Fe Concentrations In Roots Research Articles

Terbuthylazine interferes with iron nutrition in maize (Zea mays) plants

Many chemicals, including herbicides, are routinely applied to crops for weed management and food production improvement. However, the intensive use of herbicides could lead eventually to a great environmental threat due to their persistence and accumulation in the ecosystems and contamination of soils. Furthermore, the possible effect of these chemicals on nutrient uptake and assimilation in crops has only recently been discussed. The present study aimed at understanding the effect of the herbicide terbuthylazine (TBA), a herbicide commonly applied to control weeds in leguminous species and triazine tolerant crops, on the capability of maize plants to cope with iron (Fe) shortage. The application of 2 and 5 mg L−1 TBA caused a significant reduction of root Fe concentration. This reduction might be attributed to a decreased release of phytosiderophores, which in turn could be ascribed to a reduced sulfur assimilation. Results provide evidence that TBA impairs Fe uptake and accumulation in non-target plants most likely interacting with sulfur-assimilating enzymes [ATP sulfurylase and O-acetylserine(thiol)lyase].

ACCUMULATION AND PARTITION OF Fe, Zn, Cu, Mn AND Na IN MACRO AND MICRONUTRIENT-DEFICIENT COWPEA PLANTS

Cowpea (Vigna unguiculata) is an important crop for people living in the semi-arid tropics where it is used as food, animal feed and forage. Researches related to nutritional status of plants are important, principally in crops commonly grown in nutrient-poor soils. This study aimed to analyze the growth and accumulation/distribution of some micronutrients in cowpea plants submitted to macro and micronutrient deficiency. Cowpea seeds were germinated in grit and after five days, ten uniform seedlings were transferred to complete nutrient solution for an acclimatization period. After three days, the plants were grown in nutrient solution containing all macro and micronutrients or in nutrient solution without N, Ca, K, Mg, P, S, Fe, B or aeration. In all case, omission of mineral nutrients and the aeration caused reductions in the dry mass of cowpea plants, except for B; however, the absence of Ca was the most limiting for plant growth. Interestingly, the root Fe content significantly increased in Mg-, P- and S-deficient plants. Yet, Fe-deficient plants displayed a significant increase in Cu and Mn content, regardless of plant organ. Our data clearly demonstrate that the Ca is the most important nutrient for V. unguiculata growth, followed by N and Fe. The accumulation and partition of Fe, Zn, Cu and Mn in cowpea vary differentially in root, stem and leaf as affected by nutritional deficiency.

Phytate induced arsenic uptake and plant growth in arsenic-hyperaccumulator Pteris vittata

Phytate is abundant in soils, which is stable and unavailable for plant uptake. However, it occurs in root exudates of As-hyperaccumulator Pteris vittata (PV). To elucidate its effect on As uptake and growth, P. vittata were grown on agar media (63 μM P) containing 50 μM As and/or 50 or 500 μM phytate with non As-hyperaccumulator Pteris ensiformis (PE) as a congeneric control for 60 d. Phytate induced efficient As and P uptake, and enhanced growth in PV, but had little effects on PE. The As concentrations in PV fronds and roots were 157 and 31 mg kg−1 in As50+phytate50, 2.2- and 3.1-fold that of As50 treatment. Phosphorus uptake by PV was reduced by 27% in As treatment than the control (P vs. P+As) but increased by 73% comparing phytate500 to phytate500+As, indicating that PV effectively took up P from phytate. Neither As nor phytate affected Fe accumulation in PV, but phytate reduced root Fe concentration in PE (46–56%). As such, the increased As and P and the unsuppressed Fe uptake in PV probably promoted PV growth. Thus, supplying phytate to As-contaminated soils may promote As uptake and growth in PV and its phytoremediation ability.

Gibberellins regulate iron deficiency-response by influencing iron transport and translocation in rice seedlings (Oryza sativa).

