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Constantinos Tzerakis, Dimitrios Savvas, Nick Sigrimis, and Georgios Mavrogiannopoulos

nutrient and water uptake by plants. Based on research carried out in The Netherlands, De Kreij et al. (1999) and Sonneveld and Voogt (2009) published recommendations for Mn and Zn levels in NS used in closed hydroponic crops of cucumber to compensate

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Karim Keshavarz, Kourosh Vahdati, Mahmoud Samar, Behzad Azadegan, and Patrick H. Brown

Persian walnut is sensitive to B and Zn deficiency ( Ramos, 1997 ), especially in sandy soils with low organic matter and also in calcareous soils ( Storey, 2007 ). These conditions are predominant in many walnut orchards around the world

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Chen Chen, Meng-Ke Zhang, Kang-Di Hu, Ke-Ke Sun, Yan-Hong Li, Lan-Ying Hu, Xiao-Yan Chen, Ying Yang, Feng Yang, Jun Tang, He-Ping Liu, and Hua Zhang

; Gupta et al., 1993 ). Cu/Zn-SOD is a kind of SOD, which is commonly present in the cytoplasm of eukaryotic cells. It is composed of two subunits which contain one Cu 2+ and one Zn 2+ , respectively. Some progress has been made in the research of Cu/Zn

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David R. Byrnes, Fekadu F. Dinssa, Stephen C. Weller, and James E. Simon

( Weller et al., 2015 ). Previous studies have shown success in selecting increased Fe and Zn content in rice ( Oryza sativa ) without consequence to yield performance; these entries of rice were later observed to be effective as a food source for the

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Joseph P. Albano

Soluble fertilizers are typically formulated with metal-aminopolycarboxylic acids [APCA (i.e., chelating agents)] of Cu, Fe, Mn, and Zn. These metal–APCA complexes, however, are also applied as single-metal chelate solutions to foliage, soil

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Dariusz Swietlik

The effects of soil and foliar Zn applications on growth, yield, and fruit quality of `Rio Red' grapefruit were studied in the field for 4 years. Two annual foliar sprays applied in winter (W), spring (S), or W+S were compared to a single application of 10 or 30 g of Zn/tree applied to the soil around the tree as ZnDTPA or ZnEDTA chelate. In the first 2 years, when control trees displayed severe Zn deficiency symptoms affecting 60% to 70% of the tree foliage, the W and W+S sprays resulted in significant yield increases. Similar yield increases were obtained after a single soil application of 30 g Zn as ZnEDTA. The effects of other soil treatments were statistically insignificant. Foliar Zn deficiency symptoms were much more severe in winter than summer months irrespective of treatment. As the trees aged, however, the severity of symptoms decreased in all treatments. Corrective foliar or soil Zn applications were found to increase grapefruit yield when 15% or more of the canopy foliage showed Zn deficiency symptoms in January, ≈2 months before anthesis.

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Kathryn C. Taylor and Danielle R. Elli

A 22-kDa Zn-binding protein (ZBP) was isolated from the phloem tissue and evacuated xylem sap of `Valencia' sweet orange [Citrus sinensis (L.) Osbeck] on rough lemon [C. jambhiri (L.)], as well as Valencia on Rangpur lime [Citrus limonia Osbeck]. Phloem and xylem Zn was associated with the 22 kDa ZBP. The Mr value of this ZBP was estimated to be 19,500 by size exclusion chromatography and 22,800 by SDS-PAGE. This protein was isolated with an isoelectric point of 7.5. Ion exchange chromatography demonstrated that 22-kDa ZBP was highly anionic, requiring 0.43 M NaCl for elution from QAE Sepharose. The 22-kDa ZBP appears unique to citrus, having no cross reaction with protein from several tissues from a range of plant species. Accumulation decreased under Zn-deficient conditions, was enhanced by osmotic stress, and the protein completely disappeared with wounding. Amino acid composition demonstrated that the protein was rich in aspartate, and glutamate; and contained 6 cysteine, and 4 histidine residues. These amino acids may be involved in metal binding. N-terminal amino acid sequencing demonstrated that the 22-kDa ZBP had identity with sporamin A&B precursors, Kunitz-type trypsin inhibitors, and miraculin. It is suggested that the genes that encode these proteins are derived from a common ancestral gene.

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M.R. Johanson and C.F. Williams

We conducted a preliminary field study that examines the accumulation of Pb, Cd, Zn, Mn, and Cu in plants and soil along a roadway in Zion National Park. The study is designed to determine the effects of motor traffic on the accumulation of these heavy metals in various plant species and soil during 1 year and to determine if these accumulations decrease as you move away from the roadway. Preliminary results indicate that the amount of Pb, Cd, Zn, Mn, and Cu concentrations found are a function of the number of vehicles passing during a year and the distance from the roadway. Higher concentrations of these heavy metals are found in areas close to the road and in areas where traffic is moving slowly or even stopped. The heavy metal concentrations decreased as the distance from the roadway increased, and the speed of passing vehicles increased.

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Juan Pablo Arce, J. Benton Storey, and Calvin G. Lyons

Fall soil treatments of ZnEDTA and ZnSO4 at three increasing rates (32.2, 64.4 and 128.8 g. Zn/tree) and 1, 2 and 3 spring foliar sprays of NZN (0.35 g. Zn/tree/application) were tested to correct Zn deficiency in three year old `Earligrande' peach trees. All Zn carriers increased the Zn leaf content. Peach trees treated with three applications of NZN were equal to the medium or high rates of soil applied ZnEDTA or ZnSO4 respectively, in appearance, chlorophyll content and foliar Zn content. Three applications of NZN at 0.35 g. of Zn/tree (473 ml/378 gal H2O) gave excellent tree response and was cost effective.

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Ksenija Gasic and Schuyler S. Korban

Phytochelatins (PCs) are heavy metal binding peptides that play important roles in sequestration and detoxification of heavy metals in plants. To develop transgenic plants with increased tolerance and/or accumulation of heavy metals from soil, an Arabidopsis thaliana FLAG–tagged AtPCS1 cDNA encoding phytochelatin synthase (PCS) under the control of a 35S promoter was expressed in Indian mustard (Brassica juncea). Four transgenic Indian mustard lines, designated pc lines, with different levels of AtPCS1 mRNA accumulation and correspondent AtPCS1 protein levels were selected and analyzed for tolerance to cadmium (Cd) and zinc (Zn). Heavy metal tolerance was assessed by measuring root length of 10-day-old seedlings grown on agar medium supplemented with different concentrations of Cd (0, 100, 150, and 200 μm CdCl2) and Zn (200, 400, 600, and 800 μm ZnCl2). All transgenic lines showed significantly longer roots when grown on a medium supplemented with 100 μm CdCl2. No significant differences were observed between transgenic lines and wild type when plants were grown on higher levels of Cd. This indicated that only partial tolerance to Cd was observed in these transgenic lines. Similarly, partial tolerance for Zn was also observed in these transgenic lines, but up to levels of 400 μm ZnCl2. Expression levels of AtPCS1 protein were not related to tolerance responses for either Cd or Zn stresses in transgenic lines.