Fe In Plants Research Articles

Quantitative Changes in Soil Properties and Plant Uptake of Metals on Municipal Solid Waste Dumpsite in Nigeria

In this work concentrations of Cd, Pb, Cr, Fe, Co, Ni, Cu, Zn and Mn were determined in soils and plants from refuse dumpsites in Ado Ekiti, Nigeria. The refuse dump soils were evaluation using contamination/pollution factor (C/P), Enrichment factor (EF), Index of Geoaccumulation (Igeo) and Pollution load index were calculated. The observation suggests high C/P values of the dump soil are polluted by Cd, Cr and Ni acts as a sink for heavy metals contributed from anthropogenic sources in the study area. C/P data, EF, PLI and (Igeo) indicated that these heavy metals originate from anthropogenic sources. Fe and Ni loads in plants from the refuse dump soils pronounced maximum concentration than Nigeria guideline. Transfer ratios for Cd, Co, Cu, Zn, Pb and Fe of plants from the control soils were higher than those from the refuse dump soils.

Effect of iron stress on Withania somnifera L.: antioxidant enzyme response and nutrient elemental uptake of in vitro grown plants.

In the present study the response of antioxidant enzyme activities and the level of expression of their corresponding genes on bioaccumulation of iron (Fe) were investigated. In vitro germinated Withania somnifera L. were grown in Murashige and Skoog's liquid medium with increasing concentrations (0, 25, 50, 100 and 200µM) of FeSO4 for 7 and 14days. Root and leaf tissues analyzed for catalase (CAT, EC 1.11.1.6), superoxide dismutase (SOD, EC 1.15.1.1) and guaiacol peroxidase (GPX, EC 1.11.1.7), have shown an increase in content with respect to exposure time. Isoforms of CAT, SOD and GPX were separated using non-denaturing polyacrylamide gel electrophoresis and observed that the isoenzymes were greatly affected by higher concentrations of Fe. Reverse transcriptase polymerase chain reaction analysis performed by taking three pairs of genes of CAT (RsCat, Catalase1, Cat1) and SOD (SodCp, TaSOD1.2, MnSOD) to find out the differential expression of antioxidant genes under Fe excess. RsCat from CAT and MnSOD from SOD have exhibited high levels of gene expression under Fe stress, which was consistent with the changes of the activity assayed in solution after 7days of treatment. Analysis by proton induced X-ray emission exhibited an increasing uptake of Fe in plants by suppressing and expressing of other nutrient elements. The results of the present study suggest that higher concentration of Fe causes disturbance in nutrient balance and induces oxidative stress in plant.

Impact of rice cultivar and organ on elemental composition of phytoliths and the release of bio-available silicon.

The continental bio-cycling of silicon (Si) plays a key role in global Si cycle and as such partly controls global carbon (C) budget through nutrition of marine and terrestrial biota, accumulation of phytolith-occluded organic carbon (PhytOC) and weathering of silicate minerals. Despite the key role of elemental composition of phytoliths on their solubility in soils, the impact of plant cultivar and organ on the elemental composition of phytoliths in Si high-accumulator plants, such as rice (Oryza sativa) is not yet fully understood. Here we show that rice cultivar significantly impacts the elemental composition of phytoliths (Si, Al, Fe, and C) in different organs of the shoot system (grains, sheath, leaf and stem). The amount of occluded OC within phytoliths is affected by contents of Si, Al, and Fe in plants, while independent of the element composition of phytoliths. Our data document, for different cultivars, higher bio-available Si release from phytoliths of leaves and sheaths, which are characterized by higher enrichment with Al and Fe (i.e., lower Si/Al and Si/Fe ratios), compared to grains and stems. We indicate that phytolith solubility in soils may be controlled by rice cultivar and type of organs. Our results highlight that the role of the morphology, the hydration rate and the chemical composition in the solubility of phytoliths and the kinetic release of Si in soil solution needs to be studied further. This is central to a better understanding of the impact of soil amendment with different plant organs and cultivars on soil OC stock and on the delivery of dissolved Si as we show that sheath and leaf rice organs are both characterized by higher content of OC occluded in phytolith and higher phytolith solubility compared to grains and stems. Our study shows the importance of studying the impact of the agro-management on the evolution of sinks and sources of Si and C in soils used for Si-high accumulator plants.