Gibberellins (GAs) are a class of plant hormones with diverse functions. However, there has been little information on the role of GAs in response to plant nutrient deficiency. To evaluate the roles of GAs in regulation of Fe homeostasis, the effects of GA on Fe accumulation and Fe translocation in rice seedlings were investigated using wild-type, a rice mutant ( eui1 ) displaying enhnaced endogenous GA concentrations due to a defect in GA deactivation, and transgenic rice plants overexpressing OsEUI . Exposure to Fe-deficient medium significantly reduced biomass of rice plants. Both exogenous application of GA and an endogenous increase of bioactive GA enhanced Fe-deficiency response by exaggerating foliar chlorosis and reducing growth. Iron deficiency significantly suppressed production of GA 1 and GA 4 , the biologically active GAs in rice. Exogenous application of GA significantly decreased leaf Fe concentration regardless of Fe supply. Iron concentration in shoot of eui1 mutants was lower than that of WT plants under both Fe-sufficient and Fe-deficient conditions. Paclobutrazol, an inhibitor of GA biosynthesis, alleviated Fe-deficiency responses, and overexpression of EUI significantly increased Fe concentration in shoots and roots. Furthermore, both exogenous application of GA and endogenous increase in GA resulting from EUI mutation inhibited Fe translocation within shoots by suppressing OsYSL2 expression, which is involved in Fe transport and translocation. The novel findings provide compelling evidence to support the involvement of GA in mediation of Fe homeostasis in strategy II rice plants by negatively regulating Fe transport and translocation.

Efficient acquisition of iron confers greater tolerance to saline-alkaline stress in rice (Oryza sativa L.).

To elucidate the mechanisms underlying tolerance to saline-alkaline stress in two rice genotypes, Dongdao-4 and Jigeng-88, we exposed them to medium supplemented with 10 mM Na2CO3 and 40 mM NaCl (pH 8.5). Dongdao-4 plants displayed higher biomass, chlorophyll content, and photosynthetic rates, and a larger root system than Jigeng-88 under saline-alkaline conditions. Dongdao-4 had a higher shoot Na+/K+ ratio than Jigeng-88 under both control and saline-alkaline conditions. Dongdao-4 exhibited stronger rhizospheric acidification than Jigeng-88 under saline-alkaline conditions, resulting from greater up-regulation of H+-ATPases at the transcriptional level. Moreover, Fe concentrations in shoots and roots of Dongdao-4 were higher than those in Jigeng-88, and a higher rate of phytosiderophore exudation was detected in Dongdao-4 versus Jigeng-88 under saline-alkaline conditions. The Fe-deficiency-responsive genes OsIRO2, OsIRT1, OsNAS1, OsNAS2, OsYSL2, and OsYSL15 were more strongly up-regulated in Dongdao-4 than Jigeng-88 plants in saline-alkaline medium, implying greater tolerance of Dongdao-4 plants to Fe deficiency. To test this hypothesis, we compared the effects of Fe deficiency on the two genotypes, and found that Dongdao-4 was more tolerant to Fe deficiency. Exposure to Fe-deficient medium led to greater rhizospheric acidification and phytosiderophore exudation in Dongdao-4 than Jigeng-88 plants. Expression levels of OsIRO2, OsIRT1, OsNAS1, OsNAS2, OsYSL2, and OsYSL15 were higher in Dongdao-4 than Jigeng-88 plants under Fe-deficient conditions. These results demonstrate that a highly efficient Fe acquisition system together with a large root system may underpin the greater tolerance of Dongdao-4 plants to saline-alkaline stress.

Role of Silicon Counteracting Cadmium Toxicity in Alfalfa (Medicago sativa L.).

