N时,根中铜的含量较高。在供铁条件下,NH₄⁺-N处理的玉米植株四个不同器官中锰和锌的含量显著低于NO₃^--N处理的植株,而铜的含量正好相反。在缺铁条件下,玉米新叶中活性锰、活性锌的含量显著高于供铁处理;与NO₃^--N相比,NH₄⁺-N的供应也显著降低了玉米新叶中活性锰以及活性锌的含量。     

Effects of humic acid and Ca(NO3)2 on nutrient contents in pepper (Capsicum annuum) seedling under salt stress

This study was carried out in order to determine the effects of calcium nitrate (Ca(NO₃)₂) and humic acid (HA) applications on nutrient uptake of pepper seedling under salt stress in a plant growth room. Before sowing Demre variety of pepper seeds, 60?mM NaCI was added to each 300?cm³ pot. The experiment was ended at eighth week after the sowing. Applications of HA significantly affected K, Ca, Fe, Mn, Zn (p?p?3)₂ applications did not show a significant effect on Fe and Cu contents of pepper seedling. However, Ca(NO₃)₂ applications significantly affected N and P contents (p?<.05) and K, Ca, Mn, and Zn contents (p?相似文献   

Some interactions of cadmium with other elements in plants

Abstract

Cadmium in solution culture at 10^‐4 M decreased Mn concentrations in bush beans (Phaseolus vulgaris L. C.V. Improved Tendergreen) at both low and high concentrations of Mn (noncompetitive inhibition). When Mn was decreased, the concentrations of Fe and several other ions were simultaneously increased, particularly in leaves and roots. Toxicity due to the 10^‐6 M Cd and the 10^‐4 M Mn was additive in the experiment. When barley (Hordeum vulgare L. Atlas57)was grown in amended soil, 15μg Fe as DTPA (diethylene triamine pentaacetic acid) per g soil resulted in increased uptake of Cd and in somewhat greater yield depression for soil pH of 3.9, 6. 0, and 7.6. Acidification of soil without DTPA also increased Cd uptake to high levels with associated yield decrease. The Cd decreased the uptake of Mn and Cu most when CaCO₃ had also been added to the soil. When salts were added to soil with Cd before bush beans were grown, KCl (200 μg K/g soil), and equivalent KH₂PO₄ increased Cd concentrations of leaves while CaSO₄ and KCl did so for roots. In bush beans with different levels of Cd and Zn, there were no yield interactions, but some interactions of Cd on Zn concentrations in leaves, stems, and roots at the high Zn level.     

Responses of barley to hypoxia and salinity during seed germination,nutrient uptake,and early plant growth in solution culture

The resistance of most plants to salt can be impaired by concurrent waterlogging. However, few studies have examined this interaction during germination and early seedling growth and its implications for nutrient uptake. The aim of the study was to examine the response of germination, early growth, and nutrient uptake to salt (NaCl) and hypoxia applied to barley (Hordeum vulgare L. cv. Stirling), in solution culture. Hypoxia, induced by covering seeds with water, lowered the germination from 94% to 28% but salinity and hypoxia together lowered it further to 13% at 120 mM NaCl. While the germination was 75% at 250 mM NaCl in aerated solution, it was completely inhibited at this NaCl concentration under hypoxia. Sodium ion (Na⁺) concentrations in germinated seedlings increased with increasing salinity under both aerated and hypoxic conditions during germination, while K⁺ and Mg⁺ concentrations were decreased with increasing salinity in 6 d old seedlings. After 20 d, control seedlings had the same dry weights of the roots and shoots with and without hypoxia but at 10 mM NaCl and higher, shoot and root dry weight was depressed with hypoxia. Sodium ion increased in roots and shoots with increased NaCl under both aerated and hypoxic conditions while K⁺ was depressed when salinity and hypoxia were applied together and Ca²⁺ was mostly decreased by NaCl. In general, hypoxia had greater effects on nutrient concentrations than NaCl by decreasing N, P, S, Mg, Mn, Zn, and Fe in shoots and by increasing B concentrations. The threshold salinity levels decreased markedly for germination, uptake of a range of nutrients, and for seedling growth of barley under hypoxic compared to well‐aerated conditions.     

Salt influence on nitrate and phosphate uptake by broad beans and barley in sand culture

Increasing salt concentration from 10^?4N to 3 × 10^?3N increased the uptake and percent of N and P in shoots and roots of barley and broad bean plants. This effect was higher the higher the cation valence and the lower the anion valence following the order CaCl₂ > KCl ? K₂SO₄. The increase in N and P uptake was higher in broad bean plants having higher C.E.C. than in barley having lower C.E.C.     

Source and mode of sulphur application on groundnut productivity

The effectiveness of 20 kg/ha sulphur (S) of the S‐containing compounds iron sulphate (FeSO₄), gypsum, phosphogypsum, elemental S, and pyrite on groundnut (Arachis hypogaea L.) productivity was determined for plants grown on calcareous soil in the field. Plants grown with S compared to those without S had increased plant height, number of flowers, nodule numbers and weight, higher dry matter, seed, haulm (leaves and stems), and oil yields; higher tissue concentrations of nitrogen (N), phosphorus (P), S, iron (Fe), and zinc (Zn); and higher total uptake of mineral nutrients. Elemental S, pyrite, and FeSO₄ were more effective than gypsum and phosphogypsum, with FeSO₄ being the most effective source of S for improving plant growth traits, yield, and nutrient uptake. The most effective method of FeSO₄ application was half to the soil at planting time (basal) followed by the remainder in three equal foliar sprays at 30,50, and 70 days after plant emergence (DAE). Pyrite and elemental S were most effective when applied to the soil only, half as a basal soil dressing, and the remainder in two equal doses at 25 and 50 DAE. Plant concentrations of S, P, and potassium (K) were similar for each source of S, but elemental S, pyrite, and FeSO₄ enhanced N, Fe, manganese (Mn), and Zn uptake. Gypsum and phosphogypsum enhanced calcium (Ca) uptake. Elemental S and FeSCM provided similar results when half was applied to the soil followed by three equal foliar sprays. The best results from pyrite, gypsum, and phosphogypsum were obtained when soil applied.     

Effectiveness of Vivianite to Prevent Lime-Induced Iron Deficiency in Lemon Trees Grown on Highly Calcareous Soil

The short-term effectiveness of three application rates of vivianite [(Fe₃(PO₄)₂·8H₂O)] in preventing lime-induced iron (Fe) chlorosis in Eureka lemon (Citrus lemon L.) cuttings grafted on sour orange (Citrus aurantium L.) was investigated and compared with the commonly applied iron ethylenediaminedi(o-hydroxyphenylacetic) acid (FeEDDHA). Treatments were suspension of vivianite injected into the soil at three rates (0.5, 1.0, and 2.0 g kg^?1 soil), 417 mg FeEDDHA per plant, and untreated plants. Chlorophyll concentration index (CCI) of the youngest fully expanded leaves was estimated. Growth vigor and leaf Fe concentration were also measured. Vivianite, particularly at the greatest two rates, resulted in significantly greater growth vigor and leaf Fe concentration and exhibited greater CCI values compared to untreated plants similar to FeEDDHA. However, if excessive growth vigor is not favorable, the 0.5 g vivianite kg^?1 soil is recommended for farmers. Vivianite is a potential environmentally safe alternative to the expensive FeEDDHA to prevent Fe chlorosis in lemon.     

Effect of potassium salts on alleviation of lime‐induced chlorosis in soybean 1

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.