Climatic Effects on Foliar Elemental Compositions of Si, Al and Fe from C4Grass Family, China

The climate controls vegetation distribution and the vegetation reflects regional climates. Understanding the effects of climate on the elemental composition of plants is important to reveal vegetation's elemental compositions -climate relationships, and to offer references for global climate change research. China's data sets including 201 observations of leaf silicon (Si), aluminum (Al), iron (Fe) for Foxtail grass (Setaria viridis), Feather grass (Chloris virgata), Goose grass (Eleusine indica) at 55 sites and their associated climate indices demonstrate an important acclimation response of the plants to climatic factors (variability in precipitation, temperature and latitude etc..). Our studies showed that, leaf Si and Al contents and the Si/Al ratio were correlated with latitude, mean annual temperature (MAT) and annual rainfall (MAP), and leaf Fe was correlated with MAP in Foxtail grass across China; Leaf Si and Fe were correlated with latitude, and leaf Al was correlated with MAT, and leaf Al and Fe were correlated with MAP in Feather grass; Leaf Fe was correlated with latitude, leaf Al and Fe were correlated with MAT, and leaf Si, Al and Fe were correlated with MAP in Goose grass. All of this indicates that geographic gradients of precipitation and temperature constrain contents and ratios of Si, Al and Fe in plants. These findings can help initiate a more holistic approach and offer references for the eventual development of alternative indices of precipitation and temperature factors in climate change research.

Iron availability thresholds for the inoculation of cucumber with Trichoderma asperellum T34

AbstractInoculation with biocontrol agents can affect iron (Fe) uptake by plants. The objective of this research was to study the necessity of defining a Fe threshold in growth media for the inoculation with the biocontrol agent Trichoderma asperellum T34. A completely randomized experiment with cucumber (Cucumis sativus L.) was performed involving two factors: Fe rate in the growth medium in the form of ferrihydrite (0, 8, 16, 32.5, and 75 mg kg–1 of citrate‐ascorbate‐extractable Fe (CA‐Fe), and plant inoculation with T34. Dry matter (DM) of aerial parts of cucumber was decreased by T34. This was related to a decreased accumulation of Fe in plants, more in aerial parts than in roots. However, at the highest Fe rate (75 mg kg–1), differences in DM yield, plant height, and the content and concentration of Fe in shoots between inoculated and noninoculated plants were not significant. The threshold of CA‐Fe in the medium for DM yield of cucumber was 37 mg kg–1 without T34. With T34, this threshold was 65 mg kg–1, which implies that, below this limit, additional Fe supply is required for inoculation with T34.

Efficiency of a new strategy involving a new class of natural hetero‐ligand iron(III) chelates (Fe(III)‐NHL) to improve fruit tree growth in alkaline/calcareous soils

Iron (Fe) chlorosis is a serious problem affecting the yield and quality of numerous crops and fruit trees cultivated in alkaline/calcareous soils. This paper describes the efficiency of a new class of natural hetero-ligand Fe(III) chelates (Fe-NHL) to provide available Fe for chlorotic lemon trees grown in alkaline/calcareous soils. These chelates involve the participation in the reaction system of a partially humified lignin-based natural polymer and citric acid. First results showed that Fe-NHL was adsorbed on the soil matrix while maintaining available Fe for plants in alkaline/calcareous solution. The effects of using three different sources as Fe fertilisers were also compared: two Fe-NHL formulations (NHL1, containing 100% of Fe as Fe-NHL, and NHL2, containing 80% of Fe as Fe-NHL and 20% of Fe as Fe-ethylenediamine-N,N'-bis-(o-hydroxyphenylacetic) acid (Fe-EDDHA)) and Fe-EDDHA. Both Fe-NHL formulations increased fruit yield without negative effects on fruit quality in comparison with Fe-EDDHA. In the absence of the Fe-starter fraction (NHL1), trees seemed to optimise Fe assimilation and translocation from Fe-NHL, directing it to those parts of the plant more involved in development. The field assays confirmed that Fe-NHL-based fertilisers are able to provide Fe to chlorotic trees, with results comparable to Fe-EDDHA. Besides, this would imply a more sustainable and less expensive remediation than synthetic chelates.