Cadmium (Cd) is one of the most phytotoxic elements causing an agricultural problem and human health hazards. This work investigates whether and how silicon (Si) ameliorates Cd toxicity in Alfalfa. The addition of Si in Cd-stressed plants caused significant improvement in morpho-physiological features as well as total protein and membrane stability, indicating that Si does have critical roles in Cd detoxification in Alfalfa. Furthermore, Si supplementation in Cd-stressed plants showed a significant decrease in Cd and Fe concentrations in both roots and shoots compared with Cd-stressed plants, revealing that Si-mediated tolerance to Cd stress is associated with Cd inhibition in Alfalfa. Results also showed no significant changes in the expression of two metal chelators [MsPCS1 (phytochelatin synthase) and MsMT2 (metallothionein)] and PC (phytochelatin) accumulation, indicating that there may be no metal sequestration or change in metal sequestration following Si application under Cd stress in Alfalfa. We further performed a targeted study on the effect of Si on Fe uptake mechanisms. We observed the consistent reduction in Fe reductase activity, expression of Fe-related genes [MsIRT1 (Fe transporter), MsNramp1 (metal transporter) and OsFRO1 (ferric chelate reductase] and Fe chelators (citrate and malate) by Si application to Cd stress in roots of Alfalfa. These results support that limiting Fe uptake through the down-regulation of Fe acquisition mechanisms confers Si-mediated alleviation of Cd toxicity in Alfalfa. Finally, an increase of catalase, ascorbate peroxidase, and superoxide dismutase activities along with elevated methionine and proline subjected to Si application might play roles, at least in part, to reduce H2O2 and to provide antioxidant defense against Cd stress in Alfalfa. The study shows evidence of the effect of Si on alleviating Cd toxicity in Alfalfa and can be further extended for phytoremediation of Cd toxicity in plants.

Impact of zinc on micronutrient content in root in different wheat cultivars

Summary For the experiment, four different wheat varieties were selected of which two were Zn-efficient (GW190 and LOK-1) and two Zn-inefficient (GW399 and GW-403) varieties having three levels viz., 0, 10 and 20 mg Zn kg -1 through zinc sulphate (21% Zn) with standard NPK fertilization. The cultivars were grown in pots (6, 7 and 10 kg capacity) upto three stages viz., 20, 50 days after germination (DAG) and upto maturity. The experiment was laid out in a Factorial Completely Randomized Design (FCRD) and treatments were repeated thrice for all three stages. The varietal trend of root Zn content was observed in order as; GW399>GW403>GW190>LOK-1. The root Fe content was observed in order as LOK-1>GW190> GW399>GW403. The Mn content was observed as in order GW403>LOK-1> GW399>GW190. The varietal trend for root content Cu was found as in order GW190>GW403>LOK-1>GW399.

Effect of sodium nitroprusside on responses of Melissa officinalis to bicarbonate exposure and direct Fe deficiency stress

In our study, one-month-old Melissa officinalis plants were subjected to Fe-deficiency treatments, such as 10 µM Fe (as direct iron deficiency, DD), and 30 µM Fe + 10 mM NaHCO3 + 0.5 g l−1 CaCO3 (as indirect iron deficiency, ID), and 30 µM Fe (as control) for 14 d. Both Fe-deficiency types reduced plant growth, photosynthetic pigment contents, an active Fe content in roots and leaves, root Fe(III)-reducing capacity, Fe-use efficiency, maximal quantum yield of PSII photochemistry, a ratio of variable to basic fluorescence, and activities of antioxidant enzymes, while they increased lipid peroxidation and a H2O2 content in leaves. These effects were more pronounced in plants exposed to ID with bicarbonate than those of DD plants. We showed that sodium nitroprusside (SNP), as NO donor, could ameliorate the adverse effects of bicarbonate on above traits. The methylene blue, as NO blocker, reversed the protective effects conferred by SNP in the ID-treated plants as well as DD plants. These findings suggests that NO protects photosynthesis and growth of IDtreated plants as well as DD plants by contribution in availability and/or delivery of metabolically active iron or by changing activities of reactive oxygen species-scavenging enzymes.

Effect of three safeners on sulfur assimilation and iron deficiency response in barley (Hordeum vulgare) plants.

Safeners are agrochemicals used in agriculture to protect crops from herbicide injuries. They act by stimulating herbicide metabolism. As graminaceous plants, to cope with iron (Fe) deficiency, activate sulfur (S) metabolism and release huge amounts of Fe-chelating compounds, or phytosiderophores (PSs), we investigated, in barley plants (Hordeum vulgare, L.) grown in Fe deficiency, the effects of three safeners on two enzymes of S assimilation, cysteine (Cys) and glutathione (GSH), and PS release. Finally, we monitored the root Fe content in plants treated with the most effective safener. Generally, all the safeners activated S metabolism and increased Cys and GSH contents. In addition, the safened plants excreted higher levels of PSs. Given that mefenpyr-diethyl (Mef) was the most effective in causing these effects, we assessed the Fe concentration in Mef-treated barley and found higher Fe levels than those in untreated plants. The three safeners, in different ways but specifically, activated S reductive metabolism and regulated Cys and GSH contents, PS release rate and Fe content (Mef-treated barley). The results of this research provide new indications of the biochemical and physiological mechanisms involved in the safening action. © 2016 Society of Chemical Industry.

A Small GTPase, OsRab6a, is Involved in the Regulation of Iron Homeostasis in Rice.

Plants have evolved two distinct strategies to acquire iron (Fe) from soils. However, the regulatory mechanisms underlying the Fe acquisition remain largely elusive. There is emerging evidence that small GTPases are involved in the responses of plants to environmental cues. Here, we identified a gene encoding a small GTPase, OsRab6a, in rice and characterized its role in Fe acquisition by generating transgenic rice plants with overexpression and knockdown of OsRab6a OsRab6a shared conserved functional domains with other known members of the Rab subfamily and localized ubiquitously in the cytoplasm and nucleus. The expression of OsRab6a was rapidly and transiently up-regulated by Fe deficiency. No differences in growth and development among the OsRab6a-overexpression, OsRab6a-RNAi (RNA interference) and wild-type plants were detected when grown in Fe-sufficient medium. However, overexpression of OsRab6a in rice plants conferred greater tolerance to Fe deficiency than RNAi and wild-type plants, as evidenced by higher seedling height, and greater biomass, Chl contents and Fe concentrations in shoots, roots and grains in the overexpression lines than wild-type and RNAi plants. Moreover, the overexpression lines exhibited larger root systems than wild-type and RNAi plants in Fe-deficient medium. Exposure to Fe-deficient medium led to up-regulation of OsIRO2, OsIRT1, OsNAS1 and OsNAS2 in both wild-type and transgenic rice plants, with the magnitude of up-regulation positively correlated with the expression levels of OsRab6a These results may suggest that OsRab6a plays an important role in the regulation of Fe acquisition in rice plants by modulating physiological processes involved in Fe acquisition and root system architecture in response to Fe-deficient medium.

ACCUMULATION OF CHEMICAL ELEMENTS BY ORGANS OF SPARGANIUM ERECTUM L. AND THEIR POTENTIAL USE IN PHYTOREMEDIATION PROCESS

The study of bottom sediments and organs of Sparganium erectum carried out in the summer of 2014 in the city of Lebork, located in Northern Poland. The aim of this study was to evaluate the content of macroelements and heavy metals in the leaves, rhizomes and roots S. erectum and in bottom sediments of the Łeba River as well as comparison of accumulation and translocation factors of N, P, K, Mg, Ca, Zn, Ni, Cu, Mn, Fe, Cd and Cr in researched organs of aquatic plant. The use of S. erectum for biomonitoring and phytoremediation has also been considered. The results of Mann Whitney U test showed a number of statistically significant differences in the content of chemical elements in the leaves, rhizomes, roots and in bottom sediments. The macroelements are mainly accumulated in leaves and heavy metals are accumulated in roots and rhizomes of S. erectum. Increased Mn and Fe content in roots and rhizomes of S. erectum, in relation this physiological needs, refers to the beneficial effects of this species in the water treatment and sludge from the bottom sediment of manganese and iron compounds. The obtained bioconcentration and translocation factors values allowed to state that S. erectum can be used for phytoremediation of contaminated bottom sediments because retains metals in their roots and limit Mn and Fe mobility from roots and rhizomes to leaves once absorbed by roots of plant.

Sufficient sulfur supply promotes seedling growth, alleviates oxidation stress, and regulates iron uptake and translocation in rice

We investigated the effect of sulfur (S) supply on growth, oxidative stress, and iron uptake and transport in rice (Oryza sativa L.) seedlings using a hydroponic culture with four S concentrations (0, 1.75, 3.5, and 7.0 mM). The length and fresh mass of seedlings were enhanced with the increased S concentration. In addition, the content of thiobarbituric acid reactive substances (TBARS) in rice leaves was the highest when no S was added to the nutrition solution and gradually declined with the increasing S supply. The higher S nutrition reduced the amount of Fe plaque on rice roots and increased Fe content in roots and leaves. The content of nicotianamine was significantly higher in rice roots under the S deficiency, whereas the reverse trend was observed in rice shoots. Taken together, the sufficient S nutrition promoted growth of rice, reduced oxidative stress, and ensured normal Fe uptake and distribution.

Effect of copper and zinc on growth characteristics, concentration of some mineral elements and translocation capacities of elements into infusion and decoction of dragon’s head (Lallemantia iberica F. & C.M) under greenhouse conditions

In order to investigate the effect of different levels of Copper (Cu) and Zinc (Zn) on morphological traits of dragon’s head, concentration of Cu, Zn, Fe, Mn, P and K in root and shoot and concentration of Cu and Zn in infusion and decoction, a greenhouse experiment was conducted as factorial based on complete randomized design with three replications. Treatments consisted of three levels of Cu (0, 5 and 25 mg CuSO4/kg soil), three levels of Zn (0, 10 and 50 mg ZnSO4/kg soil) and their interactions. Results showed that Cu and Zn had significant effect on dry weight of root, chlorophyll (SPAD), leaf area, concetration of K and P in roots and shoots and concetration of Fe and Mn in the roots. Also, their intraction had significant effect on dry weight of shoots, plant height and concentration of Cu and Zn in roots, shoots, infusion and decoction and concentarion of Fe and Mn in shoots. The highest dry weight of shoots (3.97 g/pot) and plant height (58.02 cm) was obsevred in combined treatment of Cu5Zn10 and their minimum values (2.1 g/pot and 36.18 cm, respectively) in treatment Cu25Zn50. Application Cu25Zn50 produced maximum value of concentration of Cu, Zn, Fe and Mn in roots (58.85, 338.06, 3766.91 and 135.97 mg/kg, respectively). Maximum values of concentration of Cu in shoots, infusion and decoction (28.38, 1.49 and 4.55 mg/kg, respectively) were obtained in Cu25Zn10. In general, the results of this study showed that a negative interaction occurred between Cu, Zn, Fe and Mn when higher Cu and Zn concentrations were applied. High translocation capacity of Cu and Zn in infusion and decoction was proved in this study. So, due to the lack of required standards for these elements in medicinal plants, if this plant is grown in soils contaminated with Cu and Zn, it should be used with caution in infusion and decoction.

Overexpression of the iron transporter NtPIC1 in tobacco mediates tolerance to cadmium.

Overexpression of the iron transporter NtPIC1 increases iron concentration in shoots and reduces Cd uptake/accumulation in plants, mediating tolerance to cadmium. Cadmium (Cd) is toxic to plant cells and causes plants to display a typical iron (Fe) deficiency phenotype. NtPIC1 (Permease In Chloroplast1) is an Fe transporter protein in tobacco, required for Fe homeostasis. Based on preliminary results in transformed Saccharomyces cerevisiae BY4741 cells, which showed that NtPIC1 expression increased Cd tolerance, this study evaluated Cd tolerance in tobacco plants overexpressing NtPIC1 (NtPIC1-OE). We show that these plants have longer roots and higher fresh weights than wild-type (WT) plants after Cd exposure. Under Cd stress, WT plants display more chlorosis, stronger growth inhibition, and lower chlorophyll concentrations than NtPIC1-OE plants. Importantly, NtPIC1-OE plants had higher Fe concentrations in shoots and lower Fe concentrations in roots, and Cd concentrations in NtPIC1-OE plants were significantly lower compared to those in WT plants. Moreover, Fe transport-related genes (NtPIC1, NtNRAMP1, and NtFER1) were upregulated in NtPIC1-OE plants, while Fe deficiency-related genes (NtFRO1, NtIRT1, and NtZIP1) that mediate Cd uptake were downregulated. We also found that the activities of several antioxidative enzymes were significantly higher in NtPIC1-OE plants than in WT plants under Cd stress. Overall, our results demonstrate that overexpression of NtPIC1 is an efficient way to increase shoot Fe concentrations and reduce Cd uptake/accumulation in plants.

Evaluation of rice root oxidizing potential using digital image analysis

The aerenchymal transport of oxygen to rice roots has significantly influenced the anaerobic root zone of flooded paddy soils. Therefore, the visualization of redox dynamics may be useful to characterize rice root oxidation potentials and the dynamics of redox-influenced ions in the root zone of paddy soils. In order to investigate the interaction between root oxidation potential and Fe uptake of (a) six different rice cultivars (Oryza sativa L.; Chuchung, Dongjin, Ilmi, Junam, Nampyeong, and Samkwang) were monitored in a flooded paddy soil with the aid of rhizotron experiment throughout the vegetation period, (b) digital images of the root zone were taken at the important growing stages, and (c) rice Fe uptake was characterized simultaneously. The images were processed by image analysis to display the reduction and oxidation areas in the root zones, and the distinct areas which were colorized due to varying soil redox changes were localized and quantified. Oxidized areas were mainly observed in the surrounding active roots and in a distinct layer on the soil surface. The selected rice cultivars have shown significantly different root-oxidized areas at the same rice growing stage. Root-oxidized area was significantly and positively correlated with total Fe content of rice root, but negatively correlated with the inner root Fe content. Rice cultivars having higher root oxidation potential precipitated more Fe on the outer root surface in the form of Fe plaques. In conclusion, digital image analysis is an effective tool for evaluating the oxidizing potential of rice root under anaerobic soil condition.

Brassinosteroids are involved in Fe homeostasis in rice (Oryza sativa L.).

Brassinosteroids (BRs) are steroid hormones that modulate numerous physiological processes in plants. However, few studies have focused on the involvement of BRs in sensing and responding to the stress of mineral nutrient deficiency. In the present study, we evaluated the roles of BRs in the response of rice (Oryza sativa) to iron (Fe) deficiency during Fe uptake, transport, and translocation. Exogenous application of 24-epibrassinolide (EBR) to wild-type (WT) plants exaggerated leaf symptoms of Fe deficiency and suppressed growth. EBR increased and decreased Fe concentrations in roots and shoots, respectively, under both Fe-deficient and Fe-sufficient conditions. Transcripts involved in Fe homeostasis, including OsIRT1, OsYSL15, OsYSL2, OsNAS1, and OsNAS2, were enhanced by EBR under Fe-deficient conditions. EBR depressed expression of OsNAS1, OsNAS2, and OsYSL2 in shoots, and inhibited Fe transport and translocation via the phloem. Rice mutant d2-1, which is defective in BR biosynthesis, was more tolerant to Fe deficiency than the WT, and accumulated greater amounts of Fe in roots than the WT under Fe-sufficient conditions. A greater upregulation of OsIRT1, OsYSL15, OsYSL2, OsNAS1, and OsNAS2 in the d2-1 mutant compared to the WT was found under Fe-sufficient conditions, while expression of these genes in the d2-1 mutant was lower than in the WT under Fe-deficient conditions. The greater tolerance of the d2-1 mutant could be partly mitigated by exogenous application of EBR. These novel findings highlight the important role of BR in mediating the response of strategy II plants to Fe deficiency by regulating Fe uptake and translocation in rice.

Silicon Decreases Fe Deficiency Responses by Improving Photosynthesis and Maintaining Composition of Thylakoid Multiprotein Complex Proteins in Soybean Plants (Glycine max L.)

Silicon is considered an important element in several crops because it improves growth and mitigates biotic and abiotic stress. In this work, the role of silicon in limiting Fe deficiency responses by improving photosynthesis and composition of thylakoid multiprotein complexes (MPCs) has been studied. Two-week-old soybean (Glycine max L.) plants grown hydroponically with a Fe-deficient solution without FeIII-EDTA were fed with 1.0 mM silicon in the form of sodium silicate [Na2SiO3]. Responses to four Si and Fe combined treatments were analyzed after 3 and 5 days. Leaf chlorosis was generated under Fe deficiency, with decreased chlorophyll and carotenoid contents. The negative effects observed were more severe under a prolonged period of Fe deficiency. Biomass and Fe concentration in roots and shoots were largely improved by Si supply under Fe deficiency. The rates of net photosynthesis, transpiration and stomatal conductance were highly improved by the supply of Si under Fe deficiency. MPCs proteins (thylakoid complex proteins) evaluated by the first dimension followed by second-dimensional 2D-BN-SDS-PAGE and MALDI–TOF/TOF–MS observation showed that the Fe deficiency greatly decreased thylakoid MPCs and also resulted in a closure of stomata. However, these impacts of Fe deficiency were largely restored in the presence of silicon. The observed responses to silicon supply in Fe-deficient plants indicate that silicon has a significant role in limiting Fe deficiency responses by improving photosynthesis and composition of thylakoid protein complexes.

Iron efficiency of different corn hybrids grown in nutrient solution culture

Growing Fe-efficient genotype(s) could be considered as a preferred genetic approach to tackle the widespread constraint of Fe-deficiency-/lime-induced chlorosis in crop grown on alkaline soil. This study aimed to investigate morphological and physiological traits linked to expression of Fe deficiency among four corn (Zea mays) including sweet (Z. mays sacchrata cvs. H403 and H404) and grain (Z. mays indentata cvs. H500 and H700) hybrids grown in nutrient solution using two Fe concentrations (5 and 50 µM Fe-ethylenediaminetetraacetic acid (Fe-EDTA)). Significant variation was found among studied hybrids in their tolerance to Fe-deficiency stress. Sweet corn hybrids were more sensitive to Fe deficiency as compared with grain corn hybrids and greater reduction was observed in their shoot dry matter at the 5 µM Fe-EDTA treatment. The greatest decrease in plant height, leaf area, and root and shoot dry matter weight under Fe-deficiency condition was found for H403 hybrid. No significant correlation was found between shoot and root Fe concentration with crop tolerance to Fe deficiency. Furthermore, different response of corn hybrids to Fe deficiency is an important factor, which has to be considered in Fe fertilizer recommendation as well as breeding programs.

Effects of Lead on Iron, Manganese, and Zinc Concentrations in Different Varieties of Maize (Zea mays)

To investigate the effects of different levels of lead (Pb) on the concentration of iron (Fe), manganese (Mn), and zinc (Zn) in Zea mays, an experiment was conducted in a completely randomized design and 4 × 8 factorial arrangement with three replicates on a calcareous soil in a greenhouse. Factors included four levels of Pb (0 as control, 100, 200, and 400 mg Pb kg−1 soil) from PbCl2 source and eight varieties of maize (single cross 260, 301, 302, 500, 604, and 647 and double cross 370). Results showed that the accumulation of Pb was greater in roots than shoots in the maize varieties studied. Increased Pb concentration in soil decreased Mn and Fe in shoot and elevated Fe concentration in roots. The Mn concentration of roots on different levels of Pb was not affected. Zinc concentration of almost all varieties increased in shoots and decreased in roots with the increase of Pb in soil.

Effect of cadmium on growth, photosynthesis, mineral nutrition and metal accumulation of bana grass and vetiver grass

An experiment was conducted to evaluate the differential effects of Cd contamination on the growth, photosynthesis, mineral nutrition and Cd accumulation of bana grass (Pennisetum americanum×Pennisetum purpureum) and vetiver grass (Vetiveria zizanioides). Bana grass accumulated 48–453 and 25–208mgkg−1 in plant roots and shoots, respectively, at 15–100mgkg−1 soil Cd concentration, while vetiver grass accumulated 167–396 and 0.13–9.0mgkg−1. These results indicated that bana grass was a Cd accumulator while vetiver grass was a Cd excluder. The ratio of root to shoot biomass was significantly increased in vetiver grass, while it was unchanged in bana grass by Cd pollution. This suggests that excluders may allocate more energy to roots than shoots under Cd pollution compared to un-contaminated condition, while accumulators may allocate equal proportions of energy to roots and shoots. For bana grass, soil Cd pollution significantly decreased the concentration of Fe and Mn in roots as well as the translocation factors of Zn and K. For vetiver grass, soil Cd pollution significantly decreased the concentration of Fe in roots and had no influence on the translocation factors of Fe, Mn, Cu, Zn, Mg, K and Ca. Soil Cd pollution showed no significant effect on chlorophyll content and photosynthetic rates in either of the grasses. The water content and leaf transpiration rate were significantly increased by Cd pollution in bana grass, while they were unchanged in vetiver grass. The results indicated that the energy allocation and mineral nutrition characteristics may aid in screening suitable plant species for phytoremediation.