Alleviation of aluminum toxicity by hydrogen sulfide is related to elevated ATPase, and suppressed aluminum uptake and oxidative stress in barley

Greenhouse hydroponic experiments were performed to evaluate potential role of H2S on Al toxicity in barley seedlings. Seedlings pretreated with 200μM NaHS as a donor of H2S for 24h and subsequently exposed to 100μM AlCl3 for 24h had significantly longer roots than those without NaHS. The promoted root elongation was correlated with a substantial decrease in Al-induced overproduction of lipid peroxidation, electrolyte leakage and Al accumulation in roots, and a marked increase in Al-induced depress activities of Na+K+-ATPase and H+-ATPase. The alleviating role of H2S on Al-induced toxicity was also found in a time- and dose-dependent experiment. Addition of 200 and 400μM NaHS to 100μM AlCl3 effectively alleviated Al-toxicity, markedly diminished Al-induced MDA accumulation, and increased chlorophyll content, net photosynthetic rate (Pn) and maximal photochemical efficiency (Fv/Fm) compared with Al alone. Exogenous H2S significantly elevated depressed CAT activities, and further improved root POD activity. Moreover, NaHS decreased Al accumulation, but elevated concentrations of S, P, Ca, Mg and Fe in plants. These data suggest that H2S-induced alleviation in Al toxicity is attributed to reduced Al uptake and MDA accumulation, improved uptake of P, Ca, Mg and Fe, and elevated ATPase and photosynthetic performance.

Metal levels in some refuse dump soils and plants in Ghana

Concentrations of Cd, Hg, Pb, Cr, Fe, Co, Ni, Cu, Zn, Mo and As were determined in soils and leaves of plants from refuse dumpsites and background soils in two cities, a municipality and a rural community in Ghana, using a ThermoFinnigan Element 2 high resolution inductively coupled plasma mass spectrometric (HR-ICP-MS) instrument. The refuse dump soils were classified between 'Uncontaminated to Moderate' and 'Strongly Contaminated'. Pollution levels for Cd (Igeo = 2.06–2.40) and Zn (Igeo = 2.95–3.36) were higher than of the other metals. The refuse dump soil from the rural community was the least polluted with the metals. Fe and Ni loads in plants from the refuse dump soils in the cities and the municipality were beyond the normal ranges of 40–500 µg/g (Fe) and 0.02–5.00 µg/g (Ni). Transfer ratios for Cd, Hg, Cu, Zn and Pb and Fe of plants from the background soils were higher than those from the refuse dump soils, which might be due to the higher levels of organic matter, pH, phosphate, Ca and Mg in the refuse dump soils.

Effect of Trichoderma asperellum strain T34 on iron nutrition in white lupin

The production of chelating compounds (siderophores) by microorganisms increases Fe availability to plants. The main objective of this work was to study the effect of Trichoderma asperellum strain T34, a commercially available biocontrol agent, on Fe availability to white lupin ( Lupinus albus L). To this end, experiments involving three factors [viz. growing medium (siliceous or calcareous), Fe supply (ferrihydrite enrichment and no enrichment), and inoculation with T34] were performed. Chlorophyll meter readings and concentration and total content of Fe in plants grown on the siliceous medium were decreased by T34, but only in the absence of ferrihydrite. This suggests a potential competition between plants and T34 for Fe under conditions of restricted availability. By contrast, T34 increased the Fe concentration in the aerial parts of lupin plants grown on the calcareous medium. In ferrihydrite-enriched calcareous media, T34 decreased chlorophyll content of the plants. This cannot be ascribed to depressed Fe nutrition or other nutrient deficiency. Inoculation with T34 increased peroxidase (ferrihydrite-enriched calcareous media and siliceous media without ferrihydrite) and catalase activities, but decreased the peroxidase to catalase activity ratio. This effect on the activities of Fe-containing enzymes, which was not the sole result of increased Fe availability to plants, accounts for the disparate relationship between SPAD meter readings and Fe concentrations in plants in inoculated and non-inoculated media. Based on them, a higher Fe concentration in aerial parts was required for similar SPAD meter readings in plants with T34 than in those without T34. This may have resulted from an increased activity in Fe-containing enzymes (particularly catalase) reducing the availability of free Fe for chlorophyll synthesis, which is consistent with the significantly decreased SPAD readings by the effect of T34 in ferrihydrite-enriched calcareous media.

Can foliar iron-containing solutions be a potential strategy to enrich iron concentration of rice grains (Oryza sativa L.)?

The available literature on whether or not foliar iron (Fe)-containing solutions can be one of the sustainable and low-cost strategies to increase Fe concentration in edible portions of staple food crops consisted of a few previous studies of Fe in plants, and mainly focused on Fe-deficiency remedies. Our experiment was carried out to examine the effects of foliar Fe-containing solutions on Fe enrichment and on the nutritional, cooking, and eating qualities of polished rice of the japonica ‘Bing 98110’ planted on a powdery loam soil under pot conditions. The results showed that Fe concentration in polished rice could be enriched with foliar Fe(II)-amino acids [the main formulation was the complex of 0.1% (w/v) FeSO4 •7H2O and 0.4% (w/v) compound amino acids, 18.6% N] application. Compared with the control, Fe concentration increased significantly, by 88.0%. Meanwhile, the positive effects on Zn concentration and protein and amino acid content improvement were found with boric acid (H3BO3, B) added to Fe(II)-amino acids foliar application. In detail, Zn concentration significantly increased (19.6%), and protein and lysine were increased significantly by 30.1 and 35.1%, respectively. Also the cooking and eating qualities were improved with foliar Fe(II)-amino acids and B compound spray.

Effectiveness of autochthonous bacterium and mycorrhizal fungus on Trifolium growth, symbiotic development and soil enzymatic activities in Zn contaminated soil

This study investigates how autochthonous micro-organisms [bacterium and/or arbuscular mycorrhizal (AM) fungi] affected plant tolerance to Zn contamination. Zinc-adapted and -nonadapted Glomus mosseae strains protected the host plant against the detrimental effect of Zn (600 microg g(-1)). Zn-adapted bacteria increased root growth and N, P nutrition in plants colonized by adapted G. mosseae and decreased the specific absorption rate (SAR) of Cd, Cu, Mo or Fe in plants colonized by Zn-nonadapted G. mosseae. Symbiotic structures (nodule number and extraradical mycelium) were best developed in plants colonized by those Zn-adapted isolates that were the most effective in increasing plant Zn tolerance. The bacterium also increased the quantity and quality (metabolic characteristics) of mycorrhizal colonization, with the highest improvement for arbuscular vitality and activity. Inocula also enhanced soil enzymatic activities (dehydrogenase, beta-glucosidase and phosphatase) and indol acetic acid (IAA) accumulation, particularly in the rhizosphere of plants inoculated with Zn-adapted isolates. Glomus mosseae strains have a different inherent potential for improving plant growth and nutrition in Zn-contaminated soil. The bacterium increased the potential of mycorrhizal mycelium as inoculum. Mycorrhizal performance, particularly that of the autochthonous strain, was increased by the bacterium and both contributed to better plant growth and establishment in Zn-contaminated soils.

Use of > 1:1 Chelator:Iron Ratios and Strong Iron(III) Chelators in Hydroponic Solutions for Barley

This study examined two guidelines for preparing hydroponic solutions to ensure adequate iron (Fe) for Poaceae plants: (1) not to add chelator in excess of Fe concentrations and (2) to use only weaker forms of Fe(III) chelators. Barley was grown in low-Fe solutions for 9 d and transferred to 59Fe-spiked nutrient solutions at pH 8.1 containing ligand:Fe μ M concentrations of 30:10, 200:10, and 500:10 for 6 h assays. Shoot 59Fe increased with increasing citrate or N,N-bis(carbozymethyl)glycine (NTA). Shoot 59Fe was higher from treatment with citrate than with corresponding NTA treatments despite the ligands' similar Fe(III) binding affinity. Soluble Fe was higher from the citrate than the NTA solutions at the two highest chelator concentrations (P < 0.05). Citrate maintained higher soluble Fe levels and provided more Fe to barley than did NTA. Results of the second experiment found adequate Fe in barley when grown in equimolar HBED:Fe treatments (HBED is the strongest Fe(III) synthetic chelator). Recommendations that only weak Fe(III) chelators be used for the hydroponic culture of barley may be made because stronger chelators result in inadequate Fe for plants after solution Fe levels drop, as plants remove only Fe and little chelator from hydroponic solutions.

Influence of nickel-contaminated soils on fenugreek ( Trigonella corniculata L.) growth and mineral composition

Leafy vegetables accumulate higher amount of heavy metals like nickel (Ni) due to their more leafy vegetative growth. Therefore, a screenhouse experiment was conducted using an alkaline sandy loam soil equilibrated with graded levels of Ni (0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250 and 300 mg kg −1 soil) to assess the Ni accumulation pattern and its influence on growth and micronutrient distribution in fenugreek plants. Green as well as the dry matter yields of fenugreek increased slightly up to 20 g Ni kg −1 soil but decreased significantly with the application ≥40 mg Ni kg −1 soil. Crops showed characteristic toxicity symptoms of interveinal chlorosis in pots receiving ≥40 mg Ni kg −1 soil. While the total content of Ni in the plant tissues increased consistently with increasing rates of applied Ni, the roots accumulated much higher amount of this element compared to the shoot. The content of Fe in plants showed an increase whereas that of Cu and Zn experienced a decrease with the rise in the applied Ni.

Metal concentrations, growth, and yield of potato produced from In Vitro plantlets or microtubers and grown in municipal solid‐waste‐amended substrates

In vitro plantlets or microtubers (in vitro produced tubers) of ‘Spunta’ potato (Solanum tuberosum L.) were planted in a 3 soil: 2 peat moss: 1 sand substrate (by volume) amended with municipal solid waste (MS W) compost at 0, 10, 20, or 30 g 4‐1 L pot. Three months later, plant growth and tuber yield were evaluated and concentrations of shoot and tuber tin (Sn), arsenic (As), copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), manganese (Mn), cadmium (Cd), and iron (Fe) were determined. Amending with MSW resulted in significant increases in concentrations of all tested metals in the substrate. Number of proliferated shoots of plants started from rooted plantlets was greatest at 10 g pot‐1 MSW, whereas shoot weight of plants started from microtubers was greatest at 10 and 20 g pot‐1 MSW. Tuber yield of plants started from rooted plantlets or microtubers was greatest at 10 or 30 g pot‐1 MSW, respectively. In all instances, amending with MSW at 30 g pot‐1 resulted in significant increases in concentrations of all tested metals in shoots and tubers. Concentrations of shoot Ni and tuber Zn and Fe for plants started from rooted plantlets and concentrations of shoot Fe and tuber As, Cu and Pb for plants started from microtubers increased consistently with increasing MSW percentage of the substrate. Plants started from rooted plantlets produced shoots with sufficient Zn, Mn, and Ni concentrations regardless of the substrate but with toxic Cu content at 30 g pot‐1 MSW. Plants started from microtubers produced shoots with sufficient Mn and Ni concentrations regardless of the substrate but with low Zn and deficient Cu in unamended substrates. All plants had shoot Fe content higher than the sufficiency range. Although there were significant differences in concentrations of some nutrients among MSW treatments, no symptoms of nutrient toxicity or deficiency were observed. In all instances, tested elements did not accumulate in tubers to levels hazardous to human health. Concentrations of Cd, the most hazardous element, in potato tubers was not high enough to pose a threat to human. Our results indicate that there is a potential use of MSW in satisfying the needs of potato growth with negligible increases in heavy metal concentrations in tubers.

Effect of temperature on rice growth in nutrient solution and in acid sulphate soils from Vietnam

Climatic and soil factors are limiting rice growth in many countries. In Vietnam, a steep gradient of temperature is observed from the North to the South, and acid sulphate soils are frequently devoted to rice production. We have therefore attempted to understand how temperature affects rice growth in these problem soils, by comparison with rice grown in nutrient solution. Two varieties of rice, IR64 and X2, were cultivated in phytotrons at 19/21 degrees C and 28/32 degrees C (day/night) for 56 days, after 3 weeks preculture in optimal conditions. Two soils from the Mekong Delta were tested. Parallel with the growing experiments, these two soils were incubated in order to monitor redox potential (Eh), PH, soluble Al and Fe, soluble, and available P. Tillering retardation at 20 degrees C compared to 30 degrees C was similar in nutrient solutions and in soils. The effect of temperature on increasing plant biomass was more marked in solutions than in soils. The P concentrations in roots and shoots were higher at 20 degrees C than at 30 degrees C, to such an extent that detrimental effect was suspected in plants grown in solution at the lowest temperature. The translocation of Fe from roots to shoots was stimulated upon rising temperature, both in solutions and in soils. This led to plant death on the most acid soil at 30 degrees C. Indeed, the accumulation of Fe in plants grown on soils was enhanced by the release of Fe2+ due to reduction of Fe(III)-oxihydroxides. Severe reducing conditions were created at 30 degrees C: redox potential (Eh) dropped rapidly down to about 0 V. At 20 degrees C, E(h) did not drop below about 0.2 V, which is a value well in the range of Fe(III)/Fe(II) buffering. Parallel to Eh drop, PH increased up to about 6-6.5 at 30 degrees C, which prevented plants from Al toxicity, even in the most acid soil. Phosphate behavior was obviously related to Fe-dynamics: more reducing conditions at 30 degrees C have resulted in enhancement of available P, especially in the most acid soil.

The relationship between metal concentration and organic matter in sediments and metal concentration in the aquatic macrophyte Eriocaulon septangulare

Sediment cores and samples of the submerged and rooted isoetid Eriocaulon septangulare (With.) were used to examine the relationships between the concentrations of Hg, Pb, Cd and Fe in plants, and metal concentrations and organic matter (OM) content of sediments. Thirteen sites in the littoral zone of Bentshoe Lake, a software lake of the Muskoka-Haliburton region of south-central Ontario were included in the study design. Metal concentrations in sediments ranged from 0.007 to 0.247 μg g−1 for Hg, 2.8 to 167.6 μg g−1 for Pb, 0.06 to 2.53 μg g−1 for Cd and 2.55 to 34.77 mg g−1 for Fe. There were significant positive correlations between metal concentrations in sediment and OM content. Metal concentrations measured in Eriocaulon septangulare were generally comparable to or higher than those in sediments, and for each respective metal, were consistently higher in the roots than in the shoots. Concentrations of metals in E. septangulare ranged (dry weight, leaf concentration listed first and roots second for each metal) from 0.03 to 0.22 μg g−1 for Hg, from 2.6 to 62.8 μg g−1 for Pb, from 0.58 to 13.33 μg g−1 for Cd and from 0.61 to 156.20 mg g−1 for Fe. Metal concentrations in the roots and in the leaves were significantly positively correlated for Hg, Cd and Fe. Metal concentrations in the roots were not correlated with metal concentrations in the sediments. The presence of high concentrations of organic matter (OM) in sediments is shown to decrease the availability of metals to E. septangulare. However, when the total metal concentrations in sediments were normalized for organic content, there was a significant correlation with metal in the plant for Hg, but not for the other metals under consideration.

Sample preparation and determination of iron in plant tissue samples

Abstract Procedures for sample preparation of plant tissue prior to iron (Fe) determination as well as several analysis procedures are described. Iron analysis can give meaningless results unless extreme caution is used in taking and preparing samples. A significant portion of the Fe in plant leaves is derived from dust which is not easy to remove. Partial correction of the Fe value may be made from concentrations of some other elements present. Concentration of Fe in various plant parts is most meaningful for plants grown under experimental conditions where dust is not a problem. Precautions are required in the interpretation of Fe analysis results. The status of Fe in plants can be diagnosed in many cases from concentrations of other elements and their ratios to Fe. Some alternate procedures other than total Fe determination for determining the Fe status of plants are discussed.

Grain sorghum response to granular formulations of iron sources and hydrophilic polymers

Abstract Banded hydrogels containing FeSO4 have been shown to provide available Fe for plants on calcareous, Fe‐deficient soils. Because granular mixtures of gel‐forming polymers and Fe sources would be easier to apply to soil than hydrogels, several such granular products were compared with banded hydrogels in greenhouse pot experiments. Several FeSO4 + gel‐forming polymer (polyacryl‐amide) formulations were granulated in a rotary tableting press and band applied to an Fe‐deficient Epping silt loam soil (Ustic Torriorthent). None of the granular formulations of FeSO4 + polymers banded alone or with other additives (urea, ammominum sulfate, or bentonite clay) was effective in providing available Fe to grain sorghum (Sorghum bicolor L. Moench). However, a granular formulation of FeEDTA + polymer increased sorghum dry matter yields and Fe uptake. Banded hydrated polymer formulations containing either FeEDTA or FeSO4 also were effective in providing available Fe to sorghum. Results of an associated laboratory experiment showed that some gel formation occurred at granule sites of the FeSO4 + polymer formulations within one week after soil application. Apparently, gel formation was inadequate to affect Fe reactions with the soil to form unavailable products. Limited gel formation with granular products may have resulted from insufficient free water in soil, high solute concentrations in the soil solution surrounding the granules, or hard granules. These results suggest that application of granular products of FeSO4 with polymers may not be an effective method of soil application unless other polymers, additives, or ratios of polymers, additives, and FeSO4 can be identified.

Some modifications in trace metal toxicities and deficiencies in plants resulting from interactions with other elements and chelating agents‐‐the special case of iron

Abstract Whenever land becomes contaminated with trace metals, most always two or more of the trace metals are in excess simultaneously. Nearly all of the baseline studies of metal excesses, however, have been made with single metals, and such studies do not accurately reflect the critical response levels. Various critical points can shift due to interactions. Analytical data must be obtained for as many as 20 different elements and their differential distribution among various plant parts, including roots, must be known to gain even a partial understanding of the interactions. Positive and negative synergisms, competition, protection, and sequential additivity are observed among the interactions. The nature of interactions varies considerably with concentration levels, soil pH, soil texture, level of soluble Ca in soil, presence of salinity, differential distribution in soil of the metals present in toxic quantities, presence or absence of chelating agents, soil organic matter levels, and other factors. Interactions are difficult to model. All of these relate to the behavior of Fe in plants and in soil. Iron deficiency is commonly induced by excess levels of other trace metals, both singly and more commonly in various combinations. Such Fe deficiency is complex. Other essential nutrients are involved in somewhat similar interactions. When testing soil for possible problems with Fe deficiency, it is important that concentrations of available trace elements other than Fe in addition to other soil parameters be considered in the equation for prediction.

PRODUCTION OF SOME FLOWERS IN HYDROPONICS AND SOILLESS MEDIA

Production of five commercial cut flowers in different culture media, namelyI nutrient film technique (NFT), soilless media (perlite and an equal mix of perlite and peatmoss), and soil mix (2 sand: 1 loam by volume), was investigated in controlled fiberglass-house. Two rose varieties (Rosa hybrida var. Baccara and Madina); carnation (Dianthus caryophyllus var. William Sim); Chrysanthemum morifolium var. Delta, and Dahlia hybrida var. variabilis were used. Plants were watered as they needed by the same nutrient solution used for NFT.Generally, growth and yield of Baccara and Madina roses, Chrysanthemum and Dhalia plants were superior in NFT than in the other media. On the contrary, the growth and yield of carnation plants were significantly greater in conventional soil or perlite and peatmoss mix than in NFT or perlite.Flower crops grown in NFT generally reached harvest stage 5-10 days earlier than those grown in the other media except carnation plants. There were variations in the accumulation of N, P, K mg, ca, and Fe in plant leaves among the various culture